Cyclone–Fire Interactions Enhance Fire Extent and Severity in a Tropical Montane Pine Forest

Abstract

Interactions between tropical cyclones and wildfires occur widely and can tip closed forests into open-canopy structures that initiate a ‘grass–fire’ cycle. We examined cyclone–fire interactions in a monodominant tropical montane pine forest in the Dominican Republic using remotely-sensed imagery to quantify damage from fires between 1986 and 2004, a category 1 cyclone in 1998, and an extensive wildfire in 2005. We also measured forest structure and composition 14.7 years after the 2005 fire. The area inside the 2005 burn scars (fire perimeters) totaled 25,206 ha, of which 81% burned and 14% was cyclone damaged. Cyclone damage made the fire markedly more extensive and severe—high-severity fires were > 3 times more frequent with high-severity cyclone damage than no cyclone damage—but these markedly synergistic effects were restricted to areas that had not burned for at least 19 years before the 2005 fire. Though earlier fires from 1986 to 2004 were small and low-severity, they were sufficient, when present, to prevent high-severity fire in 2005 irrespective of cyclone severity. In areas with strong cyclone–fire interactions, there was a complete loss of pine canopies, yet these stands had abundant pine canopy recruitment by 2019 and showed no evidence of compositional shifts toward open-canopy structures with pyrogenic herbaceous understories, illustrating the resilience of this ecosystem to a range of cyclone–fire synergies. However, the future resilience of tropical montane pine forests to cyclone–fire synergies is uncertain as climate change increases the intensity of cyclones and frequency of drought-triggered fires in these ecosystems.