Heather A. Passmore

Hurricane and Fire Effects in Savanna-forest Landscapes: Disturbance Interactions in Coastal Southeastern USA Heather A. Passmore

Sequential large-scale disturbances may produce interacting effects that differ from those predicted for each disturbance in isolation. These non-additive effects can strongly influence the composition and structure of plant communities. Hurricanes and natural lightning-season fires are large-scale, frequent disturbances in savanna-forest landscapes of the southeastern US. Passmore develops a predictive conceptual model for interacting disturbances. She predicts that hurricane-fire interactions may influence ecotones between savannas and forests by changing species composition and structure. Based on predictions, Passmore implemented an experimental study in savanna-forest ecotone to test hypotheses of interactive effects. She hypothesized that effects of lightning-season fires differ when fires occur alone compared to when fires are preceded by hurricanes. Disturbance interactions reduced stem density and species richness of woody plants in the field study. Thus, hurricane-fire interactions influence vegetation structure in savanna-forest ecotones. Furthermore, over longer time scales interactions may result in landscape-level changes in southeastern savanna-forest ecosystems.