Classification of vegetational diversity in managed boreal forests in eastern Finland

Diversity of vegetation in managed forests is studied. A classification bas ed on forest stand structure, the abundances of vegetation species and vari ations in these abundances is developed and diversity indices are calculate d for the classes to describe the diversity of the vegetation within the cl asses. The classes were formed using detrended correspondence analysis (DCA ), global nonmetric multidimensional scaling (GNMDS) and TWINSPAN classific ation. Discriminant analysis was used to determine the environmental variab les differentiating between the classes, and Duncan's multiple range test w as used to examine the ability of the diversity measures to distinguish the classes. Beta diversity was estimated with Okland's method based on DCA or dination of the sample plots. The results point to fertility and the succes sional stage of the stand as the main factors affecting species diversity, in addition to which soil type, the number of tree species, crown cover, ba sal area and certain variables describing the management of the stand were relevant to the classification. The most distinct diversity indices were th e reciprocal of Simpson, Pielou's J' and species richness, while the highes t alpha diversity was found in young stands with a low crown cover on herb- rich or mesic forest sites. Beta diversity was quite high, its highest valu es of all for the whole data being recorded along the fertility gradient.