Precommercial Thinning Reduces Snowshoe Hare Abundance in the Short Term

Abstract

Management of young forests is not often considered in conservation plans, but young forests provide habitat for some species of conservation concern. Snowshoe hares (Lepus americanus), critical prey of forest carnivores including the United States federally threatened Canada lynx (Lynx canadensis), can be abundant in young montane and subalpine forests with densely spaced saplings and shrub cover. Precommercial thinning (PCT) is a silvicultural technique that reduces sapling and shrub density on young forest stands. We tested for effects of PCT on snowshoe hare abundance for 2 years after experimental treatment at 3 replicate study areas. We also tested the effectiveness of a precommercial thinning with reserves (PCT‐R) prescription, where 20% of the total stand was retained in uncut quarter‐hectare patches. All stands were in montane—subalpine coniferous forests of western Montana, USA, where there is a persistent population of Canada lynx. Posttreatment changes in abundance were strongly negative on stands treated with standard PCT prescriptions (100% of the stand was treated), relative to both controls and stands treated with PCT‐R. Trapping, snowtrack, and winter fecal‐pellet indices indicated that snowshoe hares used the quarter‐ha retention patches more than thinned portions of the PCT‐R‐treated stands in winter. We suggest that managing forest landscapes for high snowshoe hare abundance will require adoption of silvicultural techniques like PCT‐R for stands that will be thinned, in addition to conservation of structurally valuable early and late‐successional forest stands.

Complex effects of site preparation and harvest on snowshoe hare abundance across a patchy forest landscape

“…This result conflicts with some previous findings (Ausband and Baty, 2005;Griffin and Mills, 2007;Homyack et al, 2007). Several possibilities may explain this discrepancy.…”

“…Partial harvest also may have a negative effect on hares (Fuller and Harrison 2005), but no research has investigated the relative impacts of partial and clearcut harvest, or whether the effect of partial harvest changes over time in the same manner as with clearcuts. Pre-commercial thinning has been found to have strongly negative effects (Ausband and Baty, 2005;Griffin and Mills, 2007;Homyack et al, 2007) or virtually no effect (Etcheverry et al, 2005;Sullivan et al, 2010) on snowshoe hares, and this variability may be related to time since stands were thinned or the intensity of thinning (Sullivan et al, 2010). Response of hares to site preparation activities is less well known, but also appears to be highly variable (Sullivan and Moses, 1986;de Bellefeuille et al, 1998).…”

Biodiversity response to intensive biomass production from forest thinning in North American forests – A meta-analysis

“…Despite the generally positive response by mammals to forest thinning, some direct and indirect effects of forest thinning on species of conservation concern may warrant further review (e.g. northern flying squirrel habitat connectivity and food resources [Carey, 2000;Gomez et al, 2005] and snowshoe hare/Canada lynx population dynamics [Griffin and Mills, 2007;Hodges, 2000a,b;Homyack et al, 2007]). …”

Effects of stand density on ecosystem properties of subalpine forests in the southern Rocky Mountains, USA

“…Furthermore, the impacts of stand density on ecological processes, including insect outbreaks, are not well understood for high elevation ecosystems (Fettig et al, 2007). While many processes are likely to operate similarly to lower elevation, fire-adapted forests, variations in species composition and abiotic factors such as climate, length of growing season, and phenology may lead to significant differences in ecological outcomes (e.g., Griffin and Mills, 2007).…”