Diversity and composition of dead wood inhabiting bryophyte communities in European beech forests

Abstract

Species composition and diversity of bryophyte communities occurring on dead beech trees were analyzed in five European countries (Slovenia, Hungary, The Netherlands, Belgium and Denmark). Altogether 1.009 trees were inventoried in 19 beech dominated forest reserves. The differences in the composition of bryophyte communities were high among countries and it overwhelms the effect of decay stages, which affect the species com-position at local scale. Well decayed trees were dominated by epixylic species in Slovenia, while in other countries the proportion of opportunistic bryophytes was much higher and in Atlantic countries uproot species are also common. In Slovenia hepatics, in Hungary and Denmark pleurocarps, and in The Netherlands and Belgium acrocarps were the most fre-quent. Diversity of communities differed considerably among regions. Slovenian sites were the hotspot of bryophyte diversity characterized by high species richness (both tree and country level) and a high fraction of rare and threatened species. This richness is most likely caused by the combination of high air humidity combined with a very high degree of natu-ralness of the Slovenian sites. The diversity of Hungarian stands was intermediate reflecting the relatively high naturalness of the study sites, as well as a rather continental climate sub-optimal for epixylic liverworts. Atlantic forests have deteriorated bryophyte communities on dead trees, dominated by a few opportunistic species. This is partly a result of habitat frag-mentation and past and recent management of forest. Most of the stands the amount and quality of dead wood is not suitable for species rich epixylic bryophyte communities.