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UBC Theses and Dissertations

Biodiversity and land management from concept to practice Daust, David Kurt


The Canadian government is committed to conserving biodiversity. This thesis asks which landscape patterns will best conserve biodiversity in managed forests in British Columbia. First, I define an appropriate measurement of biodiversity; then, I develop a decision support tool to assess the impacts of planned management on biodiversity, illustrated with a case study; and finally, I provide options for the amount and pattern of old forest to preserve. Biodiversity can be measured at gene, species and ecosystem levels. Ecosystems provide the best measurement for forest managers. Ecosystems are a comprehensive measurement over large temporal and spatial scales, they develop predictably over time, and they are directly linked to the land. A coarse ecosystem approach must be accompanied by attention to certain species. Research must address the relationship between biodiversity and ecosystems and must help establish goals for management. I develop decision support software (SJMFOR) which simulates effects of forest management and stand development in 5,000 to 50,000 ha forests, calculates landscape composition and ecosystem pattern and predicts habitat distributions for selected species. In a case study, the low-profit management plan better conserves biodiversity, generating more old forest, larger patches and less edge habitat than the high-profit plan. I explore the general relationship between animal spatial requirements (home range, dispersal, and viable population size) and landscape pattern (patch size and abundance) using a scale-independent model. Home range size limits landscape suitability when patch size is smaller than home range size, and dispersal limits suitability when patch size exceeds 10 times home range size. Decreasing habitat abundance increases inter-patch distance, limiting dispersal. Landscape connectivity reflects threshold effects which depend on habitat abundance. First, landscapes are either mostly connected or mostly unconnected by dispersal, suggesting that population decline may occur without warning. Second, small habitat patches merge to form large contiguous areas at approximately 40% habitat abundance (given the assumptions used in the model). When habitat abundance is less than 40%, large patches or mixed patch sizes are good management options. When habitat abundance exceeds 40%, patch size is less important.

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