Use of Wildlife Tree Patches by Forest Birds in the Sub-Boreal Spruce (SBS) Zone

Many wildlife species are dependent on habitat attributes within forest stands such as large live trees, standing dead trees, fallen logs, and understory shrubs. Standing dead trees (snags) are especially important because they are used by many species, such as bats, woodpeckers, and furbearers, for feeding and/or nesting. Forest harvesting and silvicultural practices can eliminate or significantly reduce many important habitat attributes. Consequently, management practices that maintain important habitat attributes within forest stands are an important component of conserving biological diversity in managed forests. on all cutblocks. The unharvested patches are intended to provide habitat attributes within cutblocks, and in the forests that later regenerate on those sites. Retaining unharvested patches provides several advantages over the alternative approach of trying to keep habitat attributes distributed across a cutblock. It is not acceptable to leave snags within harvested areas because they are a safety risk to forest workers. Snags can however be safely left within unharvested patches. Thus, retaining patches is the only way that existing snags can be left on cutblocks. In addition to maintaining existing snags, unharvested patches will also retain some large trees on the cutblock. Some of those trees will die during the subsequent rotation period and provide a source of new large diameter snags. Unharvested patches will also provide an undisturbed remnant of forest floor and understory plants that can serve as a refuge for species until the ecological conditions of the regenerating cutblock are suitable for those species to become re-established. Retaining unharvested patches is also consistent with the natural disturbance ecology of boreal and subboreal forests. These forests historically experienced large wildfires at fairly frequent intervals, but fires did not destroy all of the forest in their path. Wildfires usually skip some areas, resulting in scattered patches of unburned forest that comprise 5-15% of the burned area. Those unburned patches provide a source of mature forest habitat attributes within the burn, and within the young forest that regenerates on that site. Although WTP’s in new cutblocks may provide immediate habitat values, the primary reason for retaining WTP’s is to provide mature forest habitat attributes within the regenerated forest throughout the subsequent rotation period. Consequently, WTP’s are to be retained within the stand until at least the next rotation period. At that time, WTP’s may be left for another rotation, or they can be harvested and replaced with different WTP’s within the new cutblock. The Forest Practices Code Biodiversity Guidebook recommends various management practices to maintain habitat attributes within managed stands. The most important of those is the retention of unharvested patches of forest called Wildlife Tree Patches (WTP’s) Wildlife Tree Patches retained in clearcuts, and mature forest patches within young forest stands, provide valuable habitat for many forest bird species.