Consequences of isolation of subalpine meadow communities in the Western Caucasus: Reduction of species richness without the density compensation effect

The number and occurrence of plant species are compared in isolated with forest and nonisolated areas of subalpine meadows in Western Caucasus alpine massifs. It is shown that isolation of meadow communities on small isolated massifs (0.01-36.5 km(2)) for about a thousand years has led to a decline in their species richness. However, this process is mainly due to the loss of rare plant species and was not accompanied by the density compensation effect. It is suggested that a wide manifestation of compensation processes requires a period of time significantly longer than the isolation time for most fragments of anthropogenic communities.