LECANORA COMPALLENS AND L. SINUOSA,TWO NEW OVERLOOKED CORTICOLOUS LICHEN SPECIES FROM WESTERN EUROPE

Lecanora compallens and L. sinuosa, two corticolous lichens, are described as species new to science on the basis of numerous collections. Lecanora compallens is a sorediate species, known only as sterile. It is probably common in Western Europe, but overlooked because it is very similar to L. expallens. Chemically, the new species is identical with L. strobilina, of which it may represent a sorediate counterpart. Lecanora sinuosa is a new species similar to L. chlarotera and so far only known from a limited area in the Netherlands and Germany, although it may be overlooked elsewhere. Lecanora sinuosa is very close to L. hybocarpa, with which it shares thepulicaris -type epihymenium inspersed with fine crystals but differs markedly by its thick thallus and thick and sinuous apothecium margin.     

Culturable bacteria associated with Antarctic lichens: affiliation and psychrotolerance

Antarctic habitats harbour yet unexplored niches for microbial communities. Among these, lichen symbioses are very long-living and stable microenvironments for bacterial colonization. In this work, we present a first assessment of the culturable fraction of bacteria associated with Antarctic lichens. A phylogenetic analysis based on 16S rRNA gene sequence of 30 bacterial strains isolated from five epilithic lichens belonging to four species (Lecanora fuscobrunnea, Umbilicaria decussata, Usnea antarctica, Xanthoria elegans) shows that these represent the main bacterial lineages Actinobacteria, Firmicutes, Proteobacteria and Deinococcus-Thermus. Within the Actinomycetales, two strains group in the genera Arthrobacter and Knoellia, respectively. Most of the other Actinobacteria form well-supported groups, but could be assigned with certainty only at the family level, and one is in isolated position in the Mycobacteriaceae. The strains in Firmicutes and Proteobacteria belong to the genera Paenibacillus, Bacillus and Pseudomonas, which were already reported from lichen thalli. Some genera such as Burkholderia and Azotobacter, reported in the literature as also associated with lichens, have not been detected in this study. One strain represents the first record of Deinococcus in epilithic lichens; it is related to the species Deinococcus alpinitundrae from Alpine environments and may represent a new species. Further separated and well-supported clades indicate the presence of possibly new entities. Some of the examined strains are related to known psychrophilic bacteria isolated from ice and other extreme environments, others with bacteria distributed worldwide even in temperate climates. Most of the strains tested were able to grow at low temperatures, but tolerated a wider range of temperature. Ecological and evolutionary implications of these lichen-associated bacteria are discussed.     

Tree hollows can affect epiphyte species composition

Tree hollows often harbor animals and microorganisms, thereby storing nutritive resources derived from their biological activities. The outflows from tree hollows can create unique microenvironments, which may affect communities of epiphytic organisms on trunk surfaces below the hollows. In this study, we tested whether the species richness and composition of epiphytic bryophytes (liverworts and mosses) and lichens differ above and below tree hollows of Aria japonica and Cercidiphyllum japonicum in a Japanese temperate forest. The species richness of epiphytic bryophytes and lichens did not differ above and below hollows; however, the species composition of bryophytes differed significantly above and below hollows. Indicator species analyses showed that the moss species Anomodon tristis and the liverwort species Porella vernicosa were significantly more common below than above hollows, while the liverwort species Radula japonica and four lichen species, including Leptogium cyanescens, occurred more frequently above than below hollows. Our results highlight that tree hollows can produce unique microenvironments on trunk surfaces that potentially contribute to the maintenance of epiphytic diversity on a local scale.     

Zn/Pb-tolerant lichens with higher content of secondary metabolites produce less phytochelatins than specimens living in unpolluted habitats

Many lichens can cope with heavy-metal stress, however, the mechanisms of lichen tolerance are still not fully understood. Some lichen secondary metabolites (depsides and depsidones), produced in lichens by the fungal symbiont and accumulated on the outer surface of its hyphae, are supposed to play an important role in the extracellular immoblilization of heavy metals. Lichen photobionts (algal partners in the symbiosis), although surrounded by the mycobiont hyphae, may also accumulate high amounts of trace metals. This can lead to physiological disruptions and morphological damage in algal cells and hence affect the lichen physiological status. We hypothesized that lichen species/specimens living in heavily polluted sites and showing HM tolerance possess a higher content of secondary metabolites than those living in unpolluted sites. Hence, their photobionts can be better protected from the excess of metal ions and need to produce less metal-complexing phytochelatins (PCn) to combat metal toxicity. Specimens of Hypocenomyce scalaris, Cladonia furcata and Lepraria spp. sampled from Zn/Pb-polluted and control sites were compared for the accumulation of Zn/Pb and secondary metabolites, as well as for their production of phytochelatins and glutathione in response to experimental Zn or Pb exposure. Generally, the lichen specimens sampled from the HM-polluted site contained higher amounts of Zn and Pb as well as lichen substances (different depsides and depsidones) than those from the control site. A strong positive correlation was found between the accumulation of secondary metabolites and Zn/Pb accumulation (R² = 0.98 and 0.63, respectively). For the first time, production of phytochelatins (PC_2-3) in response to Zn and Pb (50-200 μM) exposure was found in H. scalaris, L. elobata, L. incana and C. furcata. In both species of Lepraria also cysteine, a substrate for GSH and PCs synthesis was detected. The lichens from the polluted site produced under the same exposure conditions, or in response to higher metal concentrations, lower amounts of PCn than those sampled from the control site. It strongly suggests that less Zn and Pb ions reached the photobiont cells of the lichens containing higher amounts of secondary metabolites (lecanoric, fumarprotocetraric, stictic, constictic acids, antranorin). The results obtained support the putative role of some metabolites in heavy-metal tolerance of the lichens inhabiting metal-polluted habitats.     

Yeast population of the Kindo Peninsula lichens

Yeast abundance and species diversity in the lichens collected at the Kindo Peninsula (Karelia) were studied. A total of 14 lichen species analyzed belonged to the genera Bryoria, Cladonia, Hypogymnia, Icmadophila, Nephroma, Peltigera, and Ramalina. Abundance of cultured yeasts in lichens was intermediate between soil and phyllosphere. The average yeast number on lichens was ~2.5 × 10³ CFU/g, while it exceeded 8 × 10³ CFU/g on plants and reached only 1 × 10³ CFU/g in soil. Yeast population of different parts of Cladonia lichens was found to vary significantly in abundance, species diversity, and community structure. The highest yeast abundance and diversity were revealed in the growth zone. Fifteen yeast species were isolated from lichens, including 6 basidiomycetous and 9 ascomycetous ones. Unlike soils and plants, yeast population of lichens consisted mainly of ascomycetous species, with predominance of Candida sphagnicola and anamorphous yeasts of the genus Dothiora. These results show that yeasts from different taxonomic and ecological groups are a necessary component of lichens; conditions favoring the preservation and development of specific yeast communities differing from the typical soil and phyllosphere yeast complexes are formed in the lichens of northern taiga forests.     

Cyanobacteria of Rocks and Soils of the Orinoco Lowlands and the Guayana Uplands,Venezuela

The occurrence of 23 cyanobacterial species, belonging to 9 different genera and 5 cyanobacterial lichen species of 5 different genera on exposed, open rock surfaces of inselbergs and on soil in savannas of the Orinoco lowlands and the Guayana uplands is described. Their distribution patterns and frequency within the different habitats are given. The filamentous procaryotic blue-green algae/cyanobacteria Stigonema ocellatum and Scytonema crassum, together with the unicellular cyanobacterium Gloeocapsa sanguinea were the most frequent species on rocks, whereas the filamentous cyanobacterium, Schizothrix telephoroides, dominated in cyanobacterial mats on the savanna soil. All species showed intensively coloured sheaths, either brown or yellow in the case of Stigonema ocellatum and Scytonema crassum, or red in Gloeocapsa sanguinea and Schizothrix telephoroides. In addition, a number of cyanobacterial lichens occurred.     

Epiphytic lichens and bryophytes of forest ecosystems in Tuscany (Central Italy)

The distribution of epiphytic bryophytes and lichens on three species of trees (Quercus ilex, Quercus cerris and Fagus sylvatica, representing the forest ecosystems of central Italy at low, medium and high elevations, respectively) was examined with respect to host specificity and habitat differences. Although most species were host-specific, the results suggested that habitat characteristics are more important than phorophyte properties in determining the distribution of lichens and bryophytes. Factors affecting the diversity of the epiphytic flora were different for lichens and bryophytes. In the case of lichens, climatic parameters and forest monospecificity were important factors, whereas tree cover (i.e. shade) and to a certain extent the number of available trees seemed more important for bryophytes.     

Colonization by lichens and the development of lichen-dominated communities in the maritime Antarctic

Three long-term studies of lichen growth and colonization have been undertaken at Signy Island, South Orkney Islands, in the maritime Antarctic. Small individual thalli of several crustose species and uncolonized plots on 12 fresh rock surfaces were photographically monitored at intervals of 3–4 years over a period of up to 20 years. The development of Ochrolechia frigida colonies on a regenerating moss bank, recently uncovered by a receding glacier, was similarly monitored. The results indicate that many lichens growing in sites enriched by nitrogenous compounds derived from populations of sea birds, have relatively rapid colonization and growth rates. Mean percentage increase in thallus area can be as high as 15–32% per annum in some nitrophilous saxicolous species (e.g. Acarospora macrocyclos, Xanthoria elegans and species of Buellia and Caloplaca), but as low as 0·4–4% in nitrophobous species (Lecanora physciella, Lecidea sp., Rhizocarpon geographicum). Umbilicaria antarctica and Usnea antarctica also yielded data indicating high growth rates, with colonist plants reaching several centimetres after 20 years. Colonization by mixed assemblages of lichens of new rock surfaces can attain 40→90% cover after 20 years in nutrient-enriched sites, and even 20–25% in non-biotically influenced sites. Colonization by or increase in extant O. frigida on the regenerating moribund moss bank was also quite rapid. It is suggested that the ~exceptionally large thalli of several lichen species and the locally extensive dense lichen fellfield communities in the maritime Antarctic may be much younger than previously supposed.     

The flora of the Flannan Isles

Summary

The Flannan Isles provide an example of a remote flora growing under extreme conditions of salt spray and exposure. Their plant communities are described and related to physical, biotic and historical factors. Of the 32 higher plants, 1 fern, 14 bryophytes, 63 lichens and 27 species of marine algae encountered, few were rare though a lichen community discovered on the bird cliffs contained the arctic- maritime lichen Lecanora straminea. Vegetation maps of Eilean Mor and Eilean Tighe are presented and a comparison made with other remote Scottish Islands. Records of six arthropods are included.     

Species richness of vascular plants, bryophytes and lichens in dry grasslands: The effects of environment, landscape structure and competition

We studied the relative importance of local habitat conditions and landscape structure for species richness of vascular plants, bryophytes and lichens in dry grasslands on the Baltic island of Öland (Sweden). In addition, we tested whether relationships between species richness and vegetation cover indicate that competition within and between the studied taxonomic groups is important. We recorded species numbers of vascular plants, bryophytes and lichens in 4 m² plots (n=452), distributed over dry grassland patches differing in size and degree of isolation. Structural and environmental data were collected for each plot. We tested effects of local environmental conditions, landscape structure and vegetation cover on species richness using generalized linear mixed models. Different environmental variables explained species richness of vascular plants, bryophytes and lichens. Environmental effects, particularly soil pH, were more important than landscape structure. Interaction effects of soil pH with other environmental variables were significant in vascular plants. Plot heterogeneity enhanced species richness. Size and degree of isolation of dry grassland patches significantly affected bryophyte and lichen species richness, but not that of vascular plants. We observed negative relationships between bryophyte and lichen species richness and the cover of vascular plants. To conclude, effects of single environmental variables on species richness depend both on the taxonomic group and on the combination of environmental factors on a whole. Dispersal limitation in bryophytes and lichens confined to dry grasslands may be more common than is often assumed. Our study further suggests that competition between vascular plants and cryptogams is rather asymmetric.     

Bryophytes and lichens in 16th-century herbaria

The diversity of bryophyte and lichen collections in 9 of the oldest preserved herbaria (dating from ca 1542 to 1577) was compared, including the first reports of bryophytes and lichens from the ‘En Tibi’ herbarium (possibly 1542–1544) and the herbarium of Leonhard Rauwolf (1560–1563). Bryophytes and lichens formed only a minority in each herbarium compared to the numbers of vascular plant specimens; numbers ranged from representatives of 21 genera in the herbarium of Ulisse Aldrovandi to the single genus Conocephalum in the Rauwolf herbarium. The focus was on large, handsome species of bryophytes and macrolichens, apart from small amounts of additional species collected as ‘by-catch’ in mixed collections. All herbaria together included 34 genera of bryophytes (36 species and 10 specimens identified to genus level) and 13 genera of lichens (24 species and 4 specimens identified to genus level). The diversity of mosses was higher than that of liverworts, and pleurocarpous mosses were more diverse than acrocarpous mosses. The collectors probably aimed at selecting material that was either characteristic of the vegetation in the respective areas of collecting or used for certain purposes (or both). The former hypothesis is supported by the small overlap in taxonomic diversity between the herbaria, and the latter by the fact that several moss, liverwort, and lichen genera are included whose traditional uses are well documented.     

Efficacy of a biocide tested on selected lichens and its effects on their substrata

The efficacy of Koretrel^©, a biocide used in south-eastern Asia to remove epilithic photoautotrophic organisms, was tested in the field and laboratory using lichens as target organisms. In situ observations were carried out at increasing time intervals for 6 month on 15 vegetation plots and 21 saxicolous species representative of the lichen flora of Italian monuments, selected according to their different ecology, growth-form and distribution. Change in chlorophyll fluorescence was monitored in three species for 32 day after biocide treatment. The effects of the biocide on the substratum was studied by monitoring changes in capillary water absorption and surface colorimetry of two CaCO₃-containing rocks (Aurisina limestone and Muggia sandstone), and a grey granite. Rock crystal integrity was monitored by SEM. The results show that Koretrel^© is very efficient in killing the lichens. Pronounced effects were observed in all species after 1–2 weeks, with chlorophyll fluorescence reduced to zero in 4 day in the case of Lecanora muralis and Neofuscelia loxodes and in 8 days for Caloplaca saxicola. The biocide considerably decreases capillary water absorption, and alters the surface colour of the substrata, particularly for Aurisina limestone. However, no corrosion features were observed in the rock minerals.     

KEYS TO STERILE,CRUSTOSE SAXICOLOUS AND TERRICOLOUS LICHENS OCCURRING IN THE BRITISH ISLES

A set of artificial keys is presented to all those crustose lichens (except most species ofLeprariaandLeproloma) which commonly occur without fruiting bodies on rock or soil in the British Isles. A number of predominantly corticolous species that occasionally also occur on rocks are included, as well as several undescribed but well-understood entities.     

Morphology influences water storage in hair lichens from boreal forest canopies

Hair lichens (Alectoria, Bryoria, Usnea) with high surface-area-to-mass ratios rapidly trap moisture. By photography and scanning we examined how internal water storage depended on morphological traits in five species. Specific thallus mass (STM, mg DM cm⁻²) and water holding capacity (WHC, mg H₂O cm⁻²) after shaking and blotting a fully hydrated thallus increased with thallus area. STM was ≈50% higher in Alectoria and Usnea thalli than in Bryoria. WHC was highest in Alectoria while percent water content of freshly blotted thalli was lowest in Usnea. Thallus area overlap ratio (TAO), assessing branch density of the thallus, was highest in the two thinnest Bryoria; lower in the thicker Usnea. Within species, hair lichens increased their water storage by increasing branch density rather than branch diameter. The taxonomically related genera Alectoria and Bryoria shared water storage characteristics, and differed from Usnea. Hair lichens in lower canopies have among the lowest water storage capacity reported in lichens.     

Distribution and floristics of moss- and lichen-dominated soil crusts in a patterned Callitris glaucophylla woodland in eastern Australia

The distribution and abundance of soil crust lichens and bryophytes was examined in a patterned Callitris glaucophylla woodland in eastern Australia. Twenty-one lichen species and 26 bryophyte species were collected within thirty quadrats along a sequence of runoff, interception and runoff zones. Crust cover was significantly greatest in the interception zones (79.0 %), followed by the runoff zones (24.0 %), and lowest in the groved, runon zones (6.6 %). Lichens and bryophytes were distributed across all geomorphic zones, and, although there were significantly more moss species in the interception zones (mean = 9.1) compared with either the runoff (4.2) or runon (3.2) zones, the number of lichen species did not vary between zones. Ordination of a reduced data set of 32 species revealed a separation of taxa into distinct groups corresponding to the three geomorphic zones. Canonical correspondence analysis (CCA) of the 32 species and thirteen environmental variables revealed that the most important factors associated with the distribution of species were sheet and scarp erosion, soil stability and coherence, litter cover and crust cover. Surface cracking, microtopography and plant cover were of intermediate importance. The CCA biplot revealed that the timbered runon zones (groves) were dominated by `shade-tolerant' mosses Fissidens vittatus and Barbula hornschuchiana, whilst the heavily eroded runoff zones supported sparse populations of `erosion tolerant' lichens (Endocarpon rogersii) and mosses (Bryum argenteum and Didymodon torquatus). Interception zones supported a rich suite of `crust forming' mosses and lichens capable of tolerating moderate inundation by overland flow. Two other groups of taxa were identified by this analysis: the `pioneer' group, comprising mainly nitrogen-fixing lichens which occupy the zone of active erosion at the lower edge of the groves, and the `opportunists' dominated by liverworts, occupying the shallow depressions or bays at the margins of the groves and the interception zones. This study confirms that the non-vascular lichens and bryophytes in these arid soil crusts, are, like the vascular plants, strongly patterned according to geomorphic zone, being most strongly associated with soil surface and erosional features.     

Cyanobacteria and Cyanobacterial Lichens from Inselbergs of the Ivory Coast,Africa

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.     

Hidden crown jewels: the role of tree crowns for bryophyte and lichen species richness in sycamore maple wooded pastures

Tree crowns typically cover the vast majority of the surface area of trees, but they are rarely considered in diversity surveys of epiphytic bryophytes and lichens, especially in temperate Europe. Usually only stems are sampled. We assessed the number of bryophyte and lichen species on stems and in crowns of 80 solitary sycamore maple trees (Acer pseudoplatanus) at six sites in wooded pastures in the northern Alps. The total number of species detected per tree ranged from 13 to 60 for bryophytes, from 25 to 67 for lichens, and from 42 to 104 for bryophytes and lichens considered together. At the tree level, 29 % of bryophyte and 61 % of lichen species were recorded only in the crown. Considering all sampled trees together, only 4 % of bryophyte, compared to 34 % of lichen species, were never recorded on the stem. Five out of 10 red-listed bryophyte species and 29 out of 39 red-listed lichen species were more frequent in crowns. The species richness detected per tree was unexpectedly high, whereas the proportion of exclusive crown species was similar to studies from forest trees. For bryophytes, in contrast to lichens, sampling several stems can give a good estimation of the species present at a site. However, frequency estimates may be highly biased for lichens and bryophytes if crowns are not considered. Our study demonstrates that tree crowns need to be considered in research on these taxa, especially in biodiversity surveys and in conservation tasks involving lichens and to a lesser degree also bryophytes.     

Isotopic analysis of cyanobacterial nitrogen fixation associated with subarctic lichen and bryophyte species

Dinitrogen fixation by cyanobacteria is of particular importance for the nutrient economy of cold biomes, constituting the main pathway for new N supplies to tundra ecosystems. It is prevalent in cyanobacterial colonies on bryophytes and in obligate associations within cyanolichens. Recent studies, applying interspecific variation in plant functional traits to upscale species effects on ecosystems, have all but neglected cryptogams and their association with cyanobacteria. Here we looked for species-specific patterns that determine cryptogam-mediated rates of N₂ fixation in the Subarctic. We hypothesised a contrast in N₂ fixation rates (1) between the structurally and physiologically different lichens and bryophytes, and (2) within bryophytes based on their respective plant functional types. Throughout the survey we supplied ¹⁵N-labelled N₂ gas to quantify fixation rates for monospecific moss, liverwort and lichen turfs. We sampled fifteen species in a design that captures spatial and temporal variations during the growing season in Abisko region, Sweden. We measured N₂ fixation potential of each turf in a common environment and in its field sampling site, in order to embrace both comparativeness and realism. Cyanolichens and bryophytes differed significantly in their cyanobacterial N₂ fixation capacity, which was not driven by microhabitat characteristics, but rather by morphology and physiology. Cyanolichens were much more prominent fixers than bryophytes per unit dry weight, but not per unit area due to their low specific thallus weight. Mosses did not exhibit consistent differences in N₂ fixation rates across species and functional types. Liverworts did not fix detectable amounts of N₂. Despite the very high rates of N₂ fixation associated with cyanolichens, large cover of mosses per unit area at the landscape scale compensates for their lower fixation rates, thereby probably making them the primary regional atmospheric nitrogen sink.     

Observations on the Varanasi wall flora

Summary This study deals with the ecology of a man-made habitat, i.e., old walls and buildings of Varanasi, India. The wall flora of Varanasi includes 135 species of angiosperms, 1 species of pteridophyte, 4 species of bryophytes and one lichen. Abundant wall plants likeArthraxon lancifolius, Lindenbergia polyantha, Aristida funiculata and lichens are never seen off the walls. The vegetation of the three types of walls, viz., brick mortar, brick mud and mud walls, classified according to the materials of construction, show sharp differences, despite many common features. Analysis of the wall flora, according to Raunkiaer's life-form system, revealed a marked contrast from the adjoining ground flora in having a very high percentage of therophytes.It is concluded, that the distinctiveness of the wall flora is due to the unique topography, microclimate and xeric nature of the wall habitat. Differences in the physico-chemical nature of the three types of walls are responsible for the variation in their vegetation.     

Lichens toGunnera — with emphasis onAzolla

Summary N₂-fixing cyanobacteria occur in symbiotic associations with fungi (ascomycetes) as lichens and with a few green plants. The associated cyanobacterium is always a species ofNostoc orAnabaena. Only a small number of plant genera are involved but there is a remarkable range of host diversity. Associations occur with several bryophytes (e.g.Anthoceros, Blasia, Cavicularia), a pteridophyte (Azolla), cycads (nine genera includingMacrozamia andEncephalartos) and an angiosperm (Gunnera). Except forGunnera, where the cyanobacterium penetrates the plant cells, the cyanobacteria are extracellular with specialized morphological modifications and/or structures of the host plant organs providing an environment which facilitates interaction with the prokaryote.Salient aspects of current knowledge pertaining to the establishment, perpetuation, and functioning of the individual symbioses are summarized. Where possible this includes information concerning recognition and specificity, mode(s) of infection, morphological modifications/adaptations of the host plant and a synopsis of morphological, physiological and biochemical changes common to the symbiotic cyanobacteria. The latter encompasses heterocyst frequencies, enzymes involved in ammonia assimilation, photosynthetic capability and metabolic interaction with the host.TheAzolla-Anabaena symbioses, which have potential agronomic significance as an alternative nitrogen source and maintain continuity with the endophyte through the sexual cycle, are emphasized.