Phytocoenotic series in vegetation cover of wrangel island. 2. series in willow-moss tundras

摘要

The spatial pattern of the two phytocoenotic series in Wrangel island is considered as a result of interaction between the subordinate synusia in the principal community, and variation of ecological parameters in space. The decrease of edificatorian role of willows (Salix pulchra - in series II, S.glauca - in series III) when one moves off the principal community, results in the desintegration of combinations of synusia and in leaving of lower layers of the zone of coenotical influence of willows. This process, the egression of principal community, has been traced in space as a gradient of complication (or simplification) or coenotic structure. Because of lower edificatorian role of willows in Wrangel island, the structural pattern of vegetation cover is determined by both biotic and abiotic factors, and in particular, by correlation of main ecological factors. Some optimal correlation of these factors results in the formation of a principal community, but the disturbance of this correlation and drawing of any factor towards its extreme value lead to the formation of distinct horizontal heterogeneity of vegetation cover.