Response of northern populations of black spruce and jack pine to southward seed transfers: Implications for climate change

A variety of responses to climate change have been reported for northern tree populations, primarily from tree-ring and satellite-based studies. Here we employ provenance data to examine growth and survival responses of northern populations (defined here as those occurring north of 52oN) of black spruce (Picea mariana) and Jack pine (Pinus banksiana) to southward seed transfers – a space for time substitution that affords insights into potential climate change responses by these important northern tree species. Based on previous work, we anticipated relatively flat response curves that peak at much warmer temperatures than those found at seed source origin. These expectations were generally met for growth-related responses, with peak growth associated with seed transfers to environments 2.2oC and 3.6oC warmer than seed source origin for black spruce and jack pine, respectively. These findings imply that northern tree populations harbor a significant amount of resilience to climate warmi...