Abstract: The “New Forestry” practice of green-tree retention is becoming an important management tool for publicly owned lands, yet few data exist to demonstrate that this tool can succeed at enhancing biodiversity. We addressed this issue by using a retrospective approach to compare canopy lichen litter in adjacent, paired stands of rotation age (55–120 yr): one with and one without old-growth (>300 yr) remnant trees. We sampled three functional groups of lichens in 17 stands in western Oregon: alectorioid lichens, cyanolichens, and green-algal foliose lichens. Thirteen stands were low elevation (520–850 m) and four were mid-elevation (1220–1340 m). Biomass of cyanolichen and green-algal foliose lichen litter was greater in low-elevation sites, whereas alectorioid lichen litter biomass was greater in mid-elevation sites. Cyanolichens were absent from all mid-elevation sites. Biomass of alectorioid lichen and cyanolichen litter was greater in low-elevation sites with remnant trees than in those without remnant tre...

Abstract: The dispersal of algae and cyanobacteria at three Antarctic fellfield sites was investigated using microscopic and culture analysis of samples from active and passive air samplers Intersite variation in the mean number of large algal propagules (>5 μm diameter) sampled was dependent on the niche space available for algal growth and the degree to which soil was exposed to desiccating influences, these factors could be related to the degree of maturity of the sue The numbers of large algal propagules were lowest at sites from which permanent snow cover had recently disappeared and highest at sites with developed soil circles but poorly developed moss and lichen flora Mature sites with diverse and developed moss and lichen flora produced intermediate numbers of algal propagules Propagules of multicellular algae, cyanobacteria and large-celled unicellular algae were found in the air at the end of the growing season of the respective algal groups as the soil surface dried This was the case for Prasiola crispa, Pmnularia borealis, snow algae and filamentous chlorophytes and cyanobacteria Dispersal of unicellular chlorophytes was greatest during the summer period and at sites with developed secondary flora, but also occurred at other sites and in association with small thaw events during winter Cultures were obtained from samples collected whilst an air mass that had originated in South America, deposited material on Signy Island This suggests that algal propagules have the ability to survive long-distance transport and potentially provide mocula for colonization of Antarctica as regional warming continues to expose fresh habitats

Abstract: 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 plots, 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 coastto-mountains gradient, with somewhat higher diversity in the mountains and lower diversity on the Piedmont and coast. The Forest Health Monitoring (FHM) program seeks to assess the condition and trend of the forests of the United States (NAPAP 1993; Riiters et al. 1992). FHM is linked with the national sampling grid established by the Environmental Monitoring and Assessment Program (EMAP) of the Environmental Protection Agency. Epiphytic lichen communities were included in FHM 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. Hundreds of papers worldwide (chronicled in the series "Literature on air pollution and lichens" in the Lichenologist) and dozens of review papers and books (e.g., de Wit 1983; Nash & Wirth 1988; Richardson 1992; Seaward 1993; Smith et al. 1993; van Dobben 1993) published during the last century, have documented the close relationship between lichen communities and air pollution, especially SO2 and acidifying or fertilizing nitrogen and sulfur-based pollutants. In a comparison of biological responses between nearby and remote areas surrounding a coal-fired power plant, lichens gave a much clearer response (in terms of diversity, total abundance, and community composition) than either foliar symptoms or tree growth (Muir & McCune 1988). Lichens were one of the few com0007-2745/97/145-158$1.55/0 This content downloaded from 157.55.39.187 on Wed, 30 Mar 2016 05:41:06 UTC All use subject to http://about.jstor.org/terms 146 THE BRYOLOGIST [VOL. 100 ponents of terrestrial ecosystems to show a clear relationship to gradients of acidic deposition in the eastern United States (NAPAP 1991; Showman 1992). Much of the sensitivity of epiphytic lichens to air quality apparently results from their lack of a cuticle and their reliance on atmospheric sources of nutrition. Although trees may respond to moderate, chronic levels of air pollution deposition, all of the other influences on tree growth, such as variation in soils, make the responses of trees to pollutants difficult to measure in the field. Lichen communities provide, therefore, not only a measure of air pollution impacts upon lichens, but also suggest air pollution impacts on aspects of forest health that are difficult to measure directly. Elemental content of lichens in the southeastern U.S. has received some study (e.g., Bosserman & Hagner 1981; Kinsman 1990; Walther et al. 1990), but no previous published studies of lichen community response to air pollution have been made in this area. Elsewhere in eastern North America, lichen community response to urban and industrial air pollution has been studied mainly in local urban and industrial areas (LeBlanc et al. 1972; McCune 1988; Muir & McCune 1988; Rao & LeBlanc 1967; Showman 1975, 1981; Will-Wolf 1980). Only Showman (1992) has studied lichen communities on a regional gradient in air quality in North America. In Europe, regional monitoring grids have focussed primarily on elemental analysis of tissues or status of particular species, with only a few largescale studies analyzing community composition (Bruteig 1993; de Wit 1976; van Dobben 1993). In addition to their utility as indicators of air quality, epiphytic lichens are an important component of many forests. Lichens often comprise a large portion of the diversity of macrophytic species in a forest. Lichens have numerous functional roles in temperate forests, including nutrient cycling (especially nitrogen fixation in moist forests; Pike 1978) and as components of food webs (Dawson et al. 1987; Maser et al. 1985; Maser et al. 1986; Rominger & Oldemeyer 1989; Servheen & Lyon 1989). The large-scale sampling of FHM using the EMAP sampling grid allows us to describe regional gradients in lichen community composition as influenced by climate and topography. A multidisciplinary regional sampling grid of this scale is unprecedented in North America, although transcontinental transects in Canada have addressed questions at a similar spatial scale (La Roi 1967; La Roi & Stringer 1976). The current data set extends from Georgia to Virginia, inland to eastern Tennessee. Additional data collected along the whole eastern seaboard in 1994 and 1995 will be analyzed in the future. CALIBRATION PHASE

Abstract: & We tested the hypothesis that changed microclimate at induced forest edges causes reduced growth of epiphytic lichens. Two foliose, green algal lichens were transplanted to the lower canopy of a mature Picea abies forest at six distances (2, 6.25, 12.5, 25, 50 and 100 m) from a clearcut. The biomass growth in Platismatia glauca (6.2% in 16 months) was 41% higher than in Lobaria pulmonaria (4.4%). We found no growth reduction near the forest edge. In contrast, the highest growth in both species occurred within 12 m from the edge. Further, fluorescence and chlorophyll measurements showed that lichen vitality was unaffected by distance from edge. The light intensity was 4.3 times higher at the edge than in the interior during the growing season, but there were only minor differences in air temperature and relative humidity. Monitoring of thallus water content revealed clear differences in both number and length of wetting and drying cycles. However, the total time with water content sufficient for photosynthetic activity was only slightly higher at the edge. The data thus indicate that our gradient in microclimate was too small to significantly affect lichen growth, and that lichens are largely metabolically inactive when large edge-interior contrasts in microclimate occur. Lichen response to forest edge microclimate results from intricate interactions among several biotic and abiotic factors. Linking data on lichen growth, microclimate and thallus water content with physiological measurements provides a framework for future studies of the mechanisms behind abiotic edge effects.

Abstract: Total concentrations of Al, Cu, Fe, Hg, Mn, Mo and Zn in theepiphytic lichen Parmelia caperata, substrate bark andleaves of oaks (Quercus cerris and Q pubescens)from a background area in Tuscany (central Italy) werecompared The elemental composition of unwashed samples,especially bark, was clearly affected by soil dustcontamination, thereby leading to incorrect interpretations ofbaseline concentrations and relationships between elementsThe normalization of total element concentrations to thesurface soil composition (digested and analyzed by the sameprocedures), using Al as reference element, gave more reliablebaseline values and allowed comparison between differentbiomonitors The suitability of lichens, leaves and barks forstudying the environmental distribution of trace elements interrestrial ecosystems is discussed

Abstract: During three years of research on epiphytic lichen communities as indicators of environmental change in northern Thailand plots were set up in a range of forest types between 400 and 1600 m in 1991/2 and revisited in 1993. Other areas were visited in 1993 and collections made in a wider range of geographical, altitudinal and vegetation conditions in Thailand. From this data factors influencing the distribution of lichens in a monsoon climate are outlined and characteristic components of the lichen flora given at family, generic and where possible specific level. Dominant taxa of the montane forests include hygrophilous macrolichens of the ‘Lobarion’ that are also a characteristic component of old growth fagaceous forests in Europe, whereas the evergreen forests are dominated by moisture-dependent crustose taxa with a trentepohlioid photobiont, and the deciduous dipterocarp forests by often brightly coloured xerophytic lichens with a trebouxioid photobiont. Taxa are proposed as indicators of forest type including those that are indicators of old-growth forests and of disturbance. Quantitative recording of selected taxa at genus and species level is suggested to estimate rates of change in monsoon forests in southeast Asia.

Abstract: We describe the regional species richness, variation in species richness and species turnover of bryophytes and lichens from 36 sites in lowland forests of S.E. Australia. The analyses subdivided the two major taxa into their constituent sub-groups: mosses, liverworts and crustose, fruticose and foliose lichens and explored correlations between selected environmental variables and patterns of diversity. On a regional scale, there were 77 species of bryophytes and 69 species of lichens, giving a total approximately one third of the total number of vascular plant species. Mean species richness was higher for lichens than bryophytes, the two being negatively correlated as lichens favoured dry sites and bryophytes favoured moist ones. Species turnover was greater for bryophytes than lichens, a result largely dependent on the distribution of liverwort species. Foliose lichens showed higher levels of turnover than crustose lichens. Multiple regression and canonical correspondence analysis showed that both taxa and all sub-groups responded to the same three variables - vascular plant cover, time since last fire and topographic position. Other variables, including time since logging and intensity of logging explained little variation in bryophyte or lichen diversity. The data suggest that strategies for the conservation of bryophyte and lichen biodiversity will be different to reflect the different patterns of species richness and species turnover.

Abstract: To identify representative quantitative criteria for the creation of a future Red List of epiphytic lichens, 849 trees in 132 long-term ecological observation plots in the Swiss Central Plateau and the Pre-Alps were surveyed by standard sampling. Based on the trees, frequency data of the lichen taxa observed are described by the log series model, indicating the controlling effect of few ecological factors. Based on the plots, four classes of scarcity, each comprising 25% of the species, were established. As a contribution to the development of a national, representative survey of lichens, α-diversity (species richness, species density) andβ-diversity (dissimilarity) were calculated in terms of region, vegetation formation, vegetation belt and for their combinations. Differences in lichen diversity between the Central Plateau and the Pre-Alps were caused by the bigger elevational range in the Pre-Alps, which resulted in a higher species richness. α-Diversity of forest and non-forest were similar, whereas each vegetation formation showed one third of its species restricted to it. The contributions to the total lichen diversity of crustose, foliose and fruticose as well as of generative and vegetative species was calculated. Specific features along the altitudinal gradient of vegetation belts emerged: the percentage of crustose and generative lichens declined with every altitudinal step, increased in fruticose and vegetative lichens, and was the same in foliose species.

Abstract: Fragmentation of the forested landscape poses a threat to many aspects of biodiversity associated with old-growth forests. Studies of the effects of forest fragmentation are often complicated by the variation in composition and age of patches and the matrix. This study used a system of isolated stands where patch age and composition were similar and the matrix variability negligible. The patches were composed of old-growth Picea abies stands of varying size and shape in a wetland matrix. The study organisms were epiphytic crustose calicioid lichens (also known as Caliciales), many of which are very substrate-specific and restricted to old-growth stands. The aim of the study was to measure the effect of patch size, patch isolation, habitat and substrate quality on the species richness and composition of epiphytic calicioids. Twenty-four patches ranging from 0.4 to 15.9 ha in size were studied. All species of calicioid lichens were registered in 0.1 ha plots in each patch. Isolation was measured as the percentage of available habitat within 400 m of a patch. Twenty-two species were found with an average of 9.48±0.26 (SE) species per patch and 2.92±0.18 (SE) species per tree. Species richness at patch level correlated with stand structure. primarily tree density, while number of species per tree (reflecting population size) was strongly correlated with island size and several stand variables. There was no effect of isolation on species richness. Species composition was influenced by both substrate variables and patch size. The species composition on the islands showed a significant nestedness, i.e. species composition on species-poor islands constituted a non-random subset of the species composition on species-rich islands. We propose that the explanation for the strong relationship between species richness at tree level and stand size is an edge effect which implies that unaffected interior areas only occur on large islands. The different microclimate of the patch edge enables only the hardiest species to establish large populations there whilst shade and moisture demanding species are restricted to the interiors of larger islands.

Abstract: The photosynthetic response to photosynthetically active photon flux density (PPFD) was measured in the field for nine New Zealand rain forest lichen species spanning environments from the deep shade within the forest through the forest margin to outside, open ground sites. Light compensation (PPFDcomp) and light saturation (PPFDsat) were much higher for the species of the open sites (over 50 and 500 μmol/m2.s, respectively). Lichens at forest margin or within the forest had PPFDsat of 64.3-29, and 61–162, μmol/m2.s, respectively, but showed no apparent adaptive trends for these parameters. PPFD response of photosynthesis was measured at several thallus water contents (WC) for one species, Pseudocyphellaria coronata, which showed severe depression of photosynthesis at high WC because of increased diffusion resistances, at all PPFD above compensation. PPFDsat was also depressed but not dark respiration, PPFDcomp, or quantum efficiency. Green algal and cyanobacterial lichens showed no relationship ...

Abstract: The distribution of lichens in lowland deciduous and evergreen forests in Thailand is used to interpret recent changes in the distribution of these forests. The role of fire in changing the forest structure, microclimate and species content is discussed. Characteristic corticolous lichen communities of dry deciduous and moist evergreen forests are described, as well as changes in the composition of the flora following fire events. Where frequent fires have altered the forest rates of change in forest type are suggested using lichen data from randomly selected trees in forest plots, and growth rates of sampled species in quadrats. The disjunct nature of the lichen floras in lowland deciduous and evergreen forests is discussed, their origin and use in interpreting changes in forest types in monsoon climates over long periods of time.

Abstract: The distribution of epiphytic lichens on Quercus pubescens in Tuscany, central Italy, was studied by means of multivariate techniques along an altitudinal gradient from 0 to 900 m. Great differences in community structure were found and the altitude of 500 m was identified as an ecotone. Epiphytic lichen vegetation on trees below the ecotone varied significantly in relation to bark pH. Climatic parameters (temperature and rainfall) were probably related to altitude. Dust was probably responsible for the rise in bark pH. The distribution of lichen species in the sampling belts fitted the core-satellite hypothesis. The use of core and satellite species as biomonitors of air pollution and bioindicators of environmental conditions is discussed.

Abstract: In this study, we review research conducted in the La Spezia district during 1989, 1992, and 1994, using lichens and moss as indicators of air pollution. SO2 pollution was examined by means of an Index of Atmospheric Purity (IAP) based on the frequency of epiphytic lichen within a sampling grid. Metal deposits were estimated using the lichen Parmelia caperata and the moss Hypnum cupressiforme as bioaccumulators. IAP maps show progressive air quality improvement from 1989 to 1994. This trend correlates to a decrease in SO2 emissions during recent years that is attributed to the use of methane for residential heating and the closing of a coal-fired power plant. Metal contamination maps show that the most polluted area is now in the southeastern part of the gulf. The pattern of pollution coincides with the location of the chief pollution sources in the area. From 1989 to 1994, the metal concentrations in lichens decreased, but metal deposits in the southeastern area were cause for concern. High concentrations of lead in the area are related to emissions from a waste incinerator and a plant that produces lead oxide. Epidemiological investigations reveal that the area population has the highest levels of lead in their blood. The use of bioindicators and bioaccumulators permits long-term and large-scale monitoring of environmental pollutant levels in full agreement with traditional methods.

Abstract: Total concentrations ofAl, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, and Zn were compared in the peripheral (younger) and central (older) part of the thallus of the epiphytic lichen Parmelia caperata from a background area of central Italy. The results showed that the trace element content was highly variable. Concentrations were similar for several elements (As, Cr, Fe, Hg, Mn, Ni, Sb). Elements of limited metabolic significance (Al, Cd, Pb) had higher concentrations in the central parts, suggesting that they are trapped in the medulla, while elements essential for lichen metabolism (Co,. Cu, Mo, Zn) had higher concentrations in the peripheral parts, suggesting that they are easily displaced from one part of the thallus to another. Lichens are perennial, slow-growing organisms, that maintain a fairly uniform morphology in time, are highly dependent on the atmosphere for nutrients, and do not shed plant parts as readily as vascular plants. The lack of a waxy cuticle and stomata allows many contaminants to be absorbed over the whole lichen surface (Hale 1983). Contaminants are deposited on lichens by free-falling precipitation, occult precipitation such as fog and dew, dry sedimentation, and gaseous absorption (Knops et al. 1991). Occult precipitation occurs under stable atmospheric conditions and contains concentrations of nutrients and contaminants orders of magnitude higher than normal precipitation (Nash & Gries 1995). Lichens accumulate and retain many trace elements to concentrations that vastly exceed their physiological requirements, and tolerate these high concentrations by sequestering elements extracellularly as oxalate crystals or lichen acid complexes (Nieboer et al. 1978). Since the concentrations of trace elements in lichen thalli may be directly correlated with the environmental levels of these elements (Andersen et al. 1978; Herzig et al. 1989), lichens are useful for monitoring spatial and/or temporal deposition patterns of trace elements. When using lichens as monitors of metal deposition, samples of approximately the same age should be collected and analyzed in order to have comparable data. In polluted areas, the central part of the thallus of foliose lichens may have higher concentrations of certain metals than the peripheral parts, owing to the older age and longer exposure time (Bargagli et al. 1987a; Hale & Lawrey 1985; Schutte 1977; Schwartzman et al. 1987). However, this zonation pattern is not always evident, and several elements seem to be rather mobile within the thallus (Goyal & Seaward 1982; Pakarinen 1985; Seaward 1980). The aim of the present study is to compare the trace element content of the peripheral and central parts of lichen thalli in an unpolluted area. MATERIALS AND METHODS In September 1993, 5-10 whole thalli (about 5-10 cm in diameter) of the foliose lichen Parmelia caperata were collected in 10 sampling sites in a remote area of TuIscany (central Italy). This lichen species was chosen because of its wide distribution in the study area and most of Italy, and because it is commonly used in biomonitoring surveys. All samples were collected at a height of 1.5-2.0 m above ground level, from the trunks of isolated oak trees (Quercus cerris and Q. pubescens) having a circumference of at least 70 cm. Trace element concentrations in lichens were previously demonstrated to be similar in the two species of oak (Loppi et al. 1996). In the laboratory, lichen samples were air-dried and sorted to remove dead or senescent tissue and as much extraneous material (adhering bark, mosses, other lichen species, soil particles etc.) as possible. The outermost 34 mm of the thallus (distinguishable by color and lack of rhizinae) was detached and analyzed separately from the remaining central part bearing rhizinae. The samples were then powdered and homogenized and about 150 mg of material was mineralized in a pressurized digestion system with concentrated HNO3 for 8 hr at 1200C. Trace elements were determined by atomic absorption spectrophotometry (Perkin-Elmer 4100 ZL), using an oxyacetylene flame for Cr, Cu, Fe, Mn, and Zn; a graphite furnace for Al, As, Cd, Co, Mo, Ni, Pb, and Sb; and the cold vapor technique for Hg. Trace element concentrations were expressed on a dry weight basis. Precision of analysis was estimated by the coefficient of variation of four replicates and was found to be less than 10% for all elements. To check the accuracy of digestion and analytical procedures, the NBS Standard Reference Material 1572 'Citrus Leaves' was re-analyzed after every ten samples. Prior to statistical procedures, trace element concentrations were transformed to logarithms to correct for skewed distributions (Bailey 1981). Significance of differences between means was tested by one-way analysis of variance (ANOVA) using Scheffe's test, and correlations between element pairs by Pearson's product-moment coefficient. 0007-2745/97/251-253$0.45/0 This content downloaded from 207.46.13.124 on Wed, 22 Jun 2016 04:58:33 UTC All use subject to http://about.jstor.org/terms 252 THE BRYOLOGIST [VOL. 100 TABLE 1. Trace element concentrations (mean ? standard deviation, xg g-1 dry weight, and CV% in parentheses) in the peripheral and central parts of Parmelia caperata thalli from a background area of central Italy (n = 10). * = differences statistically significant at p < 0.05. Peripheral part Central part Al* 890 ? 430 (48.3) 1976 ? 1416 (71.7) As 1.009 ? 0.554 (54.9) 1.108 ? 0.494 (44.6) Cd* 0.298 _ 0.154 (51.7) 0.404 ? 0.222 (54.9) Co* 1.184 ? 0.279 (23.6) 0.834 ? 0.227 (27.2) Cr 4.76 ? 2.25 (47.3) 4.89 _ 4.34 (88.7) u* 9.2 ? 2.4 (26.1) 8.4 ? 3.6 (42.9) Fe 938 ? 404(43.1) 1148 ? 728 (63.4) Hg 0.170 ? 0.107 (62.9) 0.172 ? 0.051 (29.7) Mn 38.5 ? 21.4 (55.6) 42.3 _ 40.0 (94.6) o* 1.396 ? 0.765 (54.8) 0.947 ? 0.416 (43.9) Ni 4.78 _ 1.67 (34.9) 3.37 _ 1.64 (48.7) Pb* 5.43 ? 2.54 (46.8) 15.76 ? 11.54 (73.2) Sb 0.454 ? 0.210 (46.3) 0.550 ? 0.111 (20.2) Zn* 38.2 ? 10.0(26.2) 31.3 _ 8.8 (28.1)

Abstract: Though the ability of lichens to disaggregate and dissolve the substrate is understood, zones of disparate weathering mechanisms examined in this study were previously unobserved. On a steep (60°) ...

Abstract: Usnea longissimawas sampled in SE Norway on six main branches of onePicea abies, comprising its full vertical canopy range. Nearly all specimens (n=781) were unattached and fragmented, in contrast with associated lichens. A combination of weak axes and lack of holdfasts resulted in a population of repeatedly displaced thalli, a similar situation as in ground-dwelling vagant lichens. Comparisons with a litterfall population indicated that thalli, regardless of size, had a similar probability to end as litter on the ground. Specimens were frequently sorediate, but only 12 small thalli with a basal holdfast had been directly recruited through soredial establishment. Its patchy distribution within apparently homogenous forest stands is probably a consequence of a rare successful long-range dispersal through soredia coupled with an abundant local dispersal of coarse thallus fragments. Old forests with ample, diffuse skylight at lower and humid canopy levels are probably essential to maintain a vagant epiphytic life form with a predominantly downward dispersal of thallus fragments.

Abstract: :Biomass and distribution of arboreal fruticose lichens were studied along two environmental gradients, height along vertical tree axis and altitude, in an old growth balsam fir (Abies balsamea [L] Mill) forest in the McGerrigle Range, Gaspe Provincial Park, Quebec Biomass was estimated by subsampling 53 balsam firs selected from five plots, systematically distributed along an elevational transect Three vegetation belts (mountain, subalpine, and alpine) located between 720 and 1068 m (above sea level) were sampled Alectoria sarmentosa, Bryoria spp and Usnea spp represented the bulk of epiphytic lichen vegetation Both gradients influenced lichen biomass and species diversity on balsam fir The bulk of lichen biomass was found at intermediate heights in trees In the mountain belt, the number of lichen species was positively correlated with tree height and diameter Total lichen biomass on trees was predicted by tree diameter and vegetation belt (ln[biomass + 1] = 291x + k; R2 = 087; k = -

Abstract: A small group of fruticous lichen species, viz. Cetraria nivalis, Cladonia mitis, C. stellaris, and Stereocaulon paschale forms extensive mats in the most winter habitats of Rangifer tarandus populations in Norway. The plant communities accessible for grazing are often found on easily drained, moraine ridges. These lichen species are perennial, lying on the ground while growing slowly at the top. As they decompose they add humus to the top of the soil profile. The lichen mats catch all water from small showers, thus preventing vascular plants from obtaining a more regular water supply. Grazing removs whole plants and gradually makes larger and larger holes in the lichen mats. Wind and water erode the humus, with only coarse gravel remaining. This diminishes the soil water storage capacity. Without grazing, lichens will gradually build a humus layer, which would improve the soil water storage capacity. In time vascular plants then would take the place of the lichens. I propose the hypothesis that by (over-)grazing Rangifer improve their winter pastures by making conditions more favourable for lichens than for vascular plants.The fact that lichens are more scarce on habitats with more and regular precipitation, 1) in more oceanic climates, 2) on soils with more silt, and 3) on bird perches with thick peat due to regular fertilising, support this hypothesis.

Abstract: Thalli of the lichens Parmotrema austrosinense (Zahlbr.) Hale and P. conferedum Hale were taken from a non-polluted area and transplanted within this area, and to a downtown site in Cordoba, Argentina. Pigments, malondialdehyde, hydroperoxy-conjugated dienes and sulphur were measured after various exposure periods. Changes in the quantified compound concentrations were observed throughout the exposure period in both species and in both sites. In the urban site, however, chlorophyll concentration was lower and, in P. conferendum, malondialdehyde concentration was significatively higher. These results can be attributed to the effect of atmospheric pollutants on the transplanted lichens

Abstract: : This study focuses on the saxicolous lichens and cyanobacteria of the open, exposed rock surface of inselbergs. Twenty-three species of cyanobacteria and 17 cyanobacterial lichen species (“cyanolichens”) from several inselbergs and other rocky outcrops of three major climatic regions, savanna, transition zone and rain forest, are reported from the Ivory Coast. Inselbergs are isolated and frequently mountains consisting of Precambrian granites or gneisses that abruptly rise from the surrounding plains. Cyanobacteria were found to be the dominating organisms on all rock surfaces. The lichens found mainly belong to the family Peltulaceae and a few were present from the family Lichinaceae. Nine species of the cyanolichens and most of the cyanobacteria are new for the Ivory Coast. A gradient in total species number (cyanolichens and cyanobacteria) occurs from the savanna to the rain forest, with a decrease in species number towards the rain forest. Saxicolous cyanobacterial lichens reached a higher species number in the savanna type ecosystem (11) than on inselbergs in the rain forest (7). The cyanolichens and cyanobacteria found are characteristic for larger, light-exposed rock surfaces and species like P. congregate, P. lingulata, P. tortuosa and P. umbilicata preferentially occur on the granite or sandstone of inselbergs.