Warm Climate Opens Boreal Forest to Pine Beetles
Temperatures in boreal forests extending across Canada will soon be warm enough to accommodate mountain pine beetles. Until recently, cold winters confined the bark beetles to attacking trees west of the Rocky Mountains and south of the boreal forest. In British Columbia, the tiny insect recently killed over nine million hectares of mature lodgepole pine, and the devastating epidemic continues.
Since 1970, the amount of habitat in BC with optimal temperatures for the bark beetle has expanded by over 75% in response to a roughly 1 °C increase in average annual temperature. This has permitted the beetles to move higher up mountainsides and northward, where they’ve found plenty of prime pine. Experience in BC shows that the beetles rapidly move into new areas once winter weather allows their survival.
Under the most conservative of climate change forecasts, beetle survival in the boreal forest will no longer be thwarted by cold winters. The forecast is based on a 1% annual increase in atmospheric CO2 causing mean global temperatures to increase 1.7 °C by 2050. Jack pine, a mountain pine beetle host, forms a major component of the boreal forest.
The current infestation in central BC is so massive, that winds blow clouds of beetles across hundreds of kilometres. By 2002, the tree-boring insects had jumped the Rocky Mountains to establish in western Alberta. From there, a band of hybrid lodgepole and jack pines lying between Grande Prairie and Edmonton can take the beetles across western Alberta and into the boreal forest.
Jack pines sprawl from central Alberta and the Northwest Territories to Canada’s maritime provinces and the north-central United States. Climatic modelling shows that most of jack pine’s range will be beetle-friendly by 2070, and much sooner in central Alberta.
A.L. Carroll, J. Régnière, J.A. Logan, S.W. Taylor, B. Bentz and J.A. Powell. 2006. Impacts of Climate Change on Range Expansion by the Mountain Pine Beetle. Mountain Pine Beetle Initiative Working Paper 2006-14. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre. Victoria, BC.