Collaborative Research: Fire and water in the West: Trait-based demographic dynamics of forest communities

About This Grant

Severe drought and explosive forest fires have become a normal feature of life for communities of people living in the western United States. Tree species have evolved adaptations to survive and grow even during times of drought and when fires burn. However, increasingly intense drought and severe fires are pushing trees to their limits. A major challenge for forest ecologists is to predict how western forests will change, but it is currently not known which species will thrive or decline. This research will identify the key adaptations that will help determine the fate of western tree species by measuring how species tolerate drought and fire. The researchers will then predict how forests could change over time. Teaching resources for K-12 will be made publicly available through the Global Vegetation Project to demonstrate the impacts of drought and fire on western forests. This research provides a glimpse into the future to help people prepare for how western forests will respond to more fire and less water and provide guidance to forest managers that steward our nation’s forest resources. Drought and fire are driving widespread tree mortality and limiting tree recruitment in forests across the western United States. Forest ecologists do not fully understand which combinations of drought and fire adaptations will drive changes in tree species abundances in the future, and large gaps in existing functional trait databases prevent researchers from leveraging new analytical frameworks that integrate traits into demographic models. The aims of this project are to 1) quantify adaptive traits of tree species in the West and publish results in an open-access database, and 2) quantify the effects of traits on demographic rates that shape the contours of fitness landscapes in response to changing drought and fire. To achieve these aims, the researchers will measure and compile a comprehensive data set of traits on >100 tree species that capture key dimensions of functional strategies that evolved in response to water limitation and fire regimes, with a focus on bark thickness allometry, resprouting ability, xylem vulnerability to embolism, and rooting depth growth rate. These trait data will be combined with demographic data from the national forest inventory to test our mechanistic understanding of the demographic consequences of traits in multi-species forest communities using structured population models. The goal of this research is to provide a functional explanation for the widespread lack of forest recovery after fire in dry conditions. 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.