Avian Conservation and Ecology (Jun 2007)
Selecting Focal Songbird Species for Biodiversity Conservation Assessment: Response to Forest Cover Amount and Configuration
Abstract
Conservation of biodiversity is now a firmly entrenched objective of sustainable forest management, and emulating natural disturbance has been widely adopted as a conservation strategy. Yet the foundation for this approach is still very much a hypothesis based on first principles, and there has been little rigorous testing of the approach. In addition, practical constraints mean that the full range and character of natural patterns can never be implemented, so decisions must still be made in setting forest management targets and levels. An alternative, but complementary approach is to select a focal group of species and use their habitat requirements to define the range of conditions that should be maintained on the landscape. In this study, I used a balanced factorial sample design to test the effect of landscape vs. local scale factors for explaining relative abundance of 30 forest songbird species in boreal Ontario, and then examined components of variance, and used multivariate analysis and logistic regression to describe these relationships in more detail. Based on statistically defendable inferences and habitat model coefficients, 13 species were selected, with habitat associations ranging from high to low edge density, homogeneous to heterogeneous forest matrix, hardwood to softwood dominated overstory, young to old stands, and open to closed canopy. I found that variations in amount and configuration of mature forest cover had relatively little influence on the overall boreal forest songbird community, but that individual species differ in their response to these variables. To be successful, biodiversity conservation strategies must emulate the patterns created through natural disturbance by maintaining the full range of forest cover homogeneity and heterogeneity on the landscape. The habitat requirements for Alder Flycatcher, Black-and-white Warbler, Bay-breasted Warbler, Blackburnian Warbler, Brown Creeper, Common Yellowthroat, Chestnut-sided Warbler, Least Flycatcher, Ovenbird, Red-breasted Nuthatch, Red-eyed Vireo, Winter Wren, and White-throated Sparrow describe a broad range of habitat conditions that, at a minimum, describe necessary coarse-filter conditions to sustain the boreal songbird community in Ontario. This suite of species can also serve in developing a "bioassay" to evaluate the effectiveness of forest policy to conserve biodiversity through emulation of natural disturbance.
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