Collaborative Research: The Nature of Fire-Vegetation Relationships in Tropical Savanna-Forest Mosaics

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Once viewed as destructive, fire in tropical savannas is now seen as critical to the maintenance of species-diverse plant and animal communities. Indeed, scientists now recognize that while it is important to exclude fire from places where it is destructive (tropical forests), it is equally important to promote fire in places where it is beneficial (savannas). Appropriate fire management is key to conserving biodiversity and sustaining the livelihoods of people. However, little is known about how (or if) fire-promotion and fire-protection can be accomplished simultaneously. The overarching goal of this project is to reconcile the need for savanna fires with the need to protect forests from damaging wildfire. Using field and laboratory studies in savannas and forests of Bolivia, this project will establish the scientific basis for how people living in a savanna/forest matrix can use fire in an ecologically beneficial manner. Additionally, this project will provide opportunities for a doctoral student and a postdoctoral scholar to conduct international field research, and for undergraduate students to conduct laboratory analyses in the USA. To foster international educational exchange, a short course in tropical ecology and botanical field methods will be offered to students from the USA and Bolivia. A research symposium and workshop will be organized to further address the challenges of incorporating beneficial fire management into savanna and forest conservation initiatives.This research will provide the first-ever field-based test of alternative stable state theory in a tropical savanna-forest mosaic where fire-vegetation feedbacks can be isolated from the effects of soils and plant photosynthetic type. For most of the past century, in regions where the climate can support closed-canopy forests, ecologists attributed the existence of tropical savannas to edaphic conditions or human-caused deforestation. Such ideas are being replaced by a new paradigm in which savannas and forests are modelled as alternative stable states, maintained by feedbacks between plant communities and fire. This research, to be conducted across savanna-forest boundaries in Bolivia, will use vegetation and soil sampling, field experiments, remote sensing, plant microfossil identification and dating, and functional trait measurements to understand the contemporary, paleoecological, and evolutionary relationships between plant communities and fire. Results are expected to demonstrate that in the absence of external drivers, such as logging, a persistence-colonization trade-off in grasses promotes savanna flammability while constraining savanna expansion into forests.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.