Forests around the world account for half of the terrestrial carbon pool, and half of all forest carbon is stored in the soil. Soils may lose carbon through CO2 efflux after disturbances, with soil disruption potentially altering the microclimate and an influx of new organic material increasing decomposer activity. Wind disturbances are common natural disturbances in the southeastern US, often followed by salvage logging. We test the questions: Is soil CO2 efflux elevated as a result of wind disturbance? Do wind + salvage logging disturbances increase soil CO2 efflux when compared to wind disturbance alone? We test these questions in a mixed forest which experienced a moderate-severity wind disturbance in 2011. We use bi-monthly soil CO2 efflux measurements and environmental data to test these questions. We use ANOVA and a stepwise least-squares model to examine the patterns of soil CO2 efflux in the disturbance categories.
Results/Conclusions
We find that soil CO2 efflux is elevated for both the wind disturbed and the combined (wind + salvage logging) conditions when compared to control (undisturbed forest) in the summer months. There is no significant difference in the soil CO2 efflux rates for any of these conditions in the fall, winter, or spring months. Our stepwise least-squares model is significant (p < 0.0001). Month and disturbance (wind disturbed and combined) are included in the model with the lowest AICc. Soil moisture, soil temperature, density of coarse woody debris, and plot-level wind damage severity were not included in the best fit model. We conclude that disturbance significantly increases CO2 efflux in the summer, even 6 years post-disturbance, but salvage logging does not significantly affect CO2 efflux after wind disturbance. This work contributes to a greater understanding of the influence of disturbance on soil carbon. As wind disturbances are predicted to become more frequent and more severe in the future, understanding their effects on soil CO2 efflux has implications on the global carbon cycle.