Radial-growth response of mountain hemlock (Tsuga mertensiana) trees to climate variations along a longitudinal transect, northwestern British Columbia, Canada

This research was initiated to develop an understanding of the differential radial-growth response of mature mountain hemlock (Tsuga mertensiana) trees located along a line of latitude in northwestern British Columbia. Increment core samples were collected from mountain hemlock stands located at five high-elevation sites between the Queen Charlotte Islands and Smithers. Tree ring-width index chronologies were compared to historical precipitation and air temperature data from four climate stations, as well as the El Nino Southern Oscillation and the Pacific Decadal Oscillation. No two mountain hemlock stands had the same growth response to monthly air temperature and precipitation, indicating that the trees are responding to site-specific limiting factors. The response to El Nino Southern Oscillation events was consistent along the transect, while the response to Pacific Decadal Oscillation phase changes was greatest at coastal sites and decreased towards the interior.