Impact of alternative harvesting practices on the small mammal community in an Ontario boreal mixedwood forest

Abstract

During the current project four studies were conducted to determine the effect of alternative silvicultural systems, and harvesting methods on the small mammal community of a boreal mixedwood forest in northern Ontario. In the first study (Chapter 1) pitfall and livetrapping were used to monitor the small mammal community in uncut forest, on lands harvested under the clearcut and shelterwood silvicultural systems, and at the edge of these harvest treatments. Livetrapping was used during the second study (Chapter 2) to monitor the effect of different harvesting methods on the small mammal edge community of clearcut and shelterwood cut areas. The third study (Chapter 3) investigated how small mammals used the treated and untreated side of livetrapping grids at the edge of all six timber harvest treatments, and in uncut forest. Finally, during the fourth study (Chapter 4) radio-telemetry was used to investigate the response of Peromyscus maniculatus (deer mice) to several timber harvest treatments. Differences in the small mammal communities associated with the harvest treatments were noted during all four studies. For instance, the first study revealed that the number of Clethrionomys gapperi (southern red-backed voles) was lower, and the number of Glaucomys sabrimis (northern flying squirrel) captures was higher at clearcut edges than at shelterwood edges and in controls by the second year after timber harvest. The second study found a higher number of G. sabrinus captures at the edge of full-tree clearcuts than at tree-length clearcuts and on controls in the second post-harvest year. The third study revealed that C. gapperi and P. maniculatus utilized harvested edges differently. And the fourth study revealed differences in the way habitat was used by P. maniculatus on clearcut, shelterwood, and control treatments. These studies revealed that applying different silvicultural systems and harvesting methods can influence the small mammal community. Since small mammal species responded to the harvest treatments differently, it follows that foresters will need to implement a variety of silvicultural systems and harvest methods within boreal mixedwood forests if conservation of small mammal species diversity in these areas is of concern. Some species, such asPhenacomys intermedius (heather voles), Sorex hoyi (pygmy shrews), and Glaucomys sabrinus, were more common in this mixedwood forest than expected so they could be of particular importance in boreal mixedwood management The variability in species abundance observed among the replicates used during this work demonstrates the importance of replicating the timber harvest treatments being investigated during such projects. The conclusions from this research could have been much different if treatments had not been replicated. Also demonstrated was the importance of using several different trapping methods when assessing the abundance, richness, diversity and composition of small mammal species in a community as some species were captured by only one trapping method during this project.