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, USA, to determine the relationship of log characteristics and microsite to community composition. Species composition and abundance were estimated for 111 randomly selected fallen logs. Interior wood samples were used to identify the tree species. I determined physical and chemical characteristics for each log, acid described the log microsite. Canonical Correspondence Analysis (CCA) detected a clear gradient in cryptogam species composition which is correlated with the species of log and 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 substrate pH and density. The majority of the cryptogam species encountered on the fallen logs are commonly reported from other substrates in the forest. However, within the habitat type of fallen logs, several species were apparently restricted to certain substrate types.