Bryophyte and lichen diversity: A comparative study

Abstract We describe the regional species richness, variation in species richness and species turnover of bryophytes and lichens from 36 sites in lowland forests of southeastern Australia. The analyses subdivided the two major taxa into their constituent sub-groups: mosses, liverworts, and crustose, fruticose and foliose lichens. They also explored correlations between selected environmental variables and patterns of diversity. On a regional scale, there were 77 species of bryophytes and 69 species of lichens, giving a total of approximately one-third of the total number of vascular plant species in the region. Mean species richness was higher for lichens than bryophytes. Also, the two taxa were negatively correlated because lichens favoured dry sites and bryophytes favoured moist ones. Species turnover was greater for bryophytes than lichens, largely due to the distribution of liverwort species. Foliose lichens showed higher levels of turnover than crustose lichens. Multiple regression and canonical correspondence analysis showed that both taxa and all sub-groups responded to the same three variables: vascular plant cover, time since last fire and topographic position. Other variables, including time since logging and intensity of logging, explained little variation in bryophyte or lichen diversity. The data suggest that the strategies for the conservation of bryophyte and lichen biodiversity will be different, to reflect the different patterns of species richness and species turnover.     

Vegetation of Barton Peninsula in the neighbourhood of King Sejong Station (King George Island,maritime Antarctic)

Plant communities were studied on Barton Peninsula around King Sejong Station on King George Island, maritime Antarctic. The objective of this study was to document the occurrence and distribution of plant assemblages to provide the bases for monitoring the effects of environmental changes and human impact on the vegetation of this area. Approximately 47% of the investigated area was covered by vegetation. Crustose lichens showed the highest mean cover (21%) among vegetation components. The total mean cover of the four dominant taxa, together with the other three major subdominant components, i.e., Usnea spp., Andreaea spp. and Sanionia georgico-uncinata, was 78.2% of the total cover of all the species. Lichen cover and species diversity increased with altitude and the time of exposure from snow. Lichens contributed substantially more to the increased species density and diversity than did bryophytes. Ten plant communities were recognized within the study area. All of them belong to the Antarctic cryptogam tundra formation; they were grouped into four subformations: fruticose lichen and moss cushion subformation, crustose lichen subformation, moss carpet subformation and moss hummock subformation. The moss turf subformation was not found on this region. The Antarctic herb tundra formation was also not found; however, the populations of both Antarctic vascular plants have rapidly expanded around Barton Peninsula in recent years, which may allow development of the Antarctic herb tundra formation in the future.     

Do lichens show latitudinal patterns of diversity?

No previous study has directly investigated whether lichens show latitudinal patterns of diversity. We used vouchered data and MaxEnt models to compile richness estimates (species, genera, and families) across the western coastal region of the US. Nonparametric multiplicative regression then sought the geographic factors or interactions of factors that explained the most variability in lichen richness. Collection density was the strongest predictor of raw estimates of richness at all taxonomic ranks. Latitude was the overall single-best predictor of MaxEnt modeled species, generic, and familial richness in all models. MaxEnt modeling was necessary to minimize collection bias, which otherwise obscured any other patterns of diversity. While geography explained a sizable portion of variance in lichen richness, it does not trend linearly with latitude. Instead, lichen diversity may be influenced by a compilation of regional and local factors including climate, disturbance, and competition.     

Diversity and biogeography of the Antarctic flora

Aim To establish how well the terrestrial flora of the Antarctic has been sampled, how well the flora is known, and to determine the major patterns in diversity and biogeography. Location Antarctica south of 60° S, together with the South Sandwich Islands, but excluding South Georgia, Bouvetøya and the periantarctic islands. Methods Plant occurrence data were collated from herbarium specimens and literature records, and assembled into the Antarctic Plant Database. Distributional patterns were analysed using a geographic information system. Biogeographical patterns were determined with a variety of multivariate statistics. Results Plants have been recorded from throughout the Antarctic, including all latitudes between 60° S and 86° S. Species richness declines with latitude along the Antarctic Peninsula, but there was no evidence for a similar cline in Victoria Land and the Transantarctic mountains. Multi‐dimensional scaling ordinations showed that the species compositions of the South Orkney, South Shetland Islands and the north‐western Antarctic Peninsula are very similar to each other, as are the floras of different regions in continental Antarctica. They also suggest, however, that the eastern Antarctic Peninsula flora is more similar to the flora of the southern Antarctic Peninsula than to the continental flora (with which it has traditionally been linked). The South Sandwich Islands have a flora that is very dissimilar to that in all Antarctic regions, probably because of their isolation and volcanic nature. Main conclusions The Antarctic flora has been reasonably well sampled, but certain areas require further floristic surveys. Available data do, however, allow for a number of robust conclusions. A diversity gradient exists along the Antarctic Peninsula, with fewer species (but not fewer higher taxa) at higher latitudes. Multi‐dimensional scaling ordination suggests three major floral provinces within Antarctica: northern maritime, southern maritime, and continental. Patterns of endemism suggest that a proportion of the lichen flora may have an ancient vicariant distribution, while most bryophytes are more recent colonists.     

Host-specificity of moss-associated fungal communities in the Ny-Ålesund region (Svalbard,High Arctic) as revealed by amplicon pyrosequencing

Fungal communities play a significant role in regulating ecological processes in the Arctic tundra. However, the extent to which the Arctic moss species and host types (moss, lichen and vascular plant) determine the richness, diversity, and composition of fungal communities at a local scale has not been quantitatively explored. Using 454 pyrosequencing in the current study, we characterized the fungal communities associated with six moss species (Andreaea rupestris, Bryum pseudotriquetrum, Hymenoloma crispulum, Polytrichastrum alpinum, Racomitrium lanuginosum, and Sanionia uncinata) and compared them with fungal communities associated with lichens and vascular plants in the Ny-Ålesund region (High Arctic). Host-species preference had greater explanatory power than geographical factors (longitude, latitude, elevation) in shaping moss-associated fungal communities. Fungal communities associated with mosses differed significantly from those associated with vascular plants and lichens, suggesting specificity of the fungal communities among three host types. Pairwise comparison analysis also indicated that the relative abundance of many taxonomic groups (e.g., Chaetothyriales, Leotiales, Catenulifera, Alatospora, and Toxicocladosporium) significantly differed between mosses and the other two host types. These results suggest host factors significantly affect the distribution of the fungal species associated with these moss species in the local-scale Arctic tundra.     

Spatial gradients in species diversity of microscopic animals: the case of bdelloid rotifers at high altitude

Aim Organisms smaller than 2 mm appear not to follow the spatial patterns in richness and diversity commonly observed in macroscopic organisms. We describe spatial patterns in species diversity in a group of microscopic organisms, bdelloid rotifers, living in moss and lichen patches, in order to test the hypotheses of no relationship between species richness and composition and spatial gradients, suggested by previously published patterns in microscopic organisms. Location Moss and lichen patches as habitats for bdelloids, on high‐elevation peaks at altitudes between 2984 and 4527 m a.s.l. across the Italian, French and Swiss Alps, with distances among sample sites ranging from 1 m to 420 km, in comparison with lower‐elevation samples at altitudes from 850 to 1810 m a.s.l. Methods We sampled species assemblages of bdelloid rotifers living in isolated moss and lichen patches in 47 sites. We described the observed α, β and γ diversities; the heterogeneity of species assemblages; and the estimated number of species (incidence‐based coverage estimator). Patterns in species distribution were analysed at three different levels: (1) habitat, comparing species richness on moss and lichen substrates, testing differences in α diversity and heterogeneity (anova ), species composition (analysis of similarities test), and γ diversity (rarefaction curves); (2) altitude, comparing the observed richness with previously published data from locations well below 2000 m; and (3) distances between sites, correlating the matrix of Jaccard dissimilarities and the matrix of geographical distances with a Mantel test. Results Both species richness and species composition of bdelloid rotifers differed significantly between mosses and lichens at high elevations, but no difference was found in the heterogeneity of species assemblages. Alpha diversity was significantly lower at high‐elevation than at low‐elevation sites, but the estimated number of species was not reduced when compared with sites at low elevations. Geographical distance between sites had no effect on species composition in either mosses or lichens. The distribution of species was highly heterogeneous, with a low similarity among assemblages. Main conclusions As expected, bdelloids appear to occupy habitats selectively. The altitudinal gradient in species richness for bdelloid rotifers is limited to a decrease in α diversity only; such a decrease is not caused by a lower number of species (low γ diversity) being able to tolerate harsh conditions, and high‐altitude species are not a subset of species living at lower elevations. The observed values of α, β and γ diversity at high altitudes in the Alps are compatible with the scenario of a very low number of available propagules because of the low density of patches of favourable habitat. Our results suggest that the geographical distribution of animals, and therefore biodiversity patterns, may be strongly influenced by animal size, as small organisms such as bdelloids appear to show spatial patterns that differ from those known in larger animals. Differences in body size should be taken into account carefully in future studies of biodiversity patterns.     

Ecophysiology of Antarctic vascular plants

Most of the ice and snow-free land in the Antarctic summer is found along the Antarctic Peninsula and adjacent islands and coastal areas of the continent. This is the area where most of the Antarctic vegetation is found. Mean air temperature tends to be above zero during the summer in parts of the Maritime Antarctic. The most commonly found photosynthetic organisms in the Maritime Antarctic and continental edge are lichens (around 380 species) and bryophytes (130 species). Only two vascular plants, Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl., have been able to colonize some of the coastal areas. This low species diversity, compared with the Arctic, may be due to permanent low temperature and isolation from continental sources of propagules. The existence of these plants in such a permanent harsh environment makes them of particular interest for the study of adaptations to cold environments and mechanisms of cold resistance in plants. Among these adaptations are high freezing resistance, high resistance to light stress and high photosynthetic capacity at low temperature. In this paper, the ecophysiology of the two vascular plants is reviewed, including habitat characteristics, photosynthetic properties, cold resistance, and biochemical adaptations to cold.     

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.     

Variability in intertidal communities along a latitudinal gradient in the Southern Ocean

Despite being one of the most intensely studied habitat types worldwide, the intertidal region around Antarctica has received little more than superficial study. Despite this, the first detailed study of a single locality on the Antarctic Peninsula reported previously unanticipated levels of species richness, biomass and diversity in cryptic intertidal habitats. The current study extends the coverage achieved from this single locality. The intertidal zone at sites in the Scotia Arc, the Falkland Islands and the Antarctic Peninsula was investigated. At all the study sites selected, a wide range of macrofauna was found inhabiting the littoral fringe. These communities, although generally cryptic and occupying predominantly the undersides of boulders and protected interstices, at some locations and sites were rich at multiple taxonomic levels. Across the study locations species richness in the intertidal zone ranged from 7 to 30 species. The highest species richness and diversity were found at high latitude localities, which experienced the highest physical disturbance due to ice scour, and appeared superficially to be denuded of life. Species assemblages varied with latitude with Adelaide Island having a high proportion of bryozoans relative to all other localities.     

Factors influencing epiphytic bryophyte and lichen species richness at different spatial scales in managed temperate forests

The effect of management related factors on species richness of epiphytic bryophytes and lichens was studied in managed deciduous-coniferous mixed forests in Western-Hungary. At the stand level, the potential explanatory variables were tree species composition, stand structure, microclimate and light conditions, landscape and historical variables; while at tree level host tree species, tree size and light were studied. Species richness of the two epiphyte groups was positively correlated. Both for lichen and bryophyte plot level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for bryophytes the presence of large trees, while for lichens amount and heterogeneity of light were important. Tree level richness was mainly determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size generally increased tree level species richness, except on pine for bryophytes and on hornbeam for lichens. The key variables for epiphytic diversity of the region were directly influenced by recent forest management; historical and landscape variables were not influential. Forest management oriented to the conservation of epiphytes should focus on: (i) the maintenance of tree species diversity in mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks); (iii) conserving large trees within the stands; (iv) providing the presence of shrub and regeneration layer; (v) creating heterogeneous light conditions. For these purposes tree selection and selective cutting management seem more appropriate than shelterwood system.     

Antarctic moss carpets facilitate growth of Deschampsia antarctica but not its survival

The vegetation of the Antarctic tundra is dominated by mosses and lichens. Deschampsia antarctica, the Antarctic hairgrass, is one of two vascular plant species which grow along the west coast of the Antarctic Peninsula. However, little is known about its recruitment and interaction with non-vascular tundra plants. Although several authors propose that tolerance and/or competition should be the main forms of interaction between moss carpets and D. antarctica, no relevant studies exist so far. We investigated whether positive interactions are predominant at the Shetland Islands and the west coast of the Antarctic Peninsula and focussed on the role that moss carpets play in the recruitment of D. antarctica. Across the studied zone, D. antarctica showed a significant association with moss carpets, with higher frequencies as well as more and larger individuals than on bare ground. At one site, we conducted moss removal and seedlings transplant experiments to assess the relevance of the moss carpets for different life stages of hairgrass. All experimental individuals survived until the following summer whether the moss carpet was removed or not, but growth rate was significantly lower in tussocks with moss carpets removed. Likewise, tiller size was higher in plants growing in moss carpets than on bare ground. The detected positive interactions with mosses seem to be important for the expansion of D. antarctica, raising the question about their importance under future climate change scenarios.     

Slowest to fastest: Extreme range in lichen growth rates supports their use as an indicator of climate change in Antarctica

Global temperature rise is suggested to be greater and more rapid in polar regions. There has been a clear temperature rise of 0.056 °C y⁻¹ in the Antarctic Peninsula and this has led to changes in higher plant extent and range. In the more extreme environments of the main continent the vegetation is scattered and composed of lichens and mosses. There is interest in the possible effects of global climate change on these communities acting through changes in temperature and precipitation. Lichens have been extensively used to date the substrates on which they are growing using the techniques of lichenometry. The slow growth and longevity of lichens particularly suites them for this use. We present evidence that there appears to be a substantial (two orders of magnitude) cline in lichen growth rate from the warmer, wetter and more productive Peninsula to the cold Dry Valleys at 77°S latitude. The differences in growth rate reflect the precipitation and temperature regimes at the different sites. The large range in growth rates coupled with the simplicity of measuring lichen growth using modern techniques suggests that this could be an excellent tool for the detection of climate change in continental Antarctica.     

Competition, sub-lethal mortality and diversity on Southern Ocean coastal rock communities

Overgrowth competition, sub-lethal mortality (some zooids killed but colony survives) and subsequent growth from fragments, and diversity of communities encrusting rocks (pebble through to boulder size) were examined from five Antarctic localities, along a latitudinal gradient. There were distinct gradients in the ecology of both assemblages and individual species with latitude within the Southern Ocean. Compared with warm-water equivalents, the polar assemblages had many fewer species, considerably less variability in species richness, highly transitive interactions and lower incidences of interspecific encounters. There is no gradual transition but a dramatic alteration of assemblage and species level ecology around the margins of the Southern Ocean, which may primarily be due to ice scour. Sub-lethal mortality was common and peaked on different boulder sizes along the Antarctic Peninsula. This is indicative of the disturbance cline along the region.     

Forest edge-interior differentiation in the epiphytic lichen diversity of the forest steppe in the Khangai Mountains,Mongolia

Aims The effects of traditional land use by mobile livestock keepers on biodiversity in forest steppe ecotones are insufficiently studied. Epiphytes are an important part of forest plant diversity. Here we analyze differences in the diversity and composition of the epiphytic lichen vegetation between the edge and the interior of Siberian larch forests in the Khangai Mountains, western Mongolia, which are highly subdivided into patches. We asked whether the epiphytic lichen vegetation at the forest edge differs significantly from that in the interior, whether the edge is inhabited by more nitrophilous species than the interior and whether the density of nomad camps around the forest affects epiphytic lichen diversity.Methods Cover percentages of epiphytic lichen species were recorded from 20 trees per plot on 6 plots in the interior and 6 plots at the edge of Larix sibirica forests. The position of nomad summer camps was surveyed using Global Positioning System. Data were analyzed with pairwise significance tests, analysis of similarities, nonmetric multidimensional scaling and canonical correspondence analysis.Important findings The composition of the epiphytic lichen vegetation clearly differed between the two habitats, with more species being more frequent at the edge than in the interior. However, there was no difference in species richness (α-diversity). The epiphyte vegetation at the edge was more uniform and characterized by lower variation of tree-level α-diversity and lower β-diversity than in the interior. At the edge, only nitrophytic lichens were dominant, whereas in the interior, nitrophytes and acidophytes were among the dominant species. This pattern is probably attributable to the spatial heterogeneity of the intensity of forest grazing and was shown to be influenced by the density of nomad summer camps in the vicinity of the forests. Tree-level α-diversity increased with stem diameter, but high-diameter trees were rare. The results suggest that the present level of forest patchiness and the effect of forest grazing increases the diversity of epiphytic lichens on the landscape level, while logging of high-diameter trees reduces lichen diversity.     

Dispersal ability links to cross‐scale species diversity patterns across the Eurasian Arctic tundra

Aim The role of dispersal in structuring biodiversity across spatial scales is controversial. If dispersal controls regional and local community assembly, it should also affect the degree of spatial species turnover as well as the extent to which regional communities are represented in local communities. Here we provide the first integrated assessment of relationships between dispersal ability and local‐to‐regional spatial aspects of species diversity across a large geographical area. Location Northern Eurasia. Methods Using a cross‐scale analysis covering local (0.64 m²) to continental (the Eurasian Arctic biome) scales, we compared slope parameters of the dissimilarity‐to‐distance relationship in species composition and the local‐to‐regional relationship in species richness among three plant‐like groups that differ in dispersal ability: lichens with the highest dispersal ability; mosses and moss allies with intermediate dispersal ability; and seed plants with the lowest dispersal ability. Results Diversity patterns generally differed between the three groups according to their dispersal ability, even after controlling for niche‐based processes. Increasing dispersal ability is linked to decreasing spatial species turnover and an increasing ratio of local to regional species richness. All comparisons supported our expectations, except for the slope of the local‐to‐regional relationship in species richness for mosses and moss allies which was not significantly steeper than that of seed plants. Main conclusions The negative link between dispersal ability and spatial species turnover and the corresponding positive link between dispersal ability and the ratio of local‐to‐regional species richness support the idea that dispersal affects community structure and diversity patterns across spatial scales.     

A survey method for assessing the richness of epiphytic lichens using growth forms

The species richness of epiphytic lichens is continuously decreasing by degradation and loss of habitat. Considering that taxonomic identification of all species is time and resource consuming, rapid assessment methods to extrapolate the total number of species are needed for practical conservation. This paper describes an alternative method using the correlation between lichens growth forms and species richness. The study was conducted in 406 forest stands located in Central Spain, covering a wide range of mediterranean-climate ecosystem regions, management intensity levels, canopy cover conditions, and tree sizes. The presence/absence of epiphytic lichens was determined in 6090 trees, which were dominated by oak species (Quercus ilex, Q. faginea, and Q. pyrenaica). In all type of forests, the diversity of growth forms was positively correlated with the total epiphytic lichen richness. In all cases, species richness increased in non-managed forest stands with dense canopies. Thus, we propose the use of lichen growth forms as a helpful surrogate of species richness to detect potentially conservation priority areas in the Mediterranean region.     

Epiphytic lichen is associated with species richness of gall-inducing aphids but not with niche differentiation among them

The presence of epiphytic foliose lichen amplifies the heterogeneity of habitat by creating shelters for insects living on tree bark. It thus should enhance species number and spatial niche segregation among these canopy insects. We studied this hypothesis in a field experiment using four aphid species that induce galls on Pistacia atlantica trees covered with Xanthoria parietina lichen. In autumn 2008, 3 months after aphid fundatrices were oviposited, we marked six branches on each of 29 trees. Two served as a control, whereas the other four were isolated with insect glue; two of them were scraped with sandpaper to remove epiphytic foliose lichens. We therefore obtained three treatments comprising control branches, isolated branches with lichen, and isolated branches without lichen. In summer 2009, we counted all the galls developing on five new annual shoots on each of 174 branches. We observed more cecidogenic aphid species on all the branches with lichens than without, but each species at different proportions. The different frequencies of utilization of the lichen did not lead to habitat partitioning between species. In conclusion, although habitat heterogeneity itself was associated with species richness and population abundance, it did not induce spatial niche segregation. Considering that many economically important insect species, pests and natural enemies, oviposit or spend some portion of their lives in bark cracks, it is possible that some can use lichens too for protection or/and oviposition sites. As a consequence, lichens may affect management of agrosystems and their impacts should be investigated more deeply in such contexts.     

Response of calcareous grassland vegetation to mowing and fluctuating weather conditions

Question: What determines the balance between the cover values of vascular plants, lichens and mosses in dry calcareous grassland communities? Location: Western Estonia. Methods: A five‐year (2001–2005) study was conducted in a dry calcareous grassland. The cover of mosses, lichens and vascular plants and all moss species was recorded in permanent plots. Vascular plants were cut in half of the plots. Data from a nearby weather station were used to calculate mean values of different weather parameters and a summer moisture index for the study years. Results: Significant differences in cover values between years were found. The fluctuations of total moss cover and the cover of the dominating moss species Ctenidium molluscum followed changes in annual precipitation. Both cover values were highest in years with high precipitation. The cover change of vascular plants was best characterized by the moisture index of the growth period (three summer months). Summers with high moisture indexes facilitated vascular plant and lichen growth. Annual precipitation and the cover of mosses had a negative influence on the cover of vascular plants. The cutting of vascular plants did not have a significant effect on moss and lichen cover. Conclusions: 1. On dry calcareous grasslands the growth of mosses is enhanced by high annual precipitation, while the growth of vascular plants and lichens is influenced rather by the high summer moisture index. The cover of vascular plants is inhibited by the large moss cover. 2. Mowing of vascular plants does not influence the cover of mosses and lichens.     

The ecosystem evolution of penguin colonies in the past 8,500 years on Vestfold Hills, East Antarctica

Penguin colony is one of the Earth’s simplest ecosystems. As the seabird with the largest population in Antarctica, penguin is a unique indicator of Antarctic environment and climate changes. In this study, we collected an ornithogenic sediment core from Gardner Island in Vestfold Hills, East Antarctica, reconstructed an 8,500 years variation history of penguin population and vegetation abundance on this island, and examined the evolution of the penguin colony. We used the levels of two molecular markers cholesterol and cholestanol as the proxy indicators of penguin population size. Other molecular markers, including C_24:0 alkenoic acid, C₁₈ n-alkanol and phytol were used as the proxy indicators of aquatic moss, algae, and general vegetation, respectively. It is shown that the growth of algae was mainly affected by the nutritional supply from penguin droppings, so their abundance was positively linked with penguin population. The growth of aquatic moss, however, was controlled more by the degree of water body transparency than by nutrient availability. Because the pollution of water body increased as penguin population grew, aquatic moss abundance showed a seesaw-like relationship with penguin population. These results suggested that penguins played a dominant role in this simple ecosystem in the Antarctic environment. The reconstructed relationship between penguin population and vegetation abundance may offer new insights to understand ancient Antarctic environment and ecology.