Stand-level Attributes of Snowshoe Hare (Lepus americanus) Habitat in a Post-Fire Trembling Aspen (Populus tremuloides) Chronosequence in Central Yukon

Résumé

Large-scale fires are anticipated to increase in frequency in the boreal forest under global climate warming scenarios. To understand concomitant responses by wildlife to fire-induced habitat changes, fecal pellet counts were used to assess Snowshoe Hare (Lepus americanus) use of four age-classes of boreal forest after fire in central Yukon, Canada. Use of stands across a chronosequence of 8–177 years was bimodal. Post-fire Trembling Aspen (Populus tremuloides) stands ≤20 years old had greater densities of Snowshoe Hare pellets (median 156 pellets/dam²) than Trembling Aspen stands 21–70 years old, mixedwood stands 71–120 years old (<17 pellets/dam²), or Western White Spruce (Picea albertiana) -dominated stands 121–170 years old (71 pellets/dam²). Forty stand-level compositional and structural variables were assessed as possible predictors of Snowshoe Hare pellet densities. Multidimensional scaling was used to identify variables (n = 10) that were most strongly related to pellet densities and was followed by multiple regression. Canopy cover of Trembling Aspen <50 cm tall and Western White Spruce ≤1 m tall, and deadfall depth, in combination, were the best estimators of Snowshoe Hare pellet densities among stands in the chronosequence (P <0.001, 64.5% variance explained). Although Trembling Aspen <50 cm tall explained the most variance, its canopy cover did not exceed 10%. More Trembling Aspen cover <50 cm tall and greater deadfall depths within the chronosequence were associated with stands ≤20 years old. Peak Snowshoe Hare use occurred in early (≤20 years old) rather than mid-successional (21–120 years old) stands, contrary to use patterns reported elsewhere. The lack of tall understory shrubs likely limited the use of mid-successional stands.