United States Forest Service

• This bibliography contains citations referenced on the United States Forest Service National Lichens & Air Quality Database and Clearinghouse website
• Bracketed phrases - [ ] - are summaries from Culberson, W.L., Egan, R.S. & Esslinger, T.L. 2009. Recent Literature on Lichens. presented on the Web by E. Timdal. First posted April 14, 1997, latest update March 2, 2009, a regularly updated database containing a great many more articles the topic of lichens and air pollution.
• Text in quotation marks - "" - are taken directly from the abstract, or another part of the article. Otherwise full abstracts are often presented.

Adamson, E, and Seppelt, RD. 1990. A comparison of airborne alkaline pollution damage in selected lichens and mosses at Casey Station, Wilkes Land, Antarctica. Antarctic Ecosystems Ecological Change and Conservation. K.R. Kerry and G. Hempel (eds.). 145: Springer-Verlag, Berlin, Heidelberg. 347 pp.

[Study of the effects of airborne alkaline cement dust from a concrete batching plant on selected lichens and mosses (Usnea sphacelata, Umbilicaria decussata, Ceratodon purpureus). "Lichens growing downwind of the batching site were more susceptible to damage from airborne alkaline pollution than the mosses and were moderately to severely bleached. This chapter describes the relation between mean total chlorophyll concentration, chlorophyll a/b ratio, distance from the batching site and soil pH."]

Addison, P.A. and K.J. Puckett. 1980. Deposition of atmospheric pollutants as measured by lichen element content in the Athabasca oil sands area. Can. J. Bot. 58:2323-2334.

Al, K, S, Ti, V contents of lichens -- NW sp: Hypogymnia physodes-- were determined for up to 69 sites in the Athabasca oil sands area. Elemental conc. were related to industrial sources and a localized windblown dust component and closely followed the distribution patterns measured by physical and chemical methods. Changes in the thallus to be related to elemental conc. This ref. does not give elemental values for each species, instead it compares Pearson correlation coefficients for H. physodes and Evernia mesomorpha and enrichment factors for the spp.

Alexander, V.; Billington, M.M. 1986. Nitrogen fixation in the Alaskan taiga. In: Van Cleve, K; Chapin, FS, III; Flanagan, PW; Viereck, LA; Dyrness, CT (eds.): Forest Ecosystems in the Alaskan Taiga. Springer-Verlag, New York, pp. 112-120.

Aptroot, A.; van Herk, C.M. 2007. Further evidence of the effects of global warming on lichens, particularly those with Trentepohlia phycobionts. Environmental Pollution 146: 299-310.

Increasing evidence suggests that lichens are responding to climate change in Western Europe. More epiphytic species appear to be increasing, rather than declining, as a result of global warming. Many terricolous species, in contrast, are declining. Changes to epiphytic floras are markedly more rapid in formerly heavily polluted, generally built-up or open rural areas, as compared to forested regions. Both the distribution (southern) and ecology (warmth-loving) of the newly established or increasing species seem to be determined by global warming. Epiphytic temperate to boreo-montane species appear to be relatively unaffected. Vacant niches caused by other environmental changes are showing the most pronounced effects of global warming. Species most rapidly increasing in forests, although taxonomically unrelated, all contain Trentepohlia as phycobiont in addition to having a southern distribution. This suggests that in this habitat, Trentepohlia algae, rather than the different lichen symbioses, are affected by global warming.

Baddeley, M.S., B.W. Ferry and E.J. Finnegan. 1973. Sulphur dioxide and respiration in lichens. pp. 229-313 In: Ferry, B.W., M.S. Baddeley and D.L.Hawsworth (eds.), Air Pollution and Lichens. Althone Press, London.

Bargali, R., M. Castello, D. Gaspero, G. Lazzarin and M. Tretiach. 1992. Lichens as indicators and biomonitors of environmental pollution: different scale examples from Italy. In: Karnfelt, I. (ed.) The Second International Lichenological Symposium, IAL2, Hemmeslov, Bastad, Sweden. 30 Aug.-4 Sept. 1992. Abstracts. Dept. of Systematic Botany, University of Lund, Lund, Sweden.

Barkman, J.J. 1969. The influence of air pollution on bryophytes and lichens. In: Air pollution. Proc. of the First European Congress on the Influence of Air Pollution on Plants and Animals. Wageningen. 1968. pp. 197-209.

Beckett, P.J., L.J.R. Boileau, D. Padovan, and D.H.S. Richardson. 1982. Lichens and mosses as monitors of industrial activity associated with uranium mining in northern Ontario, Canada--Part 2: Distance- dependent uranium and lead accumulation patterns. Environmental Pollution, Series B. 4: 91-107.

["The variation in concentration (C(d)) of uranium and lead in lichens and mosses with distance (d) from emission sources associated with the mining and milling of uranium conformed to the equation: C(d) = md -n[exponent] +b." Estimates of effective radius of a macro-pollution zone can now be determined.] Study of uranium mining and milling operations at Elliot Lake, Ontario, using Cladonia rangifera and Cladonia mitis, plus the mosses Pleurozium schreberi and Sphagnum spp. Samples were taken along two transects and micro transects near active tailing ponds, mills, exhaust vents.

Beekley, P.K.and G.R. Hoffman. 1981. Effects of sulphur dioxide fumigation on photosynthesis, respiration, and chlorophyll content of selected lichens. The Bryologist 84: 379-390.

[Study conducted on Parmelia bolliana, Physcia stellaris, Xanthoria fallax, and Physconia grisea from South Dakota. Fumigation at 2.5 ppm caused decreased photosynthesis; the more xerophytic species were more sensitive. "Chlorophyll content in these species was not measurably altered by fumigation." Respiration in Physcia stellaris and Parmelia bolliana also decreased significantly following fumigation at 2.5 ppm.]

Belandria, G., J. Asta, and J.P. Garrec. 1986. Diminuations of fluorine contents in lichens due to a regression of pollution in an alpine valley (Maurienne, Savoie, France) from 1975 to 1985. Rev. Ecol. Alp., Grenoble, 1:45-58.

"F analyses were made for different spp. of lichens (NW spp: Cladonia pyxidata , Peltigera canina, Umbilicaria cylindrica, Hypogymnia physodes, Bryoria fuscescens) collected over the course of 11 years. A general decrease in F contents in lichens was observed for instance from 106-12 ppm in P. canina and from 124-44 ppm in U. cylindrica." This decrease of F reveals the variations of the level of F poll. in the atmosphere during the study.

Belandria, G., J. Asta, and F. Nurit. 1989. Effects of sulphur dioxide and fluoride on ascospore germination of several lichens. Lichenologist 21: 79-86.

[Studies using ascospores from Lecanora conizaeoides, Xanthoria parietina, Physconia distorta and Peltigera canina. "P. canina spores had the highest sensitivity to SO2 (no germination at 500 µM H2SO3). Lecanora conizaeoides spores were almost insensitive to each of the two studied pollutants (30% spore germination at 1000 µM H2SO3, or NaF). However, simultaneous exposure to 1000 µM H2SO3 and 100 µM NaF resulted in no germination, indicating a synergistic effect of these products."]

Belnap J. 1991. Effects of wet and dry pollutants on the physiology and elemental accumulation of cryptogamic crusts and selected lichens of the Colorado Plateau. National Park Service, Air Quality Division Final Report: Denver, CO, 45 p.

Belnap, J. 1990. Effects of air pollutants on cold-desert cyanobacterial-lichen crusts and rock lichens: chlorophyll degradation, electrolyte leakage and nitrogenase. In: Measurement of Toxic and Related Air Pollutants. Proceedings of the 1990 Environmental Protection Agency/Air & Waste Management Association International Symposium, pp. 661-667.

Exposure of cold-desert cyanobacterial-lichen crusts on three different substrates (sandstone, limestone and gypsum) to different pollution sources showed that while urban pollutants in the Los Angeles basin, especially particulates, significantly degraded chlorophyll on all three substrates, simulated acid rain (pH 3.5, 4.5, 5.5 and 6.5; 1:1 sulfuric and nitric acid) had an opposite, fertilizing effect on sandstone and limestone crusts. Studies around a coal-fired power plant, comparing sites 9 and 12 km away from the plant with a control site 42 km away, showed the same fertilizing effect on surrounding sandstone crusts. However, less pH-buffered rock lichens had significantly increased electrolyte leakage and chlorophyll degradation at the nearer sites; nitrogenase activity in a crustal soil lichen was depressed as well. When exposed to power plant effluents or simulated acid rain, the degree of contact with the pH-buffering substrate was important: cyanobacteria, embedded in soils that buffered acidity, may use nitrates and sulfates as fertilizers. Rock and soil lichens, with less contact and less buffering, showed opposite effects. Chlorophyll degradation in crusts by urban pollutants, especially particulates, suggests that pollutants other than acid-producing or gaseous ones injure crusts as well. Combined, these data suggest that the deleterious effects seen in this study from power plant emissions and simulated acid rain are caused by different agents than those injuries due to urban pollutants.

Belnap, J. 1991. Sensitivity of desert cryptogams to air pollutants: soil crusts and rock lichens. In: Mangis, D/Baron, J/Stolte, K (eds.): Acid Rain and Air Pollution in Desert Park Areas. Technical Report NPS/NRAQD/NRTR-91/02, U.S. Department of the Interior, National Park Service, pp. 112-119.

Parks throughout the West are being faced with increasing air pollution threats from current or proposed industries near their boundaries. For this reason, it is important to understand the effects these industries may have on desert ecosystems. Rock lichens can be excellent biomonitors, acting as early warning systems of impending damage to other components of the desert ecosystem. Cryptogamic crusts, consisting mostly of cyanobacteria and lichens, may not only be excellent bioindicators, but also are an essential part of the desert ecosystem. Their presence is critical for soil stability as well as for the contribution of nitrogen to the ecosystem in a form available to higher plants. Air pollutants, such as emissions from coal-fired power plants, may threaten the healthy functioning of these non-vascular plants. The purpose of this study is to determine if, in fact, air pollutants do have an impact on the physiological functioning of Cryptogamic crusts or rock lichens in desert ecosystems and, if so, to what extent. Some results have already been obtained. Both rock lichens and Cryptogamic crusts exhibit physiological damage in the vicinity of the Navajo Generating Station in Page, Arizona. Increased electrolyte leakage and chlorophyll degradation, along with reduced nitrogen fixation, have been found. Preliminary studies comparing sensitivity between substrates indicate that crusts on limestone and sandstone substrates may be more sensitive than those on gypsum.

Belnap, J. 1992. Characteristics of cyanobacterial-lichen soil crusts in long-term saguaro monitoring plots. In: Stone, CP; Bellantoni, ES (eds.): Proceedings of the Symposium on Research in Saguaro National Monument. , pp. 259-262.

Belnap, J., et al. 1993. Indentification of Sensitive Species. In: Huckaby, LS, et al. 1993. Lichens as biomonitors of air quality. Proc. of a workshop sponsored by the NPS and USDA-FS. USDA/USFS Rocky Mountain Forest and Range Exp. Sta. GTR RM-224.

Procedures for determining the responses and sensitivities of lichen spp. are discussed. Primary and secondary pollutants are defined. Fumigation and gradient types of studies are discussed, advantages and disadvantages of each method are also considered.

Belnap, J. 1995. Surface disturbances: their role in accelerating desertification. Environmental Monitoring and Assessment 37: 39-57.

Belnap, J. 2002. Impacts of off-road vehicles on nitrogen cycles in biological soil crusts: resistance in different U.S. deserts. Journal of Arid Environments 52: 155-165.

Belnap, J.; Phillips , S.L.; Flint, S.; Money, J.; Caldwell, M. 2008. Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions. Global Change Biology (2008) 14, 670-686.

Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring-fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV-protective pigments, nitrogenase activity, and extra-cellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, b-carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV-protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute to the stability and fertility of soils in dryland regions.

Berryman, S.; Geiser, L.; Brenner, G. 2004. Depositional gradients of atmospheric pollutants in the Athabasca Oil Sands region, Alberta, Canada: an analysis of lichen tissue and lichen communities. Lichen Indicator Pilot Program 2002-2003. Final Report Submitted to the Terrestrial Environmental Effects Monitoring (TEEM) Science Sub-committee of the Wood Buffalo Environmental Association (WBEA) February 25, 2004.

The 2002-2003 WBEA/TEEM pilot program documented the geographic deposition of air emissions from the oil sand facilities in the Athabasca Oil Sands (AOS) region using epiphytic lichens as bioindicators of air pollution. Oil sands operations are the main source of SO2, NOx and trace metals in the region. Pollution impacts were evaluated using elemental analysis of lichen tissue and epiphytic macrolichen species presence and relative abundance. Lichens were sampled in 44 circular plots, 0.4 hectares in size, along four transects radiating in each cardinal direction from a central point equidistant between the Syncrude and Suncor oil sands operations. Pinus banksiana forests and Picea mariana dominated stands were sampled at d at 5 km, 10 km, 15 km, 20 km, 25 km, 30 km, 50 km, 60 km, 80 km, 100 km, and 120 km along each transect. The leafy arboreal lichens Evernia mesomorpha and Hypogymnia physodes, and a ground-dwelling lichen Cladina mitis, were analyzed for 29 elements. Concentrations of N, S, Al, Cr, Fe, Ni, and V decreased with distance from the mines and were generally elevated in lichen tissues within 30 km of the mines. Patterns of lichen community composition were weakly correlated with distance from the oil sands facilities. Shrubby lichens that are sensitive to air pollution, such as Usnea and Bryoria, were less abundant at sites and showed signs of stress such as dwarfing, hyper-growth of asexual structures, discoloration of the lichen, and increased parasitism by fungi at sites closer to the mining operations.

Berryman, S.; Straker, J. 2008. Nitrogen Loading and Terrestrial Vegetation - Assessment of Existing Regional Monitoring and Recommendations Report prepared for the Cumulative Environmental Management Association (CEMA) NOx-SO2 Management Working Group (NSMWG) Eutrophication Task Group. CE Jones and Associates,Sidney, BC.

Biazrov, L. 1993. Lichens as indicators of radioactive contamination. Journal of Radioecology 1: 15-20.

Biazrov, L.G. 1994. Radionuclide content in lichen thallus in the forest adjacent to the Chernobyl atomic power plant. Science of the Total Environment 157: 25-28.

Bjerke, J.W.; Zielke, M.; Solheim, B. 2003. Long-term impacts of simulated climatic change on secondary metabolism, thallus structure and nitrogen fixation activity in two cyanolichens from the arctic. New Phytologist 159: 361-367.

Although the most pronounced effects of stratospheric ozone depletion and climate warming probably will occur in Polar Regions, arctic lichens have not been much studied in relation to climate change. Samples of two arctic cyanolichens of the genus Peltigera , exposed in situ to ambient and enhanced UV-B radiation and ambient and increased temperatures, were collected in 2001, 5 yr after the establishment of the experimental set-up. Thallus dimensions and size, coverage of soralia, nitrogen fixation activity and levels of UVC- absorbing substances were measured. Warming had pronounced positive effects on the tridepsides: methyl gyrophorate and gyrophoric acid, and on unidentified trace substances. However, the combination of enhanced UV-B and increased temperatures did not lead to higher than control levels. Warming reduced coverage of soralia. There were no significant treatment effects on thallus size, dimensions and nitrogen fixation activity. UV-B radiation did not to have any adverse effects. The accumulation of tridepsides with warming may be related to increased activity of pathogenic microorganisms or insect herbivores.

Blum, O.B., and Y.G. Tjutjunnik. 1992. Quantitative biogeochemical monitoring of air pollution in urban areas by heavy metals: a new approach and new methods. The Second International Lichenological Symposium, IAL2, Hemmeslov, Bastad, Sweden.

"In order to create a quantitative method of heavy metal atm. poll., we now propose a new approach: the estimation of a regression between an absolute metal content of city boundary layer atm. air and the corresponding content in lichen or tree bark. The basis for developing this method is the known correlation between metal conc. in air and lichens. Results obtained from our investigations in 28 cities in the SW part of the European region (Ukraine, Russia, Belorussia) show that there is a significant correlation between heavy metal content (Fe, Mn, Cu, and Pb) of city air(3-5 yrs of avgd. data) and its content in epiphytic lichens (Xanthoria parietina, Parmelia sulcata, Physcia stellaris, Hypogymnia physodes); however, no correlations were found for Zn and Ni. Similar investigations with Populus nigra resulted in highly significant correlations between heavy metals in P. nigra bark and city air. The bark was found to be a better bioindicator than the lichens and requires less time and complications for sampling and preparation for elemental analysis."

Bobbink, R., Ashmore, M.R., Braun, S., Fluckiger, W., van der Wyngaert, I.J.J. 2003. Empirical nitrogen critical loads for natural and semi-natural ecosystems: 2002 update. In: B. Achermann and R. Bobbink (eds.), Empirical Critical Loads for Nitrogen, Environmental Documentation 164, Background document for Expert Workshop on Empirical Critical Loads for Nitrogen on Semi-natural Ecosystems. Berne, Switzerland, 11-13 November 2002. Swiss Agency for the Environment, Forests and Landscape. pp. 43-170.

Böhm, M., B. McCune, and T. Vandetta. 1995. Ozone regimes in or near forests of the western United States: Part 2 Factors influencing regional patterns. J. Air & Waste Manage. Assoc. 45: 477-489.

Boonpragob, K, T.H. Nash III, and C.A. Fox. 1989. Seasonal deposition patterns of acidic ions and ammonium to the lichen Ramalina menziesii Tayl. in Southern California. Environmental & Experimental Botany 29: 187-197.

[Study conducted at two-week intervals over 50 weeks at both polluted and non-polluted sites. "During interstorm periods accumulation of leachable ions occurred with the highest levels found at the end of extended summer drought periods. Leachable NO3- was always the ion in highest concentration and the ions NH4+, H+ and Cl- were found in intermediate concentrations. During summers all ions except Cl- were consistently higher at the polluted site than at the control site."] Study demonstrates: 1. Lichens are able to accumulate ionic deposition of NO3-, NH4+, H+, SO42-, PO43-, F-, and Cl-. 2. The ions that accumulated by the thalli of Ramalina menziesii were higher in summer than winter. The magnitude of accumulation varies markedly with seasonal precipitation patterns and air quality of locations.

Boonpragob, K., and T.H. Nash III. 1990. Seasonal variation of elemental status in the lichen Ramalina menziesii Tayl. from two sites in southern California: evidence for dry deposition accumulation. Environmental & Experimental Botany 30: 415-428.

[Transplant study in California in relation to air pollution levels.] "Total concentration of most elements did not exhibit distinct seasonal patterns but the higher concentrations exceeded background levels by factors of 1.3-3.7, depending on the element. In contrast, the elements in the leachates at the control and the polluted site exhibited distinct seasonal patterns with higher concentrations generally present in summer than in winter. These elemental patterns reflected not only atmospheric deposition patterns, but also intracellular release of elements as injury occurred and to a lesser extent accumulation of marine aerosols and soil particulates."

Boonpragob, K., and T.H. Nash III. 1991. Physiological responses of the lichen Ramalina menziesii Tayl. to the Los Angeles urban environment. Environmental & Experimental Botany 31: 229-238.

[Transplant experiments show a decline in chlorophyll content and net photosynthesis associated with the accumulation of 23 ions, particularly nitrate and fluoride.] In Southern CA the lichen Ramalina menziesii was transplanted from a control area to a polluted area for three periods during the year. Net photosynthetic rates, recorded under standard conditions in the laboratory, chlorophyll contents and % phaeophytins were measured at 2-week intervals for samples from both sites. During summer periods at the polluted site chlorophyll and net photosynthesis declined substantially and % phaeophytins increased, but during the winter period no changes in these parameters was observe during the transplant periods. During the winter there was no difference in net photosynthesis for samples collected from the two sites. During the summers the decline in the lichen at the polluted site was associated with the accum. of 23 ions. Although no demonstrably toxic, nitrate concentrations alone explained over 75% of the variations of each physiological parameter. Fl was the second most important variable and was probably accumulated to toxic levels.

Boritz, S., and H. Ranft. 1972. Zur SO2 und HF Empfindlichkeit von flechten und moosen. Biologisches Zentralblatt 91(5): 613-623.

Brace, S. 1996. The Spatial Distribution of Ozone in the Mt. Rainier National Park Region. Master of Science Thesis. University of Washington, Seattle, WA.

Britton, A.J.; Fisher, J.M. 2007. Interactive effects of nitrogen deposition, fire and grazing on diversity and composition of low-alpine prostrate Calluna vulgaris heathland. Journal of Applied Ecology 44: 125-135.

Low-alpine heathlands world-wide have high biodiversity value but are increasingly impacted by the effects of nitrogen deposition as well as fire and grazing. We conducted a 5-year fertilization experiment to examine the interactive effects of these three factors on vegetation diversity and species composition. Factorial combinations of nitrogen addition (0, 10, 20 and 50 kg N ha- 1 yr -1), burning (burned once or not burned) and grazing (annual clipping, 0% or 12% of current year shoots removed) were applied to internationally important prostrate Calluna-Cladonia heathland in the Cairngorm Mountains, Scotland. Species diversity (higher plants, mosses and lichens) and percentage cover were recorded annually. Fire had a large effect on vegetation diversity and composition, but both were quick to recover. Species richness recovered within 4 years and vegetation composition was predicted to recover within 7 years. Vegetation composition appeared resilient to the effects of disturbance and there was little invasion by graminoids. Nitrogen deposition interacted with fire. Burned plots showed no significant effect of nitrogen treatment on species diversity, while the diversity of unburned plots was significantly reduced only 1 year after treatment with 50 kg N ha- 1 yr -1. After 5 years, significant diversity reductions were seen in the 10 kg N ha- 1 yr -1treatment. Impacts of nitrogen on species richness were primarily through reductions in lichen diversity. Severe winter browning of Calluna vulgaris in plots receiving 50 kg N ha- 1 yr -1 followed early snowfall in 2002-03. This interaction affected only Calluna vulgaris and may have the potential to trigger species composition changes by reducing the dominance of this species. Although resilient to small-scale fires, species richness of low-alpine heaths is reduced by exposure to low levels of nitrogen deposition (background + 10 kg N ha- 1 yr -1). The lichen component of the vegetation is most sensitive to additional nitrogen, although higher plants can be affected via interactions with climate. These data support the current critical load of nitrogen for this community of 5-15 kg N ha- 1 yr -1 and suggest that lichen diversity could be a useful indicator of nitrogen deposition impacts in alpine habitats. Effective conservation of biodiversity in low-alpine heathland will require action at national and international levels to reduce nitrogen deposition in the many areas where the critical load is currently exceeded.

Brodo, I.M. 1961. Transplant experiments with corticolous lichens using a new technique. Ecology 42: 838-841.

Brodo, I.P., Duran Sharnoff, S.; Sharnoff, S 2001. Lichens of North America Yale University Press, New Haven & London, 795 pp

Part I includes 14 chapters of introductory information about many aspects of lichen biology and systematics. Part Two provides keys, descriptions and color photographs for more than 800 conspicuous foliose, fruticose and crustose lichen species, as well as a summary classification scheme, a glossary, and a bibliography for further reading.

Brown, D.H., and R.P. Beckett. 1983. Differential sensitivity of lichens to heavy metals. Ann. of Bot. 52: 51-57.

"Zn, Cd, and Cu inhibited photosynthesis in lichens containing cyanobacterial phycobionts at substantially lower concentrations than those causing decreased photosynthesis in lichens containing chlorophycean phycobionts. This distinction was not related to differences in total thallus conc. of Zn, Mg, Ca, or K or to the quantitiy of Zn taken up to intracellular sites. When incubated with concentrated Zn solutions the chlorophycean lichen Cladonia rangiformis accumulated more Zn on extracellular exchangeable sites than did the cyanobacterial lichen Peltigera horizontalis."

Brown, D.H., and N. Smirnoff. 1978. Observations on the effect of ozone on Cladonia rangiformis. Lichenologist 10: 91-94.

Cladina rangiferina was taken from the field (Somerset, Eng.) and samples were hydrated for 24 hrs before O3 exposure. The ozonated air was humidified. O 2 between 2 ppm for 2-5 hr, did not alter photosynthetic CO-2 fixation and release of radioactivity in C. rangiferina. One poss. reason the authors gave for C. rangiferina 's tolerance to ozone was that while ozone goes thru the stomata of vasc. plants, the fungal layer of the lichen may block ozone to the algal layer. Also after fumigation the authors noted a "distinctly decaying fungal smell, possibly indicative of hyphal damage." The authors conclude that C. rangiferina "in the field is unlikely to be directly damaged by exposure to the highest conc. of ozone reported to occur."

Brown, DH; Tomlinson, H 1993. Effects of nitrogen salts on lichen physiology. In: Feige, GB; Lumbsch, HT (eds.): Phytochemistry and Chemotaxonomy of Lichenized Ascomycetes - A Festschrift in Honour of Siegfried Huneck. Bibliotheca Lichenologica, J. Cramer, Berlin, Stuttgart, pp. 27-34.

Bruteig, I.E. 1993. The epiphytic lichen Hypogymnia physodes as a biomonitor of atmospheric nitrogen and sulphur deposition in Norway. Environmental Monitoring and Assessment 26(1): 27-47.

Hypogymnia physodes was sampled from 179 sites of Scots pine forests regularly distributed throughout Norway. The purpose was to map the N and S contents of lichen thalli on a large-scale geographical basis, and to relate these values to differences in atmospheric deposition and climate. The lichen N and S concentrations showed large differences; the highest concentration values being 4-5 times greater than the lowest. The highest N and S values occurred along the coast of southern Norway and on some sites in the inland of southern Norway. There was a close correlation between the two elements. The lichen N/S ratio decreased with increasing latitude. The N and S contents of Hypogymnia physodes were both significantly correlated to estimated atmospheric deposition of these two elements in Norway. The degree of explanation improved when climatic variables such as temperature sum, altitude, annual precipitation and temperature were included. Factors promoting growth, such as high bark pH, mild winters, hot summers, high precipitation, high ammonium deposition and high evapotranspiration, were all associated with lower lichen N and/or S concentrations. Unfavorable growth conditions, such as at high altitude, was related to higher concentrations than expected from deposition models. This indicates that differences in element concentration between nearby localities might be related to local differences in climate and lichen growth conditions. This should be taken into consideration whenever using lichens for biomonitoring.

Cameron RP, Neily,T, Richardson, DHS. 2007. Macrolichen Indicators of Air Quality for Nova Scotia. Northeastern Naturalist 14: 1-14.

Presence and frequency of epiphytic macrolichens were measured along an air-quality gradient in Halifax City, NS, Canada. Species frequency plots over distance and multidimensional scaling (MDS) suggested lichen-community changes consistent with expected air-quality changes. A provisional list of air-quality indicators was selected based on: 1) demonstrated variation along the air-quality gradient, 2) frequency across the province, 3) literature values of air-quality sensitivity, and 4) ease of field identification. Indicators were placed in one of three classes: 1) pollution tolerant, 2) intermediate pollution tolerance, and 3) pollution sensitive. MDS analysis suggests an elevation gradient in Nova Scotia and this should be investigated with a further study.

Carlberg, G.E., E.B. Ofstad, H. Drangsholt, and E. Steinnes. 1983. Atmospheric deposition of organic micropollutants in Norway studied by means of moss and lichen analysis. Chemosphere 12(3): 341-356.

Carroll, J.A.; Caporn, S.J.M.; Cawley, L.; Read, D.J.; Lee, J.A. 1999. The effect of increased deposition of atmospheric nitrogen on Calluna vulgaris in upland Britain. New Phytologist 141(3): 423-431.

Case, J.W. 1980. The influence of three sour gas processing plants on the ecological distribution of epiphytic lichens in the vicinity of Fox Creek and Whitecourt, Alberta Canada. Water, Air and Soil Poll. 14: 45-68.

"The ecological distribution of epiphytic lichens have been reduced by SO2 emissions form three sour gas processing plants located near Fox Creek and Whitecourt, Alberta. Pollutants tend to concentrate in drainage channels leading to the Athabasca River. These channels parallel the prevailing wind. No sites were encountered which totally lacked lichens, but at sites within 1-2 km downwind of gas plants and associated S storage blocks, the epiphytic lichen flora was reduced in variety, cover and vitality. IAP was used and improvements for methodologies are suggested."

Chapin, F.S. III; Bloom, A; Field, C.B.; Waring, R.H. 1987. Plant responses to multiple environmental factors. Bioscience 37: 49-57.

Chapin, F.S. III; Shaver G.R.; Giblin, A.E.; Nadelhoffer, K.J.; Laundre, J.A. 1995. Responses of arctic tundra to experimental and observed changes in climate. Ecology 76: 694-711.

We manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes in these parameters might affect community and ecosystem processes. Some of these manipulations altered nutrient availability, growth-form composition, net primary production, and species richness in less than a decade, indicating that arctic vegetation at this site is sensitive to climatic change. In general, short-term (3-yr) responses were poor predictors of longer term (9-yr) changes in community composition. The longer term responses showed closer correspondence to patterns of vegetation distribution along environmental gradients. Nitrogen and phosphorus availability tended to increase in response to elevated temperature, reflecting increased mineralization, and in response to light attenuation, reflecting reduced nutrient uptake by vegetation. Nutrient addition increased biomass and production of deciduous shrubs but reduced growth of evergreen shrubs and nonvascular plants. Light attenuation reduced biomass of all growth forms. Elevated temperature enhanced shrub production but reduced production of nonvascular plants. These contrasting responses to temperature increase and to nutrient addition by different growth forms "canceled out" at the ecosystem level, buffering changes in ecosystem characteristics such as biomass, production, and nutrient uptake. The major effect of elevated temperature was to speed plant response to changes in soil resources and, in the long term (9 yr), to increase nutrient availability through changes in N mineralization. Species within a growth form were similar to one another in their responses to changes in resources (light or nutrients) but showed no consistent response to elevated temperature. Species richness was reduced 30-50% by temperature and nutrient treatments, due to loss of less abundant species. Declines in diversity occurred disproportionately in forbs, which are important for animal nutrition, and in mosses, which maintain soil thermal regime. There was no increased abundance of initially rare species in response to any treatment. During our 9-yr study (the warmest decade on record in the region), biomass of one dominant tundra species unexpectedly changed in control plots in the direction predicted by our experiments and by Holocene pollen records. This suggests that regional climatic warming may already be altering the species composition of Alaskan arctic tundra.

Cornelissen, J.H.C., Callaghan, T.V., Alatalo, J.M., Michelsen, A., Graglia, E., Hartley, A.E., Hik, D.S., Hobbie, S.E., Press, M.C., Robinson, C.H., Henry, G.H.R., Shaver, G.R., Phoenix, G.K., Gwynn Jones, D., Jonasson, S., Chapin, F.S. III, Molau, U., Neill, C., Lee, J.A., Melillo, J.M., Sveinbjonsson, B. and Aerts, R. 2001. Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass? Journal of Ecology 89, 984-994.

Macrolichens are important for the functioning and biodiversity of cold northern ecosystems and their reindeer-based cultures and economies. We hypothesized that, in climatically milder parts of the Arctic, where ecosystems have relatively dense plant canopies, climate warming and/or increased nutrient availability leads to decline in macrolichen abundance as a function of increased abundance of vascular plants. In more open high-arctic or arctic-alpine plant communities such a relationship should be absent. To test this, we synthesized cross-continental arctic vegetation data from ecosystem manipulation experiments simulating mostly warming and increased nutrient availability, and compared these with similar data from natural environmental gradients. Regressions between abundance or biomass of macrolichens and vascular plants were consistently negative across the sub-arctic and mid-arctic experimental studies. Such a pattern did not emerge in the coldest high-arctic or arctic-alpine sites. The slopes of the negative regressions increased across 10 sites as the climate became milder (as indicated by a simple climatic index) or the vegetation denser (greater site above-ground biomass). Seven natural vegetation gradients in the lower-altitude sub- and mid-arctic zone confirmed the patterns seen in the experimental studies, showing consistent negative relationships between abundance of macrolichens and vascular plants. We conclude that the data supported the hypothesis. Macrolichens in climatically milder arctic ecosystems may decline if and where global changes cause vascular plants to increase in abundance. However, a refining of our findings is needed, for instance by integrating other abiotic and biotic effects such as reindeer grazing feedback on the balance between vascular plants and lichens.

Coxson, D.S. 1988. Recovery of net photosynthesis and dark respiration on rehydration of the lichen, Cladina mitis, and the influence of prior exposure to sulphur dioxide while desiccated. New Phytologist 108: 483-487.

["These results point to importance of considering the effects of dry deposition on physiological processes and suggest that in some cases limited SO2 exposure may result in short-term enhancement of photosynthetic uptake."]

Crittenden, P.D. 1989. Nitrogen relations of mat-forming lichens. In: Lee, JA;, McNeill, S; Rorison, IH; eds. Nitrogen, Phosphorus and Sulphur Utilization by Fungi. Cambridge University Press, Cambridge, UK pp 243-268.

Crittenden, P.D. 2000. Aspects of the ecology of mat-forming lichens. Rangifer 20(2-3): 127-139.

Lichen species in the genera Cladonia (subgenus Cladina), Cetraria, Stereocaulon, and Alectoria are important vegetation components on well-drained terrain, and on elevated micro-sites in peatlands, in boreal-Arctic regions. These lichens often form closed mats, the component thalli in which grow vertically upwards at the apices and die off in the older basal regions; they are therefore only loosely attached to the underlying soil. This growth habit is relatively unusual in lichens being found in 0.5% of known species, might facilitate internal nutrient recycling and higher growth rates, and together with the production of allelochemicals it might underlie the considerable ecological success of mat-forming lichens; experiments to critically assess the importance of these processes are required. Mat-forming lichens can constitute in excess of 60% of the winter food intake of caribou and reindeer. Accordingly there is a pressing need for data on lichen growth rates, measured as mass increment, in order to help determine the carrying capacity of winter ranges for these herbivores and to better predict recovery rates following grazing. Trampling during the snow-free season fragments lichen thalli; mat-forming lichens regenerate very successfully from thallus fragments provided trampling does not re-occur. Frequent recurrence of trampling creates disturbed habitats from which lichens will rapidly become eliminated consistent with J.P. Grime's CSR strategy theory. Such damage to lichen ground cover has occurred where reindeer or caribou are unable to migrate away from their winter range such as on small islands or where political boundaries have been fenced; it can also occur on summer range that contains a significant lichen component and on winter range where numbers of migratory animals become excessive. Species of Stereocaulon, and other genera that contain cyanobacteria (most notably Peltigera and Nephroma), are among the principal agents of nitrogen fixation in boreal-arctic regions. Stereocaulon-dominated subarctic woodlands provide excellent model systems in which to investigate the role of lichens in nitrogen cycling. Mat-forming lichens are sensitive indicators of atmospheric deposition partly because they occur in open situations in which they intercept precipitation and particulates directly with minimal modification by vascular plant overstories. Data from both the UK and northern Russia are presented to illustrate geographical relationships between lichen chemistry and atmospheric deposition of nitrogen and acidity. The ecology of mat-forming lichens remains under-researched and good opportunities exist for making significant contributions to this field including areas that relate directly to the management of arctic ungulates.

Crittenden, P.D.; Kalucka, I.; Oliver, E. 1994. Does nitrogen supply limit the growth of lichens? Cryptogamic Botany 4: 143-155.

Crittenden, P.D.; Kershaw, K.A. 1978. Discovering the role of lichens in the nitrogen cycle in boreal-arctic ecosystems. The Bryologist 81: 258-267.

Evidence that lichenized blue-green algae are among the principal agents of N2 fixation on drier terrain in the Arctic and Subarctic has prompted attempts to quantify N-input by lichens in these habitats. The nitrogenase activity in Stereocaulon paschale mats in spruce-lichen woodland of central subarctic Canada has been examined in relation to thallus water content, temperature and incident radiation. The results revealed that while the level of activity at any point in time is dependent upon operative levels of these environmental factors, it can also be strongly influenced by pretreatment. It is suggested that simple predictive models are not yet able to accurately describe levels of nitrogenase activity in nature and that estimates of N-input on an annual or seasonal basis may be precarious. Leaching of metabolites from, and decomposition of the thallus are the two principal potential pathways for nitrogen, subsequent to fixation by cyanophilic lichens. Quantitative information on the operation of these pathways in nature is required.

Crock, J.G., L.P. Gough, D.R. Mangis, et al. 1992. Element concentration and trends for moss, lichen, and surface soils in and near Denali National Park and Preserve, AK. USGS Open-File Report 92-323. USGS-NPS, Air Quality Division. Crock, J.G., R.C. Severnson, and L.P. Gough. 1992. Determining baselines and variability of elements in plants and soils near the Kenai Natl. Wildlife Refuge, AK. Water, Soil, and Air Poll. 63: 253-271.

Curtis, C.J.; Emmett, B.A.; Grant, H.; Kernan, M.; Reynolds, B.; Shilland, E. 2005. Nitrogen saturation in UK moorlands: the critical role of bryophytes and lichens in determining retention of atmospheric N deposition. Journal of Applied Ecology 42: 507-517.

Curtis, C.J.; Emmett, B.A.; Grant, H.; Kernan, M.; Reynolds, B; Shilland, E. 2005. Nitrogen saturation in UK moorlands: the critical role of bryophytes and lichens in determining retention of atmospheric N deposition. Journal of Applied Ecology 42: 507-517

Anthropogenic nitrogen (N) deposition may have several impacts on upland moorland ecosystems, including changes in vegetation composition, eutrophication and surface water acidification through nitrate leaching, but few studies linking N deposition to key biogeochemical processes have been published. A stable isotope tracer (15N) was used to determine the fate of inorganic N inputs to four moorland catchments across gradients of N deposition and leaching, through 2-weekly additions to experimental plots on major soil types over 1 year. An apparent decline in total 15N recovery from soils and vegetation as the proportion of leached N deposition increased was not significant at the P = 0&middot;05 level, but a significant relationship was found for recovery in mosses and lichens. Vegetation retained 31-68% of 15N inputs, and 15N recovery increased significantly (P = 0&middot;01) with biomass for all compartments except woody shrubs. Mosses and lichens showed far greater 15N recovery per unit biomass than grasses or ericaceous shrubs. There was no significant variation in the proportion of 15N recovered in higher plants across the N deposition gradient (24-29%). In contrast, the proportion recovered in mosses and lichens declined from 44% to 2% as deposition increased, mirroring a decline in their biomass and showing a highly significant inverse relationship (P = 0&middot;01) with nitrate leaching. The proportion of 15N recovered in litter plus surface soils (33-39%) was remarkably constant across the deposition gradient for a variety of soil types. However, significantly declining recovery per unit biomass in litter (P < 0&middot;05) suggested progressive N saturation of this sink and increasing importance of retention in underlying surface soils as deposition increased. Past studies have demonstrated a decline in mosses and lichens in response to increasing N deposition, but we show here for the first time that reduced N retention might result together with increased nitrate leaching into surface waters. The conservation of bryophyte and lichen flora on moorlands is therefore critical to prevent excessive nitrate leaching and associated surface water acidification and eutrophication. Ensuring management practices such as grazing or burning are at an intensity that does not further degrade the bryophyte and lichen communities may help minimize the impact of N deposition on freshwaters, but the only effective means to reduce the risk of N leaching is a reduction in N emissions.

DaSilva, EJ; Henriksson, LE; Henriksson, E. 1975. Effect of pesticides on blue-green algae and nitrogen-fixation. Arch. Envir. Contamination Toxicol. 3: 193-204.

Davidson, C.I., et al. 1985. Airborne trace elements in Great Smoky Mountains, Olympic and Glacier National Parks. Environ. Sci. Technol. 19(1): 27-35.

Davidson, D.W.; Bowker, M.; George, D.; Phillips, S.L.; Belnap, J. 2002. Treatment effects on performance of N-fixing lichens in disturbed soil crusts of the Colorado Plateau. Ecological Applications 12: 1391-1405.

Biological soil crusts arrest soil erosion and supply nitrogen to arid ecosystems. To understand their recovery from disturbance, we studied performances of Collema spp. lichens relative to four experimental treatments plus microtopography of soil pedicels, oriented north-northwest to south-southeast in crusts. At sites in Needles (NDLS) and Island in the Sky (ISKY) districts of Canyonlands National Park, lichens were transplanted to NNW, SSE, ENE, WSW, and TOP pedicel faces and exposed to a full-factorial, randomized block experiment with four treatments: nutrient addition (P and K), soil stabilization with polyacrylamide resin (PAM), added cyanobacterial fiber, and biweekly watering. After 14.5 mo (NDLS) and 24 mo (ISKY), both visual rankings of lichen condition and measures of chlorophyll fluorescence were generally higher at ISKY than on more fertile but less stable soils at NDLS. On ENE and NNW pedicel faces, both these values and nitrogenase activity (NDLS only) exceeded corresponding values on WSW and SSE faces. Treatment effects were site specific and largely negative at NDLS; both nutrient and cyanobacterial addition led to poorer lichen condition, and added nutrients led to reduced fluorescence. Responses to nutrients may have been mediated partly by disturbance of unstable soils and by competition with cyanobacteria. In a separate experiment investigating recruitment responses to adding fungal spores or Nostoc cells, rates of Collema establishment responded significantly to the former but not the latter. Low establishment overall suggests that natural recruitment may occur mainly from isidia or thallus fragments, not spores. Measured simultaneously on artificial soil pedicels at NDLS and ISKY, both deposition and erosion declined at NDLS across the four pedicel micro-aspects as: WSW . SSE . NNW . ENE (or ENE . NNW), during fall and spring trials. Patterns were similar at ISKY, but WSW &oslash; SSE for spring deposition, and deposition did not differ by micro-aspect in fall. Greater deposition at ISKY, despite higher abundance of cyanobacteria, may be explained by stronger wind velocities. Together, micro-topographic differences in erosion, microclimate, and nutrient regimes help explain variable lichen performance, but microtopography influenced lichen performance more consistently than did any treatment. Demonstrated effects of pedicel development in crust recovery concur with prior surveys showing greatest microbial biomass and/or cover on ENE and NNW exposures at various spatial scales.

Davies, L.; Bates, J. W.; Bell, J. N. B.; James, P. W.; Purvis, W. O. 2007. Diversity and sensitivity of epiphytes to oxides of nitrogen in London. Environmental Pollution 146(2): 299-310.

This study investigated the distribution and diversity of epiphytes in London in relation to NOx using fine-scale atmospheric dispersion modeling. The survey recorded over 3000 epiphytes from 334 trees (Fraxinus excelsior) representing 74 lichen, 14 moss, 7 fungal and 3 algal species. There was a significant inverse relationship between diversity and NOx. Diversity declined where NOx exceeded 70 mg m-3and NO2 exceeded 40 mg m-3, suggesting a phyto-toxic effect. However, there was a significant positive relationship between NOx and lichen abundance due to the ubiquitous distribution of pollution tolerant species, mainly associated with eutrophication. A scale of lichen sensitivity to NOx has been derived.

Davis, WC; Gries, C; Nash, TH III. 2000. The ecophysiological response of the aquatic lichen, Hydrothyria venosa to nitrates in terms of weight and photosynthesis over long periods of time. Bibliotheca Lichenologica 75: 201-208.

Hydrothyria venosa Russ. Was exposed to nitrate concentrations from 0.5 to 30 mM. Concentrations of 4-30 mM were detrimental with the effect increasing with greater concentration. However, response to continuous low-level nitrate concentrations in the 1.0-2.0mM range, promoted growth and photosynthesis over a period of 350 days in the laboratory.[ synonym: Peltigera hydrothyria]

Davis, WC; Gries, C; Nash, TH III. 2003. The influence of temperature on the weight and net photosynthesis of the aquatic lichen Peltigera hydrothyria over long periods of time Bibliotheca Lichenologica 86: 243-255.

This study reports the change in weight and the net photosynthetic response of the aquatic lichen Peltigera hydrothyria across long-term incumbations of water temperatures form 5-30 oC, from periods of hours to months. At a temperature of 5 oC there was little change in weight or net photosynthetic response for periods as longas 400 days. At a temperature of 11oC, a declien in net photosynthetic response was apparent after 150 days; at 15 oC, after 120 days, at 18 oC, in 30 days. At 21 oC, net photosynthesis ceased within 15 days; at 26 oC within six days; and at 30 oC, within three days. Although some decline in weight also occurred, the magnitude was not as great as that observed for net photosynthesis. The results helps support the obseration that this species is restricted to cold, temperature streams. [synonym: Peltigera hydrothyria]

De Bruin, M., and E. Hackenitz. 1986. Trace element concentrations in epiphytic lichens and bark substrate." Environmental Pollution, Series B. 11:153-160.

"Elemental concentrations of 20 trace elements in inner bark, outer bark and epiphytic lichens were correlated. Inner bark concentrations were generally lower than the conc. in the outer bark and lichens. "For most of the elements studied, uptake from the substrate bark into the lichen is not likely to occur. But for Ca, Mn, Zn, Cd, and Ba, the possibility of such uptake has to be considered seriously; where high soil conc. or long-term air poll may be indirectly reflected in the lichens, obscuring the direct uptake from the atmosphere."

De Vries, W; Kros, H; Reinds, G Wamelink, W; Mol, J; van Dobben, H; Bobbink, R; Emmett, B; Smart, S; Evans, C; Schlutow, A; Kraft,P; Belyazid, S; Sverdrup, H; van Hinsberg, A; Posch, M; Hettelingh, J-P 2007. Developments in deriving critical limits and modeling critical loads of nitrogen for terrestrial ecosystems in Europe. Alterra, Alterra-rapport 1382, 206 pp.

This collaborative report of Alterra and the Coordination Center for Effects (MNP-CCE), in cooperation with various participants of the International Cooperative program on Modeling and Mapping (ICP-MM) includes: 1. A summarizing overview of adverse nitrogen deposition effects on terrestrial ecosystems in terms of impacts on plant species and faunal biodiversity, forest nutrient status in relation to impacts on soil and solution chemistry and on ground water quality. 2. An overview of integrated dynamic biogeochemical models with plant species diversity models, that allow the assessment of critical loads and target loads of nitrogen in view of plant species diversity impacts. 3. A review of currently used critical limits for N concentrations in soil solution and derivation of new critical limits, based on field (literature) data and integrated soil vegetation models, that can be used in the computation of critical loads by steady state soil models. This updated knowledge of N effects, critical N load methodologies (integrated models) and critical N limits a can contribute to a more appropriate data submission on critical N loads by the National Focal Centers to the CCE, specifically in view of biodiversity impacts, to be used for support of the UNECE and EU air pollution policies.

Denison, R., B. Caldwell, B. Bormann, et al. 1977. The effects of acid rain on nitrogen fixation in western Washington coniferous forests. Water, Air and Soil Pollution. 8: 21-34.

"Even the low conc. of SO2 presently found in the Pacific NW are thought to have an adverse effect on N2 fixation by limiting the distribution of the epiphytic N2-fixing lichen, Lobaria pulmonaria, which is found mainly in deciduous forests. A close relative Lobaria oregana, was found to be the major N2 fixer in old-growth coniferous forests. L. oregana fixes less N2 following exposure to H2SO4 of pH 4 or less." Harvesting practices are also a threat -- " L. oregana is a late successional spp. and doesn't develop in forests where short cutting cycles are practiced."

Denison, W.C., and S.M. Carpenter. 1973. A Guide to Air Quality Monitoring with Lichens. Lichen Technology, Inc., 39 pages.

Lots of illustrations. The scale used in this guide is based on data from 170 sites in the Willamette valley. The two most resistant (Class 1) lichens, Xanthoria polycarpa and Parmelia sulcata were found almost everywhere except for downtown Portland and a very few isolated industrial sites. In areas with slightly cleaner air, these two species were accompanied by three slightly more sensitive (Class 2) lichens: Ramalina farinacea, Melanelia subaurifera, Usnea subfloridana. In still cleaner areas, these spp. as well as the still more sensitive class 3 lichens (Leproloma membranaceum, Evernia prunastri) were present. Finally, in the cleanest areas, Class 4 lichens (Lobaria pulmonaria, Physcia aipolia) were found in addition to the other spp. " This is a simplified approach for laypersons including ID, and surveying techniques.

Deruelle, S. 1977. Influence de la pollution atmospherique sur la vegetation lichenique des arbres isoles dans la Region De Mantes (Yvelines). Rev. Bryol. Lichenol. 43(2): 137-158.

Deruelle, S. 1978. Les lichens et la pollution atmospherique. Bull. Ecol. 9(2): 87-128.

DeSloover, J., and F. LeBlanc. 1968. Mapping of atmospheric pollution on the basis of lichen sensitivity. Proc. Symp. Recent Adv. Trop. Ecol. 1968: 42-56.

De Wit, T. 1976. Epiphytic lichens and air pollution in the Netherlands. Bilio. Lichenol. 5:1-227. J. Cramer, Vaduz.

Diamantopoulos, J; S. Pirintsos, J.R. Laundon, and D. Vokou. 1992. The epiphytic lichens around Thessaloniki (Greece) as indicators of sulphur dioxide pollution. Lichenologist 24: 63-71.

The epiphytic lichens of 21 pine stands, planted around Thessaloniki, was investigated in an attempt to relate its characteristics to SO2 pollution. Data were further processed with detrended correspondence analysis and two-way indicator spp. analysis. Four epiphytic lichen zones could be detected in the study area, characterized by particular groups of lichen spp. with different sensitivity to SO2 pollution. NW spp: Hypogymnia physodes, Evernia prunastri, Physcia aipolia, Physconia americana, Melanelia exasperatula, Melanelia glabratula, Physcia adscendens, Parmelia sulcata, Xanthoria parietina.

Dillman, K. 2007. Air quality biomonitoring with lichens on the Tongass National Forest. Report.

To assess status and trends in air quality in Tongass National Forest Wildernesses, air- quality bio-monitoring sites were established in 1987-2005. Provisional thresholds for concentrations of S, N, Al, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Si, Sr, Ti, V and Zn were for the epiphytic macrolichens Alectoria sarmentosa, Hypogymnia enteromorpha, Lobaria oregana and Platismatia glauca using 1989-2005element concentrations and the 97.5% quantiles for element concentration distributions from remote sites. Thresholds are element concentration uppermost limits for target lichen from background (clean) sites. There were no significant differences in lichen element concentrations in four Wilderness Areas and one Research Natural Area (RNA) that had repeated element concentration data. No significant relationships between element concentrations in lichens and physiographic characteristics such as latitude, longitude, precipitation and elevation were observed. Some lichens near beaches may be enhanced in S and N due to the use of adjacent bays as popular marine vessel anchorages. Lichens from the Greens Creek mine vicinity on Admiralty Island had more elements above thresholds than other monitoring sites including S, N, Cd, Cr, Cu, Fe, Pb, and Zn. Lichens from Juneau's Mt Roberts were above thresholds for S, N, Cu, Cr, Fe, P, Ni, and Zn. Enhanced element concentrations provide evidence of the assimilation of anthropogenic airborne pollutants by the environment.

Dobbins, R.A. 1979. Atmospheric Motion and Air Pollution. John Wiley & Sons. New York.

Eilers, J.M., C.L. Ross, and T.J. Sullivan (eds.). 1994. Status of Air quality and effects of atmospheric pollution on ecosystems in the Pacific NW region of the National Park Service. Tech. Report NPS/NRAQD/NRTR-94/160.

Gives info on 5 National Parks in the PNW: Crater Lake, Craters of the Moon, Mt. Ranier, North Cascades, Olympic. Includes as summary table of some NW spp., lichen sensitivity, study type, parks where sp. is present, country of the study and reference; included with every chapter. The most useful chapt. (my opinion, JLH) is V: Interim Guidelines for the Protection of Sensitive Resources Relative to Air Quality Concerns. Gives a summary of research on vascular plants and sensitivities, as well as more lichen info. Most of the info on lichens is derived from Peterson et al 1992.

Emmett, BA 2007. Nitrogen saturation of terrestrial ecosystems: some recent findings and their implications for our conceptual framework Water, Air and Soil Pollution 7:99-109

The consequences of nitrogen (N) enrichment for terrestrial and freshwater ecosystems are of increasing concern in many areas due to continued or increasing high emission rates of reactive N. Within terrestrial ecosystems various conceptual frameworks and modeling approaches have been developed which have enhanced our understanding of the sequence of changes associated with increased N availability and help us predict their future impacts. Here, some recent findings are described and their implications for these conceptual frameworks and modeling approaches discussed. They are: (a) an early loss of plant species that are characteristic of low N conditions as N availability increases and a loss of species with high N retention efficiencies (so called N 'filters'), (b) suppression of microbial immobilization of deposited NO3- due to increased NH4+ availability in the early stages of N saturation, (c) the early onset of NO3- leaching due to these changes (a and b above) in both plant and microbial functioning, (d) reduced sensitivity of vegetation to N additions in areas with high historical N deposition, (e) delayed changes in soil C:N changes due to increased net primary productivity and reduced decomposition of soil organic matter. Some suggestions of early indicators of N saturation are suggested (occurrence of mosses; NH4+: NO3- ratio in surface soils) which indicate either a shift in ecosystem function and/or structure.

Erdman, J.A., and L.P. Gough. 1975. Trace elements in soil, lichens, and grama grass of the Powder River Basin. Geochemical Survey of the Western Coal Regions. Open File Report 75-436, USGS, Denver.

Erdman, J.A., and L.P. Gough. 1977. Variation in the element content of Xanthoparmelia chlorochroa from the Powder River Basin of WY and MT. The Bryologist 80: 292-303.

Elemental conc.for 26 elements are given for Xanthoria parietina in the Powder River basin, using analysis of variance, only 7 showed "statistically significant 'regional' variation at scales above 10 k" (Al, Cd, Cu, F, Pb, Se, Si). The conc. of elements in X. parietina are compared to sagebrush and grama grass.

Esseen, P.A. et al. 1981. Occurrence and ecology of Usnea longissima in central Sweden. Lichenologist 13: 177-190.

[A study of populations of Usnea longissima at 31 localities indicated that the observed decline was due to various forestry practices and, to a minor extent, air pollution. "Specific habitat demands and low dispersal ability make U. longissima very senstive to environmental disturbances."]

Eversman, S. 1980. Observations on two lichen species in the Colstrip area, 1979. In: Preston EM, DW O'Guinn, RA Wilson (eds.), The Environmental Impact of a Coal-Fired Power Plant, Sixth Interim Report. Colstrip MT. pp.185-197. EPA Corvallis OR.

Eversman, S. 1982. Epiphytic lichens of a ponderosa pine forest in southeastern Montana. Bryologist 85: 204-213.

Nineteen lichen spp. were collected from Pinus ponderosa in Custer NF in southeastern MT; 340 trees in four vegetation zones were samples. The dominant lichen sp. at all heights of the trunks and lower branches was Usnea hirta, constituting 31-74% of total lichen cover. The % of U.hirta was highest in the driest vegetation type (PIPO-AGSP) and lowest in the most moist veg. type (PIPO-PRVI). The majority of lichen cover and diversity on trunks was on the lowest 50 cm; diversity and cover increased with ascending moisture levels. Parmeliopsis ambigua, Bryoria fuscescens, Cetraria pinastri increased most substantially from drier to wetter sites. Most of the lichen spp. found in this forest type are regular components of Rocky Mtn and/or northern coniferous forests. Other conifer forest types in the Rocky Mtns and Black Hills support richer lichen floras.

Eversman, S. 1987. Effects of low-level SO2 on Usnea hirta and Parmelia chlorochroa. Bryologist 81: 368-377.

[Field study conducted in Powder River County, Montana. Respiration rates significantly decreased in exposed organisms and 100% of algal cells were plasmolyzed in 60 days. U. hirta was more sensitive than P. chlorochroa, and the lichens were damaged faster than the adjacent vascular plant vegetation.]

Eversman, S, and L.L. Sigal. 1984. "Ultrastructural effects of peroxyacetyl nitrate (PAN) on two lichen species. Bryologist 87: 112-118.

[Effects of PAN fumigation on Hypogymnia enteromorpha and Parmelia sulcata showed that photosynthetic rates "...decreased in both species, with more decrease in P. sulcata than in H. enteromorpha. Analysis of transmission electronmicrographs revealed abnormally high accumulation of starch in the chloroplasts of both species and slight decreases in amount of pyrenoid area. Anticipated significant deterioration and disappearance of thylakoid membranes did not occur."]

Farkas, E., L. Lokos, and K. Verseghy. 1985. Lichens as indicators of air pollution in the Budapest agglomeration. I. Air pollution map based on floristic data and heavy metal concentration measurements. Acta Botanica Hungarica 31: 45-68.

Farmer, A.M., J.W. Bates, and J.N.B. Bell. 1991. Seasonal variarions in acidic pollutant inputs and their effects on the chemistry of stemflow and epiphyte tissues in three oak woodlands in NW Britain. New Phytologist 115: 431-437.

"Rainfall, throughfall and stemflow chemistry, bark chemistry and gaseous air pollutant levels were monitored for one year within three Quercus petraea woodlands in NW Britain. Tissue chemistry of Lobaria pulmonaria and the moss Isothecium myosuroides were studied at the sites where they were abundant. The sites were found to differ in the levels of acidic and nutrient inputs, bark chemistry and levels of gaseous pollutants, although the latter were low at all sites. The epiphyte tissue chemistry responded to changes in stemflow chemistry across the season." "It is concluded that acid ppt. will affect epiphytes by reducing the bark's buffering capacity and increasing its acidity. The extent to which this occurs will depend on tree spp., soil chemistry, and the nature of the atm. inputs." Critical load for epiphytes is defined.

Farmer, A.M., J.W. Bates, and J.N.B. Bell. 1992. Ecophysiological effects of acid rain on bryophytes and lichens. In: Bates, J.W., and A. M. Farmer (eds.). Bryophytes and Lichens in a Changing Environment. Clarendon Press, Oxford.

Literature review includes SO2, Photochemical oxidants, NOx, Wet acidic deposition/fertilizing effect/community changes related. to, Experiments. NW spp: Lobaria pulmonaria, Lobaria scrobiculata, Peltigera membranacea, Hypogymnia physodes, and some Cladonia and Parmelia.

Farmer, A.M. 1994. Evidence of altitude enhancement of nitrogen deposition in the Mourne Mountains, Co Down. Irish Naturalists' Journal 24(12): 489-492.

Farmer, AM; Bates, JW; Bell, JNB. 1992. Ecophysiological effects of acid rain on bryophytes and lichens. In: Bates, JW/Farmer, AM (eds.): Bryophytes and Lichens in a Changing Environment. Clarendon Press, Oxford, pp. 284-313.

FEMAT. 1993. Forest Ecosystem Management: An Ecological, Economic and Social Assessment. Report of the Frest Ecosystem Management Assessment Team. USDA-Forest Service, USDC-National Oceanic & Atmospheric Admin. and National Marine Fisheries Service, USDI-Bureau of Land Management, Fish & Wildlife Service, National Park Service and the Environmental Protection Agency.

Fenn, M. E.; Geiser, L.; Bachman, R.; Blubaugh, T. J.; Bytnerowicz, A. 2007. Atmospheric deposition inputs and effects on lichen chemistry and indicator species in the Columbia River Gorge, USA. Environmental Pollution 146(1): 77-91.

Topographic and meteorological conditions make the Columbia River Gorge (CRG) an 'exhaust pipe' for air pollutants generated by the Portland-Vancouver metropolis and Columbia Basin. We sampled fog, bulk precipitation, throughfall, airborne particulates, lichen thalli, and nitrophytic lichen distribution. Throughfall N and S deposition were high, 11.5-25.4 and 3.4-6.7 kg ha-1 over 4.5 months at all 9 and 4/9 sites, respectively. Deposition and lichen thallus N were highest at eastern- and western-most sites, implicating both agricultural and urban sources. Fog and precipitation pH were frequently as low as 3.7-5.0. Peak NOx, NH3, and SO2 concentrations in the eastern CRG were low, suggesting enhanced N and S inputs were largely from particulate deposition. Lichens indicating nitrogen-enriched environments were abundant and lichen N and S concentrations were 2&times; higher in the CRG than surrounding national forests. The atmospheric deposition levels detected likely threaten Gorge ecosystems and cultural resources. Nitrogen, sulfur and acidic deposition threaten natural and cultural resources in the Columbia River Gorge National Scenic Area.

Fenn, M.E.; Baron, J.S.; Allen, E.B.; Rueth, H.M.; Nydick, K.R.; Geiser, L.; Bowman, W.D.; Sickman, J.O.; Meixner, T.; Johnson, D.W.; Neitlich, P. 2003. Ecological effects of nitrogen deposition in the western United States. BioScience 53(4): 404-420.

In the western United States vast acreages of land are exposed to low levels of atmospheric nitrogen (N) deposition, with interspersed hotspots of elevated N deposition downwind of large, expanding metropolitan centers or large agricultural operations. Biological response studies in western North America demonstrate that some aquatic and terrestrial plant and microbial communities are significantly altered by N deposition. Greater plant productivity is counterbalanced by biotic community changes and deleterious effects on sensitive organisms (lichens and phytoplankton) that respond to low inputs of N (3 to 8 kilograms N per hectare per year). Streamwater nitrate concentrations are elevated in high-elevation catchments in Colorado and are unusually high in southern California and in some chaparral catchments in the southwestern Sierra Nevada. Chronic N deposition in the West is implicated in increased fire frequency in some areas and habitat alteration for threatened species. Between hotspots, N deposition is too low to cause noticeable effects or has not been studied.

Fenn, M.E.; Haeuber, R.; Tonnesen, G.S.; Baron, J.S.; Grossman-Clarke, S.; Hope, D.; Jaffe, D.A.; Copeland, S.; Geiser, L.; Rueth, H.M.; Sickman, J.O. 2003. Nitrogen emissions, deposition, and monitoring in the western United States. BioScience 53(4): 391-403.

Nitrogen (N) deposition in the western United States ranges from 1-4 kilograms (kg) per hectare (ha) per year over much of the region to as high as 30-90 kg per ha per year downwind of major urban and agricultural areas. Primary N emissions sources are transportation, agriculture, and industry. Emissions of N as ammonia are about 50% as great as emissions of N as nitrogen oxides. An unknown amount of N deposition to the West Coast originates from Asia. Nitrogen deposition has increased in the West because of rapid increases in urbanization, population, distance driven, and large concentrated animal feeding operations. Studies of ecological effects suggest that emissions reductions are needed to protect sensitive ecosystem components. Deposition rates are unknown for most areas in the West, although reasonable estimates are available for sites in California, the Colorado Front Range, and central Arizona. National monitoring networks provide long-term wet deposition data and, more recently, estimated dry deposition data at remote sites. However, there is little information for many areas near emissions sources.

Fenn, M.E.; Jovan, S.; Yuan, F.; Geiser, L.; Meixner, T.; Gimeno, B.S. 2008. Empirical and Simulated Critical Loads for Nitrogen Deposition in California Mixed Conifer Forests Environmental Pollution 155: 492-511

Empirical critical loads (CL) for N deposition were determined from changes in epiphytic lichen communities, elevated NO3- leaching in stream water, and reduced fine root biomass in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) at sites with varying N deposition. The CL for lichen community impacts of 3.1 kg ha-1 yr-1 is expected to protect all components of the forest ecosystem from the adverse effects of N deposition. Much of the western Sierra Nevada is above the lichen-based CL, showing significant changes in lichen indicator groups. The empirical N deposition threshold and that simulated by the DayCent model for enhanced NO3- leaching were 17 kg N ha-1 yr-1. DayCent estimated that elevated NO3- leaching in the San Bernardino Mountains began in the late 1950s. Critical values for litter C:N (34.1), ponderosa pine foliar N (1.1%), and N concentrations (1.0%) in the lichen Letharia vulpina ((L.) Hue) are indicative of CL exceedance.

Ferry, B.W., S. Baddeley, D.L. Hawsworth (eds). 1973. Air Pollution and Lichens. London, Athlone Press.

Ferry, B.W., and B.J. Coppins. 1979. Lichen transplant experiments and air pollution studies. Lichenologist 11(1):63-73.

"Several groups of workers have shown that SO2 in solution inhibits both photosynthesis and respiration in lichens, occuring at levels as low as 10-20 ppm (w/w). It has been argued such concentrations could occur in the field. Difficulties in relating lab work to the field include: vacuum infiltration of thalli w/ solutions aren't conducive to maximum photosynthetic rates; measured metabolic processes (resp and Ps) may not show the primary response to SO2; material used may not be representative of the critical phases of the life cycle ( reprod, establishment); using strongly buffered solutions may override lichen buffering abilities; choice of pH might not be relevant to the field situation; fumigation studies w/ solutions tend to yield higher sensitivities than those using gas in the case of Hypogymnia physodes (Turk, et al. 1974). The results of a series of transplant experiments with corticolous lichens were designed to assess relative sensitivities to SO2 pollution by measuring physiological damage. The results were compared with results from lab experiments and mapping data. Acid bark species transplants correlated well with mapping data. Basic bark species gave a poor correlation between the three sets of data. NW spp: H. physodes (acid bark sp.), Ramalina farinacea (basic), Parmelia sulcata (basic), Xanthoria parietina (basic).

Fields, R.F. 1988. Physiological responses of lichens to air pollutant fumigations. In: Nash, T.H. III (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer, Berlin-Stuttgart.

The physiological responses of lichens when exposed to laboratory fumigations with such pollutants as SO2, NO2, peroxyacetyl nitrate are viewed. ["The response variables used to measure metabolic disturbance include inhibition of photosynthetic fixation, changes in respiration rates, increases in potassium efflux and total electrolyte leakage, as well as chlorophyll degradation. The order of sensitivity of lichen physiological processes to fumigation appears to be: N2 fixation > K+ efflux/total electrolyte leakage > photosynthesis, respiration > pigment status."] Due to problems encountered while exposing the lichens to the gas--sensitivity may have been greatly underestimated--see Hyvarinen et al. 1993. While different fumigation methods are mentioned in the intro, the table doesn't give that info. NW spp: Bryoria fuscescens, Cladina rangiferina, Cladonia furcata, Collema nigrescens, Dermatocarpon miniatum, Evernia prunastri, Hypogymnia enteromorpha, Hypogymnia physodes, Lobaria pulmonaria, Parmelia saxatilis, Parmelia sulcata, Peltigera aphthosa,l Peltigera canina, Peltigera collina, Peltigera rufescens, Physcia adscendens, Physcia stellaris, Platismatia glauca, Punctelia subrudecta, Ramalina farinacea, Rhizoplaca chrysoleuca, Rhizoplaca melanophthalma, Xanthoparmelia chlorochroa, Xanthoria fallax, Xanthoria parietina.

Fields, R.D., and L.L. St. Clair. 1984. The effects of SO2 on photosynthesis and carbohydrate transfer in the two lichens: Collema polycarpon and Parmelia chlorochroa.. American J. Botany 71: 986-998.

"Exposure of Xanthoria parietina and Collema polycarpon to 1 and 2 ppm gaseous SO2 initially stimulated photosynthesis but prolonged exposure depressed it. Carbohydrate transfer decreased on both species but increased significantly after a 12 hr exposure in C. polycarpon. Interference with normal oxidation-reduction and denaturation of enzymes and membrane proteins by sulfite and bisulfite ions may account for the observed results. Increased conductivity of leacheates reflected SO2-induced damage at both 1 and 2 ppm SO2."

Folkeson, L., and E. Andersson-Bringmark. 1988. Impoverishment of vegetation in a coniferous forest polluted by copper and zinc. Can. J. Bot. 66: 417.

"Copper and zinc concentrations in raw humus were elevated> 440 and > 80 times, respectively, near and old and new foundry -- virtually no SO2 was being emitted. Effects on veg. were most evident in the ground layer and 4 stages or zones were defined: 1. common mosses of mature coniferous forests began to decline 2. Lichens of mature dry forests were reduced in cover. 3. Pioneers typical of successional communities increased slightly in cover 4. Even tolerant spp. of lichens and mosses disappeared and only Pohlia nutans remained. Deterioration of the ground layer makes the polluted thin soil prone to erosion." NW lichens: Cladina rangiferina, Cladonia chlorophaea, C.furcata, C. squamosa Cladonia ochrochlora, C. carneola, C.cenotea, C.pyxidata.

Follmann, G 1995. On the impoverishment of the lichen flora and the retrogression of the lichen vegetation in coastal central and northern Chile during the last decades. Cryptogamic Botany 5(3): 224-231.

A drastic lichen decline has been observed in the coastal range of semiarid central and hyper-arid northern Chile (Atacama Desert) during the past three decades. At the population level, about 300 characteristic species formerly classified as frequent or numerous showed a considerable decrease in their cover-abundance index. At the species level, 14 taxa could not be found again, among these 9 local endemics. At the flora level, the relative lichen diversity of special habitats like the world-famous loma formations declined as far as 46%. At the community level, a marked impoverishment or partial disappearance of some formerly landscape-determining lichen associations was noticed. These findings are substantiated by comparative floristic and sociological data and discussed in terms of recent climatic fluctuations and environmental alterations. Two new combinations are also proposed: Protorocella minima (Sant.) Follm. (bas. Roccella minima Sant.) and Santessonia cervicornis (Follm.) Follm. (bas. Roccella cervicornis Follm.).

Forman, RTT; Dowden, DL 1977. Nitrogen fixating lichen roles from desert to alpine in the Sangre de Cristo Mountains, New Mexico. The Bryologist 80: 561-570.

Frati, L.; Santoni, S.; Nicolardi, V.; Gaggi, C.; Brunialti, G.; Guttová, A.; Gaudino, S.; Pati, A.; Pirintsos, S. A.; Loppi, S. 2007. Lichen biomonitoring of ammonia emission and nitrogen deposition around a pig farm. Environmental Pollution 146(2): 311-316.

Effects of high ammonia emissions and nitrogen deposition were investigated on lichens around a pig stockfarm (ca. 7,000 animals) in central Italy. Four sites were selected along a transect at 200, 400, 1000 and 2500 m from the stock farm, the diversity of epiphytic lichens was measured and transplanted thalli of Xanthoria parietina and Flavoparmelia caperata exposed, together with passive NH3 (diffusion tubes) samplers. Ammonia dramatically decreased from the centre of the stock farm to the sampled sites, where it was correlated with bark pH. Total lichen diversity was not associated with either NH3 concentrations or bark pH, but the diversity of strictly nitrophytic species was highly correlated with both parameters. Physconia grisea was the best indicator species for NH3 pollution. Total N accumulated in X. parietina and F. caperata was correlated with NH3 concentrations.

Fremstad, E., J. Paal, & T. Möls. 2005. Impacts of increased nitrogen supply on Norwegian lichen-rich alpine communities: a 10-year experiment. Journal of Ecology 93: 471-481.

Species cover was tested during a 10-year fertilization experiment in the low-alpine Cetrarietum nivalis community and the middle-alpine Phyllodoco-Juncetum trifidi community in the Dovre mountains of south-central Norway . Nitrogen was added at 7, 35 and 70 kg N ha-1 year-1, with the highest dose corresponding to approximately 3.5 times the annual deposition in south-west Norway . Both communities are dominated by lichens (Cladonia spp. and Cetraria spp., respectively), have a patchy structure and are 'conservative' as regards species content. Lichens, which showed a decrease in cover and size, and after some years developed discoloured thalli, are the best organisms for monitoring changes in alpine vegetation that is exposed to increased nitrogen deposition. The most sensitive species in Cetrarietum nivalis appeared to be Alectoria nigricans and Cetraria ericetorum, but more abundant species (Cladonia mitis, C. stellaris and Cetraria nivalis) are likely to be more reliable indicators. Cetraria delisei seems to be a reliable indicator species for monitoring in Phyllodoco-Juncetum trifidi. Fertilization had no significant effect on the vascular plants (dwarf shrubs and a few graminoids) in either community, except for Festuca ovina, the cover of which increased slightly. Nitrogen pollution may affect oligotrophic, alpine communities differently, depending on their species composition and horizontal structure (patchiness). It is suggested that other factors, such as climate, soil properties and community structure, may be more important than long-range nitrogen pollution for determining species composition and species cover in many of the oligotrophic, alpine communities in southern Norway . However, in lichen-rich communities, critical loads have already been exceeded in the most polluted areas of south-west Norway .

Friedel, A.; Müller, F. 2004. Bryophytes and lichens as indicators for changes of air pollution in the Serrahn Natural Forest Reserve (Mueritz National Park). Herzogia 17: 279-286.

Fritz-Sheridan, RP 1985. Impact of simulated acid rains on nitrogenase activity in Peltigera aphthosa and P. polydactyla. Lichenologist 17: 27-31.

Furbish, C.E.; Geiser, L. ; Rector, C . 2000. Lichen-Air Quality Pilot Study for Klondike Gold Rush National Historical Park and the City of Skagway, Alaska. Final Report. US National Park Service, Klondike Goldrush National Historic Park, Natural Resources Management Program, Skagway, AK, 47pp. http://gis.nacse.org/lichenair/?page=reports#R10

The concentrations of chemical elements in lichen tissues from the Klondike Park - city of Skagway area were used to assess local air quality. Two tube lichens (Hypogymnia enteromorpha and H. inactiva) and rag lichen (Platismatia glauca) from the Klondike-Skagway area showed signs of air pollution. The Klondike-Skagway lichens had higher levels of heavy metals and sulfur in lichen tissues than baseline values for unpolluted areas of Southeast Alaska. The Klondike-Skagway area exceeded air pollution indication thresholds for the USDA-Forest Service Pacific Northwest and Alaska Regions for heavy metals, sulfur and other elements. All of this study's sites, two in the Skagway valley and two in the Taiya valley, showed signs of air pollution, but the site closest to the town hub of Skagway had the highest occurrence and highest levels of pollutants in lichen tissues. These results are discussed and options for continued monitoring are presented.

Gaige, E.; Dail, D.B.; Hollinger, D.Y.; Davidson, E.A.; Fernandez, I.J.; Sievering, H.; White, A.; Halteman, W. 2007. Changes in canopy processes following whole-forest canopy nitrogen fertilization of a mature spruce-hemlock forest. Ecosystems (2007) 10: 1133-1147.

Most experimental additions of nitrogen to forest ecosystems apply the N to the forest floor, bypassing important processes taking place in the canopy, including canopy retention of N and/or conversion of N from one form to another. To quantify these processes, we carried out a large-scale experiment and determined the fate of nitrogen applied directly to a mature coniferous forest canopy in central Maine (18-20 kg N ha-1 y-1 as NH4NO3 applied as a mist using a helicopter). In 2003 and 2004 we measured NO3-, NH4+, and total dissolved N (TDN) in canopy throughfall (TF) and stemflow (SF) events after each of two growing season applications. Dissolved organic N (DON) was greater than 80% of the TDN under ambient inputs; however NO3- accounted for more than 50% of TF N in the treated plots, followed by NH4+ (35%) and DON (15%). Although NO3- was slightly more efficiently retained by the canopy under ambient inputs, canopy retention of NH4+ as a percent of inputs increased markedly under fertilization. Recovery of less than 30% of the fertilizer N in TF suggested that the forest canopy retained more than 70% of the applied N (>80% when corrected for N which bypassed tree surfaces at the time of fertilizer addition). Results from plots receiving 15N enriched NO3- and NH4+ confirmed bulk N estimations that more NO3- than NH4+ was washed from the canopy by wet deposition. The isotope data did not show evidence of canopy nitrification, as has been reported in other spruce forests receiving much higher N inputs. Conversions of fertilizer-N to DON were observed in TF for both 15NH4+ and 15NO3- additions, and occurred within days of the application. Subsequent rain events were not significantly enriched in 15N, suggesting that canopy DON formation was a rapid process related to recent N inputs to the canopy. We speculate that DON may arise from lichen and/or microbial N cycling rather than assimilation and re-release by tree tissues in this forest. Canopy retention of experimentally added N may meet and exceed calculated annual forest tree demand, although we do not know what fraction of retained N was actually physiologically assimilated by the plants. The observed retention and transformation of DIN within the canopy demonstrate that the fate and ecosystem consequences of N inputs from atmospheric deposition are likely influenced by forest canopy processes, which should be considered in N addition studies.

Gailey, F.A.Y., G.H. Smith, L.J. Rintoul, and O.Ll. Lloyd. 1985. Metal deposition patterns in central Scotland, as determined by lichen transplants. Environmental Monitoring and Assessment 5: 291-309.

["Lichen transplants of Hypogymnia physodes were used in a high-density network of sites for collecting airborne metals from the atmosphere in Armadale, a small industrial town in central Scotland. The mapping of the concentrations of various metals revealed a gradient of metal values which decreased outwards from the town's steel foundry."]

Gailey, F.A.Y., and O.Ll. Lloyd. 1986a,b,c. Methodological investigations into low technology monitoring of atmospheric metal pollution: Parts 1,2,3. Environmental Pollution (Series B) 12:41-59, 85-109, 61-74.

Part 1: Env.Poll. 12:41-59. Methodological investigations determined the optimal sizes of three types of transplant samplers: the spherical moss bag (SMB), the lichen Hypogymnia physodes and the tak, or synthetic fabric sampler. Various sizes of samplers were exposed for two months near a source of metallic atm. poll. Analysis of the data showed that the optimal size for the SMBs was 0.1-0.2 gm d.w., H. physodes thallus diameter of 0.8-1.2 cm and a surface area of 70 cm2 for the tak.

Part 2: Comparisons of indigenous: moss, Lecanora conizaeoides, grass, and soils; and transplants: SMBs, H. physodes , and tak. Other samplers were added: flat moss bags, fresh moss and water washed SMBs, dead H. physodes and a fruticose lichen. All samplers, except the surface soils gave concentrations of most metals that were well within an acceptable range of variability. Of the samplers flat moss bags, water washed SMBs and dead H. physodes have very replicable concentrations while the fresh moss SMBs and the fruticose lichen gave the least consistent values.

Gaio-Oliveira, G; Dahlman, L; Palmqvist, K; Máguas, C 2004. Ammonium uptake in the nitrophytic lichen Xanthoria parietina and its effects on vitality and balance between symbionts. Lichenologist 36(1): 75-86.

The aim of this investigation was to determine the NH4Cl concentration threshold, above which negative physiological effects would occur in the nitrophytic lichen Xanthoria parietina. Over a 10 month period, X. parietina thalli growing on roof tiles were exposed weekly to NH4Cl concentrations of 0&middot;04, 0&middot;17, 0&middot;34 or 0&middot;69 M. Nitrogen (N) uptake from ammonium and the concentrations of total thallus N and biont markers (chlorophyll a, ergosterol and chitin) were measured on four occasions, over the experimental period. Xanthoria parietina was able to assimilate a significant quantity of the applied ammonium. However, lichens exposed to the two higher concentrations suffered damage to both the photobiont and the mycobiont, as evidenced by reduced chlorophyll a and ergosterol concentrations, while lichens exposed to the two lower concentrations showed no significant changes in either chlorophyll a or ergosterol that could be related to the ammonium inputs. Xanthoria parietina tolerated a weekly irrigation of at least 0&middot;17 M NH4Cl, corresponding to an N deposition of c. 1000 kg ha-1 yr-1, suggesting that this species has a very high tolerance to N pollution.

Galun, M., and R. Ronen. 1988. Interactions of lichens and pollutants. pp. 55-72 In: Galun, M (ed.), CRC Handbook of Lichenology Vol III. CRC Press, Inc., Boca Raton.

Galun, M., J.Garty, and R. Ronen. 1984. Lichens as indicators of air pollution. Webbia 38:371-383.

Garty, J., Y. Karary, and J. Harel. 1993. The impact of air pollution on the integrity of cell membranes and chlorophyll in the lichen Ramalina duriaei (De Not.) Bagl. transplanted to industrial sites in Israel. Archives of Environmental Contamination and Toxicology 24(4): 455-460.

Garty, J. 2001. Biomonitoring atmospheric heavy metals with lichens: theory and application. Critical Reviews in Plant Sciences 20(4): 309-371./P>

Garty, J 2003. About the applicability of the lichen Ramalina maciformis (lichenized Ascomycetes, Ramalinaceae) as a biomonitor of air pollution in the Negev desert, Israel. In: Jensen, M (ed.): Lichenological Contributions in Honour of G.B. Feige. Bibliotheca Lichenologica, J. Cramer, Berlin, Stuttgart, pp. 243-255.

Garty, J; Levin, T; Cohen, Y; Lehr, H 2002. Biomonitoring air pollution with the desert lichen Ramalina maciformis. Physiologia Plantarum 115: 267-275.

To investigate the environmental impact of anthropogenic activity in the Negev Desert, we monitored the following in order to determine the physiological integrity of the epilithic fruticose lichen Ramalina maciformis: (1) production of ethylene; (2) potential quantum yield of photosystem II expressed as chlorophyll fluorescence ratio Fv/Fm; and (3) electrolyte leakage of cell membranes in terms of electric conductivity. The degree of pollution was assessed by measuring the amounts of B, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sr and Zn in the lichen thallus. Some of the lichen-carrying stones collected in the relatively unpolluted control site were relocated on the same hill, to test the possible impact of relocation. An additional amount of lichen-carrying stones was marked as controls. The greater part of the lichen-carrying stones was transferred to 10 biomonitoring sites in and around Ramat Hovav, an industrial area in the Negev Desert, Israel. Transplanted lichen in polluted sites contained higher amounts of mineral elements than lichens in the control site after an exposure period of 7 months. Statistical analysis revealed positive correlation of ethylene production and Ni content, negative correlation of Fv/Fm ratios and B, Cu, Mn, Na, Ni, Sr and Zn, and positive correlation of electric conductivity and B, Mn, Ni and Sr. Both elemental content and physiological alterations in transferred samples of R.maciformis point to a high degree of contamination in Ramat Hovav. The present study suggests that the lichen R.maciformis should be classified as a sensitive species endangered by anthropogenic activity in the desert. Furthermore, this lichen species is likely to be suitable as a bioindicator of pollution in other parts of the Negev Desert. Ethylene production and electric conductivity as parameters of lichen-vitality, indicated stress in 5 of the 12 biomonitoring sites (42%) and may therefore be considered as more sensitive than the Fv/Fm ratio, which indicated stress in 3 of the 12 sites (25%).

Geiser, L. 2004. Manual for Monitoring Air Quality Using Lichens on National Forests of the Pacific Northwest. USDA-Forest Service Pacific Northwest Region Technical Paper, R6-NR-AQ-TP-1-04. 126 pp. http://gis.nacse.org/lichenair/doc/AQBPMthds.pdf

Geiser, L.H., C.C. Derr, and K.L. Dillman. 1994. Air quality monitoring on the Tongass National Forest: Methods and Baselines using Lichens. USDA- Forest Service Alaska Region Technical Bulletin R10-TB-46.

Geiser, L.; Szymoniak, J.; Mikulin, A. [2009/2010]. Lichen indication of nitrogen and sulfur deposition patterns in Hell's Canyon National Recreation Area: Implications for historic petroglyphs and pictographs. The Bryologist (In Review)

Over 200 pictographs and petroglyphs, radio-dated from 200 to 7100 years BP are located in the Snake River corridor of Hell's Canyon National Recreation Area. Air pollution is a suspected factor in the apparent deterioration of these artifacts during the past 25 years. We found indications of elevated nitrogen deposition in riparian corridors where lichen communities were dominated by species responsive to alkalinized, nutrient-rich environments. Cover of lichen genera indicating excess nitrogen, Xanthomendoza and Xanthoria, and N concentrations in Xanthoparmelia cumberlandia, were highest along the Snake River and lower along tributary corridors. Bark alkalinity was positively correlated with lichen cover, indicating ammonia as the N source. Mean N concentrations in X. cumberlandia collected within 80 m of the Snake River were higher than concentrations at regional sites with enhanced nitrogen deposition. S concentrations in lichens were not different from regional background sites. Regional ammonia emissions and fertilizing pollutants in the Snake River are the most probable anthropogenic sources. N -containing depositional compounds, probably dominated by ammonia, are readily available in the Canyon, especially the valley floor, and may be contributing to degradation of the rock art.

Geiser, L.H.; Glavich, D.A.; Jovan, S.E.; Porter, M.; et al. 2008. Lichen-based critical loads and levels for nitrogen deposition in western Oregon and Washington. In Prep

We summarize progress in the determination of lichen-based critical loads for nitrogen (N) deposition in temperate coniferous rainforests of western Oregon and Washington; lichens being among the most N-sensitive ecosystem component. Linear models were used to relate lichen community or biological (% N in lichen thalli) responses to available deposition estimates. Lichen-community based air scores from a non-metric multidimensional scaling (NMS) ordination model were most closely correlated with average annual ambient N from (NH4)2SO2 and NH4NO3 in fine particulates (<2.5 um) measured by 12 co-located Interagency Monitoring of Protected Visual Environments (IMPROVE) monitors in the study area (r2 = 0.92, p < 0.0001). Air scores associated with incipient declines in highly sensitive lichen species corresponded to a critical level for average annual ambient N of 0.42-.52 &micro;g N m-3. In the Columbia River Gorge (CRG), where air scores were unavailable, % N in epiphytic and saxicolous lichens was directly correlated (r2 = 0.90 and 0.64) with canopy throughfall measurements, or total deposition, measured using ion exchange resin columns at 8 sites. Lichen %N was linked to a community-level response using simple indices of lichen indicator species. Enhanced lichen N, 1% for epiphytes and 1.5% for the saxicoles, corresponded to critical loads of 4 and 5.2 kg N ha-1 yr-1, respectively. To relate lichen response to measures of wet deposition, it was necessary to account for precipitation because highly concentrated inputs have a more detrimental effect than high total input diluted by plentiful precipitation. After accounting for precipitation, critical loads derived from air scores correlated with long term annual averages of wet deposition measured at 8 National Atmospheric Deposition Program monitors for 45 lichen survey sites or modeled by Community Multi-scale Air Quality (CMAQ; 6 x 6 km cell size) for 1470 lichen survey sites were 0.0- 0.7 to 3.8-5.5 kg N ha-1 yr-1 for the driest and wettest sites, corresponding to ~45 and 450 cm annual precipitation. Average precipitation in the study area was ~200 cm, corresponding to critical loads of 1.2 to 2.1 kg N ha-1 yr-1 for wet deposition. Similarly, critical loads for total deposition calculated from the relationship between air scores and total annual average N deposition predicted by CMAQ, after accounting for precipitation, was 1.5-2.7 to 8.0-9.2 kg N ha-1 yr-1 at 45 and 450 cm rain, respectively; and 3.7-5 kg N ha-1 yr-1 at 200 cm precipitation.

Geiser, L.H.; Ingersoll, A.R.; Bytnerowicz, A.; Copeland, S.A. 2008. Evidence of enhanced atmospheric ammoniacal nitrogen in Hell's Canyon National Recreation Area: Implications for natural and cultural resources. Journal of the Air & Waste Management Association 58:1223-1234

Agriculture releases copious fertilizing pollutants to air sheds and waterways of the northwest US. To evaluate threats to natural resources and historic rock paintings in remote Hells Canyon, Oregon and Idaho, USA, we passively sampled NH3, NOx, SO2, and H2S at five stations along 60 km of the Snake River valley floor from July 2002-June 2003, and obtained ozone data and particulate chemistry from the Interagency Monitoring of Protected Visual Environments (IMPROVE) station at Hells Canyon. Ammonia concentrations were high, biweekly averages peaked at 15-19 ppb in spring and summer; the nutrient-laden Snake River is the most likely source. Fine particulate NH4NO3 averaged 2.6 &micro;g/m3 during the 20% of worst visibility days with winter drainage of air masses from the Snake River Basin and possibly long distance transport from southern California. Other pollutants were within background ranges. Ammonia is corrosive to clay-based pictographs; nitrogen deposition can alter natural biotic communities and terrestrial ecosystem processes at levels reported here.

Geiser, L.H.; Neitlich, P.N. 2007. Air pollution and climate gradients in western Oregon and Washington indicated by epiphytic macrolichens. Environmental Pollution 145: 203-218.

Human activity is changing air quality and climate in the US Pacific Northwest. In a first application of non-metric multidimensional scaling to a large-scale, framework dataset, we modeled lichen community response to air quality and climate gradients at 1416 forested 0.4 ha plots. Model development balanced polluted plots across elevation, forest type and precipitation ranges to isolate pollution response. Air and climate scores were fitted for remaining plots, classed by lichen bioeffects, and mapped. Projected 2040 temperatures would create climate zones with no current analogue. Worst air scores occurred in urban-industrial and agricultural valleys and represented 24% of the landscape. They were correlated with: absence of sensitive lichens, enhancement of nitrophilous lichens, mean wet deposition of ammonium >0.06 mg l-1, lichen nitrogen and sulfur concentrations >0.6% and 0.07%, and SO2 levels harmful to sensitive lichens. The model can detect changes in air quality and climate by scoring re-measurements.

Gerson, U., and M.R. D. Seaward. 1977. Lichen-inverterbrate associations. In: Lichen Ecology, M.R.D. Seaward, ed. Academic Press, London. Pp. 69-119.

Gilbert, O.L. 1965. Lichens as Indicators of Air Pollution in the Tyne Valley Ecology and the Industrial Society. Fifth Symposium of the British Ecological Society. Blackwell Scientific Publications, Oxford. Pp 35-47.

Gilbert, O.L. 1969. The effect of SO2 on lichens and bryophytes around Newcastle upon Tyme. In: Air Pollution: proceedings of the first European symposium; Wageningen, Netherlands: Center for Agricultural Publ. and Documentation. pp.223-235

Gilbert, O.L. 1970. A biological scale for the estimation of sulphur dioxide air polllution. New Phytologist 69: 629-634.

This is basically the same scale Richardson (1992) cites. "To discover a general order of tolerance, lichens and bryophytes were examined along a wide belt of country stretching from an area of pure air to the middle of Newcastle upon Tyne. Once the order had been approximately fixed, it was checked on different radii out from the city until the tolerance limit of the major species had been determined." Zones based on SO2 mg/m3: 1: > 170; 2: 125-170; 3: 60-125; 4: 45-60; 5: 40-45; 6 < 40. Includes table of substrates: acid stone walls, asbestos roofs, boles of deciduous trees.

Gilbert, O.L. 1971. The effect of airborne fluorides on lichens. Lichenologist 5: 26-32.

Gilbert, O.L. 1985. Environmental effects of airborne fluorides for aluminum smelting at Invergordon, Scotland 1971-1983. Environmental Pollution (Series A) 39: 293-302.

A network of 20 recording stations was set up to monitor an aluminum smelting plant. The recording stations were all within 12 k of the plant. In 1971, less than 3 months after the smelter began operation, the regional forester reported spectacular damage to lichens on exposed trees 1-7 k from the smelter. The smelter was eventually shut down in 1983, late 1975 was determined the peak damage period. NW spp Ramalina farinacea is mentioned and F conc. are given.

Gilbert, O.L. 1986. Field evidence for an acid rain effect on lichens. Environmental Pollution (Series A). 40: 227-231.

"Field evidence for an acid rain effect on lichens at two sites in northern England --well established pops of Lobaria pulmonaria on oak and Sticta limbata on ash in remote rural areas were observed to decline to extinction. This was accompanied by bark acidification. Only lichens containing a blue-green algal symbiont (Nostoc) and growing on poorly buffered acidic habitats were affected."

Gilbert, O.L.; GiavariniI, V. J. 1997. The lichen vegetation of acid watercourses in England. The Lichenologist 29: 347-367

The lichen vegetation of forty-five acid watercourses in England is described and related to ecological variables. The zonation scheme adopted for chalk and limestone streams that involves four overlapping bands of lichen vegetation related to length of submergence is also appropriate for this habitat. The flora involves around 90 species, a number of which are rarely recorded specialists. Evidence is presented that substratum chemistry is a more powerful ecological factor than water chemistry. An attempt has been made to relate the lichen flora to homogeneous stream segments from the headwaters down to the alluvial lowlands. An investigation into the effects of water quality showed that both suspended solids (silting) and eutrophication are highly deleterious to the lichen flora; the submerged and fluvial mesic zones are the first to be affected. The zonation across streams in England is compared with those reported from Germany and found to be closely similar.

Glavich, D.A. 2008. The distribution, rarity, and habitats of three aquatic lichens in the US Pacific Northwest. The Bryologist 112(1), pp. 54-72

Using a large-scale random sampling approach and the inclusion of historical site data, frequency, distribution, and habitat 'preferences', which included water quality, forest age, and land use allocations, were assessed for Dermatocarpon meiophyllizum, Leptogium rivale, and Peltigera hydrothyria on federal land in western Washington, Oregon, and northern California. A total of 256 sites were surveyed, of which, 216 were randomly selected. All three species were distributed throughout the study area in all three states, but only L. rivale was widespread. Peltigera hydrothyria was mostly found in the Cascade mountain range of southern Washington south through Oregon, and the distribution of D. meiophyllizum was highly scattered. The frequency and geographic distribution results suggest that both D. meiophyllizum and P. hydrothyria are rare at the northwest forest plan scale but can become locally common in some watersheds. All three lichens probably benefit from older stream-side forests, but association with the greater watershed forest age was inconclusive. Study results suggest association of P. hydrothyria with unprotected federal land allocations while the other two lichens were not associated with land use type. Nonparametric Multiplicative Regression models indicated that climate factors are important to habitat suitability for aquatic lichens. Site level habitat parameters, such as stream channel 'depth', substrate 'preference', and exposure are also summarized. General water quality results find study site streams to be clean, and diatom indices suggest that these aquatic lichens are subject to disturbances from siltation. Results from this study can be used to guide management and research needs are discussed.

Glavich, D.A.; Geiser, L.H. 2008. Potential approaches to developing lichen-based critical loads and levels for nitrogen, sulfur and metal-containing atmospheric pollutants in North America. The Bryologist 111(4): 638-649

'Critical load' and 'critical level' (the deposition or concentration, respectively, of atmospheric pollutants above which negative ecosystem effects occur) concepts are reviewed for the North American lichenological community with the objective of stimulating interest and participation in this emerging field of research. We focus on how regional, lichen-based critical loads for nitrogen-, sulfur- and metal-containing pollutants could be developed for various terrestrial ecosystems in the US utilizing existing data. Specifically we provide examples of how lichen community and element concentration responses to air pollution can be linked with measured or modeled estimates of depositional air pollutants. Preliminary critical loads of 0.26 - 0.33 kg ha-1 yr-1 for deposition of inorganic N in fine particulates and critical levels of 0.044 to 0.055 mg L-1 for wet deposition of ammonium ions are suggested for coniferous forests of western Oregon and Washington. These correspond to initial declines in presence and abundance of sensitive species and a % N concentration of 0.55 to 0.61 in Platismatia glauca. Indicator species distribution and abundance as well as physiological, morphological, growth or reproduction responses can also be used to set critical loads. Further research needs are identified.

Glenn, MG, Webb, SL,Cole, MS. 1998. Forest integrity at anthropogenic edges: air pollution disrupts bioindicators. Environmental Monitoring and Assessment 51: 163-169.

The response of corticolous lichens, bryophytes, and vascular plants to anthropogenic edges in northern hardwood forest preserves is compared in east-coast and mid-west (NW MN) sites, using micro-epiphytes on red oak (Quercus rubra) and sugar maple (Acer sacacharum). The drastically attenuated lichen flora in the east, apparently due to regional air pollution, restricts the usefulness of these bioindicators, even 120 km from NYC. The forest edge is not necessarily equated with increased light. Established edges may have pronounced shoot growth that shades epiphytes. In the absence of air pollution, lichen and bryophyte species exibit individual responses to light, humidity, and substrate chemistry. Thus summary variables such as total cover or species richness have limited value as bioindicators of forest integrity.

Godoy, R; Oyarzún, C; Gerding, V 2001. Precipitation chemistry in deciduous and evergreen Nothofagus forests of southern Chile under a low-deposition climate. Basic and Applied Ecology 2(1): 65-72.

The chemistry of rainfall and its redistribution were studied during the periods July 1997-December 1998 in a Nothofagus pumilio (summergreen) forest and in April 1999-March 2000 in a Nothofagus betuloides (evergreen) forest in two experimental micro-catchments, located in the Puyehue National Park, southern Chile (41 °S). Annual precipitation varied from 5406 to 6559 mm during the studied periods, with about 68- 80% as rain and 32-20% as snowfall. The average pH of bulk precipitation was 5.7. In the N. pumilio forest, the pH of throughfall, stemflow and effective precipitation was 5.7. In the infiltrating water it increased to 5.9 and in the runoff to 7.0. In the N. betuloides forest, the pH value of the precipitation was 6.1 and showed a slight increase in throughfall and soil water to 6.2 and in runoff to 6.5. NO3-N concentrations increased inside of both forests, especially in stemflow, suggesting biological N fixation in the canopy due to the presence of epiphytic lichens of the genera Peltigera, Pseudocyphellaria and Sticta living on the trunks, but decreased in the runoff. NH4-N concentrations decreased in all compartments inside the forests, especially in runoff water, compared with bulk precipitation. Concentrations of K+, Na+, Ca2+ and Mg2+ were higher in throughfall, stemflow and soil solution than in the bulk precipitation. The runoff water both of the N. pumilio and the N. betuloides forest was enriched with cations, especially with Ca2+ and Mg2+, indicating active weathering processes. The input of inorganic nitrogen (NO3-N + NH4-N) via precipitation amounted 3.3 kg ha-1yr-1 in the studied area, suggesting some anthropogenic contribution from the agricultural activities in the Central Valley and pointing at high levels of rainfall in the Cordillera de los Andes of southern Chile. The water chemistry data are compared with corresponding data from European and North American forests with a particular emphasis on nitrogen deposition.

Gombert, S; Asta, J; Seaward, M R D. 2006. Lichens and tobacco plants as complementary biomonitors of air pollution in the Grenoble area (Isöre, southeast France). Ecological Indicators 6(2): 429-443.

Gombert, S; Asta, J; SSeaward, M R D. 2003. Correlation between the nitrogen concentration of two epiphytic lichens and the traffic density in an urban area. Environmental Pollution 123: 281-290.

Gordon, C; Wynn, JM; Woodin, SJ. 2001. Impacts of increased nitrogen supply on high arctic heath: the importance of bryophytes and phosphorus availability. New Phytologist 149: 461-471.

This study investigates effects of nitrogen and phosphorus on high Arctic heath vegetation, particularly bryophytes. Heath communities received factorial combinations of nitrogen (0, 10 and 50 kg ha-1 yr-1) and phosphorus (0 and 5 kg ha-1 yr-1) in five applications per growing season, for 8 yr. Nitrogen decreased lichen cover but did not affect cover of any other functional type. However, just 10 kg ha-1 yr-1 increased the proportion of physiologically active bryophte shoots, and decreased their nitrate assimilation capacity. Phosphorus had greater effects, and the combination of both nutrients altered species composition. Individual bryophyte species displayed contrasting responses to fertilization, suggesting that they should not be grouped as a single functional type. The 'critical load' of nitrogen for Arctic heath lies below 10 kg ha-1 yr-1. Nitrogen and phosphorus are colimiting in this sytem, so the critical load of nitrogen will be lower where phosphorus availability is greater. Responses of vegetation to any increase in net mineralisation due to soil warming will depend on the ratio in which nitrogen and phosphorus availabilities increase. The effects of nutrient enhancement are very persistent.

Gough, L.P. 1975. Cryptogam distributions on Pseudotsuga menziesii and Abies lasiocarpa in the Front Range, Boulder Co., CO. Bryologist 78: 124-145.

Included bark conditions for 5 conifer spp. and Populus trichocarpa. " The rate of bark scaling appeared to be the most important substrate feature governing the abundance of epiphytic growth on different conifer spp." Includes a table w/ bark pH and moisture holding capacities, which may interaction with pollutants to affect lichen spp.

Gough, L.P., and J.A. Erdman. 1977. Influence of a Coal-Fired Powerplant on the Element Content of Xanthoparmelia chlorochroa. Bryologist 80: 492-501.

The operations of the Dave Johnston coal-fired power plant near Glenrock WY have had a measurable effect on trace-element conc. in Xanthoparmelia chlorochroa, which is common to the area. Conc. of 35 elements were measured in samples collected along upwind and downwind transects. Of these elements, conc. of Ca, Fl, Li, Sel, Str, U as well as ash yields, decreased with distance from the power plant. compared to background levels established for this lichen form the Powder River Basin only the selenium values near the power plant are considered unusually high.

Gough, L.P., J.L. Peard, R.C. Severson, L.L. Jackson, et al. 1988. Determining baseline element composition of lichens: I. Parmelia sulcata at Theodore Roosevelt NP, ND. Water, Air, and Soil Poll. 38: 157-167.

"Element-conc. baselines are given for Parmelia sulcata and assoc. soils. Xanthoparmelia chlorochroa was found sporadically and therefore only representative conc. ranges are reported for this sp." "Very little (usually <10%) of the variability in the element data for lichen material occurs regionally (> 7.2 k); thus, P. sulcata is, in general, chemically similar throughout the park. This same uniformity was found for soil geochemistry." "No instances of elemental phototoxic conditions were found; however, P. sulcata apparently possesses large conc. of Ba, Cu, Fe, Pb, S, V and possibly Zn."

Gough, L.P., L.L. Jackson, et al. 1987. Element baselines for Redwood National Park, California--Composition of the Epiphytic Lichens Hypogymnia enteromorpha and Usnea spp: Open-file Report 87-169. U.S. Department of the Interior, Geological Survey, Denver.

Gough, L. P., L. L. Jackson, and J. A. Sacklin. 1988. Determining baseline element composition of lichens. II. Hypogymnia enteromorpha and Usnea spp. at Redwood National Park, California. Water, Air and Soil Pollution 38: 169-180.

Elemental baselines are presented for Hypogymnia enteromorpha and Usnea spp. Geometric means are used in my tables and are based on n=29, because 6 of the original 35 samples are analytic splits, the method cited to obtain the geometric mean is Cohen (Miesch, 1976). Gough et al expected larger analytic error terms for Usnea spp, than for H. enteromorpha, but H. enteromorpha had 13 elements with error terms of > 50%, where Usnea spp. had only 5. Ultramafic soils are noted as probably being responsible for elevated levels of Cr, Co, Mg, Mn, and Ni in lichen samples.

Goward, T. 1987. Notes on the distributional ecology of epiphytic macrolichens in the Kamloops area, with special reference to the wolf lichen (Letharia vulpina).138: Ministry of Environment and Parks, Waste Management Branch, Southern Interior Region, Kamloops.

Goyal, R., and M.R.D. Seaward. 1981, 1982a, 1982b. New Phytol. 89:631, 90:73, 90:85.

"The nature of the accumulation patterns within the lichen is assessed in terms of metal localization within the different thallial components (ie. rhizinae, thallus w/out rhizinae, , phycobioint, mycobiont)" "Peltigera canina, P.polydactyla, Peltigera rufescens, Cladonia furcata, C. implexa, C. unicalis...were analyzed for Cr, Fe, Mn, Ni, Pb, Zn." "Metal accumulation capacity (&micro;g/gm) of the rhizinae was maximum for Fe Mn, Pb. The phycobiont was found to have maximal accumulation capacity for Cu, Ni, Zn. The metal accumulation capacities by rhizinae and thallus without rhizinae as well as phycobiont and mycobiont without rhizinae were found to be interrelated and were dependent upon the biologically available metal conc. in their assoc. soils as well as the type of substrate." "Rhizinae accumulate the highest conc. of all metals under enhanced environments." "The observed modifications of the morphology and histology of P. canina and P. rufescens in metal-polluted environments are: reduction in thallial size and rhizinal length, and dense rhizinal growth, profusely-branched veins and hypertrophy of the medulla. The value of terricolous lichens as bioindicators of metal-enriched substrata is related to the biologically available metal concentrations in the assoc. soils and the nature of the substratum." "Lab experiments critically assess the role of rhizinae and thallial surfaces of P. canina in the accumulation and translocation of metals (Cu, Fe, Mn, Ni, Pb, Zn) from external medium to and within the thallus."

Grace, B., T.J. Gillespie, and K.J. Puckett. 1985a. Uptake of gaseous sulphur dioxide by the lichen Cladina rangiferina. Canadian J. Botany 63: 797-805.

["Potassium release was shown to increase with an increasing uptake of sulphur dioxide (time-integrated flux), but was not uniquely related to sulphur dioxide concentration alone."]

Grace, B., T.J. Gillespie, and K.J. Puckett. 1985b. Sulphur dioxide threshold concentration values for Cladina rangiferina in the Mackenzie Valley, N. W. T. Canadian J. Botany 63: 806-812.

["A simulation model for the prediction of threshold concentration values of gaseous sulphur dioxide for damage to Cladina rangiferina over a 24-h period is presented. Boundary-layer resistance was found to be not as important as internal thallus resistance to sulphur dioxide uptake. Thus, it was possible to determine the threshold atmospheric SO2 concentrations under field conditions that would produce a specified uptake and hence lichen damage."]

Gries, C., M.-J. Sanz, and T.H. Nash III. 1995. The effect of SO2 fumigation on CO2 gas exchange, chlorophyll fluorescence and chlorophyll degradation in different lichen secies from western North America. Crypt. Bot. 5: 239-246.

Gunther, A.J. 1988. Effect of simulated acid rain on nitrogenase activity in the lichen genus Peltigera under field and laboratory conditions. Water, Air and Soil Pollution 38: 379-385.

"Lichens of the genus Peltigera were exposed to simulated acid rain in the lab and at a field site in SW Alaska. Exposure to simulated rainfall of pH 4.4 had no effect upon acetylene reduction in P. rufescens after experiments of 28 and 60 days duration, although in the former experiment there was some evidence of a transient effect after 14 days. Simulated acid rain of pH 3.4 or 4.4 also had no effect on nitrogenase activity in P. aphthosa during a 21-day field study, indicating that nitrogenase activity in Peltigera is not sensitive to precipitation in this range of acidity."

Gunther, P.M., B.S. Horn, and G.D. Babb. 1983. Small mammal populations and food selection in relation to timber harvest practices in the western Cascade Mountains. Northwest Science 57:32-44.

Hahn, SC; Tenhunen, JD; Popp, PW; Meyer, A; Lange, OL. 1993. Upland tundra in the foothills of the Brooks Range, Alaska: diurnal CO2 exchange patterns of characteristic lichen species. Flora 188: 125-143.

Detailed field study of CO2 exchange relative to water content and microclimate conditions in seven lichen species: Masonhalea richardsonii, Cetraria cucullata, Stereocaulon alpinum, Thamnolia vermicularis, Dactylina arctica, Peltigera aphthosa, P. malacea. "Even short periods of favourable hydration were used by lichens for positive net photosynthesis (NP). There was no indication of adverse consequences of "resaturation respiration." Even after a dry period of 3 days, sudden rehydration resulted in carbon gain without delay. For short periods of time, the combinations of water content, temperature and light imposed on the lichens enables high rate of NP. Individual species differed greatly in their maximal NP rate, which correlated with chlorophyll and nitrogen content. At favourable times in the field, observed NP rates approached the maximum capacity found in the laboratory experiments at natural ambient CO2. Often with sufficient hydration, carbon gain was limited by light. CO2 exchange became negative even during daylight hours due to the effects of fog and clouds with light below compensation levels. Reduced but still positive rates of NP were observed with snow and with frozen lichens."

Hale, M.E. 1979. Phytosociology of corticolous cryptogams in the upland forests of southern Wisconsin. Ecology 36(1): 45-63.

Hale, M.E. 1981. Lichens as bioindicators and Monitors of Air Pollution in the Flat Tops Wilderness Area, Colorado. Final Report: USFS Contract No. ON RFP R2-81-SP35.

Hale, M.E. 1983 Cortical structure in Physcia and Phaeophyscia . Lichenologist 643-651

Hallgren, JE; Nyman, B 1977. Observations on trees of Scots pine (Pinus silvestris L.) and lichens around a HF and CO2 emission source. Stud. For. Suecica 137: 1-40.

Hallingback, T. 1989. Occurrence and ecology of the lichen Lobaria scrobiculata in southern Sweden. Lichenologist 21: 331-341.

[Revisitation and study of 50 sites where Lobaria scrobiculata had been collected between 1850 and 1950, as well as 17 sites discovered since 1980. Of the old sites, the species was confirmed at only 2.] The present occurrence and vitality of L. scrobiculata were investigated at 67 localities (50 old and 17 new) in southern Sweden. Before 1950,L. scrobiculatawas found at more than 300 localities in southern Sweeden. However it was only confirmed at two out of 50 thoroughly investigated old localities. An investigation of recently found localities (new) and confirmed old sites showed that there have been a decrease in pop. sie, thallus size, fertility,, number of phorophytes, and cliff colonization. In southern Sweden today, L. scrobiculata is confined to old deciduous trees in regions with comparatively low air pollution and a high relative humidity. Apothecia have not been found in southern Sweden since 1947, although in the past, fertile material was collected from 35 localities in the region. The author suggests that this species, like many other lichens with the cyanobacterium Nostoc as photobiont, is currently more endangered by air pollution than by any other human activity and that it is seriously endangered in the southern part of Sweden.

Hallingback, T., and O. Kellner. 1991. Effects of simulated nitrogen rich and acid rain on the nitrogen-fixing lichen Peltigera apthosa (L.) Willd.

"The nitrogen-fixing lichen Peltigera apthosa was treated under semi-natural conditions with simulated rain containing different combinations of ammonium, nitrate, and sulfuric acid. Nitrogen in neutral solution had no negative effect on the nitrogen fixing rate. Sulfuric acid had a negative effect on the nitrogen fixing rate, especially in combination with ammonium. (Low pH is the main reason why acid rain is detrimental to P. apthosa.) The results could suggest an explanation for the sudden decline in P. apthosa. in southern Sweden."

Hallingbäck, T.; Kellner, O. 1992. Effects of simulated nitrogen rich and acid rain on the nitrogen-fixing lichen Peltigera aphthosa (L.) Willd. New Phytologist 120(1): 99-103.

The nitrogen-fixing lichen Peltigera aphthosa was treated under semi-natural conditions with simulated rain containing different combinations of ammonium, nitrate and sulphuric acid. Nitrogen in neutral solution had no negative effect on the nitrogen fixation rate. Sulphuric acid had a negative effect on nitrogen fixation rate, especially in combination with ammonium. The results could suggest an explanation for the sudden decline of P. aphthosa in southern Sweden.

Hanley, T.A., C.T. Robbins, and D.E. Spalinger. 1989. Forest habitats and the nutritional ecology of Sitka black-tailed deer; a research synthesis with implications for forest management. USDA-Forest Service Pcific Northwest Experiment Station GTR.

Harper, K.T., and J. R. Marble. 1988. A role of nonvascular plants in management of semiarid rangelands. In: Vegetation Science Applications for Rangeland Analysis and Management, ed. P. T. Tueller, pp. 135-60. London: Kluwer Academic Publishers.

Harper, KT; Pendleton, RL 1993. Cyanobacteria and cyanolichens: can they enhance availability of essential minerals

Hasse, T; Daniëls, FJA 2006. Species responses to experimentally induced habitat changes in a Corynephorus grassland. Journal of Vegetation Science 17: 135-146.

To which extent do external ecological factors effect Corynephorus grassland vegetation? Location: Central Netherlands. Methods: We implemented different treatments (sand deposition, litter deposition, nitrogen input, mechanical disturbance, control) in permanent plots representing different successional phases in Corynephorus grassland. Plots were recorded just before the treatments and during the subsequent two years. Vegetation changes were analysed by Redundancy Analysis for repeated measurements and Correspondence Analysis, changes in single species abundances by ANOVA. Results: Species composition hardly changed during the observation period. Several single species abundances showed significant responses to different treatments, most often decrements as direct effects of cover, removal, or dieback. However, Corynephorus canescens and Polytrichum piliferum benefited from sand deposition, the exotic moss Campylopus introflexus from litter deposition. In the colonization phase Polytrichum, Campylopus and Cladonia diversa increased irrespective treatment. Therophytes such as Spergula morisonii showed the strongest negative response to drought, grasses (e.g. Corynephorus canescens) and bryophytes (e.g. Polytrichum piliferum) were less susceptible. Most lichens did not respond at all. Conclusions: The experiment confirms the high stability of Corynephorus grassland vegetation. Most vegetation changes are in accordance with the hypothetical series of successional phases. In contrast, changes in abundance of single species express considerable dynamics within the vegetation. Species responses also depend on extreme weather conditions as well as on the successional phase of the grassland vegetation and therefore on the competition situation.

Hauck, M. 2005. Epiphytic lichen diversity on dead and dying conifers under different levels of atmospheric pollution. Environmental Pollution 135: 111-119.

Based on literature data, epiphytic lichen abundance was comparably studied in montane woodlands on healthy versus dead or dying conifers of Europe and North America in areas with different levels of atmospheric pollution. Study sites comprised Picea abies forests in the Harz Mountains and in the northern Alps, Germany, Picea rubens-Abies balsamea forests on Whiteface Mountain, Adirondacks, New York, U.S.A. and Picea engelmannii-Abies lasiocarpa forests in the Salish Mountains, Montana, U.S.A. Detrended correspondence analysis showed that epiphytic lichen vegetation differed more between healthy and dead or dying trees at high- versus low-polluted sites. This is attributed to greater differences in chemical habitat conditions between trees of different vitality in highly polluted areas. Based on these results, a hypothetical model of relative importance of site factors for small-scale variation of epiphytic lichen abundance versus atmospheric pollutant load is discussed.

Hawsworth, D.L., and F. Rose. 1970. Qualitative scale for estimating sulphur dioxide pollution in England and Wales using epiphytic lichens. Nature (London) 227: 145-148.

Scale designed for use in Britain on deciduous trees in open areas. NW spp: non-nitrophilous -- Hypogymnia physodes, Parmelia sulcata, Hypogymnia enteromorpha, Collema nigrescens, Peltigera rufescens, Parmelia saxatilis, Melanelia glabratula, Puntelia subrudecta, Parmeliopsis ambigua, Ramalina farinacea, Evernia prunastri, Platismatia glauca, Melanelia exasperatula, Bryoria fuscescens, Normandina pulchella, Lobaria pulmonaria, Lobaria scrobiculata, Sticta limbata, Teloschistes flavicans. Nitrophilous: Physcia adscendens, Xanthoria parietina, Phaeophyscia orbicularis, Physcia tenella, Ramalina farinacea, Xanthoria candelaria, Physcia aipolia, Candelaria concolor, Ramalina pollinaria.

Hawsworth, D.L., and F. Rose. 1976. Lichens as Pollution Monitors. The Institute of Biology's Studies in Biology no.66. London: Edward Arnold Ltd.

A comprehensive study including: What are lichens?, SO2, other Pollutants, other Factors affecting Lichen Distribution, Mapping Air Pollution Patterns, Impact of SO2 on the British Lichen Flora, Trends and Conservation, Appendices on ID and Methodology. NW spp:Evernia prunastri, Hypogymnia physodes, Ramalina farinacea, Parmelia saxatilis, Parmelia sulcata, Peltigera rufescens, Teloschistes flavicans, Xanthoria elegans, Nephroma laevigatum, Caloplaca saxicola, Physcia caesia, Pannaria rubiginosa, Normandina pulchella, Lobaria pulmonaria, Lobaria scrobiculata, Sticta limbata, Xanthoria parietina, Physcia adscendens, Phaeophyscia orbicularis, Physcia tenella, Xanthoria candelaria, Ramalina pollinaria, Bryoria fuscescens, Candelaria concolor, Platismatia glauca. "Lobarion" and "Xanthorion" communities are explained.

Hawsworth, D.L., F. Rose, and B.J. Coppins. 1973. Changes in the lichen flora of England and Wales attributable to pollution of the air by sulphur dioxide. Pp 330-367. In: Ferry, B.W., M.S. Baddeley, and D.L. Hawksworth, (eds.) Air Pollution and Lichens, London.

Henriksson, LE; DaSilva, EJ 1978. Effect of some inorganic elements on nitrogen-fixation in blue-green algae and some ecologial aspects of pollution. Zeitschrift fur Allgemeine Mikrobiologie 18: 487-494.

Herben, T., and J. Liska. 1984. The use of average number of neighbours for predicting lichen sensitivity: a case study. Lichenologist 16: 289-296.

[Study in Czechoslovakia compared the rates of disappearance of lichen species with the ecological index (average number of neighbors of a given species). "Linear correlation showed that this ecological index is a reasonably accurate indicator of species sensitivity." This measure was not as reliable for non-SO2 related conditions.]--when the selection of spp. was performed according to criteria other than SO2 sensitivity, viz. according to the predilections of lichens for eutrophicated bark, the ecological index proved reliable only when trees whose conditions were non-optimal for this group were excluded. When applied to the group of spp. that avoids eutrophicated bark, the ecological index proved most reliable, although the group of nitrophilious spp. may also be used in air poll. indicator studies. NW spp growing on eutrophicated bark (Nitrophilous)--w/no reference to the barks N2 content: Melanelia exasperatula, Parmelia sulcata, Physcia adscendens, Physcia aipolia, Physcia caesia, Physcia tenella, Physcia stellaris, Phaeophyscia orbicularis, Physconia enteroxantha, Ramalina farinacea, Xanthoria parietina, Xanthoria polycarpa. NW Non-nitroph spp: Bryoria fuscescens, Candelaria concolor, Tuckermannopsis chlorophylla, Evernia prunastri, Hypogymnia physodes, Melanelia glabratula, Platismatia glauca, Ramalina pollinaria, Usnea hirta. Lichen sensitivity was assessed according to the rate of change of individual lichen occurrence over a 5-yr period. The most common phorophytes were Tilia spp., Fraxinus excelsior, Acer platonoides, and Quercus spp.

Herzig, R., et al. 1989. Passive biomonitoring with lichens as a part of an integrated biological measuring system for monitoring air pollution in Switzerland. International J. Environmental Analytical Chemistry. 35: 43-57.

"Hypogymnia physodes possesses good accumulation capacity for important air pollutants. The passive biomonitoring and calibrated lichen indication method (IAP) compose together an integral biological testing system for air pollution in Switzerland. IAP is useful in measuring total air pollution, while passive biomonitoring gives precise conclusions on prevalent single pollutants. IAP is based on presence/absence and classifies by 5 zones, 1 being lichen desert and 5 being the normal zone. The authors used passive biomonitoring: multi-element analysis on H. physodes using samples from trees in the vicinity near each of the Bieler emmission stations -- both methods were used and results compared. H. physodes is noted in the intro as being one of the most studied plant sp. in relation to different emmission components (SO2, NOx, O3, dust, heavy metals, pesticides, and other organic compounds). The authors found H. physodes accumulation: environmental deposition as follows: Pb, Cu, S -- and SO2 five yr mean all correlated well. There were problems with Zn (contaminated by zinc fencing and street lamps). Calibration by natural samples of H. physodes and transplants worked equally well and the natural (passive) method has the advantage of lower cost.

Herzig, R., et al. 1990. Lichens as biological indicators of air pollution in Switzerland: passive biomonitoring as part of an integrated measuring system for monitoring air pollution. In: H. Lieth and B. Markert (eds.). Element Concentration Cadasters in Ecosystems Methods of Assessment and Evaluation. 141: VCH Verlagsgesellschaft, Weinheim. 317p.

[Hypogymnia physodes was used as the biomonitoring species. "With the aid of passive biomonitoring it is possible to determine which single(s) pollutant(s) affect(s) the lichen community, discovered by calibrated lichen method and seem to be relevant in producing patterns of degradations in lichen vegetation."]

Hobbie, SE; Shevtsova, A; Chapin, FS III 1999. Plant responses to species removal and experimental warming in Alaskan tussock tundra Oikos 84: 417-434

We manipulated air temperature and the presence of the seven dominant plant species in Alaskan tussock tundra and measured shoot growth, branching. Above-ground biomass, and reproduction of the remaining plant species. Warming stimulated shoot growth of the dominant sedges and shrubs after one and two years of manipulation and total leaf biomass of the dominant shrubs after three years. Warming decreased aboveground biomass of Eriophorum vaginatum, Cassiope tetragona and most non-vascular species. Warming also reduced total reproductive output of two of three species measured. Removal of single species had no effect on shoot growth of the remaining species. However, total aboveground biomass and reproduction of Ledum palustre increased with removal of other shrub species, suggesting that competition limits biomass accumulation L. palustre. Sphagnum removal increased the aboveground biomass of Betula nana. The higher frequency of significant warming versus species removal effects on plant growth and biomass suggests that direct limitation by environmental conditions is more important than limitation by species interactions in tussock tundra. Furthermore, we found no significant interactions between warming and species removal, suggesting that increased temperature per se will not alter the intensity of species interactions. When combined with knowledge of dispersal abilities and controls over establishment, extrapolation of species responses to environmental manipulation may thus allow us to predict effects of climate change on community composition.

Hoffman, G.R. 1974. The Influence of a paper pulp mill on the ecological distribution of epiphytic cryptogams in the vicinity of Lewiston, Idaho and Clarkston, Washington. Environmental Pollution. 7: 283-301.

Högberg, P; Fan, H; Quis, M.; Binkley, D; Tamm 2006. Tree growth and soil acidification in response to 30 years of experimental nitrogen loading on boreal forest Global Change Biology 12, 489-499,

Relations among nitrogen load, soil acidification and forest growth have been evaluated based on short-term (<15 years) experiments, or on surveys across gradients of N deposition that may also include variations in edaphic conditions and other pollutants, which confound the interpretation of effects of N per se. We report effects on trees and soils in a uniquely long-term (30 years) experiment with annual N loading on an unpolluted boreal forest. Ammonium nitrate was added to replicated (N53) 0.09 ha plots at two doses, N1 and N2, 34 and 68 kg N ha-1 yr-1, respectively. A third treatment, N3, 108 kg N ha-1 yr-1, was terminated after 20 years, allowing assessment of recovery during 10 years. Tree growth initially responded positively to all N treatments, but the longer term response was highly rate dependent with no gain in N3, a gain of 50 m3 ha-1 stemwood in N2 and a gain of 100m3 ha-1 stemwood in excess of the control (N0) in N1. High N treatments caused losses of up to 70% of exchangeable base cations (Ca2+, Mg2+, K+) in the mineral soil, along with decreases in pH and increases in exchangeable Al31. In contrast, the organic mor-layer (forest floor) in the N-treated plots had similar amounts per hectare of exchangeable base cations as in the N0 treatment. Magnesium was even higher in the mor of N-treated plots, providing evidence of up-lift by the trees from the mineral soil. Tree growth did not correlate with the soil Ca/Al ratio (a suggested predictor of effects of soil acidity on tree growth). A boron deficiency occurred on N-treated plots, but was corrected at an early stage. Extractable NH4+ and NO3- were high in mor and mineral soils of on-going N treatments, while NH4+ was elevated in the mor only in N3 plots. Ten years after termination of N addition in the N3 treatment, the pH had increased significantly in the mineral soil; there were also tendencies of higher soil base status and concentrations of base cations in the foliage. Our data suggest the recovery of soil chemical properties, notably pH, may be quicker after removal of the N-load than predicted. Our long-term experiment demonstrated the fundamental importance of the rate of N application relative to the total amount of N applied, in particular with regard to tree growth and C sequestration. Hence, experiments adding high doses of N over short periods do not mimic the long-term effects of N deposition at lower rates.

Holopainen, T.H. 1984. Cellular injuries in epiphytic lichens transplanted to air polluted areas. Nordic J. Botany 4: 393-408.

Holopainen, T., and L. Karenlampi. 1984. Injuries to lichen ultrastructure caused by sulphur dioxide fumigations. New Phytologist 98: 285-294.

Holopainen, T., and M. Kauppi. 1989. A comparison of light, fluorescence and electron microscopic observations in assessing the SO2 injury of lichens under different moisture conditions. Lichenologist. 21: 119-134.

Hypogymnia physodes, Bryoria capillaris, Peltigera canina, were fumigated with 215 mg/m3 (6hrs/day, 5 days/wk) and were examined with electron, fluorescence, and light microscopes. Electron was the most sensitive method for revealing cellular injury. The intervals of examination were 5,10, 15, and 20 days. All spp. were clearly more sensitive to SO2 when cultured in high humidity and additional moisture tended to protect the lichens from injury.

Holopainen, JK; Mustaniemi, A; Kainulainen, P; Satka, H; Oksanen, J 1993. Conifer aphids in an air-polluted environment. I. Aphid density, growth and accumulation of sulphur and nitrogen by scots pine and norway spruce seedlings. Environmental Pollution 80: 185-191.

Holopainen, T.; Karenlampi, L. 1985. Characteristic ultrastructural symptoms caused in lichens by experimental exposure to nitrogen compounds and fluorides. Annales Botanici Fennici 22: 333-342.

Transmission electron microscopy was used to study the effects of fumigation with NO2 (0.3 and 1.0 ppm) and treatment with solutions of some other nitrogen compounds (NH4Cl, NaNO3, NH4NO3) and fluorides (HF, KF) on Bryoria capillaris and Hypogymnia physodes. The N compounds and fluorides were observed to cause characteristic ultrastructural symptoms in the lichens. These symptoms could be distinguished from the injuries caused by fumigation with SO2. All the N compounds used induced accumulation of electron-opaque substances, visible as dark bodies, in the vacuoles of both the algal and fungal cells. These bodies were different from the polyphosphate granules caused by treatment with KH2PO4. General degeneration of the fungal cells was observed after treatment N compounds, especially with NO2. The structural injury caused by fluorides in the algal cells began as severe swelling of thylakoids and their interspaces and granulation of the cytoplasm and mitochondrial matrix. Later the thylakoids disintegrated and formed vesicles and membrane whorls, and finally were seen in the electron micrographs as a granular white-stippled mass. No distinct type of injury was observed in the fungal cells. The experimental results accord with earlier observations made on lichens in industrial environments where N compounds and fluorides are known to be emitted.

Holopainen, T.H. 1983. Ultrastructural changes in epiphytic lichens, Bryoria capillaris and Hypogymnia physodes, growing near a fertilizer plant and a pulp mill in central Finland. Annales Botanici Fennici 20: 169-185.

The effects of industrial air pollution on Bryoria capillaris and Hypogymnia physodes were studied at light and electron microscopic level in material sampled in the surroundings of a fertilizer plant and a pulp mill. The changes observed at light and electron microscopic levels were very similar in the two industrial environments. Light microscopy revealed an increase in the number of algal cells in both species, and a decrease in the thickness of the cortex layer in H. physodes. At electron microscopic level changes could be seen in both visibly damaged and undamaged thalli. The chloroplast of Trebouxia phycobionts had a rounded appearance, instead of the normal lobate shape and showed changes in the thylakoid arrangement. The pyrenoglobuli and cytoplasmic storage droplets in algal cells remained small throughout the year compared with those in the controls. The algal cells of the polluted lichens frequently contained dark vacuolar bodies, which were only occasionally seen in the controls. In the mycobiont cells abnormally strong vacuolization occurred and their cytoplasmic storage droplets were smaller than those in the controls, or absent, throughout the year. The fungal vacuoles often contained dark accumulations which were never seen in control lichens. It is concluded that both symbionts are affected during long-term atmospheric pollution stress. The ultrastructural changes observed are attributed mainly to SO2 and nitrogen compounds.

Hornveldt, R. 1974. The response of epiphytic lichens to fluoride pollution. pp. 93-94. In: Karenlampi, L. (ed.), Proceedings, Kuoppio, Finland. Kuopio Natualist's Soc.

Huebert, D.B., S.J. L'Hirondelle, P.A. Addison. 1985. The effects of sulphur dioxide on net CO2 assimilation in the lichen Evernia mesomorpha Nyl. New Phytologist 100: 643-651.

Hultengren, S., C. Kannesten , and S. Svensson. 1993. Om nagra oceaniska lavar i Sydvastsverige [On some oceanic lichens in southwestern Sweden]. Graphis Scripta 5: 24-38.

[Discusses the present status of the oceanic lichens Degelia plumbea, Lobaria amplissima, L. scrobiculata, L. virens, Normandina pulchella, Pannaria conoplea, P. mediterranea, and P. rubiginosa, and makes comparisons to the results of Gunnar Degelius in 1935.]

Hutchinson, T.C., M. Dixon, and M. Scott. 1986. The effect of simulated acid rain on feather mosses and lichens of the boreal forest. Water, Air, & Soil Poll. 31: 409-416.

"...field sprayed lichens were also visibly damaged. At pHs less than 3.5 Cladina rangiferina and C. stellaris had reduced podetial height and dry wt; while C. mitis was affected by a combination of the acid rain treatment and other associated factors." [Study in Canada on Cladina spp. "While ambient rains of pH 4.2 may not in themselves be harmful to the boreal ground flora, it is apparent that the feather mosses and lichens, lacking a cuticle and true roots, are very sensitive to occasional, extremely acid rain events."]

Hultengren, S; Gral é n, H 2004. Recovery of the epiphytic lichen flora following air quality improvement in south-west Sweden. Water, Air, and Soil Pollution 154(1-4): 203-211.

The development of the epiphytic lichen vegetation on tree trunks inside and nearby twelve towns and industrial areas in south-west Sweden was investigated 1986/88 and 1997 using a photographic technique. The lichen vegetation studied in terms of area cover as well as the air pollution sensitivity and preference for nitrogen of the individual lichens. During both surveys the lichen flora was strongly impoverished in urban areas compared to suburban areas and especially to the countryside (reference) areas nearby. The air pollution situation has improved in the area both before and during the study period. This holds especially for SO2, to a lesser extent also for NO2. Following the improvement of the air quality, an increased lichen area cover on the tree trunks was observed. Also the cumulative pollution sensitivity of the lichens present was higher in 1997 compared to 1986/88 in suburban and countryside areas. For the nitrogen impact, the increase from 1986/88 to 1997 was smaller than for pollution sensitivity, but still statistically significant. The trends are interpreted as signs of a normalization of the lichen flora. It is concluded that the observed pattern of lichen recovery reflects the fact that the reduction of the air pollution level in the central parts of the towns is still not large enough to permit a large-scale recovery of the lichen flora, while in the suburban areas and the countryside next to the towns, the air quality has now improved to an extent, which permits the reinvasion of a number of lichens.

Hyvärinen, M.; Crittenden, P.D. 1998. Growth of the cushion-forming lichen, Cladonia portentosa, at nitrogen-polluted and unpolluted heathland sites. Environmental and Experimental Botany 40: 67-76.

Biomass increments in the cushion-forming heathland lichen Cladonia portentosa were measured at five heathland sites differing in precipitation acidity, wet nitrogen deposition and annual rainfall. Pre-weighed thalli were placed in the field to grow; one half of the material was native to the sites and the second half was transplanted from a background site in northernmost Scotland. After 1 year, lichens were harvested, weighed and the total N concentration in transplanted lichens was measured in the apical 5 mm of thalli (apices) and in a stratum between 40 and 50 mm from the top (base). Site means for 1 year's biomass yield varied between 20 and 60% and relative growth rates (RGRs) (mg mg-1 yr-1) ranged between 0.13 and 0.43. No significant regional differences in the growth of native lichens were encountered which may have implications for pollution monitoring. Transplanted thalli grew significantly slower than native material suggesting a poor adaptability to alien environments. Nitrogen concentration in both apices and bases of transplanted lichens increased significantly during the year at those sites subject to high N deposition but, owing to retarded growth at these locations, estimated total N uptake by the lichen (N concentration in the thallus base-mass increment) was broadly similar at all sites. Thus, at the site with the highest wet N deposition load, N input greatly exceeded uptake whereas at the background site the two quantities were similar. In contrast, estimated N uptake in lichens native to each site was similar to the site-specific quantity of wet deposited N.

Hyvärinen, M.; Crittenden, P.D. 1998. Relationships between atmospheric nitrogen inputs and the vertical nitrogen and phosphorus concentration gradients in the lichen Cladonia portentosa. New Phytologist 140: 519-530.

The relationship between precipitation chemistry and the concentrations of N and P in the cushion-forming lichen Cladonia portentosa was investigated. Samples of C. portentosa were collected from heathlands and upland moorlands close to 31 rural sampling stations in the UK Acid Deposition Monitoring Network, which provides data on wet deposition and NO2 concentrations in air. [N] and [P] were measured in the top 5 mm of lichen thallus apices and also in a horizontal stratum between 40-50 mm from the apices (thallus base). The dw [N] was 0.08-1.82% and [P] was 0.04-0.17%, depending on collection site and lichen fraction analyzed. Concentrations of both elements were c. 2-5 x greater in the apices than in the basal strata, and [N] and [P] in each stratum were strongly positively correlated. Lichen [N] was positively correlated with N deposition: this relationship was stronger when using [N] values for thallus bases than for the apices. By contrast, thallus [N] was poorly correlated with [N] values in precipitation. When [NO2] in air was included together with NO3- deposition in a linear regression model explaining thallus base N, the model fit was significantly improved, whereas modeled values of NH3 deposition rate for the heathland sites did not correlate with lichen [N]. It is suggested that the proportionately greater enrichment of [N] in the thallus base might reflect a perturbation of internal recycling of thallus N at polluted sites. Thallus [P] was generally weakly linked to wet N deposition but positively correlated with [NO2] in air. It is not known whether the trend for increasing thallus [P] values indicates decreasing lichen growth rate and reduced growth dilution of P in polluted areas, or is due to regional variation in P deposition rate.

Hyvärinen, M.; Walter, B.; Koopmann, R. 2002. Secondary metabolites in Cladina stellaris in relation to reindeer grazing and thallus nutrient content. Oikos 96: 273-280.

We analysed concentrations of phenols and key macro-nutrients in a dominant mat-forming lichen, Cladina stellaris, in dry heath forests subjected to heavy reindeer grazing in Finnish Lapland. Lichen samples were collected in the beginning of two growth seasons from six to eight sites with old reindeer exclosures that served as control plots within sites. The concentration of perlatolic acid in lichen apices (top 10 mm) was higher in grazed plots than in control ones, whereas usnic acid did not seem to respond unequivocally to grazing. Moreover, there was a strong negative relationship between nitrogen and phenolic content of Cladina stellaris in intact plots but this relationship was absent in grazed ones. Changes in nitrogen and phosphorus contents caused by reindeer grazing were not correlated with changes in the level of phenolics in lichen thalli. The present result demonstrated that the carbon-nutrient balance (CNB) hypothesis may well explain some of the variation in lichen phenolic content but is not sufficient for explaining changes caused by reindeer grazing. We hypothesized that physical changes in the lichen microenvironment induced by reindeer have more profound impact on lichen phenolic content than alterations in thallus nutrient content.

Hyvärinen, M.; Walter, B.; Koopmann, R. 2003. Impact of fertilisation on phenol content and growth rate of Cladina stellaris: a test of the carbon-nutrient balance hypothesis. Oecologia 134: 176-181.

Responses of concentrations of usnic (UA) and perlatolic (PA) acids and the relative growth rate (RGR) of a mat-forming lichen, Cladina stellaris, to enhanced N and P input were studied in a fertilisation experiment. It was predicted on the basis of carbon-nutrient balance (CNB) hypothesis that the concentrations of these phenolics would decline and the growth rate increase in response to increased nutrient uptake. The concentration of UA showed a convex response pattern to increased N input whereas the concentration of PA was non-responsive. An ecologically realistic, "moderate", N treatment clearly lowered the level of UA both with and without the P application. Applying P alone caused a significant increase in the level of UA. The RGR of C. stellaris did not respond to nutrient addition. The results indicate that even though the CNB hypothesis may be applicable in explaining concentrations of lichen secondary metabolites, it may be applied under a relatively narrow set of conditions. Especially inherited constraints in the growth of lichen fungi may seriously limit the responsiveness of lichens to short-time changes in the availability of resources. These limitations may also apply to other perennials adapted to nutrient-poor conditions.

Hyvärinen,M.; Crittenden, P. D. 1998. Relationships between atmospheric nitrogen inputs and the vertical nitrogen and phosphorus concentration gradients in the lichen Cladonia portentosa. New Phytologist 140 (3) , 519-530.

The relationship between precipitation chemistry and the concentrations of nitrogen ([N]) and phosphorus ([P]) in the cushion-forming lichen Cladonia portentosa (Dufour) Coem. (=C. impexa (Harm)) was investigated. Samples of C. portentosa were collected from heathlands and upland moorlands close to 31 rural sampling stations in the UK Acid Deposition Monitoring Network, which provides data on wet deposition and NO2 concentrations in air. The [N] and [P] were measured in the top 5 mm of lichen thalli (thallus apices) and also in a horizontal stratum between 40-50 mm from the apices (thallus base). The [N] (per unit dry mass) was 0&middot;08-1&middot;82% and [P] was 0&middot;04-0&middot;17%, depending on collection site and lichen fraction analysed. Concentrations of both elements were c. 2-5 times greater in the apices than in the basal strata, and [N] and [P] values in each stratum were strongly positively correlated. Lichen [N] was positively correlated with N deposition: this relationship was stronger when using [N] values for thallus bases than for the apices. By contrast, thallus [N] was poorly correlated with [N] values in precipitation. When [NO2] in air was included together with NO3- deposition in a linear regression model explaining thallus base N, the model fit was significantly improved, whereas modelled values of NH3 deposition rate for the heathland sites did not correlate with lichen [N]. It is suggested that the proportionately greater enrichment of [N] in the thallus base might reflect a perturbation of internal recycling of thallus N at polluted sites. Thallus [P] was generally weakly linked to wet N deposition but positively correlated with [NO2] in air. It is not known whether the trend for increasing thallus [P] values indicates decreasing lichen growth rate and reduced growth dilution of P in polluted areas, or is due to regional variation in P deposition rate.

Insarova, I.D.,G.E. Insarov, S.Brakenhielm, S. Hultengren, P.O. Martinsson, and S.M. Semenov. 1992. Lichen Sensitivity and Air Pollution - A Review of Literature Data. 150 Report 4007, Swedish Environmental Protection Agency, Uppsala.

[Provides a tabular summary of sensitivity levels, etc., for 259 lichen species, based on the literature. Obtainable from: The Information Department, Swedish Environmental Protection Agency, S-171 85 Solna, Sweden.] Includes NW spp: Bryoria capillaris, Bryoria fuscescens, Bryoria trichodes, Candelaria concolor, Tucchl, Vulpicida pinastri, Cladonia squamosa, Collema nigrescens, Evernia prunastri, Hypogymnia physodes, Hypogymnia tubulosa, Leptogium cyanescens, Leptogium saturninum, Lobaria pulmonaria, Lobaria scrobiculata, Menegazzia terebrata, Nephroma bellum, Nephroma helveticum, Nephroma laevigatum, Nephroma parile, Normandina pulchella, Pannaria mediterranea, Pannaria rubiginosa, Parmelia saxatilis, Parmelia sulcata, Parmeliopsis ambigua, Parmeliopsis hyperopta, Peltigera canina, Peltigera collina, Phaeophyscia orbicularis, Physcia adscendens, Physcia aipolia, Physcia biziana, Physcia caesia, Physcia stellaris, Physcia tenella, Physconia enteroxantha, Physconia perisidiosa , Platismatia glauca, Ramalina farinacea, Ramalina pollinaria, Ramalina roesleri, Xanthoria polycarpa. Most of the references are European and deal with deciduous tree spp. Gives pH is for hardwoods. SO2 is the major pollutant listed most of the time.

Jackson, L. L., Geiser, L., Blett, T., Gries, C., and Haddow, D. 1996. Biogeochemistry of lichens and mosses in and near Mt. Zirkel Wilderness, Routt National Forest, Colorado: influences of coal-fired power plant emissions. U.S. Department of the Interior, Open-file Report 96-295. Denver.

Jaffe, D; Zukowski, MD. 1993. Nitrate deposition to the Alaskan snowpack. Atmospheric Environment 27A (17-18): 2935-2941

Snowpack samples were collected from interior and arctic Alaska during March 1988 and analysed for pH, conductivity, NO3-, SO42- and other constituents. The mean snowpack NO3- and SO42- concentrations in the interior Alaska snowpack were found to be 160 and 179 mg g-1, respectively. The interior snowpack was observed to have concentrations and deposition fluxes of NO3- which are approximately 1.5 and 1-3 times, respectively, those observed in Greenland. In the arctic samples, collected in the Sagavanirktok River Valley, wind-deposited loess substantially increases both pH and SO42- concentrations in the snowpack. Snowpack nitrate in these samples is unaffected by the windborne loess and had a mean NO3- concentration of 688 ng g -1. The NO3- deposition flux in the Arctic is approximately two times that found in the interior snowpack. The most plausible explanation for the elevated NO3- deposition flux is that the snowpack deposition is strongly influenced by the presence of the "arctic front", a meteorological boundary which acts to contain the polluted, arctic air mass. Alternatively, local NOx emissions on Alaska's arctic coast or substantial changes in the scavenging efficiencies may also influence the observe north-south gradient in NO3- concentrations in the snowpack.

Jeran, Z.; Mrak, T.; Jaöimoviö, R.; Batiö, F.; Kastelee, D.; Mavsar, R.; Simonöiö, P. 2007. Epiphytic lichens as indicator of atmospheric pollution in Slovenian forests. Environmental Pollution 146(2): 324-331.

Two country-wide surveys using epiphytic lichens as biomonitors of atmospheric pollution carried out during 2000 and 2001 in Slovenia were compared with surveys in 1991 and 1992. In the first survey, epiphytic lichen cover was studied in more than 500 plots of the 4x4 km national grid carried out within the framework of forest decline inventories. In the second survey, the epiphytic lichen Hypogymnia physodes (L.) Nyl., was collected on a 16x16 km bioindication grid and analyzed for S, N, As, Br, Ce, Cd, Cr, K, La, Mo, Rb, Sb, Th, U and Zn contents. Only 'forested area' sampling points were included in the present study. Lichen cover was low, with about 70% of plots with less than 10% foliose lichen cover. No relationship was found between Hypogymnia trace element, N and S concentrations and foliose epiphytic lichen cover.

Johnsen, I., and U. S&oslash;chting. 1973. Influence of air pollution on the epiphytic lichen vegetation and bark properties of deciduous trees in the Copenhagen area. Oikos 24: 344-351.

"Epiphytic lichen veg. of trees in Copenhagen was mapped, pH, total S content and buffer capacity of the lichen substrate were measured. The SO-2 isopleths coincide well with the inner distrib. limits of the lichens indicating specific critical SO2 levels for different spp. Bark properties changed approaching city center: avg. pH decreased from 5-3, S dry wt. increased from 25% to 45%; buffer capacity was higher at city center and rural areas than it was in the middle area." SO2 conc. are compared w/ HR 1970 scale.

Johnsen, I., and U. S&oslash;chting. 1976. Distribution of crytogamic epiphytes in a Danish city in relation to air pollution and bark properties. The Bryologist 79: 86-92.

"Distribution of epiphytic lichens and bryophytes in the Aalborg-Norresunby area of Denmark were mapped and compared with pollution data and bark properties. The distributions are well-correlated with SO2 emissions and bark pH. No correlation was found with dust fall levels, bark buffer capacity, or S content of bark."

Johnson, D.W. 1979. Air Pollution and the Distribution of Corticolous Lichens in Seattle, Washington. Northwest Science 53: 257-263.

Lichen species were sampled at 85 sites within the city of Seattle. These data expressed numerically, were used to construct a map consisting of five zones which reflected variances in the composition of the lichen flora along air pollution gradients. The topography of the city, land use patterns, and prevailing winds were found to affect the dispersion of air pollutants and therefore the distribution of lichen species. NW spp: Candelaria concolor, Cladonia chlorophaea, Hypogymnia physodes, Parmelia sulcata, Xanthoria candelaria, Hypogymnia tubulosa \, Parmeliopsis ambigua, Usnea hirta, Ramalina farinacea, Evernia prunastri .

Jovan, S.; McCune, B. 2005. Air quality bioindication in the greater Central Valley of California, with epiphytic macrolichen communities. Ecological Applications 15(5): 1712-1726.

Air-quality monitoring in the United States is typically focused on urban areas even though the detrimental effects of pollution often extend into surrounding ecosystems. The purpose of this study was to construct a model, based upon epiphytic macrolichen community data, to indicate air-quality and climate in forested areas throughout the greater Central Valley of California (USA). The structure of epiphytic lichen communities is widely recognized as an effective biological indicator of air-quality as sensitivities to common anthropogenic pollutants vary by species. We used nonmetric multidimensional- scaling ordination to analyze lichen community data from 98 plots. To calibrate the model, a subset of plots was co-located with air-quality monitors that measured ambient levels of ozone, sulfur dioxide, and nitrogen dioxide. Two estimates of ammonia deposition, which is not regularly monitored by any state or federal agency in California, were approximated for all plots using land-use maps and emissions estimates derived from the California Gridded Ammonia Inventory Modeling System. Two prominent gradients in community composition were found. One ordination axis corresponded with an air-quality gradient relating to ammonia deposition. Ammonia deposition estimates (r = 20.63 and 20.51), percentage nitrophilous lichen richness (r = 20.76), and percentage nitrophile abundance (r = 20.78) were correlated with the air-quality axis. Plots from large cities and small, highly agricultural towns had relatively poor air-quality scores, indicating similar levels of ammonia deposition between urban and agrarian land uses. The second axis was correlated with humidity (r = 20.58), distance from the coast (r = 0.62), kriged estimates of cumulative ozone exposure (r = 0.57), maximum one-hour measurements of ozone (r = 0.58), and annual means of nitrogen dioxide (r = 0.63). Compared to ammonia, ozone and nitrogen dioxide impacts on lichen communities are poorly known, making it difficult to determine whether the second axis represents a response to climate, pollution, or both. Additionally, nitric acid may be influencing lichen communities although the lack of deposition data and research describing indicator species prevented us from evaluating potential impacts.

Jovan, S; Carlsberg, T 2006. Nitrogen content of Letharia vulpina tissue from forests of the Sierra Nevada, California: Geographic patterns and relationships to ammonia estimates and climate Environmental Monitoring & Assessment 129: 243-251.

Nitrogen (N) pollution is a growing concern in forests of the greater Sierra Nevada, which lie downwind of the highly populated and agricultural Central Valley. Nitrogen content of Letharia vulpina tissue was analyzed from 38 sites using total Kjeldahl analysis to provide a preliminary assessment of N deposition patterns. Collections were co-located with plots where epiphytic macrolichen communities are used for estimating ammonia (NH3) deposition. Tissue N ranged from 0.6% to 2.11% with the highest values occurring in the southwestern Sierra Nevada (range: 1.38 to 2.11). Tissue N at 17 plots was elevated, as defined by a threshold concentration of 1.03%. Stepwise regression was used to determine the best predictors of tissue N from among a variety of environmental variables. The best model consisted only of longitude (r 2 = 0.64), which was reflected in the geographic distribution of tissue values: the southwestern Sierra Nevada, the high Sierras near the Tahoe Basin, and the Modoc Plateau, are three apparent N hotspots arranged along the tilted north- south axis of the study area. Withholding longitude and latitude, the best regression model suggested that NH3 estimates and annual number of wetdays interactively affect N accumulation (r 2 = 0.61; % N ~ NH3 + wetdays + (NH3 &times; wetdays)). We did not expect perfect correspondence between tissue values and NH3 estimates since other N pollutants also accumulate in the lichen thallus. Additionally, other factors potentially affecting N content, such as growth rate and leaching, were not given full account.

Jovan, S; McCune, B 2004. Regional variation in epiphytic macrolichen communities in northern and central California forests. The Bryologist. 107(3): 328 339.

We studied epiphytic macrolichen communities in northern and central California to 1) describe how gradients in community composition relate to climate, topography, and stand structure and 2) define subregions of relatively homogeneous lichen communities and environmental conditions. Non-metric multidimensional scaling was used to characterize landscape-level trends in lichen community composition from 211 plots. We found two gradients in lichen community composition that corresponded with macroclimatic gradients: one correlated with temperature variables and elevation, the second with moisture variables. Moist, warm plots supported more cyanolichen species, while warm but dry plots supported a diverse nitrophilous flora. Ammonia pollution, which was not accounted for in the analysis, may also explain spatial patterns in nitrophilous species and deserves further study. Cluster analysis and indicator species analysis were used to divide lichen communities into more homogeneous groups and identify group indicator species. Three groups of plots differing in geography, macroclimate, and community composition were defined: the Greater Central Valley group; the Sierra, Southern Cascades, and Modoc group; and the NW Coast group. Communities in the Greater Central Valley group were typically diverse and dominated by nitrophilous species, averaging 14 species and 40% nitrophiles. Cyanolichens common to this group were mainly diminuitive species from the genera Leptogium and Collema. Indicator species strongly associated with the Greater Central Valley included Melanelia glabra, Candelaria concolor, and Parmelina quercina. Communities from the Sierra, Southern Cascades, and Modoc group had the lowest species richness and total lichen abundance. Cyanolichens were absent, while nitrophiles such as Candelaria concolor and Xanthoria fulva were frequent. Indicator species included Letharia vulpina, L. columbiana, and Nodobryoria abbreviata. The NW Coast group had the highest species richness, cyanolichen diversity, and cyanolichen abundance while nitrophiles were rare. Indicator species included Platismatia glauca, Esslingeriana idahoensis, and Cetraria orbata.

Jovan, S; McCune, B 2006. Using epiphytic macrolichen communities for biomonitoring ammonia in forests of the greater Sierra Nevada, California Water, Air and Soil Pollution 170:69-93.

Chronic, excessive nitrogen deposition is potentially an important ecological threat to forests of the greater Sierra Nevada in California.We developed a model for ammonia bioindication, a major nitrogen pollutant in the region, using epiphytic macrolichens. We used non-metric multidimensional scaling to extract gradients in lichen community composition from surveys at 115 forested sites. A strong ammonia deposition gradient was detected, as evidenced by a high linear correlation with an index of ammonia indicator species conventionally known as "nitrophytes" (r = 0.93). This gradient, however, was confounded by elevation (r = -0.54). We evaluated three statistical techniques for controlling the influence of elevation on nitrophytes: simple linear regression, nonlinear regression, and nonparametric regression. We used the unstandardized residuals from nonlinear regression to estimate relative ammonia deposition at each plot, primarily because this model had the best fit (r2 = 0.33), desirable asymptotic properties, and it is easy to apply to new data. Other possible sources of noise in the nitrophyte-ammonia relationship, such as substrate pH and acidic deposition, are discussed. Lichen communities indicated relatively high deposition to forests of the southern Sierra Nevada, the Modoc Plateau, as well as in stands near urban areas. Evidence of elevated ammonia was also detected for popular recreation areas such as Sequoia and Yosemite National Parks. Lichen communities from forests in the Tahoe basin, northern Sierra Nevada, southern Cascades, and eastern Klamath Range appeared considerably less impacted. This model will be used for continual assessment of eutrophication risks to forest health in the region.

Jovan, Sarah. 2008. Lichen bioindication of biodiversity, air quality, and climate: baseline results from monitoring in Washington, Oregon, and California. Gen. Tech. Rep. PNW-GTR-737. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 115 p.

Lichens are highly valued ecological indicators known for their sensitivity to a wide variety of environmental stressors like air quality and climate change. This report summarizes baseline results from the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) Lichen Community Indicator covering the first full cycle of data collection (1998-2001, 2003) for Washington, Oregon, and California. During this period, FIA conducted 972 surveys of epiphytic macrolichen communities for monitoring both spatial and long-term temporal trends in forest health. Major research findings are presented with emphasis on lichen biodiversity as well as bioindication of air quality and climate. Considerable effort is devoted to mapping geographic patterns and defining lichen indicator species suitable for estimating air quality and climate.

Jönsson, AM 1998. Bark lesions on Beech (Fagus sylvatica) and their relation to epiphytes and site variables in Scania, South Sweden. Scandinavian Journal of Forest Research 13(3): 297-305.

Jürgling, P. 1971. Rindflechten und Luftverunreinigung im Stadtgebiet von Graz. mitt. Naturwiss. Ver. Steiermark 100: 151-189.

Jürgling, P. 1975. Epiphytische flechten als bioindikatoren der luftverunreinigung. Bibliotheca Lich. 4:165 pp.

Kärnefelt, I., and J.E. Mattsson. 1989. Cetraria cucullata and C. nivalis, two vanishing lichens from southernmost Sweden. International J. Mycology and Lichenology. 4: 299-305.

[Human activities and development seem to be the primary cause for the decline in these species, not regional air pollution.]

Kauppi, M., and A. Mikkonen. 1980. Floristic versus single species analysis in the use of epiphytic lichens as indicators of air pollution in a boreal forest region, northern Finland. Flora 169: 255-281.

Kauppi, M. 1983. Role of lichens as air pollution monitors. Memoranda Soc. Fauna Flora Fennica 59: 83-86.

Kershaw, K.A. 1972. The relationship between moisture content and net assimilation rate of lichen thalli and its ecological significance. Can. J. Botany 50: 543-555.

Investigates the relationship between net assimilation rates (respiration + photosynthesis)and percentage thallus saturation. NW spp: Xanthoria fallax, Peltigera praetextata, Parmelia sulcata. Physiological plasticity is discussed in terms of ecological niches. The mycobiont may be the contributor to plasticity.

Kershaw, K.A. 1985. The Physiological Ecology of Lichens. Cambridge University Press, Cambridge, UK.

Ketner-Oostra, R.; van der Peijl, M. J.; Sýkora, K. V. 2006. Restoration of lichen diversity in grass-dominated vegetation of coastal dunes after wildfire. Journal of Vegetation Science 17: 147-156.

Can lichen diversity of an earlier succession stage be restored in dune grassland after fire in a region with high nitrogen deposition? We sampled dune grassland on calcium-poor coastal dunes in the Wadden district The Netherlands. by using a large continuous transect of 4 m &times; 4 m blocks on both a south slope and a west slope. The sampling was conducted in the lichen-rich Violo-Corynephoretum in 1966, in the vegetation dominated by tall graminoids in 1990 and in the recovering vegetation for eight years after a wildfire in 1993. Vegetation succession in the blocks is visualised in stacked bar graphs and ordination diagrams (DCA). In 1966 relevés were made within the blocks, and from 1990 until 2001 permanent quadrats were studied. Between 1966 and 1990 the lichen-rich open grassland became dominated by tall graminoids and developed partly into a dwarf-shrub heath, resulting in a severe loss of lichen diversity. After the fire a lush vegetation of tall graminoids with an abundant moss cover developed. In 2001 the vegetation was still very different from the lichen-rich vegetation in 1966. Fire alone will not change dunes dominated by tall graminoids into open lichen-rich grasslands in an area with high aerial nitrogen deposition. After fire, additional intervention is recommended, such as large-scale clearing of the burned vegetation and actively promoting deposition of sand, either blown in from foredunes, from re-activated blow-outs or artificially brought to the site.

Kuusinen, M., K.Mikkola, and E.L. Jukola-Sulonen. 1990. Epiphytic lichens on conifers in the 1960's to 1980's in Finland. In: P. Kauppi, et al. (eds.) Acidification in Finland. 145: Springer-Verlag, Berlin. 397p.

[Long term studies on the frequency of Usnea, Bryoria and Hypogymnia physodes in litterfall, and the (IAP) mapping of the occurrence and abundance of these 3 plus 10 other common lichens on more than 6,000 trees throughout Finland have documented the effects of increased sulphur deposition, especially in the southern part of the country.] NW spp: Alectoria sarmentosa, Parmeliopsis ambigua, Tuckermannopsis chlorophylla, Vulpicida pinastri, Parmeliopsis hyperopta, Platismatia glauca, Parmelia sulcata, Evernia prunastri.

Kytöviita, M.-M.; Crittenden, P. D. 2007. Growth and nitrogen relations in the mat-forming lichens Stereocaulon paschale and Cladonia stellaris. Annals of Botany 2007 100(7):1537-1545.

Mat-forming lichens in the genera Stereocaulon and Cladonia have ecosystem-level effects in northern boreal forests. Yet the factors affecting the productivity of mat-forming lichens are not known. The aim of the presented work was to investigate whether mat-forming lichens adapted to low N availability employ N-conserving mechanisms similar to those of vascular plants in nutrient-poor ecosystems. Specifically, the following questions were asked: (a) Do lichens translocate N from basal areas to apical growth areas? (b) Are the quantities of N translocated of ecological significance. (c) Is lichen growth dependent on tissue N concentration [N]. Two different, but complementary, field experiments were conducted using the mat-forming N2-fixing Stereocaulon paschale and non-fixing Cladonia stellaris as model species. First, N translocation was investigated by feeding lichens with Na15NO3 either directly to the apex (theoretical sink) or to the basal part (theoretical source) and observing the redistribution of 15N after a growth period. Secondly, growth and variation in [N] in thalli of different lengths was measured after a growth period. 15N fed to lower parts of lichen was translocated towards the growing top, but not vice versa, indicating physiologically dependent translocation that follows a sink-source relationship. In the growth experiment where thalli were cut to different lengths, the significant decrease in [N] in apices of short vs. longer thalli after a growth period is consistent with internal relocation as an ecologically important source of N. The presented results demonstrate that internal recycling of N occurs in both species investigated and may be ecologically important in these mat-forming lichens under field conditions. The higher nitrogen use efficiency and relative growth rate in C. stellaris in comparison with S. paschale probably enable C. stellaris to dominate the ground cover vegetation in dry boreal coniferous forests under undisturbed conditions.

Laaksovirta, K., H. Olkkonen, and P. Alakuijala. 1976. Observations on the lead content of lichen and bark adjacent to a highway in southern Finland. Environ. Poll. 11.

"Lead contents of Hypogymnia physodes and its substrate, Pinus sylvestris bark were studied aling a busy four-lane highway on the coast of southern Finland. The decrease in the lead content of the lichens was statistically significant between 20-100 m from the road, but not between 100-200 m. There appeared to be no correlation between the lead content of lichens and traffic density. In this study, bark was a better indicator than lichens for lead emission from motor vehicles. This could be caused by effective lead accumulation in lichens even where there was moderate traffic flow."

Lambley, P 2003. Workshop on nitrogen in the environment. British Lichen Society Bulletin 92: 1-5.

Lamontagne, S 1998. Nitrogen mineralization in upland Precambrian Shield catchments: contrasting the role of lichen-covered bedrock and forested areas. Biogeochemistry 41: 53-69.

The upland boreal forest at the Experimental Lakes Area (northwestern Ontario, Canada) is characterized by treed soil islands interspersed within lichen and moss-covered bedrock outcrops. N mineralization was 2.5-x and net nitrification was 13-x higher on an aerial basis over bedrock surfaces because of high mineralization rates under lichen and moss patches. The higher average soil temperature in lichen and moss patches could not account for the difference in mineralization rates. Lichens did not provide a significant additional source of N because they did not fix atmospheric N. A refractory conifer litter with a high C:N probably favors the immobilization of N in forest islands. Buried bag and in situ core incubations yielded similar net N mineralization rates but core incubations underestimated net nitrification rates. Both methods did not adequately measure dissolved organic N (DON) production rates because soil disturbance caused high initial DON concentrations. The higher export of mineral N from bedrock surfaces is probably a combination of the lower retention of N in precipitation and leaching of mineralized N from lichen and moss patches.

Lamontagne, S.; Schiff, S.L. 2000. Response of soil microorganisms to an elevated nitrate input in an open Pinus banksiana-Cladina forest. Forest Ecology and Management 137: 13-22.

Two communities of the open P. banksiana/Cladina forest have contrasting nitrogen (N) cycles. While lichen patches on bedrock surfaces have high rates of net N mineralization and net nitrification, nearby forest islands have low rates of net N mineralization and no net nitrification. Using buried soil bag incubations, we compared the changes in net N mineralization and net nitrification in forest islands and lichen patches during a short-term experimental addition of N (40 kg N ha y-1 as NaNO3) to a small catchment. While in N-amended lichen patches net nitrification increased or remained similar to references, N-amended forest islands had a strong tendency to consume NO3-1 and produce NH4+. We hypothesize that assimilatory NO3-1 reduction coupled with a decreased gross NH4+ uptake rate was the combination of mechanisms generating the net conversion of NO3-1 into NH4+ in forest islands. Observations from the open P. banksiana/Cladina forest suggest that boreal ecosystems may respond in a heterogeneous fashion to anthropogenic N inputs.

Lamontagne, S; Schiff, SL 1999. The response of a heterogeneous upland boreal shield catchment to a short term NO3- addition. Ecosystems 2: 460-473.

Boreal Shield rocky ridges at the Experimental Lakes Area, northwestern Ontario, contain two plant/soil communities with contrasting N cycles. Picea mariana-Pinus banksiana ''forest islands'' are N limited whereas the lichen, moss, and grass community (or ''lichen patches'') on the surrounding bedrock outcrops appear intrinsically N saturated. The potential for this landscape to retain a N input of eightfold ambient levels was tested with a 2-y addition of 40 kg N ha-1 y-1 as NaNO3 to one small catchment (0.40 ha). The elevated N input was poorly retained by the whole catchment during snowmelt. However, during the growing season, N retention in the treated catchment remained as efficient as in references. Forest islands and bedrock surfaces responded in opposite fashions to the elevated N input. By the second year of N addition, bedrock surfaces no longer retained additional N inputs. In contrast, N-amended and reference forest islands retained a similar proportion of N inputs, indicating that forest islands did not become N saturated. The response of the whole catchment to N addition was more similar to forest islands than bedrock surfaces. Even if forest islands only cover a small proportion of catchment area, they can have a strong impact on whole catchment element export because most of the water must move through at least one island before leaving the system. Because the different components of the boreal shield landscape are hydrologically connected, N saturation may occur as a cascading effect in this ecosystem. Monitoring boreal shield landscapes by using outlets at the lower end of the hydrological cascade can fail to detect the impacts of perturbations such as increased N deposition on upper components.

Landers, D.H., S.L. Simonich, D.A. Jaffe, L.H. Geiser, D.H. Campbell, A.R. Schwindt, C.B. Schreck, M.L. Kent, W.D. Hafner, H.E. Taylor, K.J. Hageman, S. Usenko, L.K. Ackerman, J.E. Schrlau, N.L. Rose, T.F. Blett, and M.M. Erway. 2008. The Fate, Transport, and Ecological Impacts of Airborne Contaminants in Western National Parks (USA). EPA/600/R-07/138. U.S. Environmental Protection Agency, Office of Research and Development, NHEERL, Western Ecology Division, Corvallis, Oregon.

Larsen, R. S.; Bell, J. N. B.; James, P. W.; Chimonides, J.; Rumsey, F. J.; Tremper, A.; Purvis, W. O. 2007. Lichen and bryophyte distribution on oak in London in relation to air pollution and bark acidity. Environmental Pollution 146(2): 332-340.

Epiphytic lichen and bryophyte distribution and frequency were investigated on the trunks of 145 young oak trees throughout London and surrounding counties, and compared with pollution levels and bark pH. Sixty-four lichen and four bryophyte species were recorded. Three major zones were identified: (i) two central regions with a few lichens, bryophytes absent; (ii) a surrounding region with a more diverse flora including a high cover of nitrophyte lichens; and (iii) an outer region, characterized by species absent from central London, including acidophytes. Nineteen species were correlated with nitrogen oxides and 16 with bark pH, suggesting that transport-related pollution and bark acidity influence lichen and bryophyte distribution in London today. Lichens and bryophytes are responding to factors that influence human and environmental health in London. Biomonitoring therefore has a practical role to assess the effects of measures to improve London's air quality.

Lawry, J.D. 1986. Lichens as lead and sulfur monitors in Shenendoah NP, VA. Ann. Meeting of the Botanical Soc.of America. Amherst, MA.

Lawrey, J.D., and M.E. Hale. 1979. Lichen growth response to stress induced by automobile exhaust pollution. Science 204: 423-424.

Lawrey, J.D., and M.E. Hale. 1988. Lichens as indicators of atmospheric quality in the Dolly Sods and Otter Creek Wildernesses of the Monongahela NF, WV.

Lawrey, J.D.; Hale, M.E. Jr. 1988. Lichen Evidence for Changes in Atmospheric Pollution in Shenandoah National Park, Virginia. The Bryologist 91:21-23.

Recently collected specimens of the lichen Flavoparmelia baltimorensis from Shenandoah National Park in Virginia, especially those from higher elevations, contain higher concentrations of sulfur, and lower concentrations of lead than specimens collected from the same sites at various times in the past. These results suggest long-term increases in regional sulfur pollution and a corresponding decline in lead pollution.

Lawrey, JD 1993. Lichens as monitors of pollutant elements at permanent sites in Maryland and Virginia. The Bryologist 96(3): 339-341.

Concentrations of sulfur, nitrogen, and seven metal elements are reported for the lichen Flavoparmelia baltimorensis from three monitoring stations in Maryland and Virginia. At Plummers Island, Maryland, 15 km from the center of Washington, D.C., lichens have been collected for nearly 100 years. The other two stations, Bear Island, Maryland (21 km) and Stony Man Mountain, Virginia (120 km), were established in the 1970's by Mason Hale to help document changes in ambient air quality in the Washington, D.C. area. Concentrations of cadmium, chromium, nickel, zinc, and lead were consistently highest at Plummers Island and lowest at Stony Man Mountain; concentrations of the other four elements (nitrogen, sulfur, aluminum, and copper) were also consistently higher at Plummers Island than at Stony Man Mountain. Recent collections, in 1988 and 1992, revealed marked reductions in the concentration of all nine elements except aluminum at all three stations, providing limited, but encouraging, signs of improved air quality in the region.

Lawrey, J.D., and M. E. Hale, Jr. 1981. Retrospective study of lichen lead accumulation in the northwestern United States. Bryologist 84(4): 449-456.

LeBlanc, F. 1969. Epiphytes and air pollution. In: Air Pollution, Proc. of the First Eur. Congress on the Inf. of Air Poll. on Plant and Animals. Wageningen.

LeBlanc, F., and J. De Sloover. 1970. Relation between industrialization and the distribution and growth of epiphytic lichens and mosses in Montreal. Can. J. Botany 48:1485-1496.

Epiphytic mosses and lichens are very sensitive to air poll. Their gradual disappearance from large cities and from the vicinity of industrialized complexes is due, mostly to phytoxicants. A simple method to map the long-range effect of air pollution on corticolous epiphytes is described. An IAP based on the number of species present, their coverage and frequency, and their specific tolerance to pollutants can be expressed quantitatively. NW spp: Melanelia subargentifera, Melanelia subaurifera, Parmelia sulcata, Physcia adscendens, Physcia aipolia , Phaeophyscia orbicularis, Physcia stellaris , Xanthoria fallax, Candelaria concolor.

LeBlanc, F., G.Comeau, and D.N. Rao. 1971. Fluoride injury symptoms in epiphytic lichens and mosses. Can. J. Bot. 49(9): 1691-1698.

"Arvida, Quebec, in the vicinity of an aluminum factory that releases volatile fluorides and HF. Lichen and moss bearing bark disks, cut from an unpolluted area were fixed in groups of six on boards and placed at 15 sites in different directions from the factory plus an additional control site. All disks were photographed in color and b/w. Two boards were used per site, one being removed at 4 mos, the other at 12mos. The lichens and mosses exposed in control and polluted areas were compared with respect to color, morphology, plasmolysis in algal cells, loss of green color, the nature of reactions towards neutral red and TCC, absorbtion spectra of chlorophyll and F concentrations. Results indicate that F-pollution affects moisture balance, causes chlorophyll damage, and produces other symtoms of injury which could lead to ultimate death of the organism." NWspp: Parmelia sulcata.

LeBlanc, F., and D.N. Rao. 1973a. Effects of sulphur dioxide on lichen and moss transplants. Ecology 54(3): 612-617.

"Injury symptoms in lichen and moss transplants have been correlated with the SO2 concentrations prevailing at their exposure sites in the Sudbury area during 1970. For this purpose, bark-disks bearing lichens and mosses were cut out from an unpolluted region, photographed , inventoried, mounted onto boards in groups of six and placed at 19 sites in the 5 SO2 zones. After one years the transplants were re-photographed, removed and compared with respect to external and internal morphology, biomass, acidity, total S, and chlorophyll. The results indicate that different conc. of SO2 produce different sets of harmful effects which appear to be more or less directly related to the levels of pollution. A quantitative correlation has been sought between the levels of injuries produced in these organisms and the levels of SO2 to which they are exposed in the field. NW spp: Parmelia sulcata.

LeBlanc, F., and D.N. Rao. 1973b. Evaluation of the pollution and drought hypothesis in relation to lichens and bryophytes in urban environments. Bryologist 76: 1019.

"The evidences on the pollution and drought hypothesis, which seek to explain the rarity of lichens and bryophytes in urban environments, have been critically examined. It is concluded that the premises and logic of the drought hypothesis are not acceptable. In the present paper, the importance of experimentation and of phytosociological quantification in ecological hypothesis are stressed." Shows by area lichen and moss research w/respect to air pollution.

LeBlanc, F., and D.N. Rao. 1975. Effects of air pollutants on lichens and bryophytes. pp. 237-272 In: Mudd, J.B. and T.T Kozlowski (eds.), Responses of Plants to Air Pollution. Academic Press, New York.

LeBlanc, F., D.N. Rao, and G. Comeau. 1972a. The epiphytic vegetation of Populus balsamifera and its significance as an air pollution indicator in Sudbury Ontario. Can. J. Bot. 50: 519-528. LeBlanc, F., D.N. Rao, and G. Comeau. 1972b. Indices of atmospheric purity and fluoride pollution pattern in Arvida, Quebec. Can. J. Bot. 50: 991-998.

"IAP of 42 sites located in all directions of an aluminum plant over 250 k were determined on the basis of phytosociology of epiphytes of Populus balsamifera. Index values were delineated into 6 IAP zones to represent different levels of F pollution. A relative picture was obtained by F accumulation in Parmelia sulcata thalli transplanted at various sites in the area." The author also give good definitions of the values used in the IAP determination. NW spp: Parmelia sulcata, Physcia stellaris, Phaeophyscia orbicularis, Physcia adscendens, Candelaria concolor, Xanthoria polycarpa, Melanelia subaurifera, Physcia dubia, Xanthoria fallax, Phyaip, Usnea sp., Hypogymnia physodes, Vulpicida pinastri, Xanthoria parietina.

LeBlanc, F., G.Robitaille, and D.N. Rao. 1974. Biological response of lichens and bryophytes to environmental pollution in the Murdochville Copper Mine Area, Quebec. Jour. Hattori Bot. Lab. 38: 405-433.

LeBlanc, F., G. Robitaille, and D.N. Rao. 1976. Ecophysiological response of lichens transplants to air pollution in the Murdochville Gaspe Copper Mine Area, Quebec. J. Hattori Bot. Lab. 40:27-40.

Lechowicz, M.J. 1987. Resistance of the caribou lichenCladina stellaris (Opiz) Brodo to growth reduction by simulated acidic rain. Water, Air, and Soil Pollution 34: 71-77.

Lessica, P., B. McCune, S.V. Cooper, and W.S. Hong. 1991. Differences in lichen and bryophyte communities between old-growth and managed second-growth forests in the Swan Valley, Montana. Can. J. Bot. 69:1745-1755. Liggon, C.A., and W.K. Lauenroth. 1980. Preliminary bibliography of the impacts of atmospheric sulphur deposition on ecosystems. Ann. Report RP 1635, for Electric Power Research Inst. Appendix III.

Lisick á, E 1984. Epiphytic lichens in the vicinity of a nitrogen fertilizer factory in south-west Slovakia. In: Martin, J/Nilson, E/Piin, T/Poom, K (eds.): International School on Lichen Indication. Academy of Sciences of the Estonian SSR, Tallinn, pp. 52-57.

Little, P., and M.H. Martin. 1974. Biological monitoring of heavy metal pollution. Environmental Pollution 6:1-19. Lodenius, M., and K. Laaksovirta. 1979. Mercury content of Hypogymnia physodes and pine needles affected by a chlor-alkali works at Kuusankoski, SE Finland. Annales Botanici Fennici 16: 7-10.

Longton, R.E. 1997. The role of bryophytes and lichens in polar ecosystems In: Woodin, SJ; Marquiss, M; eds. Ecology of Arctic environments. Oxford, UK: Blackwell Science, 69-96.

Longton, RE 1992. The role of bryophytes and lichens in terrestrial ecosystems. In: Bates, JW/Farmer, AM (eds.): Bryophytes and Lichens in a Changing Environment. Clarendon Press, Oxford, pp. 32-76.

Loppi, S; Corsini, A 1995. Lichens as bioindicators of air quality in Montecatini Terme (central northern Italy). Ecologia Mediterranea 21(3/4): 87-92.

Loppi, S; Francalanci, C; Pancini, P; Marchi, G; Caporali, B 1996. Lichens as bioindicators of air quality in Arezzo (central Italy). Ecologia Mediterranea 22(1/2): 11-16.

Mahon, D.C. 1982. Uptake and translocation of naturally-occurring radionuclides of the uranium series. Bull. of Env. Contamination & Toxicology 29: 697-703. 5 tables. [Study done in central British Columbia with high levels of natural radioactivity included analysis of Bryoria fremontii and Alectoria sarmentosa.]

Makkonen, S.; Hurri, R.S.K.; Hyvärinen, M. 2007. Differential responses of lichen symbionts to enhanced nitrogen and phosphorus availability: an experiment with Cladina stellaris. Annals of Botany 99: 877-884.

Lichens can be both nitrogen- (N) and phosphorous- (P) limited and thus may be susceptible to nutrient enrichment. Nutrient enrichment with N and P may have differing impacts on the lichen structure because of different physiological responses of fungal and algal partners to these nutrients. The hypothesis was tested that the differential responses of lichen symbionts to enhanced availability of N and P is reflected in the lichen thallus structure and the wall-to-wall interface between the algal and fungal cells. Lichen cushions of Cladonia stellaris were treated with one P and two N concentrations alone and in combination that yielded total depositions of approx. 300 (moderate) and 1000 (high) mg N m-2 ( = 3 and 10 kg/ha) and 100 (high) mg P m-2 over an experiment lasting 14 weeks. The effects of N and P inputs on the relative volumes of fungal and algal cell in the medullary tissue and on the thallus structure were studied using light microscopy. The interface between algal and fungal cell walls was examined using transmission electron microscopy. The influence of excess P on the lichen thallus structure was stronger than that of additional N. Addition of P reduced the N : P ratio in podetia, the proportion of the medullary layer volume occupied by the algal cells, the thallus volume occupied by the internal lumen, and the algal cell-wall area covered by fungal hyphae. Ecologically realistic changes in the availability of key macronutrients can alter the growth of symbionts. Reduction in the proportion of photobiont cells indicates that the application of P either stimulates fungal hyphal growth in the medullary tissue or impairs the cell division of the algal cells. The results suggest that both the N and P availability and thallus N : P ratio affect the growth rates of lichen symbionts.

Margot, J. 1973. Experimental study of the effects of sulphur dioxide on the soredia of Hypogymnia physodes. In: Ferry, B.W., et al. (eds.) Air Pollution and Lichens. University of Toronto Press, Toronto.

Markert, B 1998. Distribution and biogeochemistry of inorganic chemicals in the environment. In: Schüürmann, G/Markert, B (eds.): Ecotoxicology. John Wiley and Sons, Inc. & Spektrum Akademischer Verlag, pp. 167-222.

Marsh, JE; Nash, TH III 1979. Lichens in relation to the Four Corners Power Plant in New Mexico. The Bryologist 82: 20-28.

In the region around the Four Corners Power Plant of New Mexico, 159 lichen species in 40 genera are recorded. Although the power plant has operated over 10 years, no marked gradient in species composition or lichen cover data were evident in relation to the power plant. Eight desert lichen species are shown to be sensitive to 0.5 ppm SO2 when moist but are insensitive when dry. Because of the aridity of the climate the lichens are probably rarely susceptible to SO2 injury. In addition the lack of pattern probably reflects the dominance of resistant crustose growth forms in the lichen flora and the fact that ground level SO2 concentrations are relatively low even though SO2 emissions are relatively high.

Marti, J. 1983. Sensitivity of lichen phycobionts to air pollutants. Can. J. Bot. 61: 1647-1653.

Cultured phycobionts were exposed to aqueous solutions of either sulfite, nitrite, sulfate, or nitrate, to simulate acute pollutant stress for a short time. Impact was measured effectively with 14C incorporation rates. In many species there were clear correlations with data available on the sensitivity of the entire thallus, but in some species the phycobiont was either directly less sensitive or less tolerant than would be expected from ecological studies on the geographical distribution of the lichen. Nitrate and sulfate were nontoxic at pH 4 while distinct differences were noted in the sensitivity of the various phycobionts to sulfite and nitrite.

Marti, J 1985. Die Toxizitat von Zink, Schwefel- und Stickstoffverbindungen auf Flechten-Symbionten. Bibliotheca Lichenologica 21. J. Cramer, Vaduz. 129 pp.

Maser, C., Z. Maser, J.W. Witt, and G. Hunt. 1986. The northern flying squirrel; a mycophagist in sourthwestern Oregon. Can. J. Zool. 64:2086-2089.

Maser, C., B.R. Mate, J.F. Franklin, and C.T.Dyrness. 1981. Natural History of Oregon Coast Mammals. USDA-Forest Service Pacific Northwest Expt. Sta. GTR PNW-133. Maser. Z., C. Maser, and J. M Trappe. 1985. Food habits of the northern flying squirrel (Glaucomys sabrinus) in Oregon. Can. J. Zool. 63: 1085-1088.

McClenahen, JR, Davis, DD, Hutnik, RJ. 2007. Macrolichens as biomonitors of air-quality change in western Pennsylvania. Northeastern Naturalist 14(1): 15-26.

Species richness of corticolous macrolichens was monitored at one- or two-year intervals on a total of 63 plots from 1997-2003 in a region of west-central Pennsylvania that included four coal-fired power generating stations and an industrial city. Lichen richness significantly increased from an average of 5.7 species/plot in 1997 to 9.3 species/plot in 2003. A linear mean rate of gain in species on regional monitoring plots was 0.56 species/yr. Plots along a major ridge top had a slower but significant gain in richness, and a localized area flanked by the city and two generating stations exhibited less lichen recolonization. Our results confirm the value of macrolichens as indicators of air quality and the importance of examining temporal as well as spatial changes in lichen richness to ascertain air-quality status.

McCune, B. 1988. Lichen Communities along O3 and SO2 Gradients in Indianapolis The Bryologist 91(3):223-228

Lichen community parameters (species composition, species richness, total cover index, and Index of Atmospheric Purity) were correlated with 3-year mean annual SO2 levels (range: 23-40 &micro; g/m3; 0.6 < r2 < 0.8) in and around Indianapolis, Indiana, U.S.A. Weaker relationships were found between lichen communities and peak SO2 levels. In contrast, spatial variations in ozone peaks (range: 156-264 &micro; g/m3 for yearly 1-hour highs averaged across three years) and 3-year ozone means (range: 65-77 &micro; g/m3) were not correlated with lichen communities.

McCune, B. 1993. Gradients in epiphyte biomass in three Pseudotsuga-Tsuga forests of different ages in western Oregon and Washington. Bryologist 96(3): 405-411. McCune, B., and J. Antos. 1982. Epiphyte communities of the Swan Valley, Montana. Bryologist 85(1): 1-12.

"Epiphyte communities in low elevation conifer forests of the Swan Valley of western MT appear to respond to complex gradients of canopy structure and density, stand age, and moisture. Epiphytes read the environment differently than do vasc. plants. Stand age and moisture gradients that are reflected in vasc. veg. are differently expressed by epiphytes. Epiphytes tend to equate young stands with dry stands and old stands with wet stands in the Swan Valley, more so than vasc. plants. A strategy of investigation using both ordination and classification methods was used to clarify patterns in composition and environment." Nodobryoria abbreviata, Tuckermannopsis merrillii, Tuckermannopsis platyphylla were assoc. w/young stands; Hypogymnia imshaugii, Bryoria fremontii, Bryoria fremontii, Bryoria fuscescens, Letharia vulpina, Hypogymnia tubulosa, Esslingeriana idahoensis were assoc. w/drier stands, open irreg. canopy; Alectoria sarmentosa, Platismatia glauca, Parmeliopsis hyperopta were assoc. w/moist closed canopy; using ordination. Table 3. Interpolation of stand groups was interesting and could be useful for East-side interp (Deschutes).

McCune, B., J. Dey, J. Peck, K. Heiman, and S. Will-Wolf. 1994. Lichen Communities. In: T.E. Lewis and B. L. Conckling, eds. Forest Health Monitoring: Southeast Loblolly/Shortleaf Pine Demonstration Interim Report. EPA/620/R-94/006.

McCune, B.; Dey, J.P.; Peck, J.E.; Cassell, D.; Heiman, K.; Will-Wolf, S.; Neitlich, P.N. 1997. Repeatability of community Data: Species richness versus gradient scores in large-scale lichen studies. The Bryologist 100: 40-46.

Repeated ecological assessments based on permanent plot data require sufficient data quality to detect a signal of change against a background of noise (sampling error of various kinds). We analyzed several components of error in the time-constrained method for sampling lichen communities used by the Forest Health Monitoring program; between-crew (technicians), crew-to-expert, between-expert, and seasonal variation. Data were from the southeastern United States and Oregon. Two types of dependent variables were used: species richness and scores on lichen community gradients (responses to climatic and air quality gradients). Gradient scores were repeatable to within 2-10% for experts and technicians alike and did not differ between those groups. Species richness is much more difficult to estimate reliably. Despite relatively low species capture by technicians, the high repeatability in gradient scores demonstrates the statistical redundancy in information provided by various lichen species. These results imply that repeated assessments of species richness will contain considerable observer error, but that shifts in community composition may nevertheless be detected reliably.

McCune, B.; Rogers, P. ; Ruchty, A.; Ryan, B. 1998. Lichen communities for forest health monitoring in Colorado, USA. Report to the US Forest Service. http://www.fia.fs.fed.us/program-features/indicators/lichen/pdf%20files/co98_report.pdf.

Lichen communities were included in the Forest Health Monitoring program because they help to answer several key assessment questions. These questions concern the contamination of natural resources, biodiversity, forest health, and sustainability of timber production. Field crews collected data on epiphytic macrolichens from throughout forested areas of Colorado from 1992-1996. Repeated sampling of these permanent plots will allow us to document changes in the condition of lichen communities over time. Additional plots were taken in urban and industrial areas, for a total of 185 plots reported on here.

Mcune, B; Dey, J. P.; Peck, J. E.; Heiman,K.; Will-Wolf, S. 1997. Regional lichen communities of the Southeast United States. The Bryologist 100: 145-158.

Epiphytic macrolichens were sampled in 203, 0.38 ha plots in the Southeast United States. 176 lichen species were encountered. Gradient analysis revealed two major regional gradients in lichen communities. A multivariate model based on non-metric multidimensional scaling was used to assign gradient scores to pots, based on lichen species composition. The strongest gradient in the lichen communities corresponded to a macroclimatic gradient from the coast through the Piedmont to the Appalachian Mountains. The second major gradient was correlated with air quality, with pollution-tolerant species and lower species richness in urban and industrial areas, and pollution-sensitive species and high species richness in cleaner areas. Epiphytic macrolichens were sparse in urban areas with heavy industry. In many rural areas, lichens were luxuriant and diverse. Species richness was locally variable and only weakly related to the coast-to-mountains gradient, with somewhat higher diversity in the mountains and lower diversity on the Piedmont and coast.

McCune, B., and L. Geiser. 1997. Macrolichens of the Pacific Northwest. OSU Press, Corvallis, OR.

McCune, B., and L. Geiser. 2009. Macrolichens of the Pacific Northwest. Revised Edition. OSU Press, Corvallis, OR.

McCune, B., C.C. Derr, P. S. Muir, A. M Shirazi, S. C. Sillett, J. E. Peck, and W. J. Daly. 1996. Pendants for measuring lichen growth. Lichenologist 28(2):161-169. McCune, B., et al. 1987. Foliar injury, tree growth, mortality, and lichen studies in Mammoth Cave NP. Final Report. NPS Contract CX-001-4-0058.

Mitchell, RJ; Truscot, AM; Leith, ID; Cape, JN; Van Dijk, N; Tang, YS; Fowler, D; Sutton, MA 2005. A study of the epiphytic communities of Atlantic oak woods along an atmospheric nitrogen deposition gradient. Journal of Ecology 93: 482-492.

Atlantic oak woods are of high conservation value and contain many rare lichens and bryophytes. The effects of nitrogen pollution on these epiphytic communities have not been previously studied. We investigated the composition of Atlantic oak wood epiphytic communities in relation to atmospheric N deposition in order to identify N indicator species and propose a critical load for such communities. The epiphytic communities of seven Atlantic oak woods receiving estimated total nitrogen deposition in the range 10-53 kg N ha-1 yr-1 were surveyed. Exposure of epiphytes to atmospheric N over 7 months was measured in terms of stemflow flux and concentration and airborne NH3. Redundancy analysis (RDA) related the species to stemflow chemistry and bark pH. Different groups of species were found at (i) a coastal low N deposition site (Graphina ruiziana, Lecania cyrtella , Lobaria pulmonaria, Opegrapha atra, Orthotrichum affin , Melanelia fuliginosa ssp. glabratula and Pertusaria hymenea), (ii) inland low N deposition sites (I. myosuroides, F. tamarisci, Plagiochila atlantica, Cladonia chlorophaea, C. squamosa, Hypotrachyna laevigata and Thelotrema lepadinum ) and (iii) high N deposition sites (Hypnum andoi, Hypnum cupressiforme, Calicium viride, Chrysothrix candelaris, C. coniocraea, Hypogymnia physodes, Parmelia saxatilis, Phyllospora rosei and Usnea subfloridana). RDA analysis showed that bark pH and concentration in the stemflow explained the greatest amount of variation in the species composition among the sites. The sites separated into two groups (low and high concentration) leading to an estimate for the critical load for N deposition for epiphytes in Atlantic oak woods of 11-18 kg N ha-1 yr-1. Analysis of the occurrence of species against N levels suggested that I. myosuroides and F. tamarisci are indicators of small N inputs, whereas H. andoi, C. coniocraea, P. saxatilis and H. physodes are tolerant of increased N loads. Different forms of N (NO3-, NH4+, NH3) were found to significantly affect the occurrence of different species. Some species were sensitive to total flux while others were sensitive to concentration.

Mols, T; Oall, J; Fremstad, E. 2001. Response of Norwegian alpine communities to nitrogen. Nordic Journal of Botany 20: 705-712.

The effect of nitrogen pollution on species cover was tested in the Dovre mountains, south-central Norway, through a three-year fertilisation experiment in a low-alpine community and a two-year one in a middle-alpine community, both dominated by lichens. The doses used were 0.7, 3.5 and 7 g N/m(2), the highest doses corresponding to 1.75 and 3.5 times the annual deposition of nitrogen in southwestern Norway. The results were tested using the SAS/STAT/MIXED procedure. Using the Bonferroni correction, the procedure did not confirm a change in the cover of single species due to increased nitrogen supply, but there seemed to be a general tendency for an increase in cover in the low-alpine Cetrarietum nivalis community. When less rigorous tests were applied, Arctostaphylos uva-ursi, Vaccinium vitis-idaea, Polytrichum piliferum, Cetraria nivalis and Cladonia mitis in Cetrarietum nivalis, and Cladonia coccifera in Phyllodoco-Juncetum trifidi seemed to indicate that nitrogen had some effect on these communities. The lack of a clear response in single species may be due to the application of low doses over a short time-span in an environment characterised by large interannual variations in climate, the deficiency of other important nutrients, dryness, the low growth potential of the species involved, and, to some extent, the community structure.

Moser, T.J., J.R. Swafford, and T.H. Nash III. 1983. Impact of Mt. St. Helens emissions on two lichen species of south-central Washington. Environmental & Exp. Bot. 23(4): 321-329.

Lichen specimens of Lobaria oregana and Peltigera aphthosa collected after St.Helens eruption July 1980 and Jan 1981 (Oct 1980, Mar 1981, June 1981 collections) from forested sites within 75 km of St. Helens exhibited significant reductions in internal K, P and gross photosynthetic capability in relation to control areas. In contrast, the same specimens had elevated internal levels of Al, Si, the two principal elements found in Mt St Helen's ash. No trends were found for S.

Muir, P.S. 1991. Fogwater Chemistry in a Wood-Burning Community, Western Oregon. J. Air Waste Manage. 41: 32-38.

"Fogwater chemistry in a wood-burning community was compared with the chemistry of fogwater collected in more remote and in more highly industrialized areas. Corvallis fogwater was not acidic (median pH 5.7) and was usually dominated by SO42- and NH4+. Concentrations were lower than southern CA urban areas, but higher than the more remote areas." Study suggests that there may be important non-natural and non-vehicular emissions sources of formaldehyde, formic and acetic acids to the Corvallis atm. While the seasonal and spatial distrib. of samples does not allow analysis of source contributions, it is likely that wood-burning (residential and by-products of wood industry)is an important contributor. Many areas affected by wood smoke also have frequent fog, and this research suggests that we need to understand more about the influence of wood smoke on organic composition of fogwater." See LeBlanc and Rao 1973 for more on particulates as condensation nuclei--they cite Changnon 1969.

Muir, P.S., and B. McCune. 1988. Lichens, tree growth, and foliar symptoms of air pollution: are the stories consistent? J. Env Qual. 17: 361-370.

["Lichen communities, tree growth, and foliar symptoms of Acer saccharum, Fraxinus spp., Liriodendron tulipifera, Quercus alba, and the Quercus rubra group were studied in relation to air pollutants in southern Indiana and Illinois. Both study areas receive regional pollutants, but only one is close to a large coal-fired utility, which results in a high dose of SO2 and its reaction products. Lichen communities differed significantly between the two areas; species richness and total cover were lowest in the near-utility area, and species compositional differences suggested that air quality was responsible."] Conclusions: 1. visible O3 injury was common and approx equal between near-utility and remote sites. --2. Periodic basal area increments and tree vigor were similar between near-utility and remote sites, and visible foliar symptoms did not generally differ between the areas. However, year-year variations in oak growth at the near ut. sites was neg. corr. w/SO2 emissions. 3. Lichen communities near the utility had a lower index of total cover, lower spp. richness and more poll. tolerant spp. compositions. NW spp: Physconia isidiigera, Punctelia subrudecta, Candelaria concolor, Physcia aipolia, Physcia stellaris, Xanthoria fallax.

Murphy, KJ, Alpert, P, Cosentino, D. 1999. Local impacts of a rural coal-burning generating station on lichen abundance in a New England forest. Environmental Pollution 105: 349-354.

To test whether emissions from a coal-burning, electrical generating station in rural Massachusetts have had measurable ecological impacts on the surrounding riparian forest, we compared abundance of epiphytic lichens at different distances from the station. Per cent covers of crustose, fruticose, and foliose lichens were measured along 1-km transects downwind and upwind from the station on the north and south sides of trunks of two dominant tree species, Acer saccharinum and Populus deltoides. Lichen cover increased with distance from the station, especially in the upwind direction. The tendency for lichens to be more abundant on the north than on the south side of trees also increased with distance from the station. These effects of distance and side on lichen abundance were stronger in some lichen growth forms than in others and also depended on host tree species. Two different methods of measuring lichen cover, visual estimate and point occurrence, gave similar values. We conclude that emissions from the station have had measurable impacts on the adjoining plant community.

NAPAP. 1990. Acidic Deposition: State of Science and Technology. Report 16: Changes in Forest Health and Productivity in the United States and Canada. The National Acid Precipitation Assessment Program, Washington, DC.

Nash, T.H. III. 1971. Lichen sensitivity to hydrogen fluoride. Bull. Torr. Bot. Club 98(2): 103-106.

"Lichens exposed to ambient F at 4 mg F/m3 accumulated F within their thalli. Both in the field and in the lab, whenever the level of F within the thallus exceeded 80ppm, chlorosis was observed. Subsequently all the pigments were degraded and the lichen thalli disintegrated. In the field, wherever chlorotic transplants were found, high levels of F on lime filter papers were also found, suggesting that ambient F was the cause of the lichen injury. Lichen ability to accumulate F is a function of relative humidity, which determines the moisture conditions of the thallus." Lichens used were not NWspp: Cladonia cristellata, C. polycarpoides and Parmelia plittii.

Nash, T.H. III. 1976a. Sensitivity of lichens to nitrogen dioxide fumigations. Bryologist 79(1): 103-106.

Nash, T.H. III. 1976b. Lichens as indicators of air pollution. Naturwissenschaft. 63:364-367.

Short literature review on SO2, HF, metals, oxidants: Lichens are more sensitive to SO2 under acidic conditions they extend into urban areas farthest on highly buffered substrates like asbestos and limestone; under high humidity or saturation lichens are more sensitive to SO2; HF sensitivity for lichens in general is approx. >30-80 mg/g/dry wt. lichen thalli; Zn sensitivity at 450 mg/g dry wt. and Cd at 320 mg/g dry wt., metal toxicity is by spp: some spp. can tolerate v. high levels of Cr, Cu, Fe, Pb, and Zn; lichens have been shown to be fairly resistant to NO2, but further studies on oxidants are needed.

Nash, T. H. III. 1989. Metal tolerance in lichens. In: Heavy Metal Toerance in Plants: Evolutionary Aspects, ed. A.J. Shaw pp 119-131. Boca Raton: CRC Press.

Nash, TH III 1996. Lichen Biology Cambridge University Press, Cambridge, UK, 303 pp

Nash, T.H., III, and C. Gries. 1991. Lichens as indicators of air pollution. In: Hutzinger, O. (ed.) The Handbook of Environmental Chemistry. Vol.4 Part C. Springer-Verlag, Berlin.

Nash, TH, III; Gries, C. 1995. The response of lichens to atmospheric deposition with an emphasis on the arctic. Science of the Total Environment 160/161: 737-747.

The effects of contaminants on arctic lichens are a major concern, because lichen-dominated ecosystems occur extensively in arctic regions. Lacking roots or other absorptive organs, lichens are dependent primarily on atmospheric sources of nutrients and therefore readily accumulate atmospheric contaminants. Because they lack stomatal control of gas exchange, deposition of gaseous pollutants to lichens occurs across their entire surface, and this may exceed deposition occurring to vascular plants. Pollutants such as SO2 can vastly reduce species richness and abundance of lichens and cause shifts from predominantly sexual to asexual reproduction. In surviving species, modifications of external morphology reflecting ultrastructural changes may occur. Experimental studies with arctic and other lichen species have documented a wide range of responses to various contaminants, including K+ leakage due to alteration of membrane permeability, changes in chlorophyll fluorescence characteristics, reduced nitrogen fixation, and changes in enzyme activity.

Nash, TH, III; Olafsen, AG. 1995. Climate change and the ecophysiological response of arctic lichens. Lichenologist 27(6): 559-565.

Under field conditions of optimal water hydration, lichen photosynthesis is primarily light-limited and nitrogen fixation is temperature-limited in both Peltigera canina and Stereocaulon tomentosum at Anaktuvuk Pass, Alaska. Thus, where duration of optimal hydration conditions remains unchanged from the present-day climate, the anticipated temperature increases in the Arctic may enhance nitrogen fixation in these lichens more than carbon gain. Because nitrogen frequently limits productivity in Arctic ecosystems, the results are potentially important to the many Arctic and subarctic ecosystems in which such lichens are abundant.

Nash, T.H. III, and L. Sigal. 1979. Gross photosynthetic response of lichens to short-term ozone fumigations. Bryologist 82: 280-285.

Nash, T.H. III, and L.Sigal. 1980. Sensitivity of lichens to air pollution with an emphasis on oxidant air pollutants. pp.112-151 In: Miller, P. R. (ed.), Proceedings of the Symposium on Effects of Air Pollution on Mediterranean and Temperate Forest Ecosystems: Gen. Tech. Rep. PSW-43, USFS/USDA.

Gives a general discussion of the evidence that lichens are sensitive indicators of air pollution with oxidants, SO2, HF and trace elements. Uses field study in the San Gabriel NF as an example, see Sigal and Nash III 1980.

Nash, T.H., III, and L. Sigal. 1981. Ecological approaches to use of lichenized fungi as indicators of air pollution. In: D. T. Wicklow and G. C. Carroll (eds.), The Fungal Community: Its Organization and Role in the Ecosystem. pp. 123-187

Nash, T.H. III, and M.R. Sommerfield. 1981. Elemental concentrations in lichens in the area of the Four Corners power plant, NM. Env. & Exptl. Bot. 21:153-162.

Nash, T.H. III, and V. Wirth. 1988. Correlating fumigation studies with field effects. Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer, Berlin-Stuttgart.

Nash, T. H. III, and V. Wirth (editors). 1988. Lichens, Bryophytes and Air Quality. Bibliotheca Lichenologica 30: 231-267. J. Cramer, Berlin-Stuttgart, F.R.G.

Neel, M. 1988. Lichens and Air Pollution in the San Gabriel Wilderness, Angeles National Forest, California. Earth Resources Monograph 13, Forest Service/USDA Region 5.

Nieboer, E., and D.H.S. Richardson. 1981. Lichens as Monitors of Atmospheric Deposition. pp. 112-53 In: S. J. Eisenreich (ed.). Atmospheric Pollutants in Natural Waters. Ann Arbor SciencePublishers, Ann Arbor.

Nieboer, E.A., D.H.S. Richardson, and F.D. Tomassini. 1978. Mineral Uptake and Release by Lichens: An Overview. Bryologist 81(2):226-246.

Review article: "Background and enhanced levels of elements in lichens are reviewed and the Fe/Ti content ratio is shown to reflect the presence of trapped particulates. The following uptake and release mechanisms are critically examined: extracellular ion exchange processes, extracellular electrolyte sorption, particulate trapping and subsequent solubilization, metal hydrolysis, intracellular uptake and release and the rewetting and 'resaturation respiration' phases. A brief survey of the nutritional requirements and nutritive value of lichens is also provided. Finally, it is concluded, after an examination of the mineral sources available to lichens and of mineral translocation and turnover rates in lichen thalli and mats, that lichen morphology and physiology favor their participation in mineral cycling."

Nieboer, E., D.H.S. Richardson, P. Lavoie, D. Padovan. 1979. The role of metal-ion binding in modifying the toxic effects of sulphur dioxide on the lichen Umbilicaria muhlenbergii. I. Potassium efflux studies. New Phytologist 82: 621-632.

Nieboer E.A., et al. 1976. The phytotoxicity of sulphur dioxide in relation to measurable responses in lichens. In: Mansfield, T.A. (ed.) Effect of Air Pollutants on Plants Cambridge Univ. Press. Cambridge. pp.61-85.

Nieboer E.A., et al. 1977. Ecological and physiochemical aspects of the accumulation of heavy metals and sulphur in lichens. In: Proc., Intern. Conf. on Heavy Metals in the Environment, Toronto, Canada. Oct. 1975. pp 331-352.

Neitlich, P., and B. McCune. 1995. Structural factors influencing lichen biodiversity in two young managed stands, western Oregon, USA. Report prepared for the Eugene and Salem Districts of the USDI-Bureau of Land Management.

Neitlich, P.; Rogers, P.; Rosentreter, R. 2003. Lichen communities indicator results from Idaho: baseline sampling. Gen. Tech. Rep. RMRS-GTR-103. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 14 p.

Epiphytic lichen communities are included in the national Forest Health Monitoring (FHM) program because they help us assess resource contamination, biodiversity, and sustainability in the context of forest health. In 1996, field crews collected lichen samples on 141 field plots systematically located across all forest ownership groups in Idaho. Results presented here are the baseline assessment of the statewide field survey. Seventy-five epiphytic macrolichen species were reported from Idaho. Mean species richness varied significantly from seven to 12 species per plot depending on ecoregion province (p < 0.0001). Four lichen species are reported for the first time in Idaho. Major community gradients in nonmetric multidimensional scaling (NMS) ordination are most strongly related to latitude, elevation, percent forest cover, and lichen species richness. Ecoregion provinces occupy significantly different subsections of n-dimensional species space in multi-response permutation procedures (MRPP, p < 1 x 10-8).

Neitlich, P; Rosentreter, R. 2000. FHM Lichen Communities Indicator Results from Idaho, 1996: Forest Health Monitoring Program Detection Monitoring. Report to the US Forest Service FIA/FHM program. http://www.fia.fs.fed.us/lichen/pdf-files/id96-fin.pdf

Nordin, A.; Strengbom, J.; Witzell, J.; Näsholm, T.; Ericson, L. 2005. Nitrogen deposition and the biodiversity of boreal forests: Implications for the nitrogen critical load. Ambio 34:20-24.

The critical load concept is used to establish the deposition levels which ecosystems can tolerate without significant harmful effects. Here we summarize work within the Swedish research program Abatement Strategies for Transboundary Air Pollution (ASTA) assessing the critical load of N for boreal forests. Results from both field experiments in an area with low background N deposition in northern Sweden, and from a large-scale monitoring study, show that important changes in vegetation start to take place when adding low N doses and that recovery of the vegetation after ceasing N input is a very slow process. The data presented indicate that changes in key ecosystem components occur even at a lower rate of N input than the present recommended empirical critical load for boreal forest understory vegetation of 10-15 kg N ha-1 yr-1. Based on the data presented, we suggest that the critical load should be lowered to 6 kg N ha-1 yr-1.

O'Hare, G.P. 1974. Lichens and bark acidification as indicators of air pollution in west central Scotland. J. Biogeogr. 1:135-146.

Oksanen, J., E. Laara, and K. Zobel. 1991. Statistical analysis of bioindicator value of epiphytic lichens. Lichenologist 23: 167-180.

Generalized linear modeling was applied in analyzing the bioindicator values of epiphytic lichens for air poll. around an industrial center in the Siberian mountains using data published previously by Zobel 1988. The occurrence of taxa on tree boles was systematically related to the distance from the poll. sources (pulp and paper mill and power plant) and the altitude above sea level. In the current analysis, quantitative values were assigned (linear and quadratic contrasts) to the altitude and distance levels. Most species had a significant and usually monotone response to distance. In the majority of these, the effect of distance varied between the altitude levels most often so the lichens were scarcer at low altitude and their increase was faster at high altitudes.

Pakarinen, P., A. Makinen, and R.J.K. Rinne. 1978. Heavy metals in Cladonia arbuscula and Cladonia mitis in eastern Fennoscandia. Ann. Bot. Fenn. 15: 281-286.

"Cu, Fe, Mn, Pb, Zn and ash content were determined in the lichen spp. Cladonia arbuscula and C. mitis from 23 sites throughout Finland and northern Norway. Pb, Fe, Zn, ash and Cu (ranked according to the steepness of the gradient) showed a significant decrease from south to north. this regional pattern is similar to that obtained previously with forest and bog mosses. Verticle fractionation of the lichen carpet revealed an increase in Fe, ash, Pb and Cu toward the basal part of the podetia, while Mn and Zn did not change significantly."

Palmqvist, K.; Campbell, D.; Ekblad A.; Johansson, H. 1998. Photosynthetic capacity in relation to nitrogen content and its partitioning in lichens with different photobionts. Plant, Cell and Environment 21: 361-372.

We tested the hypothesis that lichen species with a photosynthetic CO2-concentrating mechanism (CCM) use N more efficiently in photosynthesis than species without this mechanism. Total ribulose bisphosphate carboxylase-oxygenase (Rubsico) and chitin (the nitrogenous component of fungal cell walls), were quantified and related to photosynthetic capacity in 8 lichens representing 3 modes of CO2 acquisition and 2 modes of N acquisition. Species included: 1 cyanobacterial (Nostoc) lichen with a CCM and N2 fixation; 4 green algal (Trebouxia) lichens with a CCM but without N2 fization; 3 lichens with a CCM but without N2 fixation; 3 lichens with green algal primary photobionts (Coccomyxa or Dictyochloropsis) lacking a CCM but with N2-fixing Nostoc in cephalodia. When related to thallus dry weight, total thallus N varied 20-x, chitin 40x, Chl a 5-x and Rubsico 4-x among the species. Total N was lowest in 3 of the 4 Trebouxia lichens and highest in the bipartite cyanobacterial lichen. Lichens with the lowest N invested a larger proportion of N into photosynthetic components, while the species with hi N made relatively more chitin. As a result, the potential photosynthetic N-use efficiency was negatively correlated to total thallus N for this range of species. The cyanobacterial lichen had a higher photosynthetic capacity in relation to both Chl a and Rubisco compared with the green algal lichens. For the range of green algal lichens both Chl a and Rubisco contents were linearly related to photosynthetic capacity, so the data did not support the hypothesis of an enhanced photosynthetic N use efficiency in green-algal lichens with a CCM.

Pearson, L.C. 1980. Air pollution increases leakage of electrolytes from lichen cells. Bot. Soc. of America Misc. Series. Publ. 158: 87.

Pearson, L.C. 1985. Air pollution damage to cell membranes in lichens I. Development of a simple monitoring test. Atmospheric Environment 19: 209-212.

Pearson, L. 1993. Active monitoring. In: K. Stolte, D. Mangis, R. Doty, K. Tonnessen & L. S. Huckaby (eds.) Lichens as Bioindicators of Air Quality. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station General Technical Report RM-224, Fort Collins, Colorado. Pp. 89-95.

Pearson, L.C., and G.A. Rodgers. 1982. Air pollution damage to cell membranes in lichens III. Field experiments. Phyton. (Austria.) 22: 329-337.

Perkins, D.F., V. Jones, R.O.Millar, and P. Neep. 1976. Airborne fluoride and lichen growth. In: Institute of terrestrial ecology annual report, 1975. London: Her Majesty's Stationary Office: 63.

Perkins, D.F., and R.O. Millar. 1987a. Effects of airborne fluoride emissions in Wales, Parts 1 and 2. Environmental Poll. 47: 63-78 and 48: 185-196.

Parts 1 and 2 examine the effects of F emissions from a new aluminum works plant in Wales. Pt. 1: Corticolous Lichens on Broad leaved Trees: Pt. 2 Saxicolous Lichens Growing on Rocks and Walls. Three zones were established, using cover % and comparing damage. Corticolous NW spp: Evernia prunastri, Ramalina farinacea, Hypogymnia physodes, Hypogymnia tubulosa, melgla, Parmelia sulcata, Parmelia saxatilis, Peltigera canina, Physcia adscendens, Physcia aipolia, Physcia tenella, Punctelia subrudecta, Xanthoria parietina. Saxicolous NW spp: Neofuscelia loxodes, Parmelia saxatilis. Thallus concentrations of F and assoc. injury decreased with increasing distance form the works. Fruticose and sensitive foliose spp. lost 40-75% cover up to 4 k downwind, where F averaged 50-100mg/g, but < 40% losses were recorded in fruticose spp. up to 9k where F averaged 35-50 mg. Saxicolous spp. were damaged less than corticolous spp and crustose spp. of both groups were more tolerant, even growing into spaces where other morphological types had died off. Injury symptoms varied between spp. but some or all of the following. features were common: bleaching(chlorosis) due to damage of algal cells; red coloration; blackening of thallus(necrosis); weakening of attachment to substrate.

Perkins, D.F. , R.O. Millar, and P.Neep. 1980. Accumulation of airborne fluoride by lichens in the vicinity of an aluminum reduction plant. Environmental Pollution (Series A) 21: 155-168.

"Accumulation of F in lichens is described following the establishment of an aluminum reduction plant in Wales. Before emission of F pollutants, thalli of corticolous and saxicolous spp of Ramalina had mean conc. of 9 and 16 ppm of F, dry wt., respectively. After the plant opened in 1970, F conc. increased in lichens near the plant. Corticolous lichens tended to accumulate F more rapidly than saxicolous spp. with consequent accelerated damage and reduction in abundance."

Peterson, E.; Neitlich, P. 2001. Impacts of Two Coal-Fired Power Plants on Lichen Communities in Northwestern Colorado. Report to the US Forest Service FIA/FHM program. http://www.fia.fs.fed.us/lichen/pdf-files/Colorado_Emissions.pdf

The USDA Forest Health Monitoring project (FHM) includes studies of lichen communities because lichens directly relate to several forest resource issues, including concerns over air pollution. Previous FHM lichen studies in Colorado culminated in a gradient model for the state which included environmental characters and air quality. That work also developed a method for calculating an air quality index at future sites from the proportion of pollution indicator lichens in the lichen communities. The previous work and other studies suggest that air quality is low in the area of Colorado's Park Range and the Mount Zirkel Wilderness (Routt National Forest), attributable to two coal-fired power plants in the Yampa Valley, but lichen community data is sparse in the area. We added 35 plots to the area, mostly on the western and upper-eastern slopes of the Park Range. These plots should help us to understand environmental gradients and the influence of pollution in the area, and can be later re-sampled to determine changes in lichen communities with respect to changes in air quality. With a smaller study area, we found a greater number of environmental characteristics to which lichen community patterns corresponded, including elevation, the presence of hardwood trees, and forest structure. Though initial analyses hinted that we would also find strong pollution gradients in the area, once adjustments were made, any pollution gradients present were swamped by noise in the data from the complex topography and environment, and could not be statistically verified. There did remain the visual appearance of lower air quality as measured by the abundance of Bryoria fuscescens in the same area as other studies have found peaks in sulfur deposition. While no strong conclusions can be made about pollution gradients, we suggest pollution affects on lichen community composition are most likely concentrated in the area of Rabbit Ears and Buffalo Passes in the Park Range.

Peterson, J, D. Schmoldt, D. Peterson, J. Eilers, R. Fisher, and R. Bachman. 1992. Guidelines for Evaluating Air pollution Impacts on Class I Wilderness Areas in the Pacific Northwest. USDA-Forest Service Pacific Northwest Research Station General Technical Report PNW-GTR-299.

Pike, L. H. 1978. The importance of epiphytic lichens in mineral cycling. Bryologist 81(2): 247-257.

Pilkington, M.G.; Capron, S.J.M.; Carroll, J.A.; Cresswell, N.; Lee, J.A.; Emmett, B.A.; Bagchi, R. 2007. Phosphorus supply influences heathland responses to atmospheric nitrogen deposition. Environmental Pollution 148(1): 191-200.

On an upland moor dominated by pioneer Calluna vulgaris and with an understorey of mosses and lichens, experimental plots were treated with factorial combinations of nitrogen (N) at +0 and +20 kg N ha-1 yr-1, and phosphorus (P) at +0 and +5 kg P ha-1 yr-1. Over the 4-year duration of the experiment, the cover of the Calluna canopy increased in density over time as part of normal phenological development. Moss cover increased initially in response to N addition but then remained static; increases in cover in response to P addition became stronger over time, eventually causing reductions in the cover of the dominant Calluna canopy. Lichen cover virtually disappeared within 4 years in plots receiving +20 kg N ha-1 yr-1 and also in separate plots receiving +10 kg N ha-1 yr-1, but this effect was reversed by the addition of P.

Pinho, P.; Augusto, S.; a, Martins-Lou&ccedil;äo, M.A.; Pereira, M.J.; Soares, A.; Máguas, C.; Branquinho, C. 2008. Causes of change in nitrophytic and oligotrophic lichen species in a Mediterranean climate: Impact of land cover and atmospheric pollutants. Environmental Pollution (In Press).

With the aim of determining the main drivers of changes in nitrophytic and oligotrophic macro-lichen communities in an industrial region with a Mediterranean climate, we considered both land-cover types and atmospheric pollutants. We determined the relation between the abundance of nitrophytic and oligotrophic species with environmental factors considering the distance of influence of land-cover types. The results showed that oligotrophic species decreased in the proximity of artificial areas, barren land and agricultural areas, associated with higher concentrations of NO2 and Zn, and Ti, probably dust of industrial and agricultural origin. Nitrophytic species were positively related to all the mentioned land-cover types, and with higher concentrations of Fe and N. Magnesium, probably from ocean aerosols, was negatively related to oligotrophic species and positively to nitrophytic.

Pisut, I. 1962. Bemerkungen zur Wirkung der Exhaltionsprodukte auf die Flechtenvegetation in der Umgebung von Rudnany (Nordostslowakei). Biologia 17(7): 481-494.

Poikolainen, J; Lippo, H; Hongisto, M; Kubin, E; Mikkola, K; Lindgren, M 1998. On the abundance of epiphytic green algae in relation to the nitrogen concentrations of biomonitors and nitrogen deposition in Finland. Environmental Pollution 102(1): 85-92.

Green algae have become considerably more abundant in the years 19851995 in Finland and their distribution area has expanded northwards. Green algae on conifers were most abundant in southern Finland where N deposition is highest. Correlations were observed between the abundance of green algae and modeled N and S deposition as well as the N concentration of the biomonitors. The increased abundance of green algae in Finland may be caused by several concurrent changes which have taken place in the environment and which have all promoted the occurrence of green algae. A slight rise in mean annual temperature, the long-term stability of N deposition, and the clear fall in the amount of S deposition have probably all increased the growth and abundance of green algae. At a local level, the differences in microclimate have also effect on the abundance of green algae and the microclimate varies, inter alia, by the nutrient-richness of the habitat, the predominant tree species, stand age and stand density.

Porter, E., Blett, T; Potter, DU; Huber, C. 2005. Protecting Resources on Federal Lands: Implications of Critical Loads for Atmospheric Deposition of Nitrogen and Sulfur BioScience: Vol. 55, No. 7, pp. 603-612.

Critical loads are a potentially important tool for protecting ecosystems from atmospheric deposition and for promoting recovery. Exceeding critical loads for nitrogen and sulfur can cause ecosystem acidification, nitrogen saturation, and biotic community changes. Critical loads are widely used to set policy for resource protection in Europe and Canada, yet the United States has no similar national strategy. We believe that ecosystem science and resource protection policies are sufficiently advanced in the United States to establish critical loads for federal lands. Communication and interaction between federal area managers and scientists will ensure that critical loads are useful for assessing ecosystem conditions, influencing land management decisions, and informing the public about the status of natural resources. Critical loads may also be used to inform air pollution policy in the United States, regardless of whether critical loads are directly linked to air quality regulations and emissions reductions agreements, as they are in Europe.

Porter, M.K. 2006. Regional modeling of nitrogen, sulfur, and mercury atmospheric deposition in the Pacific Northwest. M.S. Thesis, Dept. of Civil and Environmental Engineering, Washington State University, Pullman, WA. 127 pp.

Power, S.A.; Green, E.R.; Barker, C.G.; Bell, J.N.B.; Ashmore, M.R. 2006. Ecosystem recovery: heathland response to a reduction in nitrogen deposition. Global Change Biology 12(7): 1241-1252.

Puckett, K.J. 1988. Bryophytes and lichens as monitors of metal deposition. In: Nash, THIII (ed.), Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer, Berlin-Stuttgart.

"The criteria for suitable biomonitors of metal deposition and to what extent bryophytes and lichens satisfy these criteria are addressed." The author also reviews factors determining choice of in situ monitors, use of transplanted material, techniques for source identification of the accumulated metals and substrate influences. "Lastly, spatial and temporal variation in metal deposition as the result of emissions from line, point, area and remote sources are summarized."

Puckett, K.J., and E.J. Finegan. 1980. An analysis of the element content of lichens from the Northwest Territories, Canada. Can. J. Bot. 58: 2073-2089.

[Fourteen lichen species from 45 sites analyzed for 20 elements.] Univariate analysis of variance did not show any significant differences between the element content of Cladina arbuscula, Cladina rangiferina, Cladina stellaris or any differences between Cetraria cucullata and Cetraria nivalis on the basis of any single element. However, multiple discriminant analysis did show that the spp. mentioned could be distinguished when all the elements were compared simultaneously. The discrimination between Cladina spp. was based on relative efficacy of these lichens in the accumulation of iron, scandium. titanium, and vanadium.

Puckett, K.J., and S. Sang. 1983. Trace element mapping with lichens and bryophytes. In: Proc. of the Symposium Assessing Air Quality with Lichens and Bryophytes -Part 1.

Purvis, O.W., B.J. Coppins, D.L. Hawksworth, P.W. James, and D.M. Moore. 1992. The Lichen Flora of Great Britain and Ireland. Natural History Museum Publications. London. 710 pp.

Purvis, W. O.; Chimonides, P. J.; Jefferies, T. E.; Jones, G. C.; Read, H.; Spiro, B. 2005. Investigating biogeochemical signatures in the lichen Parmelia sulcata at Burnham Beeches, Buckinghamshire, England. Lichenologist 37(4): 329-344.

Ra, H.S.Y.; Geiser, L.H.; Crang, R.F.E. 2005. Effects of season and low-level air pollution on physiology and element content of lichens from the U.S. Pacific Northwest. Science of the Total Environment 343: 155-167

Lichens were collected from three low-elevation sites in the western Cascade Range: HJ Andrews, OR (clean) and Bull Run, OR, and Pack Forest, WA (moderately enhanced nitrogen and sulfur deposition). The latter sites were within 50 km of Portland and Seattle/Centralia urban-industrial areas, respectively. Tissue concentrations of sulfur, nitrogen, and other macronutrients; rates of net carbon uptake; concentrations of photosynthetic pigments; and thallus density were correlated with season and seasonal changes in Platismatia glauca. Ion concentrations in precipitation and total wet deposition were measured from natural settings. Concentrations of depositional ions in precipitation, including NO3- and NH4+, were generally highest at Bull Run and Pack Forest; SO42- concentrations and acidity were highest at Pack Forest. Total wet deposition was higher in the winter rainy season than the dry summer season at all three sites. Lichens adapted physiologically and morphologically to the higher light intensity and the warm, dry climate of summer through decreased optimal water content for CO2 uptake, increased concentrations of carotenoids and increased thallus density. Compared to the clean site, the sites with enhanced deposition were associated in P. glauca with year-round higher tissue concentrations of N, S, K, and Na; higher concentrations of total chlorophyll and carotenoids; higher OD435/415 ratios; higher CO2 uptake and lower thallus density in summer; and a general absence of other sensitive lichens. These results indicate that moderate levels of fertilizing air pollutants can stimulate carbon uptake and provide protection against chlorophyll degradation in air pollution-tolerant lichens of the Pacific Northwest, especially during the dry summer season.

Ra, H.-S.Y.; Rubin, L.;Crang, R.F.E. 2004. Structural impacts on thallus and algal cell components of two lichen species in response to low-level air pollution in Pacific Northwest forests. Microscopy and Microanalysis 10(2): 270-279.

Lichens have long been regarded as bioindicators of air pollution, and structural studies typically have indicated negative impacts in highly polluted areas. In this research, Parmelia sulcata and Platismatia glauca were collected from one clean and two polluted sites in the Pacific Northwest forests of the United States to investigate the anatomical and ultrastructural responses of relatively resistant lichens to moderate air pollution. Light microscopy of polluted materials revealed only slight increases in the algal cell proportions of the thallus, and a decrease in the fungal cells of the medulla. Using transmission electron microscopy, increased lipid droplets in the cytoplasm and an increase in the cell wall thickness of the photobionts were found in the polluted lichens. These results were compared with physiological data in which the net carbon uptake did not show any significant differences; however, the total chlorophyll content was heightened in the polluted samples. The increased total chlorophyll content and the absence of any changes in the algal cell proportions of the polluted samples suggest that the photobionts possessed a higher chlorophyll content per unit volume of the photobiont at polluted sites. The results also indicate that lichens have altered their storage allocation in different cellular compartments. This may be a result of symbiotic readjustment(s) between the photobiont and the mycobiont. In comparison with the physiological results from these two species, these changes do not represent damaging effects by low-level air pollution.

Rao, D.N., and F. LeBlanc. 1966. Effects of sulphur dioxide on the lichen algae with special reference to chlorophyll. Bryologist 69:69-75.

"Thalli of NW spp: Xanthoria fallax, Xanthoria parietina were exposed to 5 ppm SO2 gas for 24 hrs at various humidities. Bleaching, permanent plasmolysis, and formation of sporadic brown spots on the chloroplasts were observed in the algal cells. Sulfurous acid and Mg2+ were detected in the extracts of the SO2 exposed thalli. Sulfate concentration increased in thalli exposed to SO2 in increased humidity. Light absorbtion was 667 mm, characteristic of phaeophytin, indicating the degradation of chlorophyll to phaeophytin under the influence of SO2."

Rhodes, F.M. 1988. Re-examination of Baseline Plots to Determine Effects of Air Quality on Lichens and Bryophytes in Olympic National Park. National Park Service Air Quality Division -- Special Publication. Northrop Environmental Sciences. SP-4450-88-13. November 1988.

Rhodes, F.M. 1996. A review of Lichen and Bryophyte Elemental Content Literature. Prepared for United States Forest Service, Mt. Baker/Snoqualmie National Forest. Mycena Consulting, Bellingham, WA.

Richardson, D.H.S. 1988. Understanding the pollution sensitivity of lichens. Bot. J. Linnean Soc. 96: 31-43.

Review that covers methods of study, mechanisms leading to accumulation, pitfalls of correlating lab studies (esp. fumigation) with field observations. General physical and physiologic signs of damage, pollutants are named, SO2 being the most harmful.

Richardson, D.H.S. 1992. Pollution monitoring with lichens. Naturalists' Handbooks 19. Richmond Publishing Co., Ltd. Slough, England. 76 pp.

Richardson, D.H.S., and E. Nieboer. 1980. Cellular Interactions in Symbiosis and Parasitism Surface binding and accumulation of metals in lichens. In: C. B. Cook, P. W Pappas & E. D. Rudolph (eds.). Cellular Interactions in Symbiosis and Parasitism . Pp 75-94. Ohio State University Press, Columbus.

Richardson, D.H.S., and E. Nieboer. 1983. Ecophysiological responses of lichens to sulfur dioxide. J. Hattori Bot. Lab. 54: 331-351.

[New data suggest the following "... sequence in terms of SO2 sensitivity: N2 fixation > photosynthesis > respiration > pigment status > K+ efflux. Evidence is now accumulating that there is a seasonal variation of SO2 sensitivity in lichens that probably reflects variations in mineral status, chlorophyll content and metabolic activity of these plants."]

Richardson, D.H.S., and C.M. Young. 1977. Lichens and vertebrates. In: Lichen Ecology, M.R.D. Seaward, ed. Academic Press, London. Pp. 121-144.

Richardson, D.H.S., and E. Nieboer. 1983. The uptake of nickel ions by lichen thalli of the genera Umbilicaria and Peltigera. Lichenologist 15(1): 81-88.

Riddell, J; Nash, T.H. III; Padgett, P. 2008. The effect of HNO3 gas on the lichen Ramalina menziesii. Flora 203: 47-54

Nitric acid (HNO3) and ozone (O3), secondary products of photochemical reactions of nitrogen oxides (NOx) and volatile organic compounds, are important pollutants in arid regions with large outputs from petrol combustion. In the Los Angeles (LA) air basin, nitrogen dry deposition rates in forests downwind of the urban areas can reach 35–40 kg ha-1 year-1, roughly equivalent to the amount of N used to fertilize agricultural fields. The marked decline in the lichen population of the LA air basin has previously been attributed to local O3 concentration gradients, which overlaid the patterns of species extirpation. Recent research in the air basin has shown that nitrate (NO3-) deposition gradients run parallel to the O3 concentration gradient, and that deposition of NO3- and HNO3 can have significant effects on forest health. Our research examines the effects of HNO3 dry deposition on the lichen Ramalina menziesii Tayl. in an effort to understand the loss of lichen species in southern California, and increase the usefulness of lichens as biomonitors of nitrogen pollutants. We transplanted healthy R. menziesii thalli from a ``pristine'' location into fumigation chambers and exposed them to HNO3 under humid and dry conditions, and moderate and high HNO3 fumigations. R. menziesii thalli treated with HNO3 in month-long fumigations experienced a significant decline in chlorophyll content and carbon exchange capacity compared to thalli in control chambers. Leachate conductivity, NO3- and K+ concentrations increased with HNO3 fumigation levels and time. We conclude that R. menziesii has an unequivocally negative response to HNO3 gas concentrations common to ambient summer conditions in the LA air basin.

Robinson, CH; Wookey, PA. 1997. Microbial ecology, decomposition and nutrient cycling In: Woodin, SJ; Marquiss, M; eds. Ecology of Arctic environments. Oxford, UK: Blackwell Science, 69-96.

Rochelle, J.A. 1980. Mature Forests, Litterfall and Patterns of Forage Quality as Factors in the Nutrition of Black-tailed Deer on Northwestern Vancouver Island. Ph.D. thesis, Univ. of British Columbia.

Rogers, P. 2007. Factors influencing epiphytic lichen communities in aspen-associated forests of the Bear River Range, Idaho and Utah Logan, UT: Utah State University. 166 p. Dissertation. http://treesearch.fs.fed.us/pubs/29037

In western North America, quaking aspen (Populus tremuloides Michx.) is the most common hardwood in montane landscapes. Fire suppression, grazing, wildlife management practices, and climate patterns of the past century are some of the threats to aspen coverage in this region. Researchers are concerned that aspen-dependent species may be losing habitat, thereby threatening their long-term local and regional viability. Though lichens have a rich history as air pollution indicators, I believe that they may also be useful as a metric of community diversity associated with habitat change. To date, few studies have specifically examined the status of aspen's epiphytic lichen community in the Rocky Mountains. A preliminary study was conducted using 10 transect-based plots to assess lichen species substrate preferences between aspen and various conifer species and to gain basic knowledge of species diversity. Following this work, I established 47 plots in the Bear River Range of northern Utah and southern Idaho to evaluate the effects of forest succession on epiphytic macrolichen communities. Plots were located in a narrow elevational belt (2,134-2,438 m) to minimize the known covariant effects of elevation and moisture on lichen communities. Results show increasing lichen diversity and a decrease in aspen-dependent species as aspen forests succeed to conifer cover types. The interactive roles of stand aspect, basal area and cover of dominant trees, stand age, aspen bark scars, and recent tree damage were examined in relation to these trends. An aspen index score was developed based on lichens showing an affinity for aspen habitat. I present a landscape-level multivariate analysis of short- and long-term factors influencing epiphytic lichen communities in aspen forests. Nonmetric multidimensional scaling (NMS) ordination stressed the importance of succession and local air pollution sources in shaping lichen communities. I also investigated the role of historic human intrusions and climate on aspen forests and aspen-dependent epiphytic lichens at the landscape-level. Implications of this work include 1) realization of nitrogen impacts on ecosystems, 2) the potential for using lichens as bioindicators for monitoring aspen stand health, and 3) suggestions for working with natural disturbance regimes to minimize human impacts on aspen and associated species.

Rope, S.K., and L.C. Pearson. 1990. Lichens as air pollution biomonitors in a semiarid environment in Idaho. Bryologist 93:50-61.

Rosentreter, R. 1990. Indicator value of lichen cover on desert shrubs. Pages 282-289 In: McArthur, E.D., Romney, E.M., Smith, S.D., Tueller, P.T., comps. Proceedings of the Symposium: Cheatgrass invasion, shrub die-off and other aspects of shrub biology and management. Gen. Tech. Report INT-276, Ogden, UT.

Ecological factors affecting the amount of lichen cover on desert shrubs are discussed. Canopy density, shrub growth rate, bark stability, pH, and ecological sites are correlated with the amount of lichen cover on shrubs. Knowledge of these relationships can indicate site characteristics useful in interpreting and managing shrub sites. Common lichen species growing on desert shrubs are briefly discussed. Anthropogenic and shrub die-off effects that increase lichen cover densities are explained. The big sagebrush (Artemisia tridentata) complex in southern Idaho is used to illustrate many of the ecological relationships involved with shrubs and their resulting lichen cover.

Rosentreter, R. 1995. Lichen diversity in managed forests of the Pacific Northwest, USA. Mitt. Eidggenöss. Forsch. anst. Wald Schnee Landsch. 70(1): 103-124. Rosentreter, R., and V. Ahmadjian. 1977. Effect of ozone on the lichen Cladonia arbuscula and the Trebouxia phycobiont of Cladonia stellaris. Bryologist 80: 600-605.

"The chlorophyll content of Cladina arbuscula thalli and of a Trebouxia phycobiont isolated from Cladina stellaris increased after the organisms were exposed for one week to an ozone concentration of 0.1 ppm. Concentrations of ozone above 0.1 ppm did not significantly affect the chlorophyll content relative to those of the controls. There were no discernable morphological effects that could be attributed to ozone exposure." This was done with levels of O3 that would be found in urban centers(some previous studies used abnormally high levels of ozone). Other previous studies' problems are discussed: crude ozoners w/high current densities, moist air, unreliable methods of analysis and organic materials that are readily attacked by ozone. O3 possibly affects other processes than photosynthesis and biological processes affected may be species specific. Ozone damage may be seasonal, as 03 conc. vary seasonally.

Ross, L.J., and T.H. Nash III. Effect of ozone on gross photosynthesis of lichens. Environ. Exp. Bot. 23(1): 71-77.

"Pseudoparmelia caperata and Ramalina menziesii were subjected to short- and long-term fumigations. P. caperata was fumigated with 200, 490, 980 mg/m3 of ozone for 12 hr. A significant decline in the rate of 14CO2 assimilation was seen at all conc. R. menzeiesii was exposed to 200, 490, 980, and 1567 mg/m3 of ozone for 12 hr with no significant reduction in the rate of photosynthesis. Both spp. were also fumigated with 200 mg/m3 of ozone for 6 hr on 5 consecutive days. P. caperata results demonstrated a significant reduction of photosynthesis, while R. menzeiesii did not. Field analyses indicated that P.caperata is undergoing stress in the Santa Monica Mtns of southern CA, where ozone has been recorded at 200 mg/m3 50-100 days per year. The results of these lab studies infer that ozone is contributing to the low lichen cover in the field, but the absence of R. menzeiesii appears to be independent of ozone pollution. Sensitive spp: Parmelia sulcata, P.caperata. Insensitive spp: R. menzeiesii , Cladina rangiferina , C. arbuscula, Hypogymnia enteromorpha.

Ruisi, S.; Zucconi, L.; Fornasier, F.; Paoli, L.; Frati, L.; Loppi, S. 2005. Mapping environmental effects of agriculture with epiphytic lichens. Israel Journal of Plant Sciences 53: 115-124.

The present paper reports the results of a study designed to check the feasibility of epiphytic lichens as biomonitors of the effects of agriculture in an area of central Italy without heavy industrialization and with an economy mainly based on agriculture. The exclusion of nitrophytic species (objectively selected using the on-line check-list of Italian lichens) from the calculation of the index of lichen diversity, which is supposed to reflect air quality, led to more realistic results. Conversely, the use of only nitrophytic species allowed us to map the eutrophication in the area, which resulted in lichens heavily affected by agricultural activities. Mapping using only strictly nitrophytic species showed two "hot spots" where ammonia emission from animal husbandry plays an important role. Two sites emerged as suffering at the same time from ammonia and NOX pollution. It is concluded that epiphytic lichens are an effective tool to detect and map the effects of agriculture also in Mediterranean countries, at least in areas without heavy industrialization, given the proper species selection.

Ruoss, E., and C. Vonarburg. 1995. Lichen diversity and ozone impact in rural areas of central Switzerland. Cryptogamic Botany 5: 252-263.

Russow, R ; Veste, M ; Littmann, T 2004. Using the natural 15N abundance to assess the main nitrogen inputs into the sand dune area of the north-western Negev desert (Israel). Isotopes Environ Health Studies 40: 57-67.

The variation of the natural 15N abundance is often used to evaluate the origin of nitrogen or the pathways of N input into ecosystems. We tried to use this approach to assess the main input pathways of nitrogen into the sand dune area of the north-western Negev desert (Israel). The following two pathways are the main sources for nitrogen input into the system: i. Biological fixation of atmospheric nitrogen by cyanobacteria present in biological crusts and by N2-fixing vascular plants (e.g. the shrub Retama raetam); ii. Atmospheric input of nitrogen by wet deposition with rainfall, dry deposition of dust containing N compounds, and gaseous deposition. Samples were taken from selected environmental compartments such as biological crusts, sand underneath these crusts (down to a depth of 90 cm), N2-fixing and non-N2-fixing plants, atmospheric bulk deposition as well as soil from arable land north of the sandy area in three field campaigns in March 1998, 1999 and 2000. The delta15N values measured were in the following ranges: grass -2.5/1000 to +1.5/1000; R. reatam: +0.5/1000 to +4.5/1000; non-N2-fixing shrubs +1/1000 to +7/1000; sand beneath the biological crusts +4/1000 to +20/1000 (soil depth 2-90 cm); and arable land to the north up to 10/1000. Thus, the natural 15N abundance of the different N pools varies significantly. Accordingly, it should be feasible to assess different input pathways from the various 15N abundances of nitrogen. For example, the biological N fixation rates of the Fabaceae shrub R. reatam from the 15N abundances measured were calculated to be 46-86% of biomass N derived from the atmosphere. The biological crusts themselves generally show slight negative 15N values (-3/1000 to -0.5/1000), which can be explained by biological N fixation. However, areas with a high share of lichens, which are unable to fix atmospheric nitrogen, show very negative values down to -10/1000. The atmospheric N bulk deposition, which amounts to 1.9-3.8 kg N ha-1 yr-1, has a 15N abundance between 4.4/1000 and 11.6/1000 and is likely to be caused by dust from the arable land to the north. Thus, it cannot be responsible for the very negative values of lichens measured either. There must be an additional N input from the atmosphere with negative delta15N values, e.g. gaseous N forms (NOx, NH3). To explain these conflicting findings, detailed information is still needed on the wet, particulate and gaseous atmospheric deposition of nitrogen.

Rühling, &Aring;. 1994. Atmospheric heavy metal deposition in Europe - estimation based on moss analysis. Nord 1994:9. Nordic Council of Ministers, Copenhagen.

Ryan, B.D. 1990a. Lichens and air quality in wilderness areas in California: A series of baseline studies. Six Reports submitted to USDA-USFS, Region 5. San Francisco. Unpublished.

Ryan, B.D. 1990b. Lichens and air quality in the Marble Mountain Wilderness, California: A baseline study. Report to USDA-USFS, Region 5. San Francisco.

Ryan, B.D., T.H. Nash III, and W. Davis. 1990. Lichens and air quality in the Mt. Baldy Wilderness Area. ASU, Tempe. Report to USDA/USFS Southwest Region.

Ryan, B., and F. Rhodes. Appendix B: Lichens, Bryophytes, and Air Quality in Pacific Northwest Wilderness Areas. In: Peterson, Janice, Daniel Schmoldt, David Peterson, Joseph Eilers, Richard Fisher, Robert Bachman. Guidelines for Evaluating Air Pollution Impacts on Class 1 Wilderness Areas in the Pacific Northwest. General Technical Report PNW-GTR-299. USDA/USFS. May 1992.

Rychert, R.C. and J. Skujins. 1974. Nitrogen fixation by blue-green algae-lichen crusts in the Great Basin Desert. Proc. Soil Sci. Soc. Amer. 38: 768-71.

Saeki, M., et al. 1977. Metal burden of urban lichens. Environmental Research 13: 256-266.

St. Clair, L. 1989a. Establishment of a Lichen Biomonitoring Program for the Salmon National Forest: Interim Report. Submitted to: Gary Jackson, Salmon NF, Salmon ID. 4 pages.

In 1988 102 species in 46 genera were collected as baseline data for the Salmon NF project, "Lichen Biomonitoring Program and Air Quality Baseline". Elemental analysis was conducted on Letharia columbiana, Umbilicaria vellea, Letharia vulpina for Cu, Pb, and S.

St. Clair, L. 1989b. Report concerning establishment of a lichen biomonitoring program for the Jarbridge Wilderness Area, Humboldt NF, NV. Submitted to J. Caywood, USFS Jarbridge RD.

115 lichens in 44 genera were collected and identified as part of a baseline study for the Jarbidge Wilderness Area in Humboldt NF, NV.

St. Clair, LL; Johansen, JR; Rushforth, SR 1993. Lichens of soil crust communities in the intermountain area of the western United States. Great Basin Naturalist 53(1): 5-12.

St. Clair, L. L., and C. C. Newberry. 1995. Establisment of a lichen biomonitorng program and baseline in the Salmon National Forest including the eastern portion of the Frank Church-River of No Return Wilderness Area, Idaho and Montana. Report submitted to G. Jackson, Salmon-Challis National Forest, Idaho, USDA-Forest Service.

Sanz, M.J., C. Gries, and T.H. Nash III. 1992. Dose-response relationships for SO2 fumigations in the lichens Evernia prunastri (L.) Ach. and Ramalina fraxinea (L.) Ach. New Phytol. 122: 313-319.

SO2 fumigation of the lichens Evernia prunastri and Ramalina fraxinea whose thallus water content was held at 100-120% throughout each experiment, resulted in changes in net ps, dark resp., and chlorophyll content in relation to both conentration and duration of exposure. Net ps was the most sensitive response variable. Significant reduction in chloropyll content was found when no recovery in net ps occurred after 2 weeks. A reduction in dark resp. was only found at high SO2 conc. E. prunastri was affected by lower conc. and shorter exposure times than R. fraxinea.

Schofield, E; Ahmadjian, V 1972. Field observations and laboratory studies of some Antarctic cold desert cryptogams. In: G. A. Llano (ed.): Antarctic Terrestrial Biology. Antarctic Research Series Vol. 20, American Geophysical Union, pp. 97-142.

Schumacher, J.; Janssen, A.-M.; Frahm, J.-P. 2006. Spiegelt der VDI-Luftgüteindex die Schadstoff-Belastung duch NO2 und SO2 wider?. Herzogia 19: 205-213.

Schutte, J.A . 1977. Chromium in two corticolous lichens from Ohio and West Virginia. Bryologist 80: 279-283.

Seaward, M.R.D. 1973. Lichen ecology of the Scunthorpe Heathlands I. Mineral accumulation. Lichenologist 5: 423-433. l

Seaward, M.R.D. 1980. the use and abuse of heavy metal bioassays of lichens for environmental monitoring. pp. 375-384 Spaleny, J. (ed.), In: Proceedings of the 3rd International Conference bioindicatores Deteriorisations Regionis; Liblice, Czeckoslovakia. Praha: Academia.

Seaward, M.R.D. 1982. Lichen ecology and changing urban environments. In: R. Bornkamm, J. Almrdse, Urban Ecology The Second European Ecological Symposium. Blackwell Sceintific Publications, Boston. pp.115-172

Seaward, M.R.D. 1987. Effects of quantitative and qualitative changes in air pollution on the ecological and geographical performance of lichens. In: Hutchinson, T. C. and K. M. Meema (eds.), Effects of Atmoshperic Pollutants on Forests, Wetlands and Agricultural Ecosystems. 133: NATO ASI Series, Vol. G16. Springer-Verlag, Berlin-Heidlberg.

[Review of changes in distributions as a result of air pollution and acid rain. "More recently, the differing effects on lichens of both wet and dry acidic deposition have been detected in the field, but as yet little experimental work has been carried out to substantiate these observations. However, a comprehensive lichen mapping programme in the British Isles has shown that some species have extended their ecological and geographical range by exploiting acidified substrata."]

Seaward, M.R.D. 1989. Lichens as pollution monitors: adapting to modern problems. In: Ozturk, M.A. (ed.), Plants and Pollutants in Developed and Developing Countries. Ege University, Bornova, Turkey.

Seniczak, S; Dabrowski, J 1993. The mites (Acari) of an old Scots pine forest polluted by a nitrogen fertilizer factory at Wloclawek (Poland). I. Zool. Beitr. N. F. 35(1): 3-17.

Shaver, GR; Johnson, LC; Cades, DH; Murray, G; Laundre, JA; Rastetter, EB; Nadelhoffer, KJ; Giblin, AE. 1998. Biomass and CO2 flux in wet sedge tundras: response to nutrients, temperature and light. Ecological Monographs 68: 75-97

The aim of this research was to analyze the effects of increased N or P availability, increased air temperature, and decreased light intensity on wet sedge tundra in northern Alaska. Nutrient availability was increased for 6–9 growing seasons, using N and P fertilizers in factorial experiments at three separate field sites. Air temperature was increased for six growing seasons, using plastic greenhouses at two sites, both with and without N 1 P fertilizer. Light intensity (photosynthetically active photon flux) was reduced by 50% for six growing seasons at the same two sites, using optically neutral shade cloth. Responses of wet sedge tundra to these treatments were documented as changes in vegetation biomass, N mass, and P mass, changes in whole-system CO2 fluxes, and changes in species composition and leaf-level photosynthesis. Biomass, N mass, and P mass accumulation were all strongly P limited, and biomass and N mass accumulation also responded significantly to N addition with a small N 3 P interaction. Greenhouse warming alone had no significant effect on biomass, N mass, or P mass, although there was a consistent trend toward increased mass in the greenhouse treatments. There was a significant negative interaction between the greenhouse treatment and the N 1 P fertilizer treatment, i.e., the effect of the two treatments combined was to reduce biomass and N mass significantly below that of the fertilizer treatment only. Six years of shading had no significant effect on biomass, N mass, or P mass. Ecosystem CO2 fluxes included net ecosystem production (NEP; net CO2 flux), ecosystem respiration (RE, including both plant and soil respiration), and gross ecosystem production (GEP; gross ecosystem photosynthesis). All three fluxes responded to the fertilizer treatments in a pattern similar to the responses of biomass, N mass, and P mass, i.e., with a strong P response and a small, but significant, N response and N 3 P interaction. The greenhouse treatment also increased all three fluxes, but the greenhouse plus N 1 P treatment caused a significant decrease in NEP because RE increased more than GEP in this treatment. The shade treatment increased both GEP and RE, but had no effect on NEP. Most of the changes in CO2 fluxes per unit area of ground were due to changes in plant biomass, although there were additional, smaller treatment effects on CO2 fluxes per unit biomass, per unit N mass, and per unit P mass. The vegetation was composed mainly of rhizomatous sedges and rushes, but changes in species composition may have contributed to the changes in vegetation nutrient content and ecosystem-level CO2 fluxes. Carex cordorrhiza, the species with the highest nutrient concentrations in its tissues in control plots, was also the species with the greatest increase in abundance in the fertilized plots. In comparison with Eriophorum angustifolium, another species that was abundant in control plots, C. cordorrhiza had higher photosynthetic rates per unit leaf mass. Leaf photosynthesis and respiration of C. cordorrhiza also increased with fertilizer treatment, whereas they decreased or remained constant in E. angustifolium. The responses of these wet sedge tundras were similar to those of a nearby moist tussock tundra site that received an identical series of experiments. The main difference was the dominant P limitation in wet sedge tundra vs. N limitation in moist tussock tundra. Both tundras were relatively unresponsive to the increased air temperatures in the greenhouses but showed a strong negative interaction between the greenhouse and fertilizer treatments. New data from this study suggest that the negative interaction may be driven by a large increase in respiration in warmed fertilized plots, perhaps in relation to large increases in P concentration.

Sheridan, RP 1979. Impact of emissions from coal-fired electricity generating facilities on N2-fixing lichens. The Bryologist 82: 54-58.

Shirazi, A. M., P. S. Muir, and B. McCune. 1996. Environmental factors influencing the distribution of the lichens Lobaria oregana and L. pulmonaria. Bryologist 99 (1): 12-18.

Showman, R.E. 1972. Residual effects of sulfur dioxide on the net photosynthesis andrespiratory rates of lichen thalli and cultured lichen symbionts. Bryologist 75: 335-341.

Showman, RE 1975. Lichens as indicators of air quality around a coal-fired power generating plant. The Bryologist 78: 1-6.

Lichens were surveyed at 128 sites around a coal-fired power plant in an unurbanized region of southeastern Ohio. Corticolous lichens were found to be useful indicators of air quality while terricolous and saxicolous species were not. Mapping revealed void areas in the distribution of Parmelia caperata (L.) Ach. and P. rudecta Ach. The area of affect was smaller than most of those reported for cities, and in this hilly region, site elevation was found to be an important factor influencing lichen distribution.

Showman, R.E. 1988. Mapping air quality with lichens, the North American experience. In: Nash, T.H., III, (ed.) Lichens, Bryophytes and Air Quality. Bibliotheca Lichenologica 30. J. Cramer, Berlin-Stuttgart.

Showman, RE 1981. Lichen recolonization following air quality improvement. The Bryologist 84: 492-497.

Air quality improvement near a coal-fired power plant led to recolonization of Parmelia caperata (L.) Ach. in a pollution-induced void area. Recolonization was first observed about four years after pollution abatement. Least-affected sites, i.e. near the edge of the original void, were first to recover while most-affected sites were slowest to recover. After eight years of improved air quality, the distribution of P. caperata has returned to near normal. Lichen bio-monitoring is useful not only to detect the effects of poor air quality but to document air quality improvement as well.

Showman, RE 1990. Lichen recolonization in the upper Ohio River valley. The Bryologist 93(4): 427-428.

Improvement in the air quality of the upper Ohio River valley has led to lichen recolonization at previously depauperate sites. Between 1973 and 1989 the number of lichen species in the area almost doubled and the mean species per site increased from 0.8 to 3.5. An indicator species, Flavoparmelia caperata, was completely absent in 1973 but occurred at half of the study sites in 1989.

Showman, RE, Long, RP 1992. Lichen studies along a wet sulfate deposition gradient in Pennsylvania. The Bryologist 95(2): 166-170.

Lichens were surveyed at four study areas along a wet sulfate deposition gradient in north-central Pennsylvania. Species richness was significantly less in high sulfate deposition areas than in low sulfate deposition areas. Although the causal agents for these differences are not known, it is hypothesized that SO2 is responsible at least in part.

Showman, RE 1998. Continuing lichen recolonization in the upper Ohio River Valley. The Bryologist 100(4): 478-481.

Improvement in the air quality of the upper Ohio River valley has led to lichen recolonization at previously depauperate sites. Between 1973 and 1996 the number of corticolous macrolichen species in the area increased from 6 to 20. During the same time the mean species richness per site increased from 0.8 to 6.5. An indicator species, Flavoparmelia caperata, was absent from all study sites in 1973, but present at 27 of 28 study sites in 1996. Lichen studies performed over time provide a good tool to document air quality improvement, but a single study in a changing air quality environment may give problematic results.

Sigal, L.L., and O.C. Taylor. 1979. Preliminary studies of the gross photosynthetic response of lichens to peroxyacetylnitrite fumigations. Bryologist 82: 564-575.

[Studies done on specimens of Collema nigrescens, Hypogymnia enteromorpha, Parmelia sulcata and Peltigera rufescens from the mountains near Los Angeles. "With the exception of C. nigrescens, laboratory results are generally consistent with unpublished observations of distribution and vitality of the species in the field."]

Sigal, L.L., and W.J. Johnston. 1986. Effects of acidic rain and ozone on nitrogen fixation and photosynthesis in the lichen Lobaria pulmonaria (L.) Hoffm. Environmental and Experimental Botany. 26: 59-64.

"Lobaria pulmonaria was subjected to ozone fumigations at 118, 235, 353 mg/m3 and simulated acid rain at pH 2.6, 4.2, 5.6 for 5 days during a 10-day period. Acid rain at pH 2.6 caused significant reductions in N fixation (100%) and 90% reduction in photosynth., thallus bleaching was apparent. There were not significant changes between pH 5.6 and 4.2 in N fixation or photosynthesis and thalli color was unchanged. O3 had no significant effects on L. pulmonaria, but there was a trend toward reduced N fixation with increasing O3 conc. There was no significant O3 -acid rain interaction."

Sigal, L.L. 1988. The relationship of lichen and bryophyte research to regulatory decisions in the United States. In: Nash III, T.H. (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer, Berlin-Stuttgart.

Sigal, L.L., and T.H. Nash III. 1983. Lichen communities on conifers in southern California: an ecological survey relative to oxidant air pollution. Ecology 64:1343-1354.and air pollution. Acta Phytogeographica Suecica 52. Uppsala.

Slack, N.G. 1988. The ecological importance of lichens and bryophytes. In: Nash, THIII (ed.), Lichens, Bryophytes and Air Quality. Bibliotheca Lichenologica 30. J. Cramer, Berlin-Stuttgart.

[Review of the ecological roles of lichens and bryophytes including primary production, nitrogen fixation, nutrient cycling, food chain relationships, and colonization. Author includes discussion of the impact of air pollution on these ecosystem functions.].

Smiley, D, George, CJ 1974. Photographic documentation of lichen decline in the Shawangunk Mountains of New York. The Bryologist 77: 179-187

Photographs of quartz rock surfaces in the Lake Mohonk area of the Shawangunk Mountains of southern New York State reveal a severe decline, during the last 100 years, in the incidence of the umbilicate lichens Lasallia papulosa, L. pensylvanica, and Umbilicaria mammulata.

Smith, C., et al. 1993. Lichens as biomonitors of air quality. In: Huckaby, LS, et al. (eds.) Lichens as Biomonitors of Air Quality. Proc. of a workshop sponsored by the NPS and USDA-FS. Draft. USDA/USFS Rocky Mountain Forest and Range Exp. Sta. GTR RM-224.

S&oslash;chting, U. 1990. Reindeer lichens injured in Denmark. Bull. British Lichen Society 67:1-4.

S&oslash;chting, U. 1995. Lichens as monitors of nitrogen deposition. Cryptogamic Botany 5: 264-269.

A method for using lichens as monitors of N deposition from the air is introduced. Total N in Cladonia portentosa and in Hypogymnia physodes growing close to the ground and not receiving canopy throughfall seem to reflect the wet deposition of nitrogen. The nitrogen content of H. physodes growing at breast height on 10 m high Picea abies is proposed as an indicator of total (dry and wet) deposition. Results of mapping Scandinavia and northwestern Europe are presented. A transplant method using H. physodes is described which can be used for monitoring total N deposition.

Sparrius, L. B. 2007. Response of epiphytic lichen communities to decreasing ammonia air concentrations in a moderately polluted area of The Netherlands. Environmental Pollution 146(2): 375-379.

Decreasing local ammonia air concentrations in a moderately polluted area in The Netherlands were accompanied by a rapid increase in nitrogen-sensitive species (acidophytes) and a decline of nitrogen-tolerant macrolichens (nitrophytes). This paper presents data on the relationship between nitrophyte abundance and species abundance for three ecological groups of epiphytic lichens: nitrophytes (positively correlated with ammonia), acidophytes (negatively correlated) and neutrophytes (which have an optimum at medium concentrations) and suggests ammonia dependent optimum curves for these groups. In this study neutrophytes were found to die-off massively at sites with a decrease of the ammonia air concentration over the period 1996-2003.

Steinnes, E., and H. Krog. 1977. Mercury, arsenic and Selenium fallout from an industrial complex studied by means of lichen transplants. Oikos 23: 160-164.

Transplants of Hypogymnia physodes were compared with naturally occurring samples. Transplants proved to be an efficient means of studying Hg fall out from local industries. Lower Hg in the naturally occurring samples may be due to SO2 damage.

Stolte, K., D. Mangis, R. Doty and K. Tonnessen (editors). 1993. Lichens as Bioindicators of Air Quality. Gen. Tech. Rep. RM-224. Fort Collins, Colorado. USDA-Forest Service, Rocky Mountain Forest and Range Experiment Station. 131 pp.

Sundberg, B.; Ekblad, A.; Näsholm, T.; Palmqvist, K. 1999. Lichen respiration in relation to active time, temperature, nitrogen and ergosterol concentrations. Functional Ecology 13: 119-125.

Respiration in eight lichen species was related to thallus hydration status, external temperature and to total nitrogen, chitin and ergosterol concentrations. Chitin is a nitrogenous and major compound of the fungal cell wall, and ergosterol is a sterol of the plasma membrane in fungi and sometimes in algae. Hydration of previously dry thalli resulted in an initially high rate of respiration. Both the amplitude of this resaturation respiration and the time required to reach steady state varied among species. Generally, peak rates were one to three times higher than steady-state rates, which were reached 3–7 h after hydration. Increases in external temperature also resulted in transient bursts in respiration. Again, both the amplitude of the burst and the time required to reach steady state varied among species. Also depending on species, a temperature increase from 5 to 15 °C resulted in two- to fivefold increases in steady-state respiration. Steady-state respiration, at optimal thallus hydration and a given temperature, varied three- to sixfold among the species, when related to thallus dry mass. This difference correlated best (r2 = 0&middot;89) with their ergosterol concentration, where a doubling in ergosterol resulted in more than a doubling in respiration. Respiration correlated less well to total nitrogen or chitin. The chitin to ergosterol ratio varied more than one order of magnitude between the species, where species with high nitrogen concentrations had the highest ratio. This implies that species with access to ample amounts of nitrogen can make more fungal cell walls in relation to plasma membrane surface area.

Sundberg, B.; Näsholm, T.; Palmqvist, K. 2001. The effect of nitrogen on growth and key thallus components in the two tripartite lichens, Nephroma arcticum and Peltigera aphthosa. Plant, Cell and Environment 24: 517-527.

Relationships between growth, nitrogen and concentration of unique biont components were investigated for the tripartite lichens Nephroma arcticum (L.) Torss. and Peltigera aphthosa (L.) Willd. Nitrogen availability was manipulated during 4 summer months by removing cephalodia and their associated N2 fixation activity, or by weekly irrigation with NH4NO3. Chlorophyll and ribulose 1&middot;5-biphosphate carboxylase/oxygenase (Rubisco), and chitin and ergosterol were used as photobiont and mycobiont markers, respectively. Nitrogen concentrations were similar in older and newer parts of the same thallus, varying between 2 and 5 g m?2, with P. aphthosa having higher concentrations than N. arcticum. Both chlorophyll (Chl a) and chitin were linearly correlated with thallus N, but N. arcticum invested more in fungal biomass and had lower Chl a concentrations in comparison with P. aphthosa at equal thallus N. During the 4 months, control and N-fertilized thalli of N. arcticum increased in area by 0&middot;2 m2 m?2 and P. aphthosa by 0&middot;4 m2 m?2. Thallus expansion was significantly inhibited in samples without cephalodia, but there was no effect on lichen weight gain. Mean relative growth rate (RGR; mg g?1 d?1) was 3&middot;8 for N. arcticum and 8&middot;4 for P. aphthosa, when time (d) reflected the lichen wet periods. RGR was 2–3 times lower when based on the whole time, i.e. when including dry periods. The efficiency (e) of converting incident irradiance into lichen biomass was positively and linearly correlated with thallus Chl a concentration to the same extent in both species. The slower growth rates of N. arcticum, in comparison with P. aphthosa, could then be explained by their lower nitrogen and Chl a concentrations and a subsequently lower light energy conversion efficiency. Functional and dynamic aspects of resource allocation patterns of the two lichens are discussed in relation to the above findings.

Tarhanen, S; Hurri, RSK; Hyvärinen, M. 2000. Morphological responses of the lichen Cladonia stellaris to nitrogen and phosphorus deposition. In: The Fourth IAL Symposium, Progress and Problems in Lichenology at the Turn of the Millennium. Universitat de Barcelona, Barcelona, pp. 38.

Taylor, R.J. 1978. Industrial impact in northwestern Whatcom Co., Washington. Water, Air and Soil Poll. 10: 199-213. Taylor, R.J., and M.A. Bell. 1983. Effects of SO2 on the lichen flora in an industrial area: Northwest Whatcom County, Washington. Northwest Science 57: 157-166.

Tomassen, H.B.M.; Smolders, A.J.P.; Limpens, J.; Lamers, L.P.M.; Roelofs, J.G.M. 2004. Expansion of invasive species on ombrotrophic bogs: desiccation or high N deposition. Journal of Applied Ecology 41(1): 139-150.

In many ombrotrophic bog areas the invasion of grass (e.g. Molinia caerulea ) and tree (e.g. Betula pubescens ) species has become a major problem. We investigated whether the invasion of such species is due to high atmospheric nitrogen (N) deposition by conducting a fertilization experiment. The effects of experimentally increased N input on Molinia , Betula and Eriophorum vaginatum were studied in desiccated bog vegetation in Ireland, where there is relatively low background N deposition. Four different N treatments were applied for 3 years: 0 (control), 20, 40 and 80 kg ha?2 yr?1. Ammonium and nitrate concentrations in the peat moisture increased at high N addition rates, leading to significantly higher C:N and N:P ratios in the top layer of the peat. The potential CO2 production rate of the peat was not stimulated at high N addition rates due to severe acidification of the peat. Despite high tissue N:P ratios (above 40), above-ground biomass production by Molinia was stimulated at high N addition rates, and foliar nutrient concentrations were unaffected. In contrast to Molinia, Betula and Eriophorum were unable to increase their above-ground biomass, probably due to P limitation. Regrowth of the lichen Cladonia portentosa was suppressed at high N addition rates. We conclude that the invasion of bogs by Molinia and Betula is likely to be less affected by desiccation than by increased N availability. Apparently, Molinia is well adapted to P-limiting conditions, which may explain its success in regions with increased N deposition levels. The high availability of P in many Dutch bogs compared with Irish bogs, together with prolonged high N deposition levels, may explain the strong increase in both Molinia and Betula observed in the Netherlands. As long as N and P availabilities in Dutch bogs are too high to prevent invasion of Betula and/or Molinia, management measures stimulating growth of Sphagnum mosses could probably reduce the negative effects of high N deposition levels.

Tomassini, F.D. 1976. The measurement of photosynthetic 14C fixation rates and potassium efflux to assess the sensitivity of lichens to sulfur dioxide and the adaptation of X-ray f fluorescence to determine the elemental content of lichens. M.Sc. Thesis, Laurentian University, Sudbury, Ont. Canada.

Tomassini, F.D., K.J. Puckett, E.Nieboer, D.H.S. Richardson, and B.Grace. 1976. Determination of copper, iron, nickel, and sulphur by X-ray fluorescence in lichens from the Mackenzie Valley, Northwest Territories, and the Sudbury District, Ontario. Can. J. Bot. 54: 1591-1603.

Trass, H. 1968. An index for the utilization of lichen groups to determine air pollution. Eesti Loodus 11:628.

Trass, H. 1973. "Lichen Sensitivity to the Air Pollution and Index of Poleotolerance." (I.P.) Folia Cryptogramica Estonia, Tartu, 3: 19-22. Turk, R., V. Wirth, and O.L. Lange. 1974. CO2-Gaswechsel-Untersuchungen zur SO2-Resistenz von Flechten. Oecologia 15: 33-64.

"Carbon dioxide exchange measurements for determination of sulfur dioxide resistance of lichens. SO2 resistance of 12 lichen spp w/ different growth forms, taken from different sites was investigated. Thalli were either exposed to SO2 gas, or treated w/ Na2S2O5 solutions. CO2 exchange was measured with an infrared gas analyzer before and after SO2 exposure. The influence of SO2 on net photosynth and dark resp. in the most sensitive spp. was detectable after exposure to 0.5 miligram/m3 (185 ppb)for 14 hr, fully hydrated. Lobaria pulmonaria suffered irreversible damage. The most resistant sp. survived tx of 4 mg/m3 (1480 ppb) for 14 hr. Xanthoria parietina was the most resistant. in order of resistance: X. parietina , Parmelia scortea, Parmelia acetabulum, Hypogymnia physodes, Parmelia saxatilis, Platismatia glauca, Lobaria pulmonaria, Parmelia stenophylla, Evernia prunastri --fructicose spp. appeared to be most sensitive. SO2 resistance can vary according to growing site, through morphological and anatomical differeces. Sensitivity is closely dependent on moisture status -- dry thalli survive high SO2 conc. Sensitvity to S in solution was not the same sequence as the gas. Damage to S solution was closely dependent on pH of the medium--low pH causes more damage. Lichen life form and surface characteristics determine SO2 resistance. Total resistance also depends on developmental state of the lichen.

Tretiach, M.; Piccotto, M.; Baruffo, L. 2007. Effects of ambient NOx on chlorophyll a fluorescence in transplanted Flavoparmelia caperata. Environmental Science & Technology 41(8): 2978-2984.

Transplants of Flavoparmelia caperata (L.) Hale were used to test possible relationships between chlorophyll a fluorescence (CaF) and ambient atmospheric conditions (temperature, precipitation, SO2 and NOx levels). Portions of the same thalli collected in a pristine site (A) of the Trieste Karst were exposed at that site, as the control, and in four other sites (B-E) in NE Italy, near to pollution monitoring stations. These sites had been selected in order to provide similar two by two climatic conditions (sites B, C: more humid; D, E: drier) and air pollution load (sites B, D: low; C, E: high). Before exposure and after 43 and 90 days of exposure, CaF measurements were carried out in the laboratory under controlled conditions. A classification of meteorological and pollution parameters recorded during exposure substantially confirmed the differences between site couplets. After 90 days, samples from sites A (control) and B (with very low pollution load) showed only slightly reduced NPQ, qN, Fo, and Fm values. Samples from site D, with medium air pollution load, and sites C, E, with high air pollution loads, showed proportionally greater variation for most of the CaF parameters. A highly significant correlation was found between NPQ, qN, Fm, and NOx pollution but not with SO2 or O3. Effects of NOx on lichens and possible action mechanisms are discussed. The results strongly suggest that CaF measurements of lichen transplants can be a valid tool in biomonitoring studies.

Turkington, R; John, E; Krebs, CJ; Dale, MRT; Nams, VO; Boonstra, R; Boutin, S; Martin, K; Sinclair, ARE; Smith, JNM 1998. The effects of NPK fertilization for nine years on boreal forest vegetation in northwestern Canada. Journal of Vegetation Science 9(3): 333-346.

Plant productivity is limited by mineral nutrient availability in many boreal forest ecosystems. This study is an analysis of the growth responses of components of a boreal plant community (cryptogams, herbaceous and woody perennials, the dominant shrubs Salix glauca (grey willow) and Betula glandulosa (bog birch) and the dominant tree Picea glauca (white spruce), to the addition of an NPK fertilizer over a nine-year period. The study was carried out in a low-nutrient boreal forest ecosystem in the Yukon territory in northwestern Canada. The following predictions were tested: (1) that there would be an overall increase in abundance (measured either as cover, density or dry mass) of all components of the vegetation, (2) that vegetation composition would change as more competitive species increased in abundance and (3) that initial community changes in response to fertilization would be transient. In general, all predictions were found to be true. Species composition changed rapidly in response to fertilizer. Graminoids (e.g. Festuca altaica) and some dicots (e.g. Mertensia paniculata and Achillea millefolium) increased in cover, while other dicots (e.g. Anemone parviflora), dwarf shrubs (e.g. Arctostaphylos uva-ursi), bryophytes and lichens declined. There was a significant increase in the growth rate of the two dominant shrubs and of Picea, but not in the cone crop or seed production by Picea. Surveys after 1 or 2 years showed responses by the vegetation but more stable patterns of response did not emerge until after 5 or 6 ears. There were consistent and directional changes in the percent cover of some of the herbaceous species on control plots. Growth rates of Salix and Betula varied considerably from year to year, independently of treatment. Long-term studies are essential if we are to understand the role of nutrient limitation in this ecosystem.

Tye, A. M.; Young, S. D.; Crout, N. M. J.; West, H. M.; Stapleton, L. M.; Poulton, P. R.; Layboum-Parry, J. 2005. The fate of 15N added to high arctic tundra to mimic increased inputs of atmospheric nitrogen released from a melting snowpack. Global Change Biology 11(10): 1640-1654.

Increases in the long-range aerial transport of reactive N species from low to high latitudes will lead to increased accumulation in the Arctic snowpack, followed by release during the early summer thaw. We followed the release of simulated snowpack N, and its subsequent fate over three growing seasons, on two contrasting high Arctic tundra types on Spitsbergen (79°N). Applications of 15N (99 atom%) at 0.1 and 0.5 g N m?2 were made immediately after snowmelt in 2001 as either Na15NO3 or 15NH4Cl. These applications are approximately 1 &times; and 5 &times; the yearly atmospheric deposition rates. The vegetation at the principal experimental site was dominated by bryophytes and Salix polaris while at the second site, vegetation included bryophytes, graminoids and lichens. Audits of the applied 15N were undertaken, over two or three growing seasons, by determining the amounts of labeled N in the soil (0–3 and 3–10 cm), soil microbial biomass and different vegetation fractions. Initial partitioning of the 15N at the first sampling time showed that 60% of the applied 15N was recovered in soil, litter and plants, regardless of N form or application rate, indicating that rapid immobilization into organic forms had occurred at both sites. Substantial incorporation of the 15N was found in the microbial biomass in the humus layer and in the bryophyte and lichen fractions. After initial partitioning there appeared to be little change in the total 15N recovered over the following two or three seasons in each of the sampled fractions, indicating highly conservative N retention. The most obvious transfer of 15N, following assimilation, was from the microbial biomass into stable forms of humus, with an apparent half-life of just over 1 year. At the principal site the microbial biomass and vascular plants were found to immobilize the greatest proportion of 15N compared with their total N concentration. In the more diverse tundra of the second site, lichen species and graminoids competed effectively for 15NH4-N and 15NO3-N, respectively. Results suggest that Arctic tundra habitats have a considerable capacity to immobilize additional inorganic N released from the snow pack. However, with 40% of the applied 15N apparently lost there is potential for N enrichment in the surrounding fjordal systems during the spring thaw.

Tyler, G. 1989. Uptake, retention and toxicity of heavy metals in lichens. A brief review. Water, Air, and Soil Pollution 47: 321-333.

[A general review with many references.] " Literature on metals, particularly heavy metals, in lichens is reviewed including mechanisms of metal uptake, retention, toxicity and tolerance. Interspecies differences in sensitivity are discussed as well as the development and nature of extreme tolerance encountered in certain taxa." NW spp: Peltigera canina, Pelfur, Hypogymnia physodes, Parmelia squarrosa, Parmelia sulcata, Cladina rangiferina, Cladonia chlorophaea, Cladonia carneola, Cladonia squamosa, Cladina arbuscula.

USDA-Forest Service and USDI-Bureau of Land Management. 1994a. Final Supplemental Environmental Impact Statement on Management of Habitat for Late-Successional and Old-Growth Forest Related Species with the Range of the Northern Spotted Owl. Appendix J2. Results of additional species analysis. February, 1994. Portland, Oregon.

USDA-Forest Service and USDI-Bureau of Land Management. 1994b. Record of Decision for amendments to USFS and BLM Planning Documents within the Range of the Northern Spotted Owl and Standards and Guidelines for Management of Habitat for Late-Successional and Old-Growth Forest Related Species within the Range of the Northern Spotted Owl. April 1994. Portland, Oregon.

US Forest Service 2007. FIA Methods for Phase 3 Measurements: Section 10. Lichen Communities; Version 4. US Forest Service Forest Inventory and Analysis/Forest Health Monitoring Program. http://www.fia.fs.fed.us/library/field-guides-methods-proc/docs/2007/p3_4-0_sec10_10_2007.pdf (accessed March 14, 2008).

US Forest Service 2008. Forest Inventory and Analysis Program http://www.fia.fs.fed.us (accessed March 14, 2008)

US Forest Service 2008. United States Forest Service National Lichens & Air Quality Database and Clearinghouse. US Forest Service Air Resource Management Program. http://gis.nacse.org/lichenair (accessed March 14, 2008).

Valencia-Islas, N.; Zambrano, A.; Rojas, J. L. 2007. Ozone Reactivity and Free Radical Scavenging Behavior of Phenolic Secondary Metabolites in Lichens Exposed to Chronic Oxidant Air Pollution from Mexico City Journal of Chemical Ecology 33(8) :1619-1634

Lichen secondary metabolites putatively protect lichens from a variety of environmental stress factors, but it is unknown whether these substances respond to air pollution. To assess such a possibility, the three major phenolics of two epiphytic lichen species with contrasting tolerance to chronic air pollution from Mexico City were studied by combining experimental reactivity data and measured field contents. The antioxidant activity and antiradical power of boninic (BO), 2-O-methylsekikaic (MA), and usnic (US) acids, isolated from the tolerant Ramalina asahinae and salazinic acid (SA), atranorin (AT), and chloroatranorin (CA), from the sensitive Parmotrema stuppeum, were determined in vitro by kinetic experiments with ozone and the free radical diphenyl picryl hidrazyl (DPPH-), respectively. In addition, the field contents of these phenolics in the lichens, and the potential antioxidant capacity (PAC) they provide, were compared among three forested sites exposed to urban emissions and a similar, relatively clean site. The six phenolics had antioxidant activity and antiradical power according to these trends: CA?>>?AT?>?US?>?SA???BO???MA for O3; and CA?>?AT?>?US?>?MA?>?SA?=?BO for DPPH-. The three most reactive phenolics are cortical compounds, located in the lichen portion most exposed to the surrounding environment. In contrast, the less reactive SA, BO, and MA are medullary. Such reactivity patterns indicate that some phenolics may provide antioxidative protection at the air–lichen interface. The higher antioxidant power of CA and AT may be due to the reactive hydroxyl groups at positions 2 and 4 of ring A, instead of the less reactive methoxyl at the same positions in both BO and MA. In the field comparisons, total quantified phenolics were significantly higher near Mexico City for both lichens, except for the tolerant R. asahinae at one site. Nevertheless, only the latter species had significantly increased PAC values at all sites near the city. This result is explained by species-dependent changes in individual phenolics. At the polluted sites, R. asahinae had consistently higher contents of its most reactive phenolic, US, with values approximately twice that of the control site. In contrast, P. stuppeum only increased its less reactive SA (26–35%), but this was counteracted by CA and, to a lesser extent, AT degradation. Thus, the substantial increase in US at the polluted sites appears to be associated with the current ecological success of R. asahinae near the city. On the other hand, the inability of P. stuppeum to overcome degradation of its most reactive phenolic (CA) at the same sites seems to partially explain the declining status of this lichen. These results provide evidence for a protective mechanism in lichens against air pollution based on secondary metabolites, which may eventually determine which species survive in forests stressed by oxidative air pollution.

Van Dobben, H.F. 1992. Effects of atmospheric acidification alkalinization and nitrogen enrichment on epiphytic lichens in The Netherlands. In: Karnfelt, I. (ed.) The Second International Lichenological Symposium IAL2, Suppl. to Abstracts. University of Lund, Sweeden.

Van Dobben, HF 1993. Vegetation as a Monitor for Deposition of nitrogen and Acidity Rijksuniversiteit te Utrecht, Utrecht. 214 pp.

Van Dobben, HF; Dirkse, GM 1993. Effects of ferilization and liming on pine forest undergrowth in areas with high and low levels of atmospheric nitrogen deposition. In: van Dobben, HF (ed.): Vegetation as a Monitor for Deposition of Nitrogen and Acidity. Rijksuniversiteit te Utrecht, Utrecht, pp. 167-189.

Van Dobben, HF; ter Braak, CJF; Dirkse, GM 1999. Undergrowth as a biomonitor for deposition of nitrogen and acidity in pine forests. Forest Ecology and Management 114(1): 83-95.

The possible use of the understory vegetation as a biomonitor for atmospheric deposition of acid and nutrients was explored by analyzing the vegetation of two pine forest stands in central and northern Sweden. Percentage cover of vascular plants, bryophytes and lichens was estimated in four factorial experiments with a total of 122 plots. In these experiments N, P, K, lime and sulfuric acid had been regularly added over a period of ca. 15 years. Redundancy analysis (RDA) was used to detect treatment effects on the composition of the vegetation, and was compared to analysis of variance (ANOVA) on Ellenberg's indicator values. Of all treatments nitrogen addition had by far the strongest effect, causing a shift in dominance from cryptogams and Ericaceae towards Deschampsia flexuosa and ruderal species. Acidification caused a decrease in the cover of most species, while liming increased the dominance of Ericaceae. There was a fairly good correspondence among the N fertilization, acidification and liming treatments and the indicator scores for nitrogen and acidity. Although the indicator method was not as sensitive as RDA in discriminating between the treatments, it may have a wider applicability in biomonitoring because it yields information on possible causal factors behind differences in vegetation.

Van Haluwyn, C., and M. Lerond 1986. Lichensociologie et qualite de l'aire: protocole operatoire et limites. Crytogamie Bryologie et Lichenologie 9(4): 313-336.

Van Herk, CM 2003. Erratum. Long distance nitrogen air pollution effects on lichens in Europe. Lichenologist 35(5-6): 413-415.

Van Herk, CM; Mathijssen-Spiekman, EAM; de Zwart, D 2003. Long distance nitrogen air pollution effects on lichens in Europe. Lichenologist 35(4): 347-359.

The epiphytic lichen flora of 25 European ICP-IM monitoring sites, all situated in areas remote from air pollution sources, was statistically related to measured levels of SO2 in air, NH4+, NO3- and SO42- in precipitation, annual bulk precipitation, and annual average temperature. Significant regression models were calculated for eleven acidophytic species. Several species show a strong negative correlation with nitrogen compounds. At concentrations as low as 0.3 mg N L-1 in precipitation, a decrease of the probability of occurrence is observed for Bryoria capillaris, B. fuscescens, Cetraria pinastri, Imshaugia aleurites and Usnea hirta. The observed pattern of correlations strongly suggests a key role of NH4+ in determining the species occurrence, but an additional role of NO3- cannot be ruled out. Some species show a distinct response to current levels of SO2 as well. It may be concluded that long distance nitrogen air pollution has strong influence on the occurrence of acidophytic lichen species.

Vestergaard, N.K., U. Stephansen, L. Rasmussen, and K. Pilegaard. 1986.. Airborne heavy metal pollution in the environment of a Danish steel plant. Water, Air and Soil Pollution 27: 363-377.

Vick, C.M., and R. Bevan. 1976. Lichens and tar spot fungus (Rhytisma acerinum) as indicators of sulfur dioxide pollution on Mereyside. Environmental Poll. 11: 203-216.

"Lichens and tar spot fungus (Rhytisma acerinum) on sycamore (Acer pseudoplatanus) were used as indicators of pollution in order to map SO2 concentrations in the new Metropolitan county of Merseyside, in England. The lichen scale of Gilbert (1970) was adapted and a mapping rechnique based on the presence/absence of a few indicator species devised. The map of the inner limit of tar spot fungus is provisional: work is in progress on the calibration of this species as an indicator of SO2. The lichen and tar spot map fulfills a requirement for environmental planning in the new county."

Villeneuve, J-P, E. Fogelquist, and C. Cattini. 1987. Lichens as bioindicators for atmospheric pollution by chlorinated hydrocarbons. International Lab. of Marine Radioactivity. IAEA, Oceanographic Museum, Monaco.

"Lichen samples from southern France were analyzed for chlorinated hydrocarbons. The concentration were in the same range as in industrial areas in Italy and Norway but higher than results reported from remote areas in Sweeden and especially in the Antarctic. PCB concentrations were also compared with atmospheric concentrations in the same area. A concentration factor of 2 x 105 (? 2.105) for PCB between lichen and tam is of the same order as that calculated for Antarctic samples. Lichens are suggested as suitable bioindicators for the study of atmospheric pollution by chlorinated hydrocarbons."

Villeneuve, J.-P., and E. Hom. Atmospheric background of chlorinated hydrocarbons studied in Swedish lichens. Chemosphere 13(10):1133-1138. Vestergaard, N.K., U. Stephansen, L. Rasmussen, and K. Pilegaard. 1986.. Airborne heavy metal pollution in the environment of a Danish steel plant. Water, Air and Soil Pollution 27: 363-377.

Vick, C.M., and R. Bevan. 1976. Lichens and tar spot fungus (Rhytisma acerinum) as indicators of sulfur dioxide pollution on Mereyside. Environmental Poll. 11: 203-216.

"Lichens and tar spot fungus (Rhytisma acerinum) on sycamore (Acer pseudoplatanus) were used as indicators of pollution in order to map SO2 concentrations in the new Metropolitan county of Merseyside, in England. The lichen scale of Gilbert (1970) was adapted and a mapping rechnique based on the presence/absence of a few indicator species devised. The map of the inner limit of tar spot fungus is provisional: work is in progress on the calibration of this species as an indicator of SO2. The lichen and tar spot map fulfills a requirement for environmental planning in the new county."

Villeneuve, J-P, E. Fogelquist, and C. Cattini. 1987. Lichens as bioindicators for atmospheric pollution by chlorinated hydrocarbons. International Lab. of Marine Radioactivity. IAEA, Oceanographic Museum, Monaco.

"Lichen samples from southern France were analyzed for chlorinated hydrocarbons. The concentration were in the same range as in industrial areas in Italy and Norway but higher than results reported from remote areas in Sweeden and especially in the Antarctic. PCB concentrations were also compared with atmospheric concentrations in the same area. A concentration factor of 2 x 105 (? 2.105) for PCB between lichen and tam is of the same order as that calculated for Antarctic samples. Lichens are suggested as suitable bioindicators for the study of atmospheric pollution by chlorinated hydrocarbons."

Villeneuve, J.-P., and E. Hom. Atmospheric background of chlorinated hydrocarbons studied in Swedish lichens. Chemosphere 13(10):1133-1138.

Von Arb, C., et al. 1990. Lichen physiology and air pollution. II: Statistical analysis of the correlation between SO2, NO2, NO and O3, and chlorophyll content, net photosynthesis, sulfate uptake and protein synthesis of Parmelia sulcata Taylor. New Phytologist 115: 431-437.

[Study conducted in Switzerland. "Most of the mean values of net photosynthesis differed less than the average standard deviation. The rates of sulfate uptake and protein synthesis were lowest and chlorophyll content was highest at the most polluted sites." Authors also conclude that "... the chlorophyll content of Parmelia sulcata ... might represent the overall status of the metabolism of this species fairly well."]Samples of the lichen P. sulcata were collected in the vicinity of 17 air pollution monitoring stations in the northern part of Switzerland and its bordering area. Net photosynthesis, dark respiration, and the content of [35S]-sulfate and [35S]-protein after cultivation with 35SO42-, as well as the chlorophyll and protein contents were measured. Mean values of dark resp. and protein content were not significantly different in the plant material from the various locations. Most of the mean values of net ps differed less than the average std. The rates of sulfate uptake and protein synthesis were lowest and chlorophyll content was highest at the most polluted sites. The values differed by a factor of 3.5 - 7 between the various locations. Multiple regression analysis gave a linear correlation between the three physiological parameters [35S]-sulfate and [35S]-protein and chlorophyll content and a combination of the annual mean concentrations of the air pollutants NO, NO2, SO2, and O3. The highest multiple correlation coefficient (r2) was estimated for chlorophyll (0.84). Its linear correlation coefficient (r) with NO2 alone was 0.91, and with SO2 alone 0.85.

Walker, TR; Crittenden, PD; Young, SD. 2003. Regional variation in the chemical composition of winter snow pack and terricolous lichens in relation to sources of acid emissions in the Usa River basin, northeast European Russia. Environmental Pollution 125(3): 401-412.

The chemical composition of snow and terricolous lichens was determined along transects through the Subarctic towns of Vorkuta (130 km west–east), Inta (240 km south–north) and Usinsk (140 km, southwest–northeast) in the Usa river basin, northeast European Russia. Evidence of pollution gradients was found on two spatial scales. First, on the Inta transect, northward decreases in concentrations of N in the lichen Cladonia stellaris (from 0.57 mmol N g?1 at 90 km south to 0.43 mmol N g?1 at 130 km north of Inta) and winter deposition of non-sea salt sulphate (from 29.3 to 12.8 mol ha?1 at 90 km south and 110 km north of Inta, respectively) were attributed to long range transport of N and S from lower latitudes. Second, increased ionic content (SO42?, Ca2+, K+) and pH of snow, and modified N concentration and the concentration ratios K+:Mg2+ and K+: (Mg2++Ca2+) in lichens (Cladonia arbuscula and Flavocetraria cucullata) within ca. 25–40 km of Vorkuta and Inta were largely attributed to local deposition of alkaline coal ash. Total sulphate concentrations in snow varied from ca. 5 ?mol l?1 at remote sites to ca. 19 ?mol l?1 near Vorkuta. Nitrate concentration in snow (typically ca. 9 ?mol l?1) did not vary with proximity to perceived pollution sources.

Wardle, DA; Nilsson, M-C; Zackrisson, O; Gallet, C 2003. Determinants of litter mixing effects in a Swedish boreal forest. Soil Biology and Biochemistry 35(6): 827-835

Weiss, M; Hobbie, SE; Gettel, GM. 2005. Contrasting responses of nitrogen-fixation in arctic lichens to experimental and ambient nitrogen and phosphorus availability. Arctic, Antarctic, and Alpine Research 37(3): 396-401.

We investigated the influence of nitrogen (N) and phosphorus (P) on N2-fixation and abundance of two of the most common N2-fixing arctic lichens, Peltigera aphthosa and P. polydactyla, in two common moist upland tundra types, acidic and non-acidic tundra, at Toolik Lake, Alaska. Acidic tundra has higher N and lower P availability than non-acidic tundra. We measured the abundance of the lichens in control (no fertilization), N- and P-fertilized plots, and N2-fixation using the acetylene reduction assay method on lichens from control and P-fertilized plots from both tundra types. Lichens on N-treated plots were too scarce to include in our N2-fixation estimates. Lichen abundance was lower in plots fertilized with N than in control and P-fertilized plots, while per-biomass N2-fixation rates were higher in P-fertilized plots than in control plots. Per-biomass rates of N2-fixation did not differ between acidic and non-acidic tundra, but both lichen species are more abundant on acidic tundra. Thus, despite per-biomass stimulation of N2-fixation by experimental P addition and reduction in lichen abundance with N fertilization, Peltigera contributes more N to the acidic tundra site, indicating that soil N and P availability are not the primary controls of N2-fixation and abundance of these lichens.

Wetmore, C.M. 1967. Lichens of the Black Hills of SD and WY. Publ. of the Museum, MI State University, East Lansing.

Wetmore, C.M. 1983. Lichens of the Air Quality Class1 National Parks. National Park Services Contract CX 0001-2-0034. USA:NPS. 158 pages.

Wetmore, C.M. 1985a. Lichens and air quality in Isle Royal NP: Final Report. NPS Contract CX 0001-2-0034.

Wetmore, C.M. 1985b. Lichens and air quality in Sequoia NP. Final Report, NPS Contract CX 0001-2-0034.

Wetmore, C.M. 1987a. Lichens and Air Quality in Boundary Waters Canoe Area of the Superior NF: Final Report, Supported by the National Forest Service, Contract 43-63A9-5-867.

Wetmore, C.M. 1987b. Mapping Elemental Concentrations in Great Smoky Mountains NP with Lichens. NPS Contract CX-0001-1-0112. Northrup Environmental Sciences. Wetmore, C.M. 1988. Lichen Floristics and Air Quality. In: Nash, THIII (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlg., Berlin-Stuttgart.

Wetmore, CM 1989. Lichens and Air Quality in Cuyahoga Valley National Recreation Area, Ohio The Bryologist 92: 273–281

Lichens were collected at numerous localities in Cuyahoga Valley National Recreation Area and compared with species lists for Cuyahoga and Summit counties to document changes in the lichen flora since 1920. There are no historical collections from the park but habitats similar to those studied by early collectors are present in the park today. The present lichen flora has 65 species, including 34 new records for the area. Of the 151 species recorded for the two counties between 1895 and 1917, only 31 were found during this study (21%). None of the species most sensitive to sulfur dioxide were found, nor were any of the cyanophilic lichens reported earlier. The lichens remaining are often small and frequently with dead parts or distorted growth. Elemental analysis of Parmelia rudecta showed high sulfur levels. It is proposed that poor air quality has destroyed 79% of the historical lichen flora of the park. Thelidium parvulum Arn. is reported for the first time from North America.

Will-Wolf, S. 1980a. Effects of a "clean" coal-fired power generating station on four common Wisconsin l ichen species. Bryologist 83(3): 296-300.

Will-Wolf, S. 1980b. Structure of corticolous lichen communities before and after exposure to emissions from a "clean" coal-fired generating station. Bryologist 83: 281-295. Will-Wolf, S. 1988. Quantitative approaches to air quality studies. In: Nash, T.H. III (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlg., Berlin-Stuttgart.

Will-Wolf, S 2009. New England FHM gradient model ms in preparation

Will-Wolf, S.; Geiser, L.H.; Neitlich, P.; Reis, A.H. 2006. Forest lichen communities and environment – How consistent are relationships across scales? Journal of Vegetation Science 17: 171-184.

Four macrolichen data sets were compiled using identical plot sample protocol: species abundance estimated in 0.4-ha permanent plots on a systematic grid, as part of government (USDA-FS) forest inventory programs. One data set in each region represented a large area; the other represented part of the large area. We used global NMS ordination of plots based on species abundance to extract major axes of variation in community composition. Correlations of species, guilds, and environmental variables with ordination axes were compared between geographic scales for the two regions. Primary axes of community variation at larger scales were correlated with climate variables and related geographic variables such as latitude and elevation, and with pollution. Forest vegetation variables such as stand age and tree species composition became more important at small scales. Community variation unexplained by macro environment variables also became more important at small scales. Of several hundred species tested, ten lichen species showed consistent behavior between scales within region (one also across regions) and are thus potential general indicators of ecological conditions in forests. Of six lichen guilds tested, several show strong patterns not consistently related to environmental conditions. Interpretation of lichen species and community composition as indicating particular environmental conditions is context-dependent in most cases. Observed relationships should not be generalized beyond the geographic and ecological scale of observation.

Winner, W.E. 1988. Responses of bryophytes to air pollution. In: Nash, T.H. III (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlg., Berlin-Stuttgart.

Winner, W.E., C.J. Atkinson, and T.H. Nash. 1988. Comparisons of SO2 absorption capacities of mosses, lichens, and vascularplants in diverse habitats. In: Nash, T.H. III (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlg., Berlin-Stuttgart.

SO2 absorption from a presumed concentration of 0.035 ppm was calculated on an annual basis for mosses and vascular plants growing n a wide range of habitats in which growing season ppt, and evapotranspiration differed. These habitats ranged from the tropics with long growing season and high precipitation, to deserts where growing seasons are short due to lack of ppt and high evapotransp. Analysis indicates that mosses in all habitats are potentially 100 to 1000 times stronger SO2-sinks on a dry weight basis than are vascular plants. Similarly Cladina rangiferina is estimated to absorb well over 100 times as much SO2 as arctic vascular plants. Adjustments for variability in moss or lichen water contents reduce absorption estimates, but estimates still exceed vascular plant absorption estimates by 100 times.

Wirth, C; Schulze, E-D; Lühker, B; Grigoriev, S; Siry, M; Hardes, G; Ziegler, W; Backor, M; Bauer, G; Vygodskaya, NN 2002. Fire and site type effects on the long-term carbon and nitrogen balance in pristine Siberian Scots pine forests. Plant and Soil 242(1): 41-63.

Effects of fire and site type on carbon (C) and nitrogen (N) balances were determined by following the change of total and component C and N pools along four chronosequences of fire-prone Siberian Scots pine ecosystems. These differed in the mean return interval of surface fires (unburned – moderately burned, 40 years – heavily burned, 25 years) and site quality (lichen versus Vaccinium site type). Of the Vaccinium site type (higher site quality) only a moderately burned chronosequence was studied. A total of 22 even-aged stands were investigated with stand ages ranging from 2 to 383 years. The C balance was dominated by the opposing dynamics of coarse woody debris (CWD) and biomass and could be divided into three phases: (1) Young stands (up to 40 years) acted as a net source for C of 6–10 mol C m?2 year?1 because the previous generation CWD pool originating from stand-replacing crown fires decayed much faster than biomass increased. During this period the C pool in the unburned lichen type chronosequence decreased from 807 to 480 mol C m?2. (2) Middle aged stands (40–100 years), being in a stage of maximum biomass accumulation, were a net sink of 8–10 mol C m?2 yr?1. (3) Mature stands (100 to > 350 years) continued to sequester C at a lower rate (0.8–2.5mol C m?2 yr?1). Differences in the rates of C sequestration during the two later phases could be explained by the complex interaction between surface fire regime and site type. Recurrent surface fires resulted in enhanced mortality and regularly redistributed C from the living to the CWD pool thereby lowering the rate of C sequestration. Site quality determined the potential to recover from disturbance by fire events. Differences in site type did not correlate with soil and total ecosystem N pool size. However, the N status of needles as well as the N pool of physiologically active tissue was highest in the stands of the Vaccinium type. The `woody' C pool (biomass + CWD) was sensitive to differences in surface fire regime and site type. It was lowest in the heavily burned lichen type chronosequence (297 &plusmn; 108 mol C m?2), intermediate in the unburned and moderately burned lichen type chronosequence (571 &plusmn; 179 mol C m?2) and highest in the moderately burned Vaccinium type chronosequence (810 &plusmn; 334 mol C m?2). In contrast, the total soil C pool (organic plus mineral layer down to a depth of 25 cm) was independent of stand age, surface fire regime and site type and fluctuated around a value of 250 mol C m?2. The organic layer C pool oscillated in response to recurring surface fires and its C pool was dependent on time since fire increasing at a rate of about 1.5 mol C m?2 yr?1 during the first 40 years and then reaching a plateau of 170 mol C m?2. The total ecosystem N pool was 7.4 &plusmn; 1.5 mol N m?2 on average of which only 25 % were stored in biomass or coarse woody debris. Total ecosystem N was independent of stand age, surface fire regime and site type. No correlation was found between total ecosystem C and N pools. Average total ecosystem C:N ratio was 114 &plusmn; 35 mol C mol N?1. A conceptual model illustrating how changes in the regime of stand-replacing crown fires and recurrent surface fires and changes in site quality interact in determining the long-term C balance in Siberian Scots pine forests is presented.

Wirth, V. 1988. Phytosocial approaches to air pollution monitoring with lichens. In: Nash, THIII (ed.) Lichens, Bryophytes and Air Quality. Biblio. Lichenol. 30. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlg., Berlin-Stuttgart.

"As composition and coverage in crytogamic communities are influenced by air pollution, especially acidic air poll., the occurrence of different lichen comm. can be correlated with different levels of air poll."

Wolseley, P.A., and P.W. James. 1992. Acidification and the Lobarion: a case for biological monitoring. Nature Conservancy Council Newsletter. In: Wolselely and James. 1991. The Effects of Acidification on Lichens 1986-1990. (CSD Report 1247). Nature Conservancy Council, Peterborough, UK.

Summary of results of a 1990 survey across Britian to determine the effects of acidification on the Lobarion community. Patterns of change in the lichen communities over a 5-year period were interpreted and pollution data reinterpreted with the change in the climatic conditions (drought conditions -- low winter rainfall.) taken into account. "It is apparent that lichens may respond to short episodic pollution events within a local area that may be undetected by conventional analysis." "The physiological effects of acidification on the Lobarion comm. are reflected in the field by declining bark pH, which is a critical factor in the establishment of acidophilous spp. of the Parmelion laevigatae which may, with continuing acidification, replace the Lobarion."

Zambrano García, A.; Nash, T.H. III; Herrera-Campos, M.A. 2000. Lichen Decline in Desierto de los Leones (Mexico City) The Bryologist 103(3): 428-441

We document the effect of Mexico City on the epiphytic lichens of Abies religiosa by comparing the communities occurring at Desierto de los Leones, a protected area near to the city, with those at El Chico National Park, a location 100 km upwind (or crosswind) from the city. The first community had 47% fewer species, 62% less lichen cover, and a species abundance pattern that revealed a highly disturbed community. The differences between these communities were greater at the trunk base than at the height of two m, and much stronger when evaluated from a species to species perspective. Among a variety of factors, site air quality may account for many of the observed differences.

Zambrano García, A.; Nash, T.H. III; Herrera-Campos, M.A. 2002. Air Pollution Effects on Lichen Communities In: Fenn, M.E.; de Bauer; L.I.; Hernindez-Tejeda, T. (eds.). Urban Air Pollution and Forests Resources at Risk in the Mexico City Air Basin. Ecological Studies 156: 283-297, Springer. 2002.

Epiphytic lichen diversity at Desierto de Leon is severely impoverished compared to El Chico National Park, a low-pollution site 100 km northeast of Mexico City. Desierto de Leon may have lost nearly 50% of its lichen species and lichen abundance is reduced by 60%, presumably as a result of the severe air pollution levels occurring at this site. Based on historical herbarium collections, the decline in lichen diversity appears to coincide with the period of accelerated industrial and population growth of Mexico City since the 1930s and 1940s (Zambrano et al.2002). Concentrations of airborne metals such as Cu, Pb, and Zn in lichens from forests near the city indicate that metal deposition was more than twice as high in forests near the city as in forests far from the city. Short-term lichen transplant experiments in Sierra de las Cruces, a montane region just SSW and downwind of the urbanized zone, showed a 30% lower carbon fixation and 15% to 25% chlorophyll degradation compared to samples in El Chico National Park (Zambrano and Nash 2000; Zambrano et al. 1999). These results suggest that chronic air pollution is a major cause of lichen decline in forests surrounding the city, along with a variety of other anthropogenic disturbance factors.

Zambrano, A.; Nash, T.H. III; Gries, C. 1999. Physiological effects of the Mexico City atmosphere on lichen transplants on oaks. Journal of Environmental Quality 28(5): 1548-1555.

Two lichen species, Usnea ceratina Ach. and Everniastrum neocirrhatum (Hale M. Wirth) Hale ex Sipman, were transplanted for 54 d into an oak forest (Quercus rugosa) in the vicinity of Mexico City to assess their ability to survive near a highly polluted urban environment. Net photosynthesis based on dry weight and chlorophyll b decreased respectively ca. 30 and 25% compared with control samples in a less polluted site, ca. 100 km north of Mexico City. There was no interspecific difference in the response of carbon fixation, but E. neocirrhatum was more sensitive to chlorophyll b degradation near Mexico City than U. ceratina. Chlorophyll a was also degraded (ca. 15%) near Mexico City. Changes in total carotenes were mostly dependent on species and time rather than on location. High concurrent levels of ozone and sulfur dioxide in the air are discussed as possible causes of the decline in the lichen photosynthesis and chlorophyll content.

Contact for this biliography Linda Geiser