NSF Award
2222437
Climate trends and predictions in the northeastern U.S. include an increase in the frequency of mid-summer droughts. Although forest managers increasingly prioritize climate adaptation and assisted tree migration as management goals, their efforts are limited by information gaps because drought impacts on northeastern trees have not previously been a high research priority. Further, how trees adapt to drought may affect their vulnerability to other stressors such as extreme cold and spring frost damage, factors that will continue to be part of northeastern winters for decades to come. This research will improve understanding of how northeastern tree species respond to drought and how different drought adaptations affect their vulnerability to other climate stressors. This will be achieved by conducting extensive measurements of drought-related plant traits across many species and site conditions in the northeastern U.S. and at a site in Alabama that contains similar species at the southern end of their current range. Data will be collected using a novel method that greatly increases the number of tissue samples that can be processed. Results will be used to improve a forest simulation model that can help forest managers evaluate the outcomes of different management strategies. This work will receive guidance from a stakeholder advisory board consisting of forest managers, conservation groups and others invested in the future well-being of northeastern forests.<br/><br/>In the northeastern U.S., climate projections include an increase in the frequency of mid-summer droughts, and winters that are warmer overall, but with periodic infusions of arctic air that can cause late-spring freezes and damaging cold-stress. The ability to predict how forests will respond is limited by knowledge of inter- and intra-specific variation in plant traits that regulate tree responses to climatic stress and the degree to which they reflect environmental or evolutionary drivers. This research addresses these uncertainties by (1) performing an in-depth study of the variation and drivers of turgor loss point—a key determinant of tree-level drought response—as well as associated cold and drought resilience traits and (2) identifying the relationship between drought and cold resilience in the individuals studied. The work will involve extensive field measurements of leaf osmotic potential and turgor loss point, associated physiological plant traits and rooting depth, as well as a manipulative experiment on genetically identical individuals. Sampling will be conducted at sites across the northeastern U.S. and at a site in Alabama with similar species at the southern end of their range. The work will be guided by an advisory board made of people invested in the forest (e.g., forest managers, conservation groups and indigenous community members). Results will be used to improve an ecosystem model that simulates forest growth under a range of climate and forest management scenarios. This will benefit a range of management objectives that prioritize climate resilience and assisted tree migration.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
