Effects of forest management on dead wood supply and implications for biodiversity

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Woody debris (WD), which includes both downed wood and snags, is thought to be an important resource for many organisms, but one that is especially sensitive to forest management practices. Although the importance of WD for biodiversity is widely recognized, and indeed WD retention guidelines to sustain wildlife habitat and ecological function are ubiquitous in forest management planning, their basis and effectiveness at present is not fully understood. The proposed research will use manipulative field studies and computer-based modelling to address these gaps in boreal northeastern Ontario. Specific objectives will be to: 1) undertake field studies in areas of different levels of downed WD removal to identify key indicator taxa and to better understand habitat supply relationships (with a focus on key groups of saproxylic insects [those dependent upon dead and dying wood], fungi, and small mammal fauna) and 2) parameterize a modelling framework in which short- and long-term effects of particular management practices on WD habitat supply can be investigated. Key hypotheses to be tested include: 1) reductions in the local supply of WD will result in reduced colonization among certain groups of organisms, with net reduction of species richness of WD; 2) small mammal population densities and productivity, movements, and foraging behaviour will vary in response to variation in the quantity and quality of WD; and 3) existing guidelines for WD retention will prove inadequate for long-term, stand-level conservation of biodiversity in the face of new biomass demands. Field work will focus on reference old-growth plots, conventional and biomass clearcuts, and a manipulative experiment in which all, one-half, or no downed WD was removed from 40-65 year-old, 2.25 ha study plots. The research is of particular significance in that it is: 1) precedent setting in that it makes use of a powerful experimental design and novel techniques to provide critical information on biodiversity indicators and WD supply thresholds and 2) will examine the relationship between harvesting practices and long-term WD habitat supply, including in operational-scale biofuel harvests.