Boreal forest provenance tests used to predict optimal growth and response to climate change. 1. Jack pine

Abstract

Height, diameter, and survival data were obtained from 16 rangewide jack pine provenance trials in eastern Canada and the United States. Climate data for each seed source and test location were used to relate height growth to 72 climate variables. Population response functions based on August minimum and January maximum temperatures were developed to predict climate values maximizing height growth for individual seed sources. Site transfer functions based on March precipitation and December minimum temperature were developed to predict climate values maximizing height growth for test locations. Contour lines representing optimal performance were fitted to current (1971–2000) and future (2041–2070) climate grids. Optimal growth is currently achieved between 46°N and 47°N latitude for most seed sources. Future temperature increases are expected to cause a northward shift of the optimal habitat by approximately 2°. Northern sources are growing at temperatures below optimum and would benefit from warmer environments provided other environmental factors do not become limiting. Central sources are growing at close to optimum and will be negatively affected by increased temperatures in the future. Southern sources performed better in cooler environments, and warmer temperatures may cause significant height growth loss and the potential extirpation of these populations.