A warming climate will change the areas where tree populations are adapted to live, potentially too quickly for trees to migrate in track with this change. Although landowners and government agencies have long been practicing reforestation by collecting and transferring forest tree seed, the existing processes for deciding where forest tree seeds can be successfully planted do not take climate change into account.

Seed transfer guidelines help land managers decide how far tree seed can safely be moved from its origin without risking trees’ growth and survival. Long-term field tests tell us that in the past, seed planted further from its source performed worse in terms of growth, survival and adaptability (i.e., maladaptation) because of climatic differences between the seed source and planting site. However, as the climate changes, we will likely need to source seed from further away to maintain climate matches, since formerly “safe” seed movement will no longer match the climate of the planting site.

Using recent advances in climate modeling, this project aims to climatically match seed collection zones and seed transfer zones in the Pacific Northwest. Existing tools and resources will contribute to the success of this project. The Pacific Northwest Tree Improvement Research Cooperative (PNWTIRC) collaborated on the development of the Seedlot Selection Tool (SST) with Oregon State University, the US Forest Service and the Conservation Biology Institute (CBI). The SST is an online tool designed to help land managers match seedlots and planting sites. In addition to facilitating seed transfer in current climates, the SST also includes limited options for evaluating assisted migration based on future climates.

This project will use the climate data and seed zones that are already in the SST, as well as additional seed zones of interest to stakeholders, to develop a new system that better accounts for climate change when matching seed collection zones and planting zones. The collaborative, region-wide approach to this project is crucial, since helping forests adapt to climate change will likely require seed transfer across state boundaries and among organizations. This project will provide the information to practice climate-based seed transfer in the Pacific Northwest to enhance forest regeneration success, forest productivity and adaptation to climate change.