Epiphytes, including vascular and non-vascular, constitute a large part of global plant biodiversity. Distribution of obligatory epiphytic bryophytes results from climate and local habitat conditions. The most important epiphytic bryophytes and at the same time poorly investigated and taxonomically problematic ones belong to the family Orthotrichaceae. Epiphytic mosses are also ideal organisms for species modelling, because of having no roots, they are highly dependent on external environmental conditions. For this purpose, we used the ecological niche modelling approach to define their potential distribution in China and adjacent areas and explore factors that shape this distribution. We used 617 occurrence records of 23 species from six genera within the Orthotrichaceae family. Our results suggest that the distribution of members of the Orthotrichaceae family is predominantly affected by bioclimatic variables, especially bio10 (mean temperature of the warmest quarter), bio15 (precipitation seasonality), bio18 (precipitation of the warmest quarter), bio19 (precipitation of the coldest quarter), bio9 (mean temperature of the driest quarter), and bio2 (mean diurnal range). However, the distribution of particular genera is ruled by a different set of those variables. The distribution of two genera (Leratia and Ulota) is also highly influenced by land cover (especially mixed/other trees), whereas human footprint shows a moderate contribution to models of three genera (Lewinskya, Orthotrichum, Nyholmiella). Based on the occupied climatic niche and distribution patterns, representatives of the studied family are divided into two groups. The 'western-montane group' is characterised by lower temperatures and lower precipitation whereas the 'eastern-lowland' group' by more humid and warmer conditions.

• Klíčová slova
• Asia, Leratia, Lewinskya, Macromitrium, Nyholmiella, Orthotrichum, Ulota, bryophytes, distribution maps, ecological niche modelling,
• Publikační typ
• časopisecké články MeSH

The pH of tree bark is affected by many factors, amongst them epiphytic bryophytes changing in their active state environment. Thus, we hypothesized that bryophytes can change bark acidity, dependently of the inclination of the branches, as inclination affect the water regime and particle deposition. We measured the pH under bryophyte cushions and compared it to nearby naked bark. Additionally, we compared results with experimental bark covering with neutral cover. We found that the pH of naked bark declines with decreasing inclination of trunks. Although bryophyte cover did not generally change the pH of the bark, there was a significant interaction with inclination: with higher inclination, bryophytes decrease the pH reaction of bark, while with lower inclination they increase it. One possible explanation may lie in changes to alkaline particle deposition, or conversely in the acidification of the bark by leaching. In addition, an experiment with a neutral cover showed that naked bark covering would substantially increase pH. As, on average, bryophytes do not change the pH of bark, there can be mutual interference between the alkalizing effect of the bark cover itself and the acidifying biological effect of bryophytes.

• Klíčová slova
• Orthotrichaceae, acidification, dust deposition, inclination, phorophytes,
• Publikační typ
• časopisecké články MeSH

Bryophytes and lichens are outstanding bioindicators, not only of the plant community in which they develop, but also the substrates on which they grow. Some epiphytic cryptogams, particularly the rare ones, are stenotopic and require a long habitat continuity, for example substrates such as old trees. It could also be a tea plantation, this is because the shrubs are not felled, and most of them may have several dozen years. In addition, the shrubs are not subject to sudden changes in microclimatic conditions as only the young leaves are harvested. As the importance of tea plantations as host plants for mosses and lichens has not yet been studied, the present study examines the species diversity of cryptogams of two tea plantations in Georgia (Caucasus). The study also examines the phytogeography, spatial pattern, environmental conditions and ecological indicators of the cryptogams. Thirty-nine cryptogam taxa were identified; typical forest taxa dominated, even in the absence of typical forest communities. Some of these species are obligatory epiphytes, rare or even critically endangered in most European countries (e.g., Orthotrichum stellatum, O. stramineum, Lewinskya striata). The fairly abundant record of such species on tea plantations indicates the importance of these phytocoenoses for the preservation of rare species, and indicates that these habitats are hot spots for these cryptogams in otherwise changed envirnonment. Additionally, as indicated the analysis of the species composition of individual plantations and the mathematical analysis made on this basis, plantations differ from each other. Another interesting result is also the spatial distributions of cryptogams on tea bushes resemble those of forest communities and lichens seems to be more sensitive than bryophytes to antropogenic changes of environment.

• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH