Abstract: Questions: How do tree age, microhabitat characteristics and epiphytic competitors affect the occurrence of crustose lichens associated with old oaks? How do microhabitat characteristics and microclimate affect the cover of competitors (bryophytes and macrolichens)? How do microhabitat characteristics cor¬relate with microclimatic variables? Location: Southeast Sweden. Methods: Eight crustose lichen species were surveyed on 165 Quercus robur trees, 17-478 years old, at three study sites. The occurrence patterns of these species were examined at two spatial scales: among trees and within trees. Occurrence patterns within trees were examined in 10 cm × 10 cm plots at all four cardinal aspects at different heights from 0.5 to 4.5 m above the ground. Results: At the tree level, age-related factors were the most important predictors of species occurrence. All species were more frequent on trees > 100 years than on younger trees. At the plot level, the frequency of occurrence increased with increasing bark crevice depth. The frequencies of all study species de¬creased with increasing cover of bryophytes. Bryophytes were in turn more frequent in plots that were exposed to rainwater and showed a low evaporation rate. Patches most exposed to rainwater were directed upwards, and the lowest evaporation rates occurred on the northern side of the trunks. Conclusions: For many crustose lichens the association with old oak trees seems at least partly to depend on their preference for the deep bark crevices that only occur on old trees. Trees represent epiphyte habitat patches that differ in size due to within-tree variability in habitat quality, such as bark crevice depth and microclimate. This study shows that variability at a finer scale, within habitat patches, contribute to explain species occurrence patterns at habitat patch level.

Abstract: Dead wood is an important habitat feature for lichens in forest ecosystems, but little is known about how many and which lichens are dependent on dead wood. We reviewed substrate use by epiphytic lichens in the combined floras of Fennoscandia and the Pacific Northwest of North America based on literature and herbarium data and analyzed substrate affinity relative to life form, reproductive mode and major phylogenetic group within the floras. A total of 550 (43%) of the 1271 epiphytic species in the combined floras use wood, and 132 species (10%) are obligately associated with dead wood in one or both regions. Obligate and facultative wood-dwelling guilds in the two floras were strongly similar in terms of internal guild structure in each region, but differ somewhat in species composition, while the bark-dwelling guild differs strongly in both. Most obligate dead wood users are sexually reproducing crustose lichens. The largest numbers of species are associated with forest structural features such as logs and snags that have been greatly reduced by forest practices. Conservation of lichens inhabiting wood requires greater attention to crustose lichen species and the development of conservation strategies that look beyond numbers and volumes of dead wood and consider biologically meaningful dead wood structure types.

Abstract: Although earlier literatures provided an insight into the uniqueness of lichens, it gave little hint of the major role these apparently insignificant organisms play in the shaping of the physical and biological environment of our planet and their importance in maintaining its equilibrium. Their role as biological weathering agents in the development of soils, for example, was formerly considered in a geological context only, but recent research has shown that these organisms are capable of biodeteriorating stone substrates within a relatively short timescale. Information is now available to demonstrate that lichens can often contribute substantial biomass and support a high biodiversity of micro- and macroorganisms, creating complex food webs and adding significantly to energy flow (Chapter 10) and mineral cycling (Chapter 12). The disappearance of lichens, due to many aspects of human interference in the natural world, has therefore led inexorably to environmental impoverishment. Lichens are natural sensors of our changing environment: the sensitivity of particular lichen species and assemblages to a very broad spectrum of environmental conditions, both natural and unnatural, is widely appreciated. Lichens are therefore used increasingly in evaluating threatened habitats, in environmental impact assessments, and in monitoring environmental perturbations, particularly those resulting from a disturbingly large and growing number of chemical pollutants (Chapter 15). Nevertheless, lichens undoubtedly represent one of the most successful forms of symbiosis in nature.

Abstract: Epiphytic bryophyte and lichen species distribution was studied in representative natural old-growth broad leaved forests in Latvia. Overall 120 epiphytic bryophyte and lichen species were found in 13 forest stands. Seven Latvian red-listed bryophyte ( Antitrichia curtipendula, Lejeunea cavifolia, Metzgeria furcata, Neckera complanata, Neckera pennata, Dicranum viride, Jamesoniella autumnalis ) and four red-listed lichen species ( Lobaria pulmonaria, Opegrapha viridis, Pertusaria pertusa, Thelotrema lepadinum ) were recorded. The relationships of total epiphytic bryophyte and lichen species richness and red-listed epiphytic bryophyte and lichen species richness with substrate factors (phorophyte species, DBH (diameter at breast height), tree bark crevice depth and tree bark pH) were evaluated.

Abstract: Question: How will warming and increased nutrient availability affect individual alpine plant species abundances (nonvascular and vascular) and community composition? Location: Dryas octopetala heath at alpine Finse, southern Norway. Methods: Four years with experimental warming (open top chambers) and nutrient addition. Detrended Correspondence Analysis and Redundancy Analysis were used to examine changes in community composition. GLM-ANOVA was used to examine treatment effects on individual species. Results: Warming alone decreased the abundance of some Carex and bryophyte species, but did not affect community composition. Nutrient addition and warming combined with nutrient addition increased the abundance of high stature species, such as grasses (Festuca spp., Poa alpina) and some forbs (e.g. Cerastium alpinum, Potentilla crantzii). Low stature forbs (e.g. Tofieldia pusilla), a lycophyte (Selaginella selaginoides) and most bryophytes and lichens decreased in abundance. After four years of warming combined with nutrient addition 57% of the mosses, 57% of the liverworts and 44% of the lichens had completely disappeared. Community composition changed significantly, with the largest shift when warming and nutrient addition was combined. Conclusions: Tall species may expand at the expense of low stature species in the alpine region if temperature and soil nutrient content increase. Contrasting responses between grasses and sedges, and species-specific responses within forbs, sedges and shrubs, within and across alpine and arctic sites, suggest that the use of functional types in environmental change research may mask important information on individual species responses. The response of one species within a functional type cannot predict the response of another.

Abstract: This study aims: (1) to quantify mollusc grazing on juvenile and mature thalli of the foliose epiphytic lichen Lobaria pulmonaria, and (2) to test the hypothesis inferring a herbivore defensive role of lichen depsidones in forests with indigenous populations of lichen-feeding molluscs. Lichens were transplanted in shaded and less shaded positions in each of two calcareous broadleaved deciduous forests, one poor in lichens, one with a rich Lobarion community. Preventing the access of molluscs significantly reduced the loss of juvenile L. pulmonaria, particularly in the naturally lichen-poor forest. Molluscs also severely grazed mature thalli in the lichen-poor forest, especially thalli placed under the more shading canopies. Furthermore, reducing the natural concentration of depsidones by pre-rinsing with acetone increased subsequent grazing significantly, showing that lichen depsidones function as herbivore defence in natural habitats. Our results suggest that mollusc grazing may play important roles in shaping the epiphytic vegetation in calcareous deciduous forests, and that recently established juvenile L. pulmonaria thalli seem to be particularly vulnerable.

Abstract: Mammalian herbivores in arctic tundra often alter plant species composition and lichen abundance, with effects dependent on grazing season and herbivore preference. We investigated how long-term mammal exclosures designed to exclude large mammals (caribou) alone, large and medium-sized mammals (e.g., ground squirrels), or all mammals (including voles and lemmings) affected lichen abundance and species composition as well as the vascular plant community. The exclosures were partly established in combination with long-term soil nutrient additions to investigate the interaction between mammal activity and nutrient availability. Our study was conducted in dry heath tundra in northern Alaska, dominated by dwarf evergreen shrubs and lichens. Excluding mammals for 17 years allowed the lichen community to increase in biomass, particularly within the genus Cladonia, which also had more intrageneric diversity in the exclosures; after 10 years, results were subtler. Fertilization, however, almost eliminated the lichens, regardless of herbivore treatment. This coincided with a dramatic shift in vascular vegetation toward a more palatable grass-dominated community, similar to studies of other arctic heaths. Our results suggest that with greater soil nutrient availability that occurs with climate warming, lichens will decrease in abundance, and this effect may be exacerbated by increased mammalian herbivory.

Abstract: Phyllopsora dominicanus sp. nov. (Bacidiaceae, Lecanorales, lichen-forming Ascomycota) is described and illustrated from Dominican amber. The diagnostic features of the lichen include a minute subfolious thallus of lacinulate, ascending squamules, a well-developed upper cortex, and a net-like pseudocortex on the lower surface. The algal symbionts are unicellular green algae, forming a distinct layer immediately below the upper cortex. The fossil demonstrates that distinguishing features of Phyllopsora have remained unchanged for tens of millions of years. The fossil also provides the first detailed views of mycobiont-photobiont contacts in Tertiary green algal lichens. The mycobiont hyphae formed apical and intercalary appressoria by pressing closely against the photobiont cells. This indicates that a conserved maintenance of structure is also seen in the fine details of the fungal-algal interface.

Abstract: Epiphytic lichens possess unique life history traits that can have conflicting effects on genetic structure: symbiotic mutualism between a fungus with its algal or cyanobacterial photobiont, association with a host plant, and ability to reproduce sexually and asexually. Our study species, Ramalina menziesii, has small ascospores that can facilitate long-distance gene movement, and it is capable of clonal reproduction. The goals of this study are to test whether different haplotypes were differentially distributed across host plant species, to look for evidence of asexual vs. sexual reproduction, and to assess the local genetic structure of the population. We sampled individuals from multiple trees of three oak species in four lichen subpopulations within a savanna ecosystem. Using DNA sequence data from four fungal nuclear loci, we found no tendency for host specialization. Alleles were randomly distributed across subpopulations. The frequency of multilocus genotypes was consistent with a randomly mating population. Sexual reproduction involving relichenization appeared to be the predominant mode of reproduction of R. menziesii at this study site. We found no significant local genetic structure suggesting widespread gene flow at the local scale. The genetic structure of this lichen is comparable to that of widely distributed epiphytic plants.

Abstract: Antioxidant agents prevent reactive oxygen species, which can cause degenerative diseases. Natural antioxidants are preferred over many synthetic antioxidants, which can be toxic, for therapeutic applications. Five lichen species were collected from King George Island, Antarctica. Antioxidant activities as assessed by DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical and ABTS•+ [2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] radical scavenging capacities were determined and compared with those of commercial standards BHA (butylated hydroxyanisole) and trolox [(±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid]. The results indicated that two lichens exhibited comparatively high antioxidant activities with the remaining three exhibiting less activity. The antioxidant activity was concentration-dependent. When compared, the antioxidant activity of crude extracts from polar lichens to previously published data for tropical and temperate lichen species, we concluded that lichens of Antarctic origin may be the potent sources of strong antioxidant agents. Such species should be explored as novel sources of effective antioxidant metabolites.

Abstract: Lichens represent symbioses between a fungus and a cyanobacterium and/or a green alga and form an important part of the biodiversity in arctic, subarctic and boreal terrestrial ecosystems. Most lichens occupy large, frequently underexplored distribution areas with frequent intercontinental and sometimes bipolar disjunctions. Because of this and the fact that lichens are often disregarded or overlooked in vegetation surveys, distribution maps are usually sketchy and the composition of lichen floras of remote regions is often poorly known. Three main problems have impeded studies on the biogeography of lichens in the past: fuzzy species concepts, incomplete knowledge of the distribution of species and a lack of fossil records. The application of molecular methods in phylogeographic studies on lichens provides some first insights into the population structure and history, but so far most studies have concentrated on boreal and bipolar taxa. The few available examples show that possible glacial refugia for so...

Abstract: For biodiversity, natural afforestation is generally more favorable than plantation-based afforestation, but the difference may be less important if both methods fail to provide habitats for sensitive old-forest species. Given that some conditions, such as substrates, can be actively restored in new forests, their effect on biodiversity should be separated from dispersal limitation. We asked whether, and to what extent, lichen and bryophyte vegetation is impoverished on old-forest substrates in non-intensively afforested lands of the twentieth century compared with similar substrates in managed long-term forestlands. We measured the diversity and abundance of all lichens and bryophytes as well as the cover of human-sensitive (hemerophobic) species on large deciduous trees, logs, snags, and windthrows on 30 random 2-km transects in a 900-km2 forest landscape in Estonia, hemiboreal Europe. Altogether, 235 species, including 39 hemerophobic species, were detected on 781 structural elements. New forests were not significantly worse than long-term forests in any of the cryptogam community characteristics, which was explained by the predominance of natural afforestation (many native tree species present), time for substrate development and cryptogam dispersal (most stands >40 years old), few cuttings in the new forests (only about 20% of stands thinned), and short distances to long-term forests (67% of substrates within 250 m). Under such conditions, afforested areas appeared to be as suitable as traditional managed forests both for developing multifunctional forestry and as starting points for habitat restoration for threatened species.

Abstract: Lichens are known to be bioaccumulators of atmospheric pollutants and are abundant in the Canadian arctic. Mining in this region may negatively impact the tundra communities and these impacts may be detected by increased accumulation of heavy metals, greenhouse gas constituents, and organic compounds in lichen tissue. The effect of sampling direction and distance from a diamond mine on bioaccumulation in three lichen species, Flavocetraria nivalis, Flavocetraria cucullata, and Cladina arbuscula, was investigated. Eight sample sites were located immediately adjacent to a diamond mine, one in each cardinal and ordinal direction, and six sample sites each were located 30 and 60 km from the mine (cardinal, NE, and SE). Thirty-three major and trace elements, sulfate (SO(4)), nitrate (NO(3)), ammonium (NH(4)), polycyclic aromatic hydrocarbons (PAH), and phthalates were analyzed in lichen tissue and soil. A significant interaction occurred between distance and direction from the mine. Highest concentrations of Al, Cr, Cu, Fe, Ni, Ti, and V in lichen were at the mine site regardless of direction. Highest concentrations for all other elements were at the mine in at least two directions. Although present in lichen tissue, there was no significant difference among sites for Hg, Mn, S, and three phthalates. PAHs were below detection limits in lichen tissue. The effect of direction was dependent on element and species, although concentrations of most elements were greatest east or southeast of the mine site. At distance from the mine, direction had less of an effect on concentrations. Elevated concentrations in tissue did not negatively impact lichen or plant cover or lichen richness. This research strongly suggests selection of sample sites and species can impact results and interpretation of data from air quality monitoring programs that use lichens as biomonitors.

Abstract: Lichen communities of forests often appear to be negatively affected by timber harvest presumably because of reduction of suitable substrate and increased desiccation. We examined species richness and composition of lichens on wood of logs of the same decay class in unlogged stands (>140 years old) and logged, 20- to 30-year-old stands. There was no significant difference in species richness or mean lichen cover between logged and unlogged stands, but species composition differed, including species that were unique to either logged or unlogged stands. Crustose lichens accounted for 71% of rare species and all of the species occurring more commonly in unlogged stands; macrolichens accounted for 82% of common species and 60% of the species occurring more commonly in logged stands. Diameter at breast height and decay characteristics of down wood were the best predictors of lichen richness. Among lichen-rich, decay class 3 logs, relatively small amounts of retained down wood sustained lichen richness equivalent to unlogged stands. It appears impor- tant to ensure that decay classes favourable to lichens are retained after harvest. Resume´ : Dans les forets, les communautes de lichens semblent souvent etre affectees negativement par la recolte de bois vraisemblablement parce qu'elle entraoˆne la perte de substrats appropries et accentue la deshydratation. Nous avons exam- inela composition et la richesse en especes de lichens sur des billes de bois appartenant ala meme classe de decomposi- tion dans des peuplements non exploitesages de plus de 140 ans et des peuplements exploitesagesd e 20 a` 30 ans. Il n'y avait pas de difference dans la richesse en especes ou la couverture moyenne par les lichens entre les peuplements ex- ploites et non exploites, mais la composition en especes etait differente, incluant la presence d'especes propres soit aux peuplements exploites, soit aux peuplements non exploites. Les lichens crustaces representaient 71 % des especes rares et toutes les especes presentes plus frequemment dans les peuplements non exploites. Les macrolichens representaient 82 % des especes communes et 60 % des especes les plus communes dans les peuplements exploites. Les caracteristiques du di- ametre a hauteur de poitrine et de la decomposition du bois au sol etaient les meilleurs predicteurs de la richesse en li- chens. Parmi les billes riches en lichens dans la classe de decomposition 3, une quantiterelativement faible de billes au sol qui avaient eteconservees supportaient une richesse en lichens equivalente acelles des peuplements non exploites. Il semble important de s'assurer que des classes de decomposition favorables aux lichens soient conservees apresl a recolte. (Traduit par la Redaction)