Hurricane and fire effects in savanna-forest landscapes

Sequential large-scale disturbances may produceinteracting effects that differ from those predictedfor each disturbance in isolation. These non-additiveeffects can strongly influence the composition andstructure of plant communities. Hurricanes andnatural lightning-season fires are large-scalefrequent disturbances in savanna-forest landscapes ofthe southeastern US. Passmore develops a predictiveconceptual model for interacting disturbances. Shepredicts that hurricane-fire interactions mayinfluence ecotones between savannas and forests bychanging species composition and structure. Based onpredictions Passmore implemented an experimentalstudy in savanna-forest ecotone to test hypotheses ofinteractive effects. She hypothesized that effects oflightning-season fires differ when fires occur alonecompared to when fires are preceded by hurricanes.Disturbance interactions reduced stem density andspecies richness of woody plants in the field study.Thus hurricane-fire interactions influencevegetation structure in savanna-forest ecotones. Furthermore over longer time scales interactions mayresult in landscape-level changes in southeasternsavanna-forest ecosystems.