PS 3-30 - The interaction of wind disturbance and management on carbon pools in southeastern forests

Abstract: Wind disturbances like tornadoes and hurricanes alter the relative distribution of forest carbon (C) pools as well as absolute forest C sequestration capacity. Subsequent to wind disturbances, forest management (e.g., logging and prescribed fire) can significantly influence immediate C storage and post-disturbance C recovery dynamics. In this study, we ask how relative and absolute forest C pools differ as a function of the interaction between management strategy and disturbance intensity in tornado-damaged forests in the southeastern US.

We established 30 15-m radius forest plots in a tornado-damaged, unlogged forest ranging from mixed pine-hardwood to open longleaf forest, and in 10 plots of similar composition in a nearby tornado-damaged, salvage-logged forest in the Oakmulgee Wildlife Management Area, Talladega National Forest, Alabama, USA. Plots represented a spectrum of wind damage and logging intensity. One year post tornado and immediately prior to prescribed fire, we estimated overstory vegetation, understory woody and herbaceous vegetation, coarse woody debris (CWD), fine woody debris (FWD), leaf litter, and soil organic layer (SOL) C within each plot.

As expected, total forest C was significantly lower in salvage-logged plots (78.4±27.3 Mg C ha^-1±SD) than unlogged plots (103.7±38.5), primarily as a function of decreased overstory C, and secondarily due to decreases in leaf litter and SOL C. While overstory was the largest C pool in unlogged plots, CWD was the largest relative C pool in logged plots, accounting for over 60% of forest C. Both absolute and relative FWD C were higher in salvage-logged plots, and understory woody and herbaceous vegetation accounted for the smallest C pool in both areas. There was an inverse relationship between severity of damage (based on number of recently down trees and canopy cover) and total C in logged plots; however, the trend was not significant in unlogged plots.

In addition to logging, this area is managed with prescribed fire; thus, these data act as a baseline for future studies on the interaction of wind damage, salvage logging, and prescribed fire on fire behavior and C consumption, and post-fire C pool shifts and recovery. Investigating interactions between management and disturbance on forest C dynamics is important if we are to understand how to manage forests for a combination of services including maximizing C sequestration, mitigating catastrophic wildfires through fuel reduction, and restoration/conservation of desired forest types. This understanding becomes increasingly important as non-human disturbances become increasingly frequent and intense as a function of global change.