Forest Clearing Widely Transforms Wildlife Habitat
Agriculture, forestry and especially oil and gas development have recently flourished across the forested landscape of northeastern British Columbia. In their wake, wildlife habitat has been restructured at an exponential rate.
A University of British Columbia study examined the cumulative impacts of these disparate industries by comparing two snapshots, from 1970 and 2005, of vegetation cover and development. On one 410,000-hectare (1600 square miles) area in the Peace-Moberly region, industrial activity cleared about 10,000 hectares of boreal forest over the 35 years.
Commercial timber harvesting accounted for half the cut forest, and 1000 hectares were cleared for farming. Another 4000 hectares were converted to roads and seismic lines, that sliced and diced the remaining forest.
Although resource development cleared trees from 2.5% of the area, its impact on wildlife habitat reached much farther. The activity left a piecemeal landscape of forest fragments and clearings. For all types and ages of forest, patches declined in average size and became more numerous. The change was most pronounced for interior forest that's located away from the edges of clearings.
The entire region has seen an 89% increase in edge habitat and a 47% increase in open, unforested landscape. Interior forest ecosystems at the same time declined by 30%.
The break-up of contiguous forest by cutblocks, fields, roads and cutlines created habitat for some animals, but destroyed it for others. Many more wildlife species gained rather than lost habitat and the net result is a greater richness of species across the landscape. The effect is particularly pronounced where development was most concentrated and had created edges in boreal white and black spruce forests.
The biggest beneficiaries are broad-winged hawks and Le Conte's sparrows, for whom the suitable terrain has nearly tripled. Many other birds have also gained habitat in the region, as have wood bison and Rocky Mountain bighorn sheep.
Meanwhile, species that need large tracts of mature and old-growth coniferous forests have fewer places to live as a result of industrial clearing. Environments appropriate for wolverines, fishers, pine martens, moose and woodland caribou declined. Among those most affected are grizzly bears, which in the 35 years lost 30% of their Peace-Moberly habitat.
Craig R. Nitschke. 2008. The cumulative effects of resource development on biodiversity and ecological integrity in the Peace-Moberly region of Northeast British Columbia, Canada. Biodiversity and Conservation. In press.