According to International Union for the Conservation of Nature (IUCN) guidelines, all species must be assessed against all criteria during the Red Listing process. For organismal groups that are diverse and understudied, assessors face considerable challenges in assembling evidence due to difficulty in applying definitions of key terms used in the guidelines. Challenges also arise because of uncertainty in population sizes (Criteria A, C, D) and distributions (Criteria A2/3/4c, B). Lichens, which are often small, difficult to identify, or overlooked during biodiversity inventories, are one such group for which specific difficulties arise in applying Red List criteria. Here, we offer approaches and examples that address challenges in completing Red List assessments for lichens in a rapidly changing arena of data availability and analysis strategies. While assessors still contend with far from perfect information about individual species, we propose practical solutions for completing robust assessments given the currently available knowledge of individual lichen life-histories.

The aim of this work was to investigate whether neoformed Ni-phyllosilicates can be observed and identified using transmission electron microscopy (TEM) in combination with energy dispersive spectroscopy (EDS). The investigations focused on Ni-phyllosilicates formed from Ni-doped montmorillonite. The reaction conditions (pH 8, [Ni]initial = 660 and 3300 µM, 0.2 M Ca(NO3)2) employed were similar to those used in previous polarized extended X-ray absorption fine structure (P-EXAFS) investigations of neoformed Ni-phyllosilicates in a Ni-montmorillonite system.

The TEM investigations of Ni-doped montmorillonite revealed the presence of small, thin particles consisting of coherent stacks that yielded only three to five lattice fringes with spacings consistent with smectites. These small particles were neoformed phyllosilicates, based on the fact that the small particles were only observed in Ni-doped samples and their Ni content, as determined from EDS analysis, was high (up to 10 wt.% NiO). Furthermore, the particles did not possess the characteristic properties of montmorillonite particles, such as a 2:1 Si to Al ratio; instead these particles were rich in Si (up to 75 wt.% SiO2). Unlike montmorillonite, these particles did not contain any Fe. The particles were also significantly more resistant to electron beam damage than montmorillonite particles, and EXAFS measurements confirmed the presence of neoformed Ni-phyllosilicates.

The TEM study further indicates the presence of a variety of additional minerals (e.g. cristobalite, halloysite) and an X-ray amorphous Si-rich phase. A Ni signal could only be detected in the latter phase at high Ni loadings (403 µmol/g), suggesting that Ni uptake at low metal loadings (<90 µmol/g) is mainly controlled by the neoformation of phyllosilicates.

In this study, we sampled L. pulmonaria thalli from Mt Kilimanjaro and Mt Meru, Tanzania. Across all sampled tree species, a range of 1–35 thalli of L. pulmonaria were counted per trunk (up to 5 m above ground level), with sampling distributed across 13 (c. 1 ha) plots located in the sub-alpine to montane forest altitudinal gradients of Mt Kilimanjaro and Mt Meru. Descriptive analyses were performed to determine the association of L. pulmonaria with particular host trees among the study sites and regions, and linear mixed effects models (LMM) were used to explore relationships with tree-level variables. The analyses showed that most thalli of L. pulmonaria were unevenly distributed among the tree species in the montane and sub-alpine forests of Mt Kilimanjaro and Mt Meru. Host tree characteristics such as trunk circumference, height on trunk, bark texture and trunk shape appeared to have an effect on the local population size of L. pulmonaria and the frequency of occurrence. Also, the results indicated an effect of trunk circumference and tree bark on the development of L. pulmonaria thallus size among the study sites. Furthermore, host tree species, for example, Hypericum revolutum and Rapenea melanophloeos were important habitats for L. pulmonaria on both mountains, whereas Ilex mitis, Bersama abyssinica and Hagenia abyssinica were important only on one mountain. The wider literature on L. pulmonaria ecology is also reviewed and it is therefore recommended that for successful conservation of the threatened L. pulmonaria in tropical montane forests, strategies should consider the type of the forests, together with the host tree species and their size.

Gene expression variation can be partitioned into different components (regulatory, genetic and acclimatory effects) but for lichen-forming fungi, the relative importance of each of these effects is unclear. Here, we studied gene expression in the lichen-forming fungus Lobaria pulmonaria in response to thermal stress and parasitism by the lichenicolous fungus Plectocarpon lichenum. Our experimental procedure was to acclimate lichen thalli to 4 °C over three weeks and then expose them to 15 °C and 25 °C for 2 hours each, sampling infected and visually asymptomatic thalli at each temperature. Quantitative Real-Time PCR was utilized to quantify gene expression of six candidate genes, normalizing expression values with two reference genes. We found that two genes encoding heat shock proteins (hsp88 and hsp98), two polyketide synthase genes (rPKS1, nrPKS3) and elongation factor 1-1-α (efa) were upregulated at higher temperatures. Moreover, we observed higher expression of hsp98 at 25 °C in samples infected by P. lichenum than in uninfected samples. Finally, in partial redundancy analyses, most of the explained variation in gene expression was related to temperature treatment; genetic variation and long-term acclimatization to sites contributed far less. Hence, regulatory effects (i.e. direct adjustments of gene expression in response to the temperature change) dominated over genetic and acclimatory effects in the gene expression variability of L. pulmonaria. This study suggests that L. pulmonaria could become a valuable lichen model for studying heat shock protein responses in vivo.

The first detailed survey is presented of a recently discovered population of Erioderma pedicellatum, a globally rare lichen, in the primeval spruce forests of the Kamchatka Peninsula, Russia. Three subpopulations are described, located in the Levaya Schapina River basin, in the Kimitina River basin, and on the slopes of the extinct volcano, Nikolka. In total, we observed 1894 thalli on 167 Yezo spruce trunks. In Kamchatka, E. pedicellatum occurs exclusively on bark-covered spruce twigs of mainly young and dwarf-stressed older trees. We discovered a high number of juvenile thalli, which suggests that this population is reproducing. However, its habitat is declining because spruce forests in the region are the target of industrial clear-cutting and there is a high incidence of forest fires. Over the next 60 years, which corresponds to three generations of E. pedicellatum, we infer that continued habitat loss will induce a 48% decline in these lichen populations. As a result of our analyses, the Asian population is classified as ‘Vulnerable’, based on IUCN Red List criteria.

The Hindu Kush Himalayan (HKH) region harbours some of the richest and most diverse ecosystems on the planet that are now facing substantial threats through changes in climate, land use and human population growth, with serious consequences for the biodiversity in this mountainous region. In this paper we evaluated the effects of climate change on the distribution of the tripartite epiphytic macrolichen Lobaria pindarensis, considered to be endemic to the Himalayas. To predict the current and future distribution of this species we applied the Random Forest modelling algorithm and climatic variables with a post-processing of projected distributions using a map of habitat types in the study region. We calibrated models based on 1397 species presences within an altitudinal range of 2036–4000 m and extrapolated them according to two IPCC scenarios of climate change (RCP 2·6 and RCP 8·5). Based on the results of ensemble modelling, two new localities where L. pindarensis might potentially occur were predicted. Our simulations predicted a range expansion of this epiphytic lichen to the north-east and to higher altitudes in response to climate change, although the species’ low dispersal abilities and the local availability of trees as a substratum will considerably limit latitudinal and altitudinal shifts. By contrast, assuming the species can migrate to previously unoccupied areas, and depending on different future climate scenarios, our models forecasted a habitat loss of 30–70% for L. pindarensis. The main reason for the simulated habitat loss is the expected increase in mean annual temperature (by 1·5–3·7 °C) and total annual precipitation (by 56–125 mm). Our results contribute further evidence for the high sensitivity of tripartite macrolichens, especially those from mountain areas, to climate change and particularly emphasize the vulnerability of L. pindarensis. Thus, we stress the need to develop and formulate conservation measures and strategies for the protection of this endemic species in the Hindu Kush Himalayan region.

Using an ITS mutation rate as calibration reference, a three-locus timetree was generated for the genus Lobaria and its most important clades. The timetree resolved most clades with strong support and gave an estimate of the diversification time for Lobaria during the early Oligocene. A fossil impression from a 12–24 million-year-old Miocene deposit is hypothesized here to belong to an ancestral Lobaria species. Additionally, the age estimate indicates that the paleoclimate and the closing or opening of the Bering Strait played a major role in shaping the current distribution of most Lobaria species. It is hypothesized that the Bering land bridge acted as a major highway during warm-temperate climate periods, but as a barrier during Arctic climate times.

Bactrospora dryina is an epiphytic lichen-forming fungus specifically related to old-growth floodplain forests, which have dramatically declined in Europe over the past centuries. In order to promote conservation management of such forest remnants, we aimed to study population genetics of this rare and threatened lichen. The newly developed 16 microsatellite markers are specific for the mycobiont of B. dryina and reliably amplify either single fruiting bodies or a sterile thallus. This allows the use of these markers for the identification of sterile crusts and for quantification of recent dispersal of the species into restored habitats. We tested the markers in 264 samples collected from 10 pedunculate oak trees growing in three localities in north-eastern Switzerland. All markers were polymorphic and showed two to five alleles per locus, and unbiased gene diversity varied from 0·06 to 0·71 over three populations. The relatively low number of alleles in B. dryina is possibly the consequence of colonization of secondary habitats created by forest management. Although oaks were largely covered with a single, continuous B. dryina colony, the microsatellite markers identified single or complex multi-genotype colonizations per tree. For future population genetic studies, we recommend collection of 5–15 specimens from one tree which would enable detection of 60–80% of the multilocus genotypes present. Hierarchical AMOVA revealed high variation (70%) on host trees, and a relatively high differentiation (12%) among the three locations in NE Switzerland indicated limited gene flow between those regions. Thus, the newly developed markers showed their applicability in population genetics at different spatial scales. They will play an important role in monitoring habitat restoration for the conservation of B. dryina and associated forests and riverscapes.

The present study investigates the photobiont diversity of the boreal felt lichen, Erioderma pedicellatum. Previously sampled genetic data from Newfoundland were reanalyzed and new sequence data (16S rDNA, rbcLX) of the boreal felt lichen from Alaska (USA), Kamchatka (Russia), and North Trøndelag (Norway) were generated. The highest genetic diversity of the photobiont is found in Alaska and Kamchatka, indicating that these may be the primary sources of the species in the Northern Hemisphere. In Newfoundland, the photobiont of E. pedicellatum was screened on leaves of the symbiotic liverwort Frullania asagrayana and it was found to occur on trees where no other lichens were present, demonstrating that the geographical distribution, and possibly also the ecological requirement of the photobiont of E. pedicellatum, is wider than that of the lichen phenotype. Finally, a postulated association between the occurrence of the vegetatively reproducing Coccocarpia palmicola and the occurrence of the compatible photobiont of E. pedicellatum on the same tree could not be established.

Eurasian Cetraria steppae and the more widely distributed C. aculeata are two lichen species traditionally distinguished by Eastern European and Spanish lichenologists on the basis of their morphological and ecological characteristics. Other specialists, however, consider them puzzling. This paper aims to evaluate the taxonomic status of these members of the C. aculeata group and thereby to clarify their conservation status in Ukraine. Morphological, chemical and ecological features of specimens originating from populations in different regions of Ukraine were tested and compared with the main characteristics commonly used for the species delimitation. Neither morphological nor chemical traits were found to correlate with ecological characteristics on a small geographical scale. Variation in the norstictic acid content detected in 256 individuals from 13 populations in Ukraine showed no correlation with the morphological characteristics that are currently used for species delimitation. These morphological features appear to vary continuously and did not support subdivision among the specimens studied. We hypothesize that C. steppae and C. aculeata are conspecific, and provide a formal synonymy. Specimens with norstictic acid are regarded as a different chemotype. Possible evolutionary and adaptive roles of norstictic acid in C. aculeata s. lat. are discussed. Based on current and historical data, we consider C. aculeata s. lat. as vulnerable in Ukraine, according to the IUCN criteria for regional Red List assessment.

Cephalodia were investigated on young and mature thalli of Lobaria pulmonaria. Cephalodia originate from contact between hyphae and cyanobacteria on the upper or lower cortex or, less frequently, in the apical zone. Young thalli were found to associate with cyanobacteria even in the anchoring zone. Cephalodia formed on the young thalli or the anchoring hyphae share the same phenotypic characteristics. In spite of being composed of paraplectenchymatous hyphae, the cortex of mature thalli preserves a considerable plasticity, enabling the formation of cephalodia. The cyanobacterial incorporation process begins with cortical hyphae growing out towards adjacent cyanobacterial colonies, enveloping them and incorporating them into the thallus. The incorporation process is the same on the upper and the lower cortex. Early stages of cephalodia are usually found in young lobes, whereas in the older parts of the thallus only mature cephalodia are found.

Phylogenetic relationships among the hypothetical species pairs Lobaria kurokawae / L. retigera and L. pseudopulmonaria / L. isidiosa were investigated based on TLC techniques and the phylogenetic analysis of the internal transcribed spacers (ITS) nrDNA. Results of TLC demonstrate that L. retigera and L. kurokawae can be chemically distinguished from L. isidiosa and L. pseudopulmonaria by the absence of retigeranic acid. Parsimony analysis of 18 specimens shows two monophyletic clades – a L.retigera lineage and a L. isidiosa lineage—both including their apotheciate counterparts. Unlike the original hypothesis of species pairs, our study reveals transitions from isidiate morphs that have the potential to rarely form apothecia, towards apotheciate morphs that produce no vegetative propagules.

In contrast to the frequently assessed macrolichens, microlichens are rarely considered in biodiversity assessments despite their high species richness. Microlichens require generally a higher species identification effort than macrolichens. Thus, microlichens are more expensive to assess. Here we evaluate if macrolichen richness can be used as an indicator of total and threatened microlichen richness. Furthermore, we tested if different sets of environmental variables (modelled climatic variables, forest structure, altitude, etc.) improve the regression models based on macrolichens only or even replace the macrolichens as predictors. Multiple linear regressions were used to model species richness of microlichens, and Poisson regressions for threatened microlichens.

On 237 forest plots (200 m2) distributed randomly across Switzerland, 77 macrolichens and 219 microlichens occurred. Macrolichen richness was positively related to the richness of microlichens (=0·27) and, in combination with threatened macrolichens as an additional predictor, also to the number of threatened microlichens (=0·14). Environmental variables alone and in different combinations explained between 0·20 and 0·41 () of the total variation of microlichen richness, and between 0·09 and 0·29 () of the total variation of threatened microlichen richness. All models based on environmental variables were considerably improved when macrolichens were included. Furthermore, macrolichen richness turned out to be the most important variable in explaining species richness of all, as well as threatened microlichens. The best models for total microlichen richness reached a of 0·56. Threatened microlichens were more difficult to model with the best model reaching a of 0·29.

We conclude that in biodiversity assessments with scarce resources, lichen sampling could be focused on the better known macrolichens, at least in many temperate lowland and mountain forests. In combination with environmental variables, reliable predictions of microlichen richness can be expected. If the focus is on threatened microlichens, however, models were not reliable and specialized taxonomists are necessary to assess these species in the field.

The potential spatial distributions of six epiphytic lichen species were assessed in Switzerland (41 000 km2) as a function of various key climatic drivers and forest types using logistic regression models. Cetrelia cetrarioides is ‘near threatened’, Lobaria pulmonaria is ‘vulnerable’, and Graphis scripta, Hypogymnia physodes, Lecanora cadubriae, Letharia vulpina are not endangered according to the Red List assessment based on IUCN criteria. Lichen presence and absence were derived from the SwissLichens database that contains spatially explicit information on both species presence and absence.

The spatial lichen niches are predicted with R2 values between 0·5 and 0·75 and AUC values between 0·63 and 0·94. Model evaluation shows that the models perform well.

Lichenologists reviewed the spatial predictions of lichen species on the basis of their expert knowledge and concluded that parsimonious regression models may suffice for successful prediction of the potential spatial niche distributions of epiphytic lichen species.

Changing land use has a major impact on lichen diversity. This study attempts to identify patterns or trends of lichen functional groups along a land use gradient, ranging from natural forests to open agricultural landscape. In eight countries, covering six main European biogeographic regions, lichen vegetation was assessed according to a standardized scheme. Data on reproductive, vegetative and ecological traits was compiled and relative species richness for all classes of all traits calculated. Relationships between the land use gradient and relative species richness of trait classes were analysed. Open and intensively managed landscapes harbour more fertile species while sterile species are relatively more important in forests. This finding is also supported by analyses of different classes of dispersal propagules. The importance of species with the principal photobiont Trebouxia s.l. increases linearly with intensification of land use. A converse pattern is revealed by species with Trentepohlia. Concerning substratum specialization only generalists show an effect along the land use intensity gradient. Their relative species richness decreases from landscapes dominated by forests to open agricultural landscape. A considerable decline in the rare lichen species richness as a result of land intensification is predicted.

The distribution of lichen species in upland regions of Aberdeenshire, Scotland, is investigated along a landuse gradient from natural forest to intensive agriculture. Quantitative data on lichen communities on saxicolous, epiphytic and terricolous substrata were collected from 16 hectares in one km2 in each landuse type. Multivariate analyses, NMDS and Cluster analysis were used to identify lichen communities associated with environmental factors including landuse, substratum type and age. The epiphytic community of native pinewoods was distinguished from all others by the highest species richness, the presence of indicators of ecological continuity and the absence of nitrophytes, while the epiphytic communities of farmland were distinguished by absence of acidophytes and a high contribution of nitrophytes. Plantations of conifers were distinguished by low species richness and an increase in tolerant species. Saxicolous communities were frequent on walls in all sites except native pinewood, where saxicolous substrata were rare. Intensively farmed sites were distinguished by an increase in percentage contribution of nitrophytes. The high acidophyte contribution in all sites suggests that crustose species of acid rocks may not respond rapidly to an increase in applied nitrogen. In landscapes where tree cover is sparse or non-existent combined assessment of habitat diversity and nitrophyte indicator species can be used to assess changes associated with agricultural intensification.

The early development of Hypogymnia physodes from soredia to the formation of stratified lobes has been studied experimentally in the vicinity of a copper-smelting plant in theMiddle Urals. SEM investigations combined with life table analyses of early developmental stages revealed decreases in soredial survival and developmental rate in polluted localities. Non-stricatified pre-thallus stages without an epicortex were tolerant to toxic impact and were able to survive even in the zone with the highest pollution (lichen desert zone). The sensitivity of developmental stagesancreased after stratified lobes had developed.

Four primers for the amplification of mitochondrial DNA of lichenforming ascomycetes are presented. The primers match the conserved regions U2, U4, and U6, respectively, of mitochondrial small subunit (SSU) ribosomal DNA (rDNA). Polymerase chain reaction using different combinations of the primers produced single amplification products from DNA of eight lichen-forming fungal species but did not amplify DNA of two axenic cultured algal species. The amplification product obtained from Lobaria pulmonaria was sequenced and the 894-bp sequence was compared with the mitochondrial SSU rDNA sequence of Podospora anserine. The two sequences revealed more than 76% identity in the conserved regions U3 to U5 demonstrating that we amplified mitochondrial DNA. The primers matching U2 and U6 yielded amplification products of 800–1000 bp depending on the species examined. The variation observed suggests that mitochondrial SSU rDNA may be useful for phylogenetic analyses of lichen-forming ascomycetes.

To identify representative quantitative criteria for the creation of a future Red List of epiphytic lichens, 849 trees in 132 long-term ecological observation plots in the Swiss Central Plateau and the Pre-Alps were surveyed by standard sampling. Based on the trees, frequency data of the lichen taxa observed are described by the log series model, indicating the controlling effect of few ecological factors. Based on the plots, four classes of scarcity, each comprising 25% of the species, were established. As a contribution to the development of a national, representative survey of lichens, α-diversity (species richness, species density) and β-diversity (dissimilarity) were calculated in terms of region, vegetation formation, vegetation belt and for their combinations. Differences in lichen diversity between the Central Plateau and the Pre-Alps were caused by the bigger elevational range in the Pre-Alps, which resulted in a higher species richness. α-Diversity of forest and non-forest were similar, whereas each vegetation formation showed one third of its species restricted to it. The contributions to the total lichen diversity of crustose, foliose and fruticose as well as of generative and vegetative species was calculated. Specific features along the altitudinal gradient of vegetation belts emerged: the percentage of crustose and generative lichens declined with every altitudinal step, increased in fruticose and vegetative lichens, and was the same in foliose species.