HYDROLOGICAL IMPACTS OF WILDFIRE IN THE SOUTHERN APPALACHIAN MOUNTAINS

More than 1.4 million acres of forest lands burned in the southeastern United States in 2016, with high fire intensities that are more typically associated with the western part of the nation. While the southeast, and in particular the Appalachian Mountains, experience wildfires every year, this year’s fires were particularly intense due to severe to extreme drought conditions that gripped much of the region. Wildfires has been shown to induce a number of physical, chemical and biological changes in soils, including creating water repellency (hydrophobicity), altering color, decreasing structural stability, and affecting the quantity, quality, location and availability of carbon and nutrients (e.g., nitrogen and phosphorus). However, such studies have primarily been conducted in the context of western forests, where the vegetation composition and soil characteristics are markedly different than those of the southeast. It is not well-known, for example, if wildfires in humid hardwood forests can induce soil hydrophobicity (i.e., water repellency), or how long any such effects might persist. In this presentation we will show preliminary results (using water drop penetration tests, infiltration tests, and complementary laboratory measurements) that reveal the distribution and persistence of soil hydrophobicity as a result of these fires. We will also present in situ measurements of soil water content that compare soil water storage and availability between burned and unburned sites. These results will highlight the hydrological impact of unprecedented wildfire activity in the southern Appalachians.