Population dynamics of small mammals in relation to forest age and structural habitat factors in northern Sweden
Article first published online: 1 OCT 2002
Journal of Applied Ecology
Volume 39, Issue 5, pages 781–792, October 2002
How to Cite
Ecke, F., Löfgren, O. and Sörlin, D. (2002), Population dynamics of small mammals in relation to forest age and structural habitat factors in northern Sweden. Journal of Applied Ecology, 39: 781–792. doi: 10.1046/j.1365-2664.2002.00759.x
- Issue published online: 1 OCT 2002
- Article first published online: 1 OCT 2002
- Received 12 December 2000; final copy received 31 May 2002
- boreal forests;
- Clethrionomys glareolus;
- forest management;
- habitat preference;
- species richness;
- 1In northern Scandinavia there are indications of a long-term decline in the abundance of the three dominant vole species, Clethrionomys glareolus , Clethrionomys rufocanus and Microtus agrestis , since the 1970s. One explanation proposes that intensified clear-cutting has created even-aged and homogeneous forest stands with poor overall conditions for survival and reproduction of the voles.
- 2We investigated the relationship between forest age and structural habitat factors and its implications for the species richness and abundance of small mammals. In particular, we assessed the population dynamics of C. glareolus , a forest-dwelling species with rather general habitat requirements .
- 3Extensive snap-trapping of small mammals was conducted during 1998–2000 on 24 study sites in boreal forests in northern Sweden. Trapping was carried out along transects running from immature forests of six age classes (0–50 years) into adjacent reference sites (> 100 years). At each trapping station we recorded 14 habitat variables that were reduced to three principal components (PCs). The PCs were related to late successional traits, such as forest age and cover of tree layers (PC1), cover of tall vegetation in the field layer (PC2) and structural heterogeneity in the forest floor (PC3).
- 4The species richness of small mammals, as well as the total abundance of C. glareolus , was positively influenced by tall vegetation (PC2) and structural heterogeneity (PC3) but not by late successional traits (PC1). The youngest forests had higher scores for both PC2 and PC3 compared with older forests.
- 5The youngest forests also had the highest species richness and total abundance of C. glareolus . This was associated with a generally higher rate of change in numbers of C. glareolus during summer in the youngest forests compared with adjacent reference sites. In contrast, survival during winter was lower in the youngest forests. We found this result to be consistent with a source–sink scenario where young individuals, primarily born in old forest stands in early summer, migrate into younger forests to breed, but where the probabilities for winter survival are poor.
- 6Our study demonstrates that both the species richness of small mammals and the population dynamics of C. glareolus are influenced to a great extent by structural habitat factors that are altered by common forest management practices in northern Sweden. In order to conserve species richness of small mammals and to minimize population fluctuations of C. glareolus in northern Scandinavia, we outline forest management practices that will provide heterogeneous environments, such as leaving logging residues on site after forest harvesting.