Influence of Physical, Chemical, and Biological Mine Soil Properties on White Oak Seedling Growth

Landowners in the Appalachian region are becoming increasingly interested in restoring the native hardwood forest on mined land after reclamation. Trees are usually planted in topsoil substitutes consisting of blasted rock strata from the geologic profile. Reforestation attempts using native hardwoods have often been unsuccessful due to the highly variable nature of the physical, chemical, and biological properties of mine spoils. The purpose of this study was to determine which mine soil properties most influence white oak seedling growth, and to test whether or not these properties are adequately reflected in a preliminary mine soil classification model. Seventy-two 3-yr-old white oak trees were randomly selected across a reclaimed site in southwestern Virginia that varied greatly in spoil type and site properties. Tree height was measured and soil samples were taken to a 40 cm depth at the base of each tree and analyzed for physical, chemical, and biological properties hypothesized to influence tree growth. Tree height and biomass, which ranged from 15 to 125 cm, and 0.24 to 190.03 g, respectively, were regressed against mine soil and site properties. Potassium, size of microbial populations, extractable nitrogen, pH, soil texture, aspect, and phosphorous accounted for over 52% of the variability in tree growth. This study indicates that white oaks are most successful growing on east-facing aspects, in slightly-acidic, sandy loam textured, fertile mine soils that are conducive to soil microbial activity. These results suggest that sandstone rock types with suitable chemical properties should be selected for topsoil substitutes when native hardwood restoration is the desired post-mining land use. Additional