PS 28-137 - Carbon storage, fuel loading, and fire behavior consequences of wind disturbances in fire-dependent forests of the southeastern U.S.

Abstract: Intense wind disturbances such as hurricanes and tornadoes occur frequently across the southeastern U.S., where both coastal and inland forests are managed with frequent prescribed fire. Wind disturbances followed by prescribed burning may decrease the capacity of forests to act as carbon (C) sinks, increasing fuel loads, and consequently, fire intensity and severity. The primary goal of this study is to understand wind disturbance impacts on fuel loading, fire behavior, and the C sequestration capacity of forests impacted by recent hurricanes or tornadoes. We hypothesize that fire-managed forests store most C in stabilized soil organic matter (SOM) and live vegetation, and wind disturbances will redistribute it into dead woody and leaf litter C pools and live understory vegetation, resulting in increased fuel loading. Consequently, increased fuel may lead to intense fire behavior and high fire severity. We also hypothesize that C recovery rates depend on the severity of wind damage. We are currently sampling coastal and inland forests of Alabama and Florida with recent wind damage from 2020 and 2021 to quantify above- and belowground C pools and fuel loading prior to fire (< 1 month), immediately after the fire (within 1 week), and 1 year after a prescribed fire. Our preliminary results show that wind disturbances followed by prescribed fire application redistribute C pools among forest strata. Notably, the reintroduction of prescribed fire on wind-damaged sites significantly reduced carbon stored in leaf litter, coarse woody debris, and understory vegetation C pools (83, 38, and 73% reduction, respectively) during the immediately post-fire sampling periods. Soil organic matter C pools varied with fire intensity, with plots experiencing higher average maximum temperature (393.5 ℃) losing more C (~ 70%) compared to those with lower average maximum temperature (248 ℃), experienced a slight increase in SOM C pools (~ 10%). Understanding forest C dynamics and recovery rates after wind disturbance followed by prescribed burning in fire-managed forests helps to predict the role of southeastern U.S. forests in climate mitigation.