THE EFFECTS OF FOREST FIRE ON THE PHYSICAL AND CHEMICAL PROPERTIES OF SOIL IN SOUTH MOUNTAIN STATE PARK, NC

This study seeks to assess the effects of a forest fire on the soils of the Chestnut Knob area of South Mountain State Park, NC. Twelve soil pits were dug, ten within the burned area and two control pits in the unaffected area. Each pit was described including recording horizonation and structure using the methodology in Birkeland (1999). Soil samples from each pit horizon were also returned to lab and analyzed for organic matter content, particle size, and hydrophobicity. Additionally, we installed crest stage gauges in colluvial hollows to determine if burned areas exhibited more surface runoff than unburned areas. Hydrophobicity results show an increase in the depth of hydrophobicity in the burn area as well as some burned pits exhibiting extreme hydrophobicity. Particle size results show a decrease in clay content in the upper most horizons of the burned pits. Soil organic matter results show a significant difference in organic matter content between the burned pits and one control pit, but not the other control pit. Thinner O horizons and thinner A horizons in the burned area suggest deflation of uppermost soils by the fire. More broadly, our study suggests that fires in the foothills of the Blue Ridge Mountains significantly impact soils including increased hydrophobicity, reduction in the A horizon of burned soils, and increased risk of erosion. Further, the runoff data shows significantly more discharge in burned colluvial hollows compared with unburned. It is unclear if this is because of an increase in hydrophobicity or because of a decrease in evapotranspiration associated with a reduction in forest floor vegetation.