MOSS SYNUSIAE IN SOUTH ESTONIAN FORESTS

On the Karula Upland, South Estonia, the forest moss layer was analyse d using a transect of 726 contiguous 0.2 x 0.2 m plots. The sample plo ts were classified according to a multistage clustering procedure base d on the sequential use of algorithms with different criteria. Several obtained clusters are rather similar in species composition, but abun dance relationships among dominant species are distinctly different. F or detailed analysis of mutual relations among societies a formal defi nition of adjacency is proposed, and two aspects of the cluster contin uum - transitionality and distinctness - are estimated. It appears tha t almost all resulting societies are very distinct (P < 0.05), but at the same time can be continual in the sense of transitionality. Spatia l changes in vegetation along transects are also discontinuous. The nu ll hypothesis assuming the independency of neighbouring sample plots t ype was refuted with P = 0.01. The spatial extent of different synusia e is typically several times larger than it should be if there were no structure in moss vegetation.