WHAT DO INDICES OF β-DIVERSITY IN ARCTIC TUNDRAS?
The values of β-diversity in two latitudinal strips of Wrangel Island are identified. The majority of the used indices (measures) (7 of 8) showed higher values in the northern strip. Two scales established at a factor of moisture served as initial models for the calculation of diversity. In order to identify the partitioning β-diversity, the two scales were divided into 5 classes, each of them has been determined by the mean value. The values obtained showed a non-synchronous behavior of the various measures from meso-xeromorphic to hygromorphic part of the gradient within each of the zonal strips. Factors that determine most of the measures are the parameters of the species distribution along environmental gradient: ecological amplitude, the position of optima, the maximum cover. Outside the model, it is possible to use some measures based on the values of α- and γ-diversity.