Douglas B. Ransome

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

Abstract Coarse woody debris (CWD) from forest harvesting and salvage wood from wildfire and insect outbreaks provide habitat for an array of forest-floor small mammal species and some of their mammalian predators. Because forest clear-cutting reduces abundance of many mammal species, strategic management of postharvest debris could help maintain abundance and diversity of forest mammals on harvested sites. We tested hypotheses that abundance and species diversity of forest-floor small mammals would be lower on conventional clear-cuts than in uncut forest; abundance and species diversity of forest-floor small mammals and relative activity and species richness of winter mammals would be higher on clear-cut sites with woody debris arranged in large piles or windrows than a dispersed treatment of debris. Small mammals were intensively livetrapped, and winter mammals snow-tracked, from 2007 to 2009 in replicated (n = 3) woody debris treatments of dispersed, piles, windrows, and uncut mature forest at 3 study areas in south-central British Columbia, Canada. We captured all 9 species of forest-floor small mammals. Compared with uncut forest, clear-cutting had no effect on mean total abundance of the small-mammal community, and species richness and diversity were either similar or higher. With respect to habitat preference, generalist species increased while specialist species declined. Habitat structures of large piles and windrows of woody debris on clear-cuts dramatically ameliorated these responses. On the basis of track counts, relative activity and species richness of winter mammals were enhanced by these structures, but the response was species specific. This is the 1st investigation showing significant increases in abundance and species diversity of forest-floor small mammals associated with constructed piles and windrows of postharvest woody debris on clear-cuts. Large-scale CWD structures as piles or windrows have clear conservation implications for mammals in commercial forest landscapes.

Silviculture and Wildlife: Snowshoe Hare Abundance across a Successional Sequence of Natural and Intensively Managed Forests

We tested the hypotheses H1 that relative habitat use by snowshoe hares (Lepus americanus) would have a bimodal distribution with the highest abundance in young lodgepole pine (Pinus contorta) stands (both managed and unmanaged), minimal numbers in mature forests, and moderate abundance in old-growth forests and H2 that habitat use would increase in response to enhanced stand attributes from PCT (precommercial thinning) and fertilization treatments. Habitat use was measured by counts of fecal pellets of hares from 1999 to 2003 in forest stands in south-central British Columbia, Canada. Our results did not support the bimodal distribution of hares among coniferous stands, such that old-growth stands, at least in our region, do not provide sufficient habitat for hare populations. High-density (5000 to 13000 stems/ha) unthinned young lodgepole pine stands provide optimum habitat for hares in terms of overstory and stand structure. Thinned and fertilized stands may also provide habitat, particularly at densities ≤1000 stems/ha, and over time as understory conifers develop. Managed stands provided habitat for hares at the same level as mature stands, at 6–10 years after PCT. Maintenance of a range of managed and unmanaged stands in a landscape mosaic would be ideal for integration of silvicultural and wildlife management goals.

Old-growth attributes in intensively managed forests: integration of stand productivity with mammal diversity

Management of forested landscapes for biological diversity is a major objective across North America. Perhaps the greatest potential to diversify future forests lies in the vast areas of young second-growth stands which may be managed silviculturally to accelerate ecosystem development. Lodgepole pine (Pinus contorta) is the dominant tree species comprising these young forests across the interior lands of the Pacific Northwest. Heavily thinned pine stands appear to develop some old-growth structural attributes such as large diameter trees, crowns, and structurally diverse vegetative communities. Three study areas near Penticton, Kamloops,and Prince George B.C. cover three forest ecological zones and are unique in that thinning treatments were conducted at operational scales relevant to wildlife habitat and population dynamics. Each replicate study area had three stands thinned to densities of 500 (low), 1000 (medium), and 2000 (high) stems/ha in 1988, with an unthinned young pine and old-growth pine stand for comparison. Crown volume index (biomass) of herbs was highest in the thinned stands, but there was no difference among stands for shrubs and trees. Mean species richness and diversity of herbs, shrubs, and trees were similar among stands. Total species diversity of vascular plants was highest in the lowand high-density stands. Mean structural diversity, in terms of richness of height classes (or layers of vegetation), of shrubs and trees tended to be greatest in the thinned stands. Mean abundance of southern red-backed voles (Clethrionomys gapperi) was significantly different among stands, with highest numbers of this microtine in old-growth stands. Mean abundance of red squirrels (Tamiasciurus hudsonicus) was similar among stands overall, but at Penticton and Kamloops was highest in the old-growth. Northern flying squirrels (Glaucomys sabrinus) were at higher numbers in the high-density than unthinned or old-growth stands; and abundance of this sciurid was lowest in the low-density stands.