COMPARATIVE-ANALYSIS OF THE FLORISTIC RICHNESS OF ALPINE COMMUNITIES IN THE CAUCASUS AND THE CENTRAL ALPS

Species richness of selected alpine plant communities in the Teberda B iosphere Reserve (Northwestern Caucasus) and the Davos area (Central A lps) was compared in series of plots from 0.0025 to 100 m(2). Communit ies developing under similar ecological conditions and with similar sy ntaxonomic positions were compared in order to estimate the role of re cent environment versus regional historical factors in determining pla nt community structure and diversity. The floristic richness of the Ca ucasian and Alpic fens was very similar. The Grasslands and Meadows we re quite similar as to floristic richness for plots > 25 cm x 25 cm, b ut the Caucasian communities had fewer species in smaller plots. The L ichen heath at Teberda was richer than the Caricetum curvulae cetrarie tosum for all plot sizes, except the two smallest ones. On the other h and, the plots of the Salix Snowbed community were richer in species t han the Caucasian snowbeds for all plot sizes. The Rhododendron Shrubl and plots were very similar as to floristic richness in larger plots ( 4 - 100 m(2)). Generally, most Alpic communities near Davos were riche r in species at small plot sizes than the corresponding communities fr om Teberda. Caucasian communities were floristically less similar to e ach other - and thus more discrete - than the Alpic ones. The possible role of different factors controlling floristic richness of the commu nities is discussed. Our results suggest that recent ecological condit ions have a big influence on local floristic diversity and may lead to high similarities between ecologically similar communities from diffe rent regions. In addition, the general floristic richness of a regions as well as island effects should be taken into account.