The utility of plastic cover slips as a substratum for in situ study of lichen developmental stages is further explored in a neotropical foliicolous lichen community and in a European temperate corticolous community. Twenty-one months after placement in the tropical forest, the cover slips bore foliicolous lichen thalli with several species producing characteristic ascocarps and ascospores, indicating the suitability of the substratum for completion of the life cycle of these lichens. On cover slips placed within the temperate corticolous community, lichen propagules anchored to the substratum with relatively short attachment hyphae but did not develop further within the one year observation period. Intimately intermixed microbial communities of short-celled, mainly pigmented fungi and chlorophyte algae developed upon the transparent substratum. Among the algae, Trebouxia cells, often in groups showing cell division and without associated lichenizing hyphae, were commonly observed. The potential significance of the free-living populations in the life cycle of Trebouxia and in those of Trebouxia-associated lichen fungi is discussed.

Dispersal patterns from seven terricolous lichen species, with a high capacity for asexual reproduction by fragmentation (Cetraria muricata, Cladonia species), were studied in differing vegetation types in north-eastern Germany. Marked lichen thalli were fragmented by trampling. After 15 days the spread of thallus fragments was monitored. Whereas most of the fragments that were dispersed by wind remained within a 20-cm radius from the source, the maximal dispersal distance was 57 cm in a dry sand grassland and 68 cm in an open pioneer pine forest. Dispersal was negligible in a closed old-growth pine forest. Several fragmented lichen cushions were disturbed and removed by animals, and led to a maximal dispersal distance of 9·70 m. These results suggest that: (a) thallus fragments provide good short-distance dispersal in open vegetation, but are inefficient for long-distance dispersal, and (b) wind and animals are important factors for the dispersal of thallus fragments. For restoration management of man-made substrata, artificial introduction of lichen thalli is proposed.

Axenic cultures of lichen mycobionts and photobionts were assayed for biological ice nucleation activity (INA), a characteristic which has recently been discovered in some species of lichens collected from nature. Of 14 species of mycobionts, five showed nuclei active at −5°C or warmer, while none of the 13 photobionts tested had INA at that temperature. It appears that biological ice nuclei in lichens are produced primarily by the mycobiont. Rhizoplaca chrysoleuca had the greatest INA. Other lichen fungi showing warm temperature INA were Cladonia boryi, Cladonia rangiferina, Lecanora dispersa, and Pertusaria flavicans. Lichen INA may be involved in moisture uptake and/or frost protection.

Chlorophyll a fluorescence was measured every three months from December 2003 to December 2004 in ten, randomly selected thalli of the epiphytic lichen Punctelia subrudecta (Nyl.) Krog occurring in a deciduous, thermophilous downy oak wood in southern Tuscany (central Italy). In situ measurements were carried out with a photosynthesis yield analyser Mini-PAM (Walz, Effeltrich, Germany) on the same measuring points of 30-minute dark-adapted, fully hydrated thalli. The results show a remarkable seasonal change in Fo, Fm, and Fv/Fm, probably caused by a long-term physiological-structural adaptation of the photobiont to the gradual modification of the climatic conditions of each measurement period and the light regime of the understorey. However, P. subrudecta is also sensitive to rapid changes in microclimatic conditions as the PSII functionality is affected by the light regime of the days preceding the field measurements. Some critical observations on the statistical analysis of chlorophyll a fluorescence parameters are also made.

A recent survey of epiphytic lichens in the Jardin du Luxembourg has shown there to be a marked improvement in the air quality of Paris over the past decade. Recolonization by at least 11 lichen species has occurred during that period. It has taken almost 100 years for epiphytic lichens to re-establish in the Jardin du Luxembourg, where William Nylander in the 1890s was able to amply confirm his far reaching hypothesis, made 30 years earlier, on the direct relationship between lichen survival and air pollution.

The development of isidia in thalli of Pseudevernia furfuracea from the Carnic Alps (North-eastern Italy), and the effects of these structures on CO2 gas exchanges were investigated. The ontogenetic events were studied by comparison of sections stained with different histochemical tests and SEM observations. A high cell turnover rate in both symbiotic partners is the first sign of isidium development, followed by an increased aplanosporogenesis of algae and growth of neighbouring medullary hyphae which become oriented upwards. Large nuclei and an intense cytoplasm activity characterize the mycobiont cells. The surface of very young isidia shows an irregular structure of spherical to ovoid protruding tips of perpendicular cortical hyphae, that are later organised in a pseudomeristematic area similar to that observed in the apex of growing lobes. CO2 gas exchange measurements carried out in the laboratory confirmed the high metabolic activity of isidia. At optimal water content and favourable light conditions, isolated isidia had rates of gross photosynthesis and dark respiration that were twice those of non-isidiate lobes. Isolated isidia also had a very low CO2 saturation point, probably because of their favourable surface/volume ratio, and a high light saturation, probably linked to their high content of photosynthetic pigments. The different roles played by isidia in the biology of Pseudevernia furfuracea, and particularly their rejuvenating effect on aged lobes, are discussed, and the presence of thalloconidia is briefly mentioned.

Wooded meadows with a history of traditional land use over thousands of years support a great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows are threatened because of the cessation of traditional management in large areas. We studied lichen communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment of traditional management on epiphytic lichen species composition, considering factors on three spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree diameter, described as much of the compositional variation as geographic location (region) or environmental conditions in wooded meadows. Of the environmental factors studied, woodland canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the community type of semi-open wooded meadows to species-poor communities characteristic of secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently observed lichen species revealed that more than half of them (21) are influenced by site openness (canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open wooded meadows. The results emphasize that the preservation of large old deciduous trees of various species and the maintenance of the semi-open structure of stands are vitally important for the protection of epiphytic lichen communities in wooded meadows.

Available evidence indicates that basal regions of well-developed lichen mats are composed largely of dead or senescent thallus material. Marked vertical gradients in concentrations of N, P and K in thalli of mat lichens, together with results of N budget studies in Cladonia stellaris and Stereocaulon paschale, suggest that these key elements may be recycled internally to fund new growth at the apices. It is argued that nutrient recycling will increase rates of both apical growth and basal necromass production and that under steady-state conditions this will result in deeper mats and facilitate dominance sensu Grime; thus accumulation of necromass may be an ecological advantage in mat-forming lichens. Basal necromass of the N2-fixing S. paschale contains more N than necromass of the non-N2-fixing C. stellaris; this may be due in part to a greater allocation of N to irrecoverable fungal cell wall components in S. paschale and may underlie a greater requirement for N in this mycobiont.

The cetrarioid core group has been the focus of numerous taxonomic and phylogenetic studies in recent years, yet the phylogenetic resolution and support among these clades remains unclear. Here we use four commonly employed loci to estimate if their use increases phylogenetic resolution and support. The present study largely confirms the topologies of previous studies, but with increased support. Approximately half of the genera in the cetrarioid core were not monophyletic. Melanelia sorediella was clustered within Cetrariella, and the combination Cetrariella sorediella (Lettau) V. J. Rico & A. Thell comb. nov. is made. Additionally, the genus Flavocetrariella was supported as part of Nephromopsis and is considered to be a synonym of the latter. Finally, a comparison of genetic distances shows that the maximum intrageneric genetic distance encompassed by many cetrarioid genera is lower than that of many other genera in Parmeliaceae.

After a discussion of changing generic concepts in the parmelioid lichens, a checklist with the current species placements is presented. Twenty-five genera and 143 species are accepted for Europe, of which 17 genera and 112 species belong to the monophyletic parmelioid clade. The individual countries from which species are reported are provided, along with references to key publications. Synonyms used at species rank in Europe are cross-referenced, and the dates of publication of all names are provided. One new combination is made: Xanthoparmelia pulvinaris (syn. Parmelia pulvinaris, X. pseudohungarica).

Maximum parsimony analysis of nuclear SSU rDNA sequences was utilized to infer the phylogenetic relationships of representatives of the macrolichen families Cladoniaceae, Sphaerophoraceae, and Stereocaulaceae (Lecanorales subord. Cladoniineae, Ascomycotina). Farris’ parsimony jackknifing, and a similar jackknife strategy with branch-swapping and multiple addition sequences in PAUP*, were performed to assess branch support. The results indicate that the Sphaerophoraceae should be emended to include Neophyllis (formerly Cladoniaceae or Stereocaulaceae) and Austropeltum (formerly Stereocaulaceae), and it is suggested that the type of boundary tissue present is a synapomorphy for the family. The families Sphaerophoraceae and Bacidiaceae form a clade, together with Psora decipiens, Tephromela atra and Scoliciosporum umbrinum. The Cladoniaceae should be emended to include Pilophorus, and the genera Metus, Cladia and Heterodea should also be included in the family. The sometimes-recognized families Cladiaceae and Heterodeaceae are shown to be derived from within Cladoniaceae. The Stereocaulaceae is recircumscribed to accommodate Stereocaulon only. Neither the possession of podetia/ pseudopodetia, a dimorphic, cladoniiform thallus, nor the presence of cephalodia, is a morphological synapomorphy for a monophyletic group in our analysis. Optimising ascus structures onto one of the most parsimonious trees suggest that tube-like apical structures may well be primitive characteristics within the Lecanorales. The two lecanoralean suborders Lecanorineae and Cladonineae are both paraphyletic groups in the present analysis. It is pointed out that if further studies confirm that Stereocaulon is the sister-group to the Cladoniaceae, as circumscribed here, then there may be no reason to accept the two families Cladoniaceae and Stereocaulaceae as distinct. Branch-swapping and several random-addition sequencesimprove resolution, adding several supported groups in the topology, and improve support values for groups already supported by parsimony jackkniring analyses, and we suggest a procedure for implementing this by using PAUP*

Diurnal courses of photosystem II (PS II) activity of Xanthoria elegans were continuously monitored using a novel technique of chlorophyll fluorescence imaging in the field (maritime Antarctica) over a period of 7 days. The lichen specimens grew on rock surfaces in a north-facing coastal area of Galindez Island (Argentine Islands). A portable fluorometer FluorCam equipped with a CCD camera and image analysis software was placed over a thallus so that false colour images of FV/FM and quantum yield of photochemical processes in PS II (ΦII) distribution over the thallus could be taken over the course of a day. Simultaneously, microclimatic parameters of the habitat were recorded: air and thallus temperatures, relative air humidity, PPFR (photosynthetic photon fluence rate) and global radiation. Photosynthetic processes in X. elegans were activated by rainfall or water from melting snow. After thallus hydration, FV/FM and ΦII gradually decreased from their maximum values due to evaporation and progressive loss of water from the thallus. Chlorophyll fluorescence imaging showed that the thallus dehydration started from the margins and moved towards the central thicker thallus zones. These zones exhibited higher activity of PS II than the margins throughout the day. The rate of inhibition of photosynthetic processes in PS II was faster at the margins than in the centre of the thallus. Dependence of ΦII on thallus water potential (WP) was investigated during gradual dehydration under laboratory conditions. After a decrease in WP from zero to −7 MPa, X. elegans exhibited only a 13·8% decrease in ΦII from its maximal value. Within the range of WP of from −8 to −20 MPa, the ΦII decrease was more rapid reaching the critical point (ΦII=0) at WP of approximately −25 MPa. Chlorophyll fluorescence imaging and WP measurements showed that X. elegans is capable of maintaining detectable photosynthetic activity even at extremely low WP. Based on our microclimatological data, X. elegans may be photosynthetically active under field conditions for several hours after being wetted by rain or snowfall. It is suggested that chlorophyll fluorescence imaging is a powerful technique, transferable to field conditions and capable of visualizing heterogeneity of photosyntetic processes over a lichen thallus subjected to periodic dehydration.

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.

Ecological studies are essential in understanding the response of crustose lichens to habitat dynamics and developing effective conservation strategy. While the combined response of individual crustose species within a community will be tremendously complex, the overall result of individualistic change can be simplified using trait-based analyses. In this paper we examine the response of crustose species with contrasting reproductive traits (predominantly sexual vs asexual reproduction) and which occur within a closely defined habitat (as epiphytes on the lower bole of aspen) to environmental drivers measured at two different scales, i.e. between and within aspen stands. Our results point to the important effect of tree age and subsequent shifts in bark quality (pH) on the composition of the crustose community. However, shifts in community composition putatively controlled by bark quality comprise a change from a community dominated by sexual species to a community with mostly asexual crusts. Our results suggest therefore that variation within this crustose community may be driven by the combined effects of allogenic change (tree age and bark quality) and autogenic processes that are related to a species’ adaptive life-history traits.

A first hypothesis for the phylogeny of Lecanora subgen. Placodium is presented by using molecular data. Previous evolutionary ideas and classification concepts for this group with non-molecular data are re-investigated using DNA sequence data from the nuclear ITS and 5.8S regions. Using Protoparmelia as an outgroup, the Lecanora subfusca group together with the L. rupicola group appear as a sister group to assemblages with lobate species. Subgen. Placodium as currently accepted, is not monophyletic. Molecular data suggest that the Lecanora dispersa group and the L. polytropa group are widened by lobate species and there is evidence from the ITS data that the monotypic genus Arctopeltis Poelt is closely related to the L. dispersa group. A congruence between molecular data and secondary chemistry supports the broader concept of the L. dispersa group suggested by the molecular data.

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.