CRYPTOGAM COMMUNITIES ON FALLEN LOGS IN THE DUKE FOREST, NORTH-CAROLINA

I studied cryptogam (i.e. bryophyte and lichen) communities on fallen logs in the Duke Forest, Durham and Orange Counties, North Carolina, U SA, to determine the relationship of log characteristics and microsite to community composition. Species composition and abundance were esti mated for 111 randomly selected fallen logs. Interior wood samples wer e used to identify the tree species. I determined physical and chemica l characteristics for each log, acid described the log microsite. Cano nical Correspondence Analysis (CCA) detected a clear gradient in crypt ogam species composition which is correlated with the species of log a nd the presence of bark. Communities on hardwood bark, hardwood wood, and pine substrates were the most distinct. CCA also revealed that the microsite is not as closely related to species composition as are sub strate pH and density. The majority of the cryptogam species encounter ed on the fallen logs are commonly reported from other substrates in t he forest. However, within the habitat type of fallen logs, several sp ecies were apparently restricted to certain substrate types.