Short‐term prescribed fire frequency manipulation alters community response to subsequent fires in a southeastern pine savanna

Abstract

Disturbances can have enduring impacts on ecological communities due to ‘legacy effects’, which result in community structure that varies with the history of recent disturbance. Further, such legacy effects can influence community—and population‐level responses to future disturbance. We leveraged a landscape‐scale fire frequency experiment in a longleaf pine savanna to assess legacy effects in understory community richness, structure, and in community response to subsequent fire. Further, we investigated species‐level responses to fire based on their burn history and attempted to explain these responses using relevant functional traits. Fire suppression for just 4 years resulted in more woody‐dominated communities. Fire suppression also resulted in more overall plant abundance. This buildup of plant material is consistent with our further finding that a greater interval between fires resulted in greater loss of cover with the next fire. Greater fire return interval led to more vegetative cover loss immediately post‐fire, but this effect attenuated within a year of recovery time. Lowland shrub‐dominated communities also experienced greater cover loss due to fire. There was no effect of fire return interval on change in species richness. Woody species responded more negatively to fire than herbaceous species. Intraspecific variation in specific leaf area increased resistance to fire only for shorter species, and it decreased resistance for taller species. Only some of the abundant species showed a sensitivity to fire history. Synthesis. Overall, our findings provide evidence that short‐term changes to disturbance regimes can create alternative responses to future disturbance at the community and species level. This work suggests that short‐term pauses to longer term burn regimes can facilitate woody encroachment and have lasting impacts through altered community responses to future fires.