The vertical gradient of the community structure of epiphytic lichens in forest canopies was studied in southern Estonian coniferous forests. All lichen species on 15 Norway spruces and 15 Scots pines were recorded; age of trees ≥100 years. Species were sampled in height ranges on entire trees from the bottom to the top. The number of lichen species on pine trunks decreased with height from the ground, whereas the number of species on branches increased. There was no significant vertical change in the number of lichen species on spruce trunks; number of species on spruce branches was highest in mid canopy. The mean number of lichen species on a tree was 41 in spruces and 34 in pines; the mean number of species on the first 2 m was 14 in spruces and 12 in pines. According to the results, about two thirds of a tree's lichen species remain unrecorded if only the first 2 m near the ground are surveyed. Many lichen species were found only higher than 2 m, including several common species (e.g. Buellia griseovirens, Lecanora pulicaris, and Melanohalea exasperatula), but also some locally rather rare (Fellhanera subtilis, Micarea nitschkeana, Rinodina efflorescens) or red-listed ones (Evernia mesomorpha, Usnea barbata, U. fulvoreagens, U. substerilis, U. wasmuthii) and one new species for Estonia, Lecanora farinaria. There were also some species, such as Chaenotheca stemonea, Cladonia cenotea and C. norvegica, that were restricted to the lowest 2 m. The results indicate that canopy lichens form a significant part of lichen diversity in coniferous forests, and could add valuable information when estimating forest lichen diversity for conservation and other purposes.

In the Netherlands a monitoring programme is in operation to map the effects of ammonia pollution with epiphytic lichens. The method is presented here and the results are statistically correlated with abiotic data. The abundance of nitrophytes on Quercus robur appears to be a useful parameter. Detailed spatial patterns of ammonia pollution can be obtained with lichens. To avoid interference, it is important to consider other influences, for example dust, climate, exposure, age of the trees and other pollutants.

This bibliographic review includes 316 works specifically devoted to lichens and biodeterioration of stonework and covers the time-span from 1825 to 1992. The list is accompanied by an analytical index in which the number of the articles is referred to under the appropriate topic category.

A phylogenetic hypothesis based on nuclear ITS sequence data is presented for the family Physciaceae based on various representatives of foliose and fruticose groups and a number of species selected from the crustose genera Rinodina and Buellia s.l. The analysis supports the monophyly of the Physcia- and the Buellia- groups. This is in agreement with existing morphological evidence, particularly ascus characters. The Physcia group in the analysis includes the genera Anaptychia, Heterodermia, Hyperphyscia, Mobergia, Phaeophyscia, Phaeorrhiza, Physcia, Physconia, Rinodina, and Rinodinella, while the Buellia group includes Amandinea, Buellia and Diploicia. The genera Physcia, Phaeophyscia, Phaeorrhiza and Rinodinella were well supported as monophyletic groups. The support for Physconia is low. Rinodina and Buellia are not supported as monophyletic genera. In agreement with ascus and ascospore characters, Buellia lindingeri is placed within the Rinodina group, close R. lecanorina. The genus Amandinea as currently circumscribed was not supported as a monophyletic group. The analysis confirms results from other lichen families that foliose members have evolved more than once from crustose lichens. Rinodina and Rinodinella species without chemical compounds in their thalli form the sister group to Phaeophyscia, and both groups form a monophyletic assemblage. A more detailed analysis of the Physcia group is presented. Whilst several of the foliose genera were well supported, there is only poor support for traditionally accepted crustose genera. The taxonomic implications of these findings are discussed.

The photobiont inventory of a stand of the Acarosporetum sinopicae, lichen community comprising saxicolous, chalcophilous lichens, has been analysed. Investigated lichen species were Acarospora rugulosa, A. sinopica, Bellemerea diamartha, Lecanora polytropa, L. subaurea, Lecidea silacea, L. lapicida, Rhizocarpon geographicum, and Umbilicaria cylindrical. For all these lichen species this is the record of the photobionts, except for L. lapicida. The photobionts were cultured axenically and investigated using light microscopical and molecular methods (ITS-sequence analyses). Every lichen species contained only one photobiont species. All photobionts belong to Trebouxia jamesii, but two different subspecies were found with the morphological differences corresponding to molecular differences. The new subspecies T. jamesii subsp. angustilobata is described, differing from the typical T. jamesii by a crenulate chloroplast but identical to the latter taxon in respect to the pyrenoid structure in the light microscope. These results are discussed with respect to the photobiont inventory of the Physcietum adscendentis, analysed in an earlier study.

Molecular phylogenetic analyses based on nuclear ITS rDNA and mitochondrial SSU rDNA sequences from 32 specimens representing Parmotrema pseudoreticulatum, P. reticulatum and P. clavuliferum from Africa, Asia, Australia, and Europe are reported. Samples from western Europe and South Africa formed an independent monophyletic group, which belongs to P. pseudoreticulatum, a species not accepted by some recent authors, that has only been reported from Portugal, Spain and Morocco. In contrast, P. reticulatum and P. clavuliferum, both widely distributed taxa, formed a monophyletic clade, supporting the synonymy already proposed on the basis of morphological features.

A number of lichen species presumed to prefer broad-leaved, deciduous woodlands of long continuity were recorded in 101 stands with different histories and in different successional stages in southern Sweden. Of 19 recorded species, Arthonia vinosa, Calicium adspersum, C. salicinum, Lobaria pulmonaria, and Mycobilimbia sabuletorum occurred in ten stands or more. Habitat variables that indicate occurrence of natural forest conditions were registered and also factors of stand and site quality used in forest surveys. The lichen species recorded were significantly correlated with the presence of large, old, deciduous, broad-leaved trees. Deciduous, broadleaved woods with many large old trees are at present being rapidly transformed into forest plantations. The recorded lichen species will decrease unless the woods are protected or have modified management.

Measurements of thalli of Rhizocarpon geographicum on the recent moraines of the Glacier de Valsorey and their surroundings are considered in relation to thallus growth rates and colonization following glacial recession. Photographs taken in 1975 and 1979 show that up to c. 3.5 cm diam the relation of maximum growth-rate to thallus size is approximated by a growth curve of the kind derived by Aplin and Hill, rising asymptotically towards a constant rate of radial growth (here c. 0.5 mm year−1). Growth-rates of many individual thalli fall well below the maximum. Parameters of the fitted growth curves are used to construct curves of thallus radius against time. Taken in conjunction with the field measurements these suggest two main phases of colonization, one from about 1880 to 1910, and one from about 1930 onwards. Some general considerations relating to lichenometry and lichen growth curves are discussed.

Zoosporogenesis was observed in the algal symbiont (Trebouxia gelatinosa) of Parmelia caperata. This is the first detailed report of this phenomenon in a Trebouxia species and, more importantly, in lichens, where zoosporogenesis in this alga is usually suppressed and the arrested zoospores form aplanospores. Observations of zoospore formation by algal cells within the natural thallus and in thallus fragments incubated on a mineral medium suggest that zoospores are released within thalli and may escape from the thallus to form free-living microcolonies. These colonies potentially could unite with hyphae derived from spores of either the same, or genetically different mycobionts (fungal symbionts) to establish new lichen associations, as has been shown in laboratory studies. Such natural resyntheses could be one cause for the observed heterogeneity characterizing fungi in many lichen populations. Other implications of free-living Trebouxia populations are discussed.

The genus Skyttea is characterized by urceolate ascomata, with a narrow pore when young, a greenish or brownish, rarely reddish exciple of conglutinate hyphae with subglobose to ± cylindrical lumina, bordered near the margin by hyaline to greenish or brownish, usually smooth, straight hairs, the absence of periphyses, rarely branched and apically hardly thickened paraphyses, asci and a hymenium that are entirely I — and KI —, a thin lateral and a very thick apical ascus wall with a small ocular chamber, and normally aseptate ascospores. It is considered to belong to the Leotiales and not to the Ostropales. It comprises at least 17 species, including S. caesii sp. nov., S. carboneae sp. nov., S. lecanorae sp. nov., S. mayrhoferi sp. nov., S. pyrenulae sp. nov., S. radiatilis comb, nov., S. tavaresae. sp. nov. and S. thelotrematis sp. nov. Rhymbocarpus is shown to be a distinct leotialean genus, distinguished from Llimoniella by a different excipular structure, different pigments and the presence of excipular hairs, which, in some species, are embedded in the excipular gel and thus not visible macroscopically. In addition to the type species, R. geographici, of which a neotype is designated, it includes R. boomii sp. nov.,R. cruciatus comb, nov., R. fuscoatrae comb, nov.,R. makarovae sp. nov.,R. neglectus comb, nov., R. pertusariae sp. nov.,R. pubescens comb. nov. and R. stereocaulorum comb. nov. Llimoniella s. str. comprises at least 6 species, including the type, L. scabridula, L. adnata, L. pertusariae sp. nov., L. pyrenulae sp. nov., L. ramalinae comb. nov. and L. vinosa comb. nov. Several species formerly assigned to Skyttea or Llimoniella are now included in the leotialean genus Unguiculariopsis, and the following new combinations are proposed: Unguiculariopsis acrocordiae comb, nov., U. groenlandiae comb. nov. and U. lesdainii comb. nov. A lectotype is chosen for Lichen stictoceros, which is shown to be a synonym of Evemia prunastri. Keys are given for the species of Skyttea, Llimoniella and Rhymbocarpus, and for the lichenicolous genera of Leotiales and Ostropales.

Decreasing abundance of epiphytic lichens with increasing Mn supply from the substratum or from stemflow was found in several coniferous forests of Europe (Germany) as well as western (Montana, British Columbia) and eastern North America (New York State). Experiments carried out with Hypogymnia physodes and other species of chloro- and cyano-lichens suggest that these correlations are causal. High Mn concentrations e.g. reduce chlorophyll concentrations, chlorophyll fluorescence and degrade the chloroplast in lichen photobionts. Excess Mn inhibits the growth of soredia of H. physodes and causes damage in the fine- and ultra-structure of the soredia. Adult lichen thalli remain structurally unaffected by Mn. Manganese uptake does not result in membrane damage. Calcium, Mg, Fe and perhaps also Si alleviate Mn toxicity symptoms in H. physodes. Lecanora conizaeoides is not sensitive to Mn in laboratory experiments or in the field. The data suggest that high Mn concentrations are an important site factor for epiphytic lichens in coniferous forests that until recently has been overlooked. Manganese reaching the microhabitat of epiphytic lichens is primarily soil-borne and is usually not derived from pollution.

Epiphytic lichen diversity in a boggy stand of Norway spruce (Picea abies) was studied in the eastern Harz Mountains, northern Germany. Spruce trees at wet sites were affected by forest dieback, whereas trees on drier sites remained unaffected. Lichen diversity was higher on diebackaffected trees than on healthy ones. The foliose lichen Hypogymnia physodes was significantly more frequent on dead trees, whereas the crustose, extremely toxitolerant Lecanora conizaeoides occurred more frequently on healthy trees. Stemflow concentrations of NH⊂4⊃+, NO⊂3⊃-, PO⊂3⊃-, and SO⊂4⊃2- were lower on affected trees. This is attributed to reduced interception from the atmosphere due to needle loss. Cover of H. physodes decreased with increasing mean SO⊂4⊃2- concentration in stemflow. The total of lichen species per sample tree also decreased with increasing SO⊂4⊃2- concentration in stemflow, indicating that most species reacted in a similar way as H. physodes. Cover of L. conizaeoides increased with increasing SO⊂4⊂2- concentration, but decreased at higher SO⊂4⊃2- concentrations. Bark chemistry had a minor influence on lichen diversity.

The distribution of epiphytic lichens on branches of a stand of Picea abies has been mapped, and patterns of succession and community structure are described. Many crustose species are of particular interest since little is known about their ecological requirements (e.g. Fuscidea pusilla Tønsb., Japewia subaurifera Muhr & Tønsb. and Gyalideopsis alnicola Noble & Vězda). Numerical treatment (correspondence analysis and canonical correspondence analysis) of the species data was used to study the lichen distribution in relation to measured environmental variables. Tree age, tree height and branch height above ground are shown to be the most important variables to explain the species distribution. No significant relationship was found between branch compass point and the distribution of lichens. The species composition and cover changed from young to old trees. The largest variation in the lichen vegetation was found on the branches of young trees. A more homogeneous and stable lichen community appears on branches of mature trees. A clear zonation of the epiphytic vegetation develops as the branches grow, resulting in the occurrence of typical ‘branch-tip’ and ‘branch-base’ species. The highest number of species was recorded on the outermost part of branches before lichen cover reached the maximum. Hyperepiphytic thalli were mainly located in specific areas with high lichen cover on the branches. Lichens with reduced vitality were most common at the base of branches.

High performance thin-layer chromatography/thin-layer chromatography, X-ray diffraction, and scanning electron microscopy analysis of thallus and lichen-rock interface samples, were undertaken to characterize biomineralization products in Fuscidea cyathoides, Ochrolechia tartarea, Ophioparma ventosa, and Pertusaria coralline, growing on sandstone in western Norway. Whewellite (monohydrate form of Ca oxalate) was found in the thallus of all species, but not in any of the weathering rinds beneath the species. A significantly higher amount of whewellite was detected in the thalli of F. cyathoides and O. ventosa than in the other two species. There were only a few differences in whewellite occurrence between the thallus edge and centre samples in the four species. HPTLC/TLC and SEM analysis indicate that lichen compounds occur within the rock beneath some of the lichen specimens. Only divaricatic acid was observed within the weathering rind beneath O. ventosa. No lichen substances were found in the weathering rind beneath F. cyathoides and P. corallina, whereas gyrophoric and lecanoric acids were found in the weathering rind beneath O. tartarea.

Terricolous lichens are the dominant vegetation in expansive areas of the Namib Desert, where fog is the main source of moisture and other vegetation is scarce. They play several important roles in soil crust stabilization and in the primary production of the Namib Desert ecosystem, yet little is known about the diversity and distribution of lichens in the northern unexplored regions of the Namib. To our knowledge, this study is the first survey of terricolous lichens to be carried out in the northern Namib Desert. Seven soil crust habitat types were identified in the study area, and a total of twenty-eight soil crust lichen species was recorded. The survey uncovered lichen species that may be unique to the northern Namib, including vagrant species, and common species were frequently found in a vagrant form. The crustose group was the most widely represented. Overall community compositions differed from those found in other regions of the Namib, and distribution patterns suggest a link to gravel clast size and physical soil crust type.

The FT-Raman spectra of encrustations of Dirina massiliensis f. sorediata on a variety of substrata collected from several locations have been recorded and analysed. This is the first time that such a comprehensive spectroscopic study has been made of lichen encrustations of the same species on different substrata. This lichen is able to bring about deterioration in all six different lichen substrata studied. Calcium oxalate dihydrate is produced in significant amounts by the reaction of lichen-generated oxalic acid with various calcareous rock substrata, as well as particles of the particular substratum itself. However, for specimens growing on a non-calcareous substratum in an exposed maritime location only traces of calcium oxalate are produced and more noticeable quartz particles are incorporated into the thalli. The results indicate that this lichen can degrade its substratum highly effectively and there is evidence of different strategies being exhibited by lichens in different habitats and geographical locations.