Prescribed burning effects on gully hydrology, erosion, and soil phosphorus pools in the Piedmont region of South Carolina
Galang, Marco Aragones
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Gullies found today in the Piedmont of South Carolina are legacies of past land abuse and erosion. Although currently covered with forest vegetation, issues related to gully contribution in nonpoint source pollution, particularly when forests are prescribed burned or otherwise disturbed, remain unanswered. This research was conducted with the goals of determining: 1) the influence of land use change on the morphological and current status of gullies; 2) the effect of prescribed burning on the hydrologic behavior of gullies; and 3) the effect of heating on the phosphorus (P) pools in soil. Three separate studies were conducted targeting these individual objectives. For the first goal, a field survey of gullies in the South Carolina Piedmont was conducted following an analysis of land cover in the area. For the second, eight individual gullies were hydrologically instrumented and monitored one year before and one year after a prescribed burning treatment. For the last objective, soil samples were heated with different temperature by duration regimes then analyzed with the modified Hedley fractionation procedure. Results from this controlled experiment were compared with results obtained for soils collected before and after prescribed burning that were similarly extracted. Results showed that: 1) legacy gullies found in older forested sites were deeper and wider than gullies found in more recently forested areas but all gullies included in the study are relatively stable; 2) not all gullies flowed during rain events but when they did flow, there was no evidence of adverse impacts of prescribed burning on hydrologic properties as inter-annual variation was greater than treatment effect; and 3) temperature and heating duration interaction play an important role in the release of P to solution.