Influence of Human Disturbance to the Small Mammal Communities in the Forests

Abstract

Small mammals have been proposed playing an important role in the energy flow and regeneration of forest ecosystems. We compared species richness, diversity (H’) of small mammal communities and abundance of six dominant species of small mammals in disturbed and protected forests (four age classes: 6 - 10, 11 - 15, 16 - 20 and 31 - 40 years old) in China. We also investigated the structural variables (such as species richness, cover rate and abundance of shrubs and grasses) in the bottom layer, which considered to be important for small mammals and might be altered by human disturbance. The relationships between small mammals and these structural variables were examined to determine the potential effects of human disturbance on the small mammals in the restored forests. Our results indicated that the structure and composition of the vegetation in the bottom layer were simplified by human disturbance, while the abundance and cover rate of grasses were significantly increased. Although no significant differences were observed in species richness of small mammals between the protected and disturbed forests at the same age, the diversity index of small mammals in the protected forests was always significantly higher than in the disturbed forests. Regression showed that the species richness and diversity of small mammals increased with the species richness of shrubs, and was negatively correlated to the cover rate of grasses in the bottom layer. Human disturbance increased the total abundance of small mammals, and the increased cover rate of grasses in the bottom layer was beneficial to the abundance of small mammals. Obvious succession of small mammal communities occurred as the protected forest aged. In the protected forests, small ground-dwelling mammals (A. chevrieri, E. miletus and M. pahari) were the dominant species in the younger forests. Other mammals (T. belangeri, D. pernyi and C. erythraeus) gradually became the dominant species as the protected forests aged. However, in the disturbed forests, the smaller ground-dwelling mammals (T. belangeri, D. pernyi and C. erythraeus) were always the dominant species at all ages of the disturbed forests. Regression indicated that the cover rate of grasses in the bottom layer was beneficial to the three smaller body size and ground-dwelling small mammal species, while the shrubs were beneficial to the three bigger body size mammal species.