UBC Theses and Dissertations
Of mice and moose : small and large mammal responses to a gradient of forest harvesting intensities across interior British Columbia Constantinou, Alexia Catherine
British Columbia’s interior forests have been heavily logged, burnt and subject to beetle outbreaks for decades. The compounding effects of these disturbances on wildlife and their habitat must be considered. Partial retention forest harvesting may be a method that could mitigate some of the negative effects of clearcut harvesting on wildlife. However, tests of the effects of partial harvests on ecosystem patterns and processes in different contexts are needed. From December 2018 and June 2020, we conducted live trapping for small mammals and camera trapping for medium-to-large-bodied mammals to estimate species diversity, population density, habitat use, and behaviours across different forest harvesting practices across a 900 km gradient in John Prince Research Forest, Alex Fraser Research Forest, and Jaffray (east Kootenays), BC. We detected 7 small mammal species, with diversity highest in the control (mean Shannon Index = 1.01, SE = 0.14) and partial retention treatments (means = 0.99, 0.98; SE = 0.17, 0.17) and significantly lower in the seed tree treatment (mean = 0.63, standard error = 0.17, p-value = 0.02). Population densities of North American deer mouse (Peromyscus maniculatus) and Southern red-backed vole (Myodes gapperi) estimated with spatially explicit capture-recapture models highlight the importance of partial harvest practices that maintain sufficient cover to support a higher diversity of small mammals and higher densities of forest specialists. Our medium- to large-bodied mammal diversity analysis suggests that the regional environmental context had a stronger effect on mammal communities than local-scale differences in harvesting practices. Vegetation productivity measured with normalized difference vegetation index was a more important predictor of habitat use for ungulates than harvest treatment, potentially due to the importance of forage availability. Across both small and large mammals, responses to forest harvesting were variable; several species used partial harvests more than clearcuts. Forest practices should consider broader implementation of partial harvests to provide suitable habitats for a broader range of species. More experimental approaches to forest operations are needed across larger spatial scales, such as adaptive management of forest practices with rigorous wildlife monitoring to ensure ecological objectives are met.
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