Assessing genetic variation of forest tree species at risk
SUMMARY:
Many forest tree species and populations face serious threats to their long-term viability, most seriously from insect and disease infestation and from the effects of climate change. To conserve the genetic foundation tree species need to survive and adapt in the face of these threats, forest management decisions must consider how genetic diversity is distributed across species’ ranges. I have worked to quantify the genetic variation of imperiled eastern forest tree species, evaluate threats to that genetic variation, and work to conserve it through on site (e.g., management) and off site (e.g., seed collection) activities. This work is an important part of efforts to maintain the ecological integrity of tree species that face serious threats to their long-term viability, most seriously from insect and disease infestation and from the effects of climate change. To conserve the genetic foundations that tree species need to survive and adapt in the face of these threats, forest management decisions must consider how genetic diversity is distributed across species’ ranges. Additionally, species restoration efforts require the collection and propagation of genetic material that effectively samples that species’ adaptive genetic variation.
Results from studies on these species influence management decisions. Characterization of the genetic diversity and structure of the two hemlock species is guiding the North Carolina State University-based Camcore conservation cooperative’s seed collections from genetically significant hemlock populations. After a ponderosa pine study uncovered evolutionary relationships among species varieties and assesses genetic variation of several small and isolated populations, the Bureau of Land Management utilized results for management activities in the western United States. The Forest Service’s National Forest System uses study results to help guide gene conservation and seed transfer strategies. The results from these studies have also been used to make more realistic predictions of future environmental suitability for ponderosa pine and eastern hemlock by generating separate projections for different evolutionary lineages within the species, each of which may have evolved to adapt to different environmental conditions.
I am also a leader and participant in the Future-Proofing Forests Genetics Team, a Federal, State, and academic partnership working to develop seed collection zones and seed transfer guidelines for the eastern U.S. This effort is necessary because appropriately sourced seed is critical for forest restoration but few species-specific seed collection and transfer zones (regions with homogenous environmental conditions in which plant materials can be effectively moved) and guidelines were previously available for the East. Seed transfer zones and guidelines can be developed for some species using provenance test and genomics data. For other species, generalized eastern seed collection zones, based on minimum temperatures and ecoregion designations (reflecting edaphic factors), can be used to define seed origin for reforestation or restoration work. These tools can also help minimize the risk that, because of climate change, trees used for production, restoration, reforestation, and afforestation will be maladapted to their planting sites.
Kevin Potter Ecology 