Adapting reforestation programs to observed and projected climate change.

Reforestation programs generally rely on locally collected seed, which is assumed to be adapted to local climate conditions. To adapt to a changing climate, current methods of choosing reforestation seed should be revised to align seed movement with the magnitude and direction of climate change. In a case study for the province of Alberta, Canada, we analyzed options for seed transfer in white spruce (Picea glauca (Moench) Voss) based on the growth of more than 1000 white spruce genotypes spanning about 40 years of field testing. We used multivariate statistics with nine climate variables to match seed source and planting site climates to improve tree growth under the past and expected future climate conditions. We found that seed transfers can improve growth in some cases. However, the climate change vector does not always align with geographic gradients, which makes finding well-adapted seed sources difficult or impossible. This issue may partially be addressed by relying on additional silvicultural adaptation options to address climate change. Our case study provides a methodological template of how jurisdictions can determine the feasibility as well as magnitude and direction of assisted migration prescriptions to adapt their reforestation programs to new planting environments. [ABSTRACT FROM AUTHOR]