Some advances in the study of lichens since the time of E. M. Holmes

Some of the principal advances in our knowledge of lichens made since the time of E. M. Holmes are briefly reviewed. Floristic studies on British lichens have continued and distribution maps of particular species are now being produced. These studies have shown that many species have disappeared from areas affected by air pollution by sulphur dioxide. Lichen taxonomy has seen the acceptance of chemical characters as valid taxonomic criteria, and the realization that ascus types, ascocarp structure and ascocarp ontogeny are more important at the generic level than ascospore characters alone. Lichens are not now thought of as a single taxonomic group but as fungi related to various orders of non-lichenized Ascomycotina, united only in their common method of nutrition (symbiosis with algae); some lichenized and non-lichenized species with identical types of ascocarps are consequently being treated as members of the same genus. Considerable progress has been made in describing lichen communities characteristic of particular substrates and situations and in understanding the factors which may affect the occurrence of particular species. Lichens have proved to be particularly valuable indicators of mean air pollution levels and scales for the estimation of these levels based solely on the lichen vegetation have been devised. Physiological and ultrastructural studies on lichens have progressed rapidly in the last decade. Carbohydrates have been demonstrated to move from the algal to the fungal component and the mobile carbohydrates found to differ in lichens with different genera of algae. The algal and fungal partners have been isolated and studied in pure culture. Most attempts to synthesize lichens have met with little success but in 1970 a thallus was formed from its components in culture. It is now possible to grow some lichens under controlled conditions in the laboratory and these techniques, together with transplant experiments, will clearly assume considerable importance in the investigation of taxonomic and ecological problems in the future. Little progress has been made in the study of lichen cytology or the factors affecting the establishment of lichen thalli. Lichens constitute an important part of some ecosystems and their decline due to anthropogenic influences is consequently a matter of concern for all biologists.     

Long-term monitoring in the Netherlands suggests that lichens respond to global warming

Abstract:There is evidence to suggest that part of the recent changes in the lichen flora of the Netherlands is attributable to an increase in temperature. Changes which have occurred over the last 22 years were studied in detail, and were subjected to a statistical treatment by comparing the change of species to their latitudinal distribution and to ecological determinants.All 329 epiphytic and terrestrial lichen species occurring in the Netherlands were considered in relation to their world distribution. Arctic-alpine/boreo-montane species appear to be declining, while (sub)tropical species are invading. The proportion of increasing species is by far the largest among the wide-tropical lichens (83%), and smallest among the arctic-alpine/boreo-montane lichens (14%). None of the wide-tropical species was found to decrease, while 50% of the arctic-alpine/boreo-montane species show a decline.Long-term monitoring of the epiphytic lichen flora in the province of Utrecht from 1979 onwards shows that the total number of taxa present increased from 95 in 1979 to 172 in 2001, while the average number of taxa per site increased from 7·5 to 18·9. The rate of increase was greatest by far between 1989 and 1995. The majority of the species (152 taxa or 85%) show a gross increase, only 17 species (10%) show a decrease.A detailed analysis of these data using multiple regression suggests global warming as an additional cause for recent changes, next to decreasing SO₂ and increasing NH₃. Changes appear to be correlated initially (1979–1995) only with toxitolerance and nutrient demand. Changes between 1995 and 2001, however, appear positively correlated to both temperature and nutrient demand, indicating a recent and significant shift towards species preferring warm circumstances, independent from, and concurrent with changes due to nutrient availability.This is the first paper reporting long-term floristic changes for lichens that appear to be correlated significantly with increasing temperatures. We suggest that future lichen monitoring programmes also pay attention to effects of climatic change, instead of focusing on air pollution effects only.     

Statistical analysis of the lichen vegetation of an avenue in freiburg (South-West Germany), with regard to injurious anthropogenous influences

Summary This paper describes the epiphytic lichen vegetation on maple trees along an 1.1-km avenue leading from the outer suburbs of Freiburg toward the city center. A special aim of this investigation was to examine the variation in the coverage by lichens altogether and by each lichen species as a function of increasing distance from the city. It required very accurate quantitative recording methods, including the method of hits and other statistical techniques. The coverage both of total trunk surface and of sectors facing different directions increases with increasing distance from the city. The distribution pattern of SO₂ pollution in winter, especially under certain weather conditions, e.g., during winter highs with very high SO₂ concentrations, implies a negative correlation between the amount of SO₂ pollution and the total percentage of lichen cover. An influence of factors specific to urban climate and traffic emissions is neglegible. The stress caused by increasing immission from outer suburbs towards the city is also indicated by the decline in coverage by the lichens of foliaceous growth form, the increase in coverage by green algae, and the lichens of crustaceous growth form, especially by the resistant Lecanora conizaeoides. The degree of lichen cover changes with exposure. The differences between the four exposure zones may be caused by climatic differences.     

Evaluation of bio-indication methods using epiphytes by correlating with SO2-pollution parameters

Abstract:In order to evaluate the relative usefulness of the numerous bio-indication methods that use epiphytes as indicators for air pollution, a range of these different methods was applied within the same region (Flanders, Northern Belgium). The study area shows important air pollution gradients and little climatic differentiation. Ninety-one IAP indices were calculated with data collected in the immediate vicinity of SO₂measuring stations on one randomly chosen tree, on ten neighbouring trees and in a sampling grid placed on the tree carrying the largest number of epiphytes. A large majority of indices showed a significant Spearman rank order correlation with mean SO₂winter values over the 5 years 1990–94. Indices based on a selection of 17 lichens gave better results than those based on all lichens. The latter indices showed higher correlation than those using all epiphytes (including bryophytes). Indices using a quantitative estimate of cover or abundance or a combination of these did not result in a higher correlation. Sampling ten trees gave slightly higher correlation than the grid method or sampling of one tree. Taking into account supplementary evaluation criteria (time investment and degree of lichenological knowledge required), sampling of 17 bio-indicator species using a sampling grid is recommended within the study area. Monitoring the presence of all corticolous lichens within a sampling grid is recommended in general.     

Influence of air pollution on the mountain forests along the Tateyama–Kurobe Alpine route

The effects of air pollution on the growth of mountain trees were investigated at Buna-daira (1,180 m a.s.l.), about half the way up Mt. Tateyama, located in Japan. Every year, about 1 million tourists are transported by highland buses through the Tateyama–Kurobe Alpine route. Since the route opened in 1971, some tree species along the road have declined and have been blighted, suggesting that bus exhaust was the cause. However, the level of regional and long-range transboundary air pollution has also increased significantly over the last few decades. The atmospheric NO₂ concentration at the roadside in the forest was highly correlated with the traffic density of buses and penetration of the exhaust into the forest was detected. However, the maximum average NO₂ concentration was lower than 3.5 ppbv during the peak traffic period in the year. At Buna-daira, the total stem cross-sectional area at breast height (BA) of the forest was nearly unchanged from 1999 to 2006, but the BA of Fagus crenata decreased 10% and that of Cryptomeria japonica increased 6%. Neither tree growth nor tree death was significantly correlated with distance from the road. The cause of the decline of F. crenata could not be attributed to the effects of road, i.e., air pollution emitted from the buses or edge effects of the road. This area was more affected by regional, long-range transport of air pollution (O₃, SO₂, etc.). The average atmospheric O₃ concentration in autumn was higher than 40 ppbv and the recent increase in the O₃ concentration may be an important factor of F. crenata decline through the changes in the interspecific relationships between F. crenata and C. japonica, O₃ sensitive and tolerant species, respectively.     

The effect of air pollution from nitrogen dioxide (NO2) on epiphytic lichens in Seville, Spain

The effect of air pollution from nitrogen dioxide (NO₂) on the epiphytic lichens of the city of Seville (Spain) has been studied. Indices of air purity (IAP) were calculated, based on the lichen flora ofMelia azedarach L. present at 25 stations distributed through the city. The arrangement and classification of the stations by principal component analysis and cluster analysis, respectively, enabled the study area to be zoned into four zones of air purity. Accordingly, the zonal map of air purity for the city of Seville yields a gradient of air purity that is very steep from the centre to the outskirts. The dependence of 77.6% of IAP variability with NO₂ pollution levels detected with air emission sensors distributed through the city suggests the relationship between NO₂ levels and zones of air purity.     

Effects of the expansion by Hippophaë rhamnoides on plant species richness in coastal dunes

Question: Is the expansion of Hippophaë rhamnoides in coastal dunes associated with a decline in plant species richness, and is this decline best described by a hump‐backed relationship between species number and shrub cover? Location: Grey and yellow dunes on the East Frisian islands Spiekeroog and Norderney. Methods: Total plant species richness as well as the number of herbaceous and cryptogam species were determined in 2001 using plots of 16 m² size. We compared shrubland plots with varying cover of Hippophaë with neighbouring dune grassland plots without shrubs as reference sites. Soil samples were collected to determine the values of some important edaphic variables (pH, organic matter, nitrogen). Results: The shrubland plots with Hippophaë had or tended to have lower soil pH and C/N ratios and higher contents of organic matter and nitrogen than the grassland plots. Total species richness was marginally significantly related to the cover of Hippophaë in a hump‐backed manner on both islands. The pattern was more pronounced for mosses and lichens than for herbaceous species. For all species groups on Spiekeroog and for the herbaceous species on Norderney, the hump‐backed relationship was much improved when using the difference in species number between shrubland and grassland plot as a dependent variable. Relationships could be improved by including the soil parameters as co‐variables. Species richness was highest at moderate levels of shrub expansion, while it was much reduced in very dense shrubland. The decrease in species number is caused by the decline in grassland species typical of the open dunes, including some rare taxa. Conclusions: The expansion of Hippophaë rhamnoides is a serious threat to the plant species richness of open coastal dunes, and needs to be counteracted by management measures.     

Fallback foods of temperate-living primates: A case study on snub-nosed monkeys

Only a few primate species thrive in temperate regions characterized by relatively low temperature, low rainfall, low species diversity, high elevation, and especially an extended season of food scarcity during which they suffer from dietary stress. We present data of a case study of dietary strategies and fallback foods in snub-nosed monkeys (Rhinopithecus bieti) in the Samage Forest, Northwest Yunnan, PRC. The snub-nosed monkeys adjusted intake of plant food items corresponding with changes in the phenology of deciduous trees in the forest and specifically showed a strong preference for young leaves in spring. A non-plant food, lichens (Parmeliaceae), featured prominently in the diet throughout the year (annual representation in the diet was about 67%) and became the dominant food item in winter when palatable plant resources were scarce. Additional highly sought winter foods were frost-resistant fruits and winter buds of deciduous hardwoods. The snub-nosed monkeys' choice of lichens as a staple fallback food is likely because of their spatiotemporal consistency in occurrence, nutritional and energetic properties, and the ease with which they can be harvested. Using lichens is a way to mediate effects of seasonal dearth in palatable plant foods and ultimately a key survival strategy. The snub-nosed monkeys' fallback strategy affects various aspects of their biology, e.g., two- and three-dimensional range use and social organization. The higher abundance of lichens at higher altitudes explains the monkeys' tendency to occupy relatively high altitudes in winter despite the prevailing cold. As to social organization, the wide temporal and spatial availability of lichens strongly reduces the ecological costs of grouping, thus allowing for the formation of “super-groups.” Usnea lichens, the snub-nosed monkeys' primary dietary component, are known to be highly susceptible to human-induced environmental changes such as air pollution, and a decline of this critical resource base could have devastating effects on the last remaining populations. Within the order Primates, lichenivory is a rare strategy and only found in a few species or populations inhabiting montane areas, i.e., Macaca sylvanus, Colobus angolensis, and Rhinopithecus roxellana. Other temperate-dwelling primates rely mainly on buds and bark as winter fallback foods. Am J Phys Anthropol 140:700–715, 2009. © 2009 Wiley-Liss, Inc.     

Site factors controlling epiphytic lichen abundance in northern coniferous forests

Epiphytic lichens are an important part of the vegetation of northern coniferous forests of Eurasia and North America. Much progress has been made during recent decades at disentangling relevant site factors, which control the diversity and distribution of epiphytic lichens in boreal and oroboreal forests. The present paper aims at summarizing the present state of knowledge. Relevant site factors include the microclimate, nutrient supply, structural diversity and, if applicable, air pollution. The continuity of site conditions decides over the presence of species with dispersal limitations. The effects of fire on epiphytic lichens are largely unstudied, although fire is an important ecological factor in boreal forests.     

Nitrogen deposition drives lichen community changes through differential species responses

Nitrogen (N) deposition has increased globally over the last 150 years and further increases are predicted. Epiphytic lichens decline in abundance and diversity in areas with high N loads, and the abundance of lichens decreases along gradients of increased deposition. Thus, although N is an essential nutrient for lichens, excessive loads may be detrimental for them. However, these gradients include many correlated pollutants and the mechanisms behind the decline are thus poorly known. The aim of this study was to assess effects of N deposition, alone, on the epiphytic lichen community composition in a naturally N‐poor boreal forest. For this purpose, whole spruce trees were fertilized daily with N at five levels, equivalent to 0.6, 6, 12.5, 25, and 50 kg N ha^?1 yr^?1, during four consecutive growing seasons (2006–2009), and changes in the abundance of lichens were monitored each autumn from the preceding year (2005). The studied lichen communities were highly dynamic and responded strongly to the environmental perturbation. N deposition detectably altered the direction of succession and reduced the species richness of the epiphytic lichen communities, even at the lowest fertilization application (6 kg N ha^?1 yr^?1). The simulated N deposition caused significant changes in the abundance of Alectoria sarmentosa, Bryoria spp., and Hypogymnia physodes, which all increased at low N loads and decreased at high loads, but with species‐specific optima. The rapid decline of A. sarmentosa may have been caused by the added nitrogen reducing the stability of the lichen thalli, possibly due to increases in the photobiont: mycobiont ratio or parasitic fungal attacks. We conclude that increases in nitrogen availability, per se, could be responsible for the reductions in lichen abundance and diversity observed along deposition gradients, and those community responses may be due to physiological responses of the individual species rather than changes in competitive interactions.     

Differential effects of reindeer on high Arctic lichens

Abstract. We studied the effects of Svalbard reindeer on the abundance of lichens in Spitsbergen. A survey was carried out in 14 areas with contrasting reindeer densities. Separate cover estimates for crustose, fructose and foliose lichens were taken in each area, and related to the density of reindeer pellet groups, a measure of reindeer density. Dominant macro lichen families were identified in 10 areas, and a full record of macrolichen species was taken in four additional areas. Variation in reindeer density is partially due to past overhunting, and subsequent incomplete recovery, releasing some areas from reindeer grazing for 100–200 yr. The cover of fruticose lichens was negatively related to reindeer pellet group density, indicating suppression by Svalbard reindeer. This makes their impact comparable to other members of the Rangifer genus around the northern hemisphere. The generally recorded low abundance of lichens in the diet of Svalbard reindeer compared to other Rangifer species, therefore, was interpreted as the depletion of fruticose lichens in Spitsbergen, and a subsequent switch to alternative foods. Of all fruticose lichens, Stereocaulon spp. appeared least sensitive to grazing. Crustose and foliose lichen cover was independent of reindeer pellet group density. The cover of crustose lichens was significantly related to latitude, with greater cover in more northern areas. Foliose lichens were more abundant in places where moss cover was high. We conclude that the impact of Svalbard reindeer on lichens is dependent on growth form, with fruticose lichens suffering from grazing, whereas foliose lichens might indirectly benefit from higher densities of reindeer or, like crustose lichens, be controlled by other factors.     

Post-fire recolonization of dominant epiphytic lichen species on Quercus hypoleucoides (Fagaceae)

Following a forest fire (27 500 ha) in 1994, post-fire recolonization of Quercus hypoeleucoides by epiphytic lichens was documented as changes in lichen cover, number of small thalli, specific factors that affected reestablishment of lichens, and modes of dispersal. Three sites in the Chiricahua Mountains (Arizona, USA) were chosen according to the severity of fire damage—unburned, moderately burned, and severely burned. From 1994 through 1997, the amount of dead lichen cover significantly increased at the moderately burned site. For the same time period, the amount of live lichen cover significantly increased at the severely burned site. Numbers of new thalli increased significantly at the severely burned site each year but only in the last year (1996–1997) for the moderately burned site. Bark texture and proximity to trees with lichens were among the most important physical factors for recolonization. The most important means of dispersal for Flavopunctelia praesignis was fragmentation. For Punctelia hypoleucites, the primary means of dispersal was spores. Increases in live lichen cover and numbers of new thalli occur faster in severely burned areas probably due to the loss of lichens on tree trunks, which provides space and a lack of competition.     

基于环境库兹涅茨曲线的我国大气污染防治重点区域环境空气质量与经济增长关系研究

改革开放以来，中国经济迅猛发展，但大气污染等环境问题日益突出。进入21世纪，我国通过颁布实施多项大气污染防治政策，将京津冀及周边地区、长三角地区、珠三角地区等大气污染较严重的区域划定为重点区域，针对性制定治污措施和实施减排工程，努力推动区域环境空气质量改善。基于2000-2019年我国31个省（自治区、直辖市）（以下简称31个省份）GDP，以及SO₂、PM₁₀、NO₂三项大气污染物浓度数据，利用环境库兹涅茨曲线（EKC，Environmental Kuznets Curve）模型，对31个省份和京津冀及周边地区、长三角地区、珠三角地区的经济增长情况、大气污染物浓度演变以及二者之间的关系进行了系统全面的分析评估。研究结果显示：（1）近年来实施的各项大气污染防治政策，特别是2013年以来颁布实施的《大气污染防治行动计划》《打赢蓝天保卫战三年行动计划》，推动环境空气质量改善的同时，促进了经济发展与环境保护长期关系协调性逐步增强，除NO₂浓度呈U型外，31个省份SO₂浓度、PM₁₀浓度与人均GDP的EKC曲线呈倒U型和倒N型，并处于快速下降阶段。（2）京津冀及周边地区SO₂浓度与人均GDP呈倒U型，且处于快速下降阶段；PM₁₀和NO₂浓度均呈现U型关系，且均处于上升期。（3）长三角地区SO₂、PM₁₀浓度与人均GDP呈现倒U型和U型，但均处于下降阶段；NO₂浓度与人均GDP无相关关系。（4）珠三角地区SO₂、PM₁₀和NO₂浓度与人均GDP均呈现倒U型关系，且均处于下降阶段。为此，建议"十四五"期间我国政府要继续实施新一轮的大气污染防治行动计划，聚焦机动车NO_x污染管控，大力推动NO₂浓度稳步下降，以实现我国环境空气质量持续改善，为统筹经济高质量发展和生态环境高水平保护奠定坚实基础。     

The pH dependence of SO2 damage to lichens

Summary In order to determine the influence of the hydrogen-ion concentration on the damage exerted to lichens by sulfur dioxide gas, thalli of the species Hypogymnia physodes and Xanthoria parietina were submerged in buffer solutions of pH 2 to pH 8 and subsequently exposed to SO₂ gas. Net photosynthesis was employed as a criterion of vitality.The degree of damage to the lichens after exposure to 4 mg of SO₂/m³ air for 14 hrs is dependent on the pH of the buffer solutions. Hypogymnia physodes shows the least damage at pH 7, Xanthoria parietina at pH 5 to pH 7. The degree of damage increases with increasing acidity. After exposure to SO₂ gas at pH 3 no apparent photosynthesis is achieved.The different degrees of impairment are due to the fact that the concentration of the toxic products, resulting from the reaction of SO₂ and water, is dependent on the pH value.The mere shift of the pH into the strong acid range of pH 3 and pH 2 damages the lichens with Xanthoria parietina being more seriously damaged than Hypogymnia physodes. Basicity, however, is already harmful to the lichens under test in the low range of pH 8. Here Xanthoria parietina is less affected than Hypogymnia physodes.     

Chlorophyll Fluorescence of Lichens Containing Green and Blue-Green Algae During Hydration by Water Vapor Uptake and by Addition of Liquid Water*

The fluorescence yield at room temperature of the lichens Ramalina maciformis and Peltigera rufescens, containing either green or blue-green algae (Cyanobacteria) as phycobionts, has been investigated during rehydration of the dry lichens by water vapor uptake or by wetting with liquid water. In the dry state the fluorescence yield with all reaction centers open, F_o, was low and no variable fluorescence could be induced with both species. Whereas R. maciformis, containing green algae, regained normal fluorescence behavior during water vapor uptake, the photosynthetic apparatus of the blue-green algae-containing P. rufescens stayed inhibited and could be reactivated only by addition of liquid water. During stepwise rehydration at increasing air humidities, a pattern was established for the recovery of the different fluorescence parameters in R. maciformis. At a dry-weight related water content between 30 and 40%, F_o rose sharply. Maximal variable fluorescence yield expressed as (F_v)_m/F_o, strongly increased in the same range of water content and remained constant above a water content of 50%. Non-photochemical fluorescence quenching, q_NP, determined at the end of a period of actinic illumination, decreased with increasing water vapor uptake. While spraying the lichen with liquid water did not induce a further decrease of q_NP, slow dehydration at lowered air humidity led to a minimal value of q_NP at a water content of 65 % indicating optimal photosynthetic rate under these conditions. These results extend the conclusions drawn from earlier gas exchange experiments that blue-green algae-containing lichens are unable to reactivate photosynthesis by water vapor uptake. During a re- and de-hydration cycle, no hysteresis in the hydration dependence of the fluorescence parameters was found. From this and the presence of a stable and low F_o value at prolonged incubation in nearly water vapor saturated air, we conclude that the reactivation of photosynthesis in blue-green algae-containing lichens is not prevented through high diffusion resistances for water.     

Lichens as air pollution indicators in the metropolitan area of San José, Costa Rica

Lichens were used as air pollution indicators in the metropolitan area of San José, Costa Rica. Transplants showed a positive correlation between the percentage of dead cells in the thallus and the ketone soluble substances deposited on it. Those parts of the city where pollution is greatest (industrial areas and heavy traffic) were also the ones where lichens suffered the most, and in some extreme cases the thallus died after 8 months of exposure. Besides this transplant experiment, the coverage of Parmelia lichens on the bark of several tree species was determined in some areas of the city. The results of these observations suggest that the city of San José has three different kinds of air environment in relation to lichen survival: normal, transitional and desertic, as reported for other cities of the world. The most frequent air pollutants in San José are: CO, CO2, C2H5OH, Cl2, HCl, H2S, H3PO4, H2CrO4, NO, NH3, NH4 Cl, SO2 and Zn.     

Digitized photographs in vegetation analysis ‐ a comparison of cover estimates

Abstract. The use of digital images in measuring plant species cover and species number in boreal forest vegetation was studied. Plant cover was estimated by manual delineation on photographs and subsequent digitized measurement of the areas. This value was regarded as the reference and compared with cover obtained by visual estimate, point frequency and automatic image analysis methods. The automatic image analysis was based on scanned photographs. Supervised image classification with ERDAS software was then used to distinguish between the covers of different plant species. When comparing the ability of the methods to detect species, the visual estimate method gave values similar to the reference. The study material was collected from three sites along a heavy‐metal pollution transect in western Finland. All four methods detected, in a similar manner, differences between the plant species abundances along the transect. Compared with the reference, the digital images underestimated the cover of the lichens Cladina spp. and Cetraria islandica, but gave similar estimates for the dwarf shrubs Empetrum nigrum and Vaccinium vitis‐idaea. The point frequency method overestimated the cover of all the species studied. The visual estimates of lichens were close to the reference, while the dwarf shrub covers were overestimated. The number of species detected using supervised image analysis and the point frequency method was lower than that with visual estimation. Visual estimation was faster, and the estimate closer to the reference cover values than the others. Digital images may be useful in detecting changes in some selected species in vegetation with a simple vertical structure but with taller, multilayered vegetation and a higher species number, the reliability of the cover estimates is lower.     

Significant decrease in epiphytic lichen diversity in a remote area in the European Alps,Austria

We present long-term (1993–2010) monitoring results of lichens from a remote site in Austria. Whereas gaseous pollution is negligible in this area, levels of long-range air pollution of S and N via rain and fog are high. Lichen cover on tree trunks have decreased significantly. Accordingly, we found that the population of all species had declined. The analyses demonstrated significant changes in lichen community composition. The lichen flora suffered a significant decrease in diversity. Our hypothesis is that the breakdown of epiphytic lichens is mainly due to eutrophication through long-term N deposition, and more particularly to ammonia in precipitation and in fog. Since many areas in the European Alps receive high wet deposition loads, a decrease in the abundance and diversity of epiphytic lichens is most probably a widespread phenomenon.     

Molecular biodiversity in the moss <Emphasis Type="Italic">Leptodon smithii</Emphasis> (Neckeraceae) in relation to habitat disturbance and fragmentation

Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population fixation index (F_ST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent to habitat fragmentation and human-induced disturbance.