Long-Term Soil Responses to Site Preparation Burning in the Southern Appalachians
The mixed oak-pine ecosystems in the southern Appalachians are in decline because of a combination of drought and southern pine-beetle infestation. A commonly applied prescription for restoration of these degraded sites has been to fell all vegetation, allow it to dry, and conduct a site-preparation burn. However, there is little information on the mid- and long-term influences of this prescription on nutrient cycling. The fell-and-burn treatment was applied to three mixed oak-pine stands in the Nantahala National Forest in western North Carolina. Each stand had an untreated control area. Our objective was to determine the effects of this treatment on soil nutrient availability and potential nutrient loss. Exchangeable soil cations, pH, total carbon (C), and total nitrogen (N) were measured before and periodically for 5 years after treatment. Nitrogen transformations and nutrient availability in soil solution and in a stream draining one site were measured before and periodically for 3 years after burning. Exchangeable calcium and magnesium concentrations, soil pH, and N availability increased after treatment. There was no treatment effect on total soil C or N. Nitrogen mineralization rates were greater on burned versus control plots in 50% of the posttreatment measurements. This treatment increased nutrient availability and, although a significant amount of total site N was lost, there were no adverse effects on total soil nutrients or water quality.