Abstract
The study is based on analysis of 1415 relevés representing communities with presence or dominance of Puccinellia tenuissima, P. gigantea, and P. kulundensis from the southern part of Western Siberia. The ecological plasticity of these species has been shown. Their phytocenotic optimum is revealed using the species indicator values in relation to soil moisture and richness-salinity gradients. The communities dominated by P. tenuissima are most common in the south of Western Siberia. This is the reason of the highest ecological plasticity of this species. In contrast, P. kulundensis is the most environmentally stable and shows the greatest dominant potential. Among the studied species P. gigantea rarely achieves high cover. The West-Siberian communities dominated by endemic P. kulundensis are described as a new association Puccinellietum kulundensis ass. nov. from the class Festuco-Puccinellietea Soó ex Vicherek 1973, the order Scorzonero-Juncetalia gerardii Vicherek 1973 and the alliance Cirsion esculenti Golub 1994.