Initial Response of Soil Nutrient Pools to Prescribed Burning and Thinning in a Managed Forest Ecosystem of Northern Alabama

Abstract

Forest management practices such as prescribed burning and thinning are commonly used to restore degraded forest communities in the Southern Appalachians. Prescribed treatments influence physical and chemical properties of soils and change the balance of nutrients such as carbon and nitrogen. This study was conducted to investigate the initial impacts of prescribed burning, thinning and a combination of prescribed thinning and burning on total carbon and nitrogen pools, as well as other properties, in soil and forest floor. Effects of these disturbance regimes were tested on Typic Hapludults at the Bankhead National Forest in Northern Alabama. Results show that prescribed burning alone led to significant increases in total C and N contents in soil surface horizons. Burning alone also resulted in changes in exchangeable Na pools and significant increases in pH values throughout the study sites. Combination of prescribed thinning and burning did not result in significant changes in total C and N concentrations. However, significant increases in K and Na concentrations were observed in these sites. Prescribed thinning alone did not appear to impact total C and total N concentrations, soil acidity or exchangeable Ca and Mg concentrations, but caused significant increases in Na and decreases in K concentrations. Results of the study indicated that prescribed burning alone appeared to have a stronger impact on total C and N pools than a combination of prescribed thinning and burning. Use of prescribed thinning alone did not have any effect on total C and N pools in soils and forest floor. While prescribed burning alone and a combination of thinning and burning led to changes in exchangeable K and Na pools, no change was detected in either Ca or Mg concentrations.