Effects of partial harvesting on vertebrate species associated with late-successional forests in Ontario’s boreal region

Abstract

In the boreal forest region, partial-harvest silviculture has been garnering increasing interest as a means of maintaining wildlife species and habitat structure associated with late-successional forests. If late-successional species can find suitable habitat in partially harvested stands with a given level of structural retention, then partial harvesting might represent a viable silvicultural tool for maintaining wildlife dependent on mature or old-forest habitat within managed stands over time. Here we summarize literature on the responses of late-successional amphibians, birds, and mammals in Ontario's boreal region to various intensities of partial harvesting. We assess species responses from comparisons of habitat use in harvested and unharvested stands; we do not explicitly consider impacts of partial harvesting applied over large areas across the landscape. At the stand scale, light-intensity harvesting (70% retention) negatively affects several passerine birds, as well as spruce grouse winter habitat, but most late-successional species (including all mammals and amphibians considered) appear to be tolerant of this level of habitat alteration. Moderate-intensity harvesting (50% retention) was found to reduce the abundance of about 40% of the species considered, particularly cavity-and snag-dependent species (martens, northern flying squirrels, owls) and passerine birds that forage or nest in the canopy and understory. Highintensity (30% retention) partial harvesting was found to provide unsuitable habitat for about one quarter of all late-successional species, including most forest raptors, pileated and black-backed woodpeckers, brown creepers, northern flying squirrels, and woodland caribou. Also, studies indicate that additional passerine bird species would decrease in abundance, as would small, moisture-dependent, terrestrial species such as short-tailed shrews, red-backed voles, and eastern red-backed salamanders. There is a need to strengthen our understanding of responses to partial harvesting for nonpasserine birds and large mammals, and to verify species responses through experimental studies within Ontario's boreal region.Key words: structural retention, selection, shelterwood, seed tree, cavities, snags, downed woody debris, habitat suitability, amphibians, birds, mammals, biodiversity, review RÉSUMÉ Dans la région de la forêt boréale, la sylviculture basée sur une récolte partielle a attiré de plus en plus d'attention en tant que moyen de préserver les espèces sauvages et la structure du milieu associé aux forêts de fin de succession. Si les espèces de fin de succession peuvent retrouver un milieu adéquat dans les peuplements ayant subi une coupe partielle qui préserve à un niveau donné la structure du milieu, alors la coupe partielle pourrait constituer un outil sylvicole viable pour la préservation de la faune dépendante d'une forêt mûre ou d'une vieille forêt retrouvée au cours du temps parmi les peuplements aménagés. Nous avons résumé dans cet article la littérature portant sur les ...

Partial cutting in old-growth boreal stands: An integrated experiment

“…In contrast, early-seral-stage species, such as White-throated Sparrow (Zonotrichia albicollis Gmelin), Tennessee Warbler (Vermivora peregrina A. Wilson), Dark-eyed Junco (Junco hyemalis L.), and American Robin (Turdus migratorius L.) were more abundant in CPRS and CPPTM (LeBlanc 2009. The effects of CPRS and CPPTM are consistent with previous observations that low retention levels (<30%) would negatively affect mature forest species (Harrison et al 2005, Vanderwel et al 2009). Harrison et al (2005) suggested that 50% retention should be sufficient for maintaining most mature forest species.…”

“…Harrison et al (2005) suggested that 50% retention should be sufficient for maintaining most mature forest species. Vanderwel et al (2009) suggested that some mature forest species, such as Brown Creeper, would still be affected by this retention level but that local extirpation would be unlikely. In our case, a 55% retention level appeared to be effective in maintaining old-growth species, including the Brown Creeper.…”

“…The main effect was a change in the relative abundance of Red-backed Voles (Myodes gapperi Vigors) and Deer Mice (Peromyscus maniculatus Wagner). The Red-backed Vole is generally associated with habitats that provide protective cover from predators and that satisfy their high demands for water (Vanderwel et al 2009). In our study, red-backed voles were most abundant in stands with high moss coverage, high vertical cover, and high conifer basal area, which are typical of high retention levels (Hodson et al 2010, i.e., uncut stands and selection cuts.…”

“…CPPTM thus appears to provide better moose habitat than CPRS. Moose benefits from increased browse availability associated with moderate-or heavy-intensity cuts (Vanderwel et al 2009). Selection cutting has been suggested as an approach for maintaining caribou (Vanderwel et al 2009), but the level of retention needs to be higher than in CPPTM.…”

Comparative effects of full-tree and tree-length shelterwood harvesting on residual tree damage and coarse woody debris volume in the Great Lakes – St. Lawrence forest

“…Retention of coarse woody material is an important part of sustaining forest productivity and biodiversity (Spies 1998, Shields et al 2007, Vanderwel et al 2009, OMNR 2010, though quantities vary considerably (Fig.. 4). Published volumes for CWD in northern hardwood and mixed forests of eastern North America show values ranging from 10.8 m 3 ha -1 to 136.7 m 3 ha -1 , and averaging 60.5 m 3 ha -1 (Fig.…”