Mitigating the effects of climate change on lodgepole pine site height in British Columbia, Canada, with a transfer function

Abstract

Provenance trials provide an opportunity to develop transfer functions that can be used to assess the effects of climate change on tree growth. A transfer function is available for lodgepole pine (Pinus contorta var. latifolia) in British Columbia, Canada, that predicts relative height (site height of a population divided by the site height of the local population) as a function of mean annual temperature transfer distance and mean annual temperature of the provenance. This model is modified to improve its fit and address some deficiencies. A dataset consisting of 2276 height observations from 136 populations planted at 40 test sites was fitted to a two-variable power/exponential function. Mean coldest month temperature and mean summer precipitation transfer distances were the predictor variables, and relative height at the age of 35 was the response variable. The transfer function was linked to a lodgepole pine height-age model to create a dynamic system that can be used to evaluate the effect of climate change on site height growth. The system can then be used to mitigate the effect of climate change on lodgepole pine site height growth by determining the expected height of seed from various provenances at the end of the rotation and selecting the optimal seed source. For an example stand, climate change is expected to reduce site height by ∼0.77 m over an 80-year rotation. However, this reduction can be fully mitigated by planting the optimal seed source.