where p_k1 – share of k-species in the community abundance at t moment of time; n – a number of species in the community at t₁ and t₂ time moments. A numerator in SD corresponds to n-measured vector rate. It is start-end coordinates describe two points in n-measured space. In the case considered these points are descriptions of species composition of phytoplankton at t₁ and t₂ moments of time; a numerator in ED, corresponds to n-measured vector length mentioned above (Euclidean distance). Both expressions obey the distance function definition (Duran, Odell, 1977) and they are a particular case of Minkovsky distance metric function. WG index, where a numerator obeys definition of distance function too, is the rate of community movement through diversity space and it is a value of relative contribution of single species to common diversity of the community. If species composition changed but community diversity stayed the same, WG would be above zero (Williams, 1975).

Annual dynamics of succession rate indices reflect the key events in phytoplankton life in Belovo reservoir as a result of dominated complexes change and main phases of hydrological cycle that is typical for limnetic systems of moderate latitudes. Statistically reliable relation of succession rate indices with temporal temperature gradient indicate that water temperature fluctuations in the reservoir effect greatly on phytoplankton communities tolerance in time. The succession rate of phytoplankton in heated Belovo reservoir is higher than in Lanao Lake, Philippines (Lewis, 1978) and in eutrophic Cross-Mir Lake, mid England (Reynolds, 1981). The conclusion that succession acceleration under change in hydrological features on seasons and its decrease-under any influence absence followed from comparison of index WG for North American Taho, Klir, Castle lakes and arctic pond with tropical lake Victoria (Williams, 1975).

The analise of fluctuation of aquatic communities structure on the basis of succession rate indices is the element of empirical statistical description model as the means of obtaining quantitative ecological forecast and paleoecological reconstruction.

Note. Abstracts are published in author's edition

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