Short term fire history alters plant community structure and response to future fire

Disturbances can have enduring impacts on ecological communities due to “legacy effects,” which result in community structure that depends on the history of disturbance. Further, such legacies can influence community- and population-level responses to future disturbance. We leveraged a four-year landscape-scale burn frequency experiment in a longleaf pine savanna to assess historical contingency in understory community structure and in community response to subsequent fire. Frequently burned plots came to resemble drier grass-dominated upland communities, while fire suppression resulted in composition like shrubby riparian communities. Recent history also affected community response to the next fire. Specifically, a greater interval between fires resulted in lowered resistance to the next fire. Fire return interval interacted with available recovery time, such that greater recovery time abated the impact of fire return interval on resistance, measured as decrease in richness and in vegetative cover. Overall, our findings provide evidence that even short-term changes in disturbance regimes can create historically contingent responses to future disturbance at the community and species level. This work is informative for managers, as punctuated changes to longer-term burn regimes can have lasting impacts.