Population dynamics of small mammals in relation to habitat factors in natural and managed forests

Abstract: The influence of forest age and structural habitat factors on species richness and the population dynamics of small mammals were evaluated. Small mammals were monitored both in old-growth and in immature managed forests, and habitat factors were recorded. Species richness and population dynamics of forest dwelling small mammal species were positively influenced by factors related to cover of vegetation in the field layer and to structural heterogeneity in the forest floor. In contrast, species richness and the overall abundance of Clethrionomys glareolus were negatively related to forest age. However, habitats in old forests were important refuges for the winter survival of C. glareolus and therefore may forest management practices, like clearcutting, enhance population fluctuations in this species. The contrasting effects of forest age indicate that population dynamics were primarily not related to the age of forests, but rather to habitat factors important to reproduction and survival of small mammals.