In steppe forests by and around the southern reaches of the Dnieper river, 53 mammal species were recorded. Their diversity is higher in forests which have a more complicated ecosystem. Numbers of species recorded in different forest types were as follows: in shelterbelts, 22-24 species; in older planted stands on the plain, 27-30; in bairak oak forests, 31-35; in pine forests on sand, 35-37; in planted pine forests, 9-12; in oak forest situated on flood-plains in narrow valleys, 44-47. These constitute 27, 54, 59, 17, 63 and 74 percent respectively of the total regional diversity of mammals. Mammal diversity depended on canopy cover, the presence of a grass cover to the forest floor, and soil moisture levels. Greatest diversity occurred in plantations with a partly shaded forest floor (22-29 species). More or less shadow was associated with a decline in this diversity: in better lit stands (4-6 species), in poorer lit stands (16-19), in fully shaded stands (13-17). The greatest number of mammal species were noted in forests where the canopy cover was 0.7 (16-25 species). When canopy cover was 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 and 0, species diversities was 4-7, 5-8, 8-11, 8-12, 9-14, 12-16 and 14-19 species respectively. When canopy cover was 0.8, 0.9 and 1.0, numbers of recorded species were 12-14, 7-9 and 4-6 respectively. Soil moisture levels were very important. Greatest species diversity was noted in forests with a soil-moisture index of 2 (22-29 species). Increase and decrease of that index was associated with a decrease in diversity: in forests with an index of 1-2 (18-21 species); semi-dry, with an index of 1 (14-17); dry, with an index of 0-1 (11-14); very dry, with an index of 0 (3-6); semi-wet, with an index of 3 (12-14); wet, with an index of 4 (9-12); very wet, with an index of 5 (6-8). These patterns should be taken into account when planting and managing forests in the steppe zone.