The subject of this study are relationships between the European ground squirrel and plant communities. The first aim was to analyze the impact of livestock grazing intensity on European ground squirrel's density in mesophilous conditions. In this research was established a grid including 40 samples, where all plant species were recorded and all borrows were counted. The results show, that increasing grazing intensity makes increase in European ground squirrel's density, but only to some extent, when with enormous livestock trampling the density decreases. The second aim was to analyze the impact of European ground squirrel on vegetation. The method was based on comparison of vegetation on-mound with borrow entrance and off-mound without any borrow entrance. The results show, that European ground squirrel's activities change species composition, decrease plant cover and increase species diversity of vegetation. Also, there are changes in vertical structure of vegetation, in composition of life forms and ecological -- functional groups of plants.