Climate and productivity of major conifer species in the interior of British Columbia, Canada

Abstract

Lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.), interior spruce (including Picea glauca (Moench) Voss, P. engelmannii Parry ex. Engelm., P. glauca x engelmannii), and interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) are the most important commercial species in the interior of British Columbia. We develop statistical models to predict site index (a measure of site productivity) from climate for these species. Using data from 193 climate stations, we first developed models that predict mean annual temperature, mean temperature of the warmest and coldest months, number of frost-free days, and frost-free period from latitude, longitude, and elevation. With these models and the Parameter-elevation Regressions on Independent Slopes Model (used to predict mean annual and mean summer precipitation), we predict 10 climate attributes for site index plots of lodgepole pine, interior spruce, and interior Douglas-fir. These attributes are then used in regression models to estimate site index. The models allow us to investigate the current relationship between climate (particularly temperature and precipitation) and site productivity for these species. The productivity for all the species studied increased as temperature increased, with lodgepole pine exhibiting the greatest response. The productivity of lodgepole pine and interior Douglas-fir also increased with increasing precipitation, with interior Douglas-fir having a greater response than lodgepole pine. We discuss the application of the models in relation to the impact of climate change on site productivity.