This study provides the analysis of the changes of taxonomic structure in diatom assemblages of lacustrine genesis under the influence of abiotic factors. The author’s method of graphical analysis of diatom assemblages was used. Three types of taxonomic proportion distribution (exponential, logistic and linear) which are formed under the influence of natural abiotic factors were distinguished. The first two types correspond to lifetime taxonomic proportions which objectively reflect environmental conditions in lakes. The third type (linear) corresponds to assemblages which are affected by processes of transfer and redeposition. We revealed three transformation scenarios of taxonomic structure. The first one is characteristic for small lakes (< 1 km²) and the second one is characteristic for middle lakes (1–4 km²). Both scenarios are developed with stable parameters of the ecosystem under negative external impact. The third type of transformation is developed in lake of any size in case of changes of physicochemical properties or morphometric parameters of the lake.

Keywords: diatom assemblages, lake ecosystems, graphical analysis

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