NSF Award
2128303
Extreme climate events, such as drought or wildfire, may occur in high frequency and/or in tandem. These extremes are likely to occur more frequently over the coming decades and will likely have more severe effects on natural and human landscapes than when extreme events occur alone. Many parts of southern Africa suffered the effects of compound extremes in 2015 and 2016 when drought and heavy wildlife use caused substantial declines in vegetative cover and mass wildlife mortality in national parks. Many areas are yet to fully recover. Ecosystem recovery after compound extremes is critical for maintaining important services that landscapes provide, such as wildlife habitat, food production, and carbon storage. The mechanisms behind recovery after extreme events are not well understood, although there is mounting evidence that the diversity of organisms (i.e., biodiversity) within ecosystems may be key. This award will experimentally impose compound extremes in a South African savanna and incorporate measured outcomes into computer models to understand how diversity of plant life controls ecosystem recovery after compound extremes. The information and tools created by this project will be important for land managers and policy makers to maximize the recovery potential of public and private lands through the promotion of biodiversity. Additionally, this project will provide important training and education opportunities for a diverse assemblage of people (local South African stakeholders, high school, undergraduate and graduate students, and postdoctoral scholars), and will prioritize advancement of diversity, equity, and inclusion in the sciences.<br/><br/>Currently, the importance of biodiversity for ecosystem recovery (i.e., resilience) is recognized at the community level, but the mechanisms underlying species diversity that can extend these concepts to other spatial and hierarchical scales are not well understood. Organismal traits provide a useful framework for understanding these mechanisms because the coordination of physiological, morphological, and anatomical characteristics determine the response of individuals to their environment; this facilitates scaling from organisms to populations, communities, and ecosystems using first principles. This study will first extend biodiversity-resilience ideas beyond simple species diversity by using methods to examine diversity of plant traits (e.g., functional dispersion). Second, it will scale biodiversity-resilience relationships from individual organisms, through populations and communities, to entire ecosystems. To these ends, this project will experimentally impose extreme drought, extreme grazing, and extreme fire, singly and in combination, in a South African savanna and determine (1) diversity of functional traits before, during, and after treatments to link with (2) responses of individuals, populations, communities, and the ecosystem during and after treatments. Empirical data will then be used to parameterize and benchmark a mechanistic demographic vegetation model to expand the inference of these effects to longer time frames and a wider range of biodiversity scenarios. The three overarching questions this project will address are: (1) How does diversity at different hierarchical scales control resilience of biological function after perturbations? (2) How do perturbations affect biodiversity at multiple hierarchical scales? (3) How does diversity and resilience change with frequency and compound perturbations?<br/><br/>This project is jointly funded by Emerging Frontiers in the Directorate for Biological Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).<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.
