Steppe ecosystems are dominant in the industrial region of the lower Dnieper river. Some have been transformed into agricultural lands, shelter belts and so-called "bairak" oak forests, and all are under considerable human pressure from agriculture, industry and recreation. The combined influence of these factors has caused a decrease in biodiversity. Mammals are one of the most endengered groups. Before intensive human influence, 23, 18, 24, and 31 mammal species were recorded in four example steppe ecosystems. These represented 30.1%, 38.4%, 39.5%, and 51.8% respectively of all mammal species known from the region. Transformation of steppe ecosystems into agricultural land has caused a decrease in species diversity of these mammals. On farmland, the diversity index is 0.78 of that in steppe ecosystems. Intensification of agriculture during the last 50 years resulted in further destruction of the fauna. In remaining undisturbed areas the diversity index has dropped to 0.91 of the original measurements; in farmland the equivalent figure is 0.67. In comparison, human pressure has caused only minor changes in shelterbelts (diversity index 0.96) and "bairak" oak forests (diversity index 0.97). These ecosystems located in zones of direct industrial pollution (where quantities of pollutants can exceed upper safety limits by as much as 5-10 and 10-20 times respectively), and subjected to additional recreation pressure, experience further deterioration in mammal diversity. Without taking into account agricultural factors, indexes of mammal diversity (according to the degree of pollution) are: 0.71 and 0.38, in steppe ecosystems; 0.75 and 0.33, in agricultural ecosystems; 0.83 and 0.48, in field-protective forest belts; and 0.81 and 0.50, in bairak oak forests. When these ecosystems are also under recreation pressure, those indexes decrease, for example in "bairak" oak forests, to 0.37 and 0.27. Mammals most sensitive to human pressure are digging species, insectivores and predators. The result is that the diversity of ecological groups is also dropping: herbivores predominate in most communities. Ecological stability is thus decreasing along with biodiversity in general. Human pressure on ecosystems increases in the following order: "bairak" oak forests, shelterbelts, steppe, farmland. To preserve the greatest possible species and ecological diversity of mammals, it is thus essential to stop felling shelterbelts, and to improve protection of "bairak" oak forests.