Spoil Type Influences Soil Genesis and Forest Development on an Appalachian Surface Coal Mine Ten Years after Placement

Surface mining for coal (or other mineral resources) is a major driver of land-use change around the world and especially in the Appalachian region of the United States. Intentional and well-informed reclamation of surface-mined land is critical for the restoration of healthy ecosystems on these disturbed sites. In Appalachia, the pre-mining land cover is predominately mixed hardwood forest, with rich species diversity. In recent years, Appalachian mine reforestation has become an issue of concern, prompting the development of the Forestry Reclamation Approach, a series of mine reforestation recommendations. One of these recommendations is to use the best available soil substitute; however, the characteristics of the “best” soil substitute have been an issue. This study was initiated to compare the suitability of several types of mine spoil common in the Appalachian region: brown sandstone (Brown), gray sandstone (Gray), mixed spoils (Mixed), and shale (Shale). Experimental plots were established in 2007 with each spoil type replicated three times. These plots were planted with a mix of native hardwood species. Ten years after plot construction and planting, tree growth and canopy cover were highest in Brown, followed by Shale, Mixed, and Gray. Soil conditions (particularly pH) in Brown and Shale were more favorable for native tree growth than Mixed or Gray, largely explaining these differences in tree growth and canopy cover. However, soil chemistry did not clearly explain differences in tree growth between Brown and Shale. These differences were more likely related to differences in near-surface soil temperature, which is related to soil color and available shade.