The habitat factors that affect the composition of bryophyte and lichen communities on fallen logs.

The composition of cryptogam (bryophyte and lichen) communities on fallen logs was studied in two old-growth forests in the Czech Republic. Altogether, 85 species (22 liverworts, 44 mosses, and 19 lichens) were recorded. The presence and abundance of the different species on 350 logs was attributed to habitat factors (e.g. humidity, wood decay, wood softness, log diameter, bark cover, thickness of humus layer and tree species) that were recorded separately for each of the logs. The aim was to identify the factors significantly affecting the composition of cryptogam communities. For the different ecological groups of species (epiphytes, epixylic species, and ground flora) forwarded canonical correspondence analysis (CCA) selected thickness of humus layer and tree species as the factors explaining most variability. In addition, the extent of log surface covered by bark, humidity and log decay were selected as significant determinants of cryptogam community composition.