Sensitivity of western redcedar to climate and western hemlock looper in British Columbia's inland temperate rainforest.

The inland temperate rainforest of British Columbia is a unique forest type dominated by large western redcedar. Uncertainty surrounding resilience of this forest to climate change and outbreaks of western hemlock looper makes development of management and conservation strategies challenging. Western redcedar trees were sampled at paired low and higher elevation sites, on north and south-facing aspects. Western redcedar growth was positively correlated with January temperature and growing season precipitation, and was negatively correlated with June temperature. Reconstruction of western hemlock looper outbreaks demonstrated that successive years of warm, dry spring seasonal conditions preceded outbreaks, and the mean return interval was 36.5 years. Western redcedar growth responded negatively to the same climate factors that were associated with looper outbreaks. Under a warmer and drier climate scenario, looper outbreaks are expected to increase in frequency, and western redcedar may not be able to survive defoliation as well as it has historically. --Leaf i.