Response of soil microarthropods and microclimatic conditions to two-age regeneration in hardwood forests in the southern Appalachians
Madson, Stephanie Lee
MetadataShow full item record
Forest stands are harvested on a scale of several hectares, whereas most microarthropods will spend their entire lives within a scale of several meters. Rarely is this mismatch between spatial scales accounted for when examining the response of soil microarthropods to forest harvesting methods, such as two-age regeneration treatments. Microhabitats, i.e. residual trees, coarse woody debris piles, grassy clearings, residual shrubs, coppices, and skid roads, are created or exacerbated by the harvesting process. Microhabitats have been shown to be a determining factor in microarthropod community composition. Microclimatic conditions, including soil temperature, soil moisture, bulk density, and litter depth, are also determinants of microarthropod community composition. We measured microclimatic conditions and used microhabitats as a common spatial unit to assess the response of soil microarthropods to two-age regeneration treatments within hardwood stands at Wine Spring Creek Watershed in the southern Appalachians. Soil temperature was measured using Hobo data loggers and soil water content was measured using the gravimetric method. Microarthropods were extracted using modified Tullgren extractors and sorted to sub-order. Natural spatial heterogeneity in the soil microarthropod communities was high in both the control and cut sites. Soil microarthropod abundance decreased in the two-age regeneration treatments, with the exception of the immature oribatids, which increased, and the oribatids, which were not significantly different between treatments. Two-age cut stands had significantly greater fluctuations in soil temperatures, higher soil temperatures in summer, cooler soil temperatures in winter, decreased litter depth, and a trend towards decreased soil water content. Understanding of microarthropod community dynamics in response to harvesting was broadened when examined at the scale of microhabitats. Microarthropod abundance was lowest in skid roads and was highest in coppiced and mature tree microhabitats. Using microhabitats as a common spatial scale between microarthropod taxa and harvested forest stands appears to be a useful tool in elucidating treatment effects on the dynamics of microarthropod communities.