Soil Resource Heterogeneity and Site Quality in Southern Appalachian Hardwood Forests: Impact of Salamander Abundance, Geology and Decomposing Stumps.

In the southern Appalachian Mountains, there is a tremendous amount of soil heterogeneity. This heterogeneity creates a complex ecosystem comprised of rich flora and fauna diversity. Three simultaneous studies were designed to address what we believe to be three major contributors to overall soil heterogeneity in southern Appalachian hardwood forests: 1) decomposing stumps and the associated root systems, 2) soil depth, and 3) the role of salamanders. In the stump study, stumps were defined as the aboveground and belowground (i.e. root system) leftover from previous harvests with the primary objective being to quantify the total soil volume occupied by stumps and compare and contrast total soil carbon (C) and nitrogen (N) between the bulk soil and soil directly influenced by stumps. For the soil depth portion of this project, ground-penetrating radar (GPR) was used to determine accurate measures of soil depth since large coarse fragments often make these estimations difficult if not impossible using more standard techniques such as soil augers. Lastly, the influence of salamanders, which constitute more biomass than any other vertebrate predator in southern Appalachia, on nutrient cycling dynamics was assessed across three different salamander density treatments using ion-exchange membranes to measure inorganic species of nitrogen as well as base cations such as magnesium, calcium and potassium. We found that 1) approximately 26% and 36% of the total nitrogen and carbon in these ecosystems is contained within soil influenced by decomposing stumps, 2) GPR showed that these soils are significantly deeper than measurements by soil augers indicate, which may increase/alter current soil nutrient pools, and 3) increasing salamander density cause a significant increase in labile N.