Small-mammal response to group-selection silvicultural systems in Engelmann spruce – subalpine fir forests 14 years postharvest

Abstract

Concerns about the impacts of clear-cut harvesting on ecosystem components in subalpine forests have generated a variety of alternative silvicultural systems in high-elevation forests in western North America. We examined responses of forest-floor small mammals, 14 years posttreatment, in four replicate units, uncut forest, a 1.0 ha group-selection cut, a large (>30 ha) clearcut, and the edge between the group-selection cut and uncut forest, in the Engelmann Spruce ( Picea engelmannii Parry ex Engelm.) – Subalpine Fir ( Abies lasiocarpa (Hook.) Nutt.) biogeoclimatic zone in south-central British Columbia, Canada. Populations of small mammals were livetrapped during five sessions from June to September 2006. The mean abundance of southern red-backed voles ( Myodes gapperi Vigors) was significantly lower on large clearcuts than in uncut old-growth forests, with intermediate numbers in 1 ha cuts. The opposite trend was found for dusky shrews ( Sorex monticolus Merriam), while there was no significant difference in mean abundance of deer mice ( Peromyscus maniculatus Wagner) among treatments. Trappability, proportion of adult females breeding, and rate of survival of red-backed voles and deer mice were similar among treatments. Our results suggest that group-selection silviculture conducted in subalpine forests may have fewer negative impacts on the small-mammal community than large clearcuts.

If we build habitat, will they come? Woody debris structures and conservation of forest mammals

“…CWD structures as piles or windrows have clear conservation implications for the native forest-floor small-mammal community. We captured all 9 common species and the persistence of the red-backed vole was particularly important, as this species disappears from clear-cuts and does not reappear in regenerated stands for decades (Ransome et al 2009;St-Laurent et al 2008;Sullivan et al 2011). The red-backed vole is a principal prey for marten, which also is uncommon on recently logged sites, and is a species of concern in Canada and other parts of North America (Thompson 1991).…”

What are the Environmental Consequences of Using Silviculturally Effective Forest Vegetation Management Treatments?

“…Some species do well in clearcuts, but others that rely on fruiting bodies of ectomycorrhizal fungi may not (Ransome et al .2009). …”

“…Research suggests that harvesting systems and physical treatments such as brush saw and mechanical site preparation can, on specific sites, decrease specific small mammal populations in the short and longer term due to the indirect effect of changes in habitat (Steventon et al 1998, Fisher and Wilkinson 2005, Ransome et al 2009). Some small mammals are directly affected by physical treatments, that is, they are frightened away by the noise of the machines, but this is temporary (Fortier et al 2005).…”

Spatial Organization of Northern Flying Squirrels,Glaucomys sabrinus: Territoriality in Females?

“…Similarly, in British Columbia, Canada, this species was more abundant in mature stands (Ransome et al 2004). Voles (Microtus) tend to increase in abundance or capture frequency in thinned sites (Sullivan and Sullivan 2001;Suzuki and Hayes 2003;Gitzen et al 2007), whereas Peromyscus may respond to thinning by increasing in abundance (Suzuki and Hayes 2003;Gitzen et al 2007) or with no discernible change (Ransome et al 2009). In the southern Washington Cascades, small experimental canopy gaps had positive influences on most forest species, likely reflecting an increase in low vegetative cover (Gitzen and West 2002).…”

“…In the southern Washington Cascades, small experimental canopy gaps had positive influences on most forest species, likely reflecting an increase in low vegetative cover (Gitzen and West 2002). In contrast, red-backed voles (M. californicus and Myodes gapperi) generally decline following thinning treatments (Suzuki and Hayes 2003;Gitzen et al 2007;Sullivan et al 2008;Ransome et al 2009). Chipmunks often respond positively to thinning (Carey 2001;Carey and Wilson 2001), likely reflecting increased shrub development and associated cover and food.…”