Expected effects of climate change on forest disturbance regimes in British Columbia

In this article we summarize the changes to forest disturbance regimes and forest damage that are projected to emerge under a changing climate in British Columbia (BC). We focus on regionally-specific expectations so that land managers can take pro-active steps to avoid or adapt to future conditions. While some projections are based on extrapolations of recent multi decadal trends, most are based on global climate models (GCMs) that utilize a range of scenarios for possible atmospheric greenhouse gas emission trajectories over the next century. Regardless of the models or emission scenarios used, it is universally expected that BC will experience warmer air temperatures. Projections for precipitation are more variable, ranging from slight decreases in some regions to substantial increases in others, which have different effects on disturbance projections. Forest fires are expected to be more frequent and more intense in the southern half of the province and in the Taiga Plains, but less important in other portions of the province. Forest insects and fungal pathogens are expected to more fully occupy the current range of their host tree species and expand ranges northward and to higher elevations along with their hosts. More frequent and more detrimental pest outbreaks are expected in some regions when several years of favourable weather align, which is more likely under current and projected climate trends. Wind damage, floods, and landslides can be expected to increase on terrain where they are already a risk factor. For many agents of tree mortality, an expansion or shifting of the seasonal window of activity is expected, but these changes vary among regions within BC. The prediction of future forest disturbance regimes is in its infancy, requiring a much more concerted effort in compiling both empirical and simulated data, but managers may wish to adjust plans accordingly where there is consensus among projections.