The Surface Mining Control and Reclamation Act of 1977 (SMCRA) requires the restoration of post-mining land-use capability to a level “equal to or better than” that which preceded mining. The majority of coal-mined lands in Appalachia were forested prior to mining; however, most mined lands are reclaimed to pasture. One reason for this change in land-use is that the reclamation practices used to achieve a post-mining landscape of “approximate original contour” to the pre-mined topography of the site, per SMCRA, tend to inhibit tree growth. Impediments to forest growth on these sites include: 1) excessive compaction of the spoil, 2) unsuitable or sometimes toxic rooting material, and 3) competition for nutrients and water by aggressive and often invasive herbaceous species that are planted to establish ground cover. Researchers at the University of Kentucky have discovered that reforestation of these sites is possible using low compaction techniques (i.e. loosely dumping 6 to 8 feet of fresh spoil on a stabilized area). In addition, others have suggested that a minimization of ground cover establishment could further enhance survivability and growth of forest species on these sites. However, neither of these practices has received widespread implementation due to unsubstantiated concerns over stability, sediment runoff, and aesthetics.
Weathered sandstone materials, mixed with surface soils, are known to be excellent materials for use in constructing surface soils on coal surface mines being prepared for reforestation. However, such materials may not be available and/or economically retrievable at a given mine. As a result, some mining firms may prefer to use un-weathered overburden materials (i.e., materials retrieved even further below the surface such as gray sandstone or shale) for mine soil construction. The properties of such materials may be poorly suited for reforestation when initially placed at the surface due to factors such as high electrical conductivity, alkaline pH, or high coarse fragment content. Weathering processes may cause these properties to change with time in a manner that improves their suitability for reforestation. Unfortunately, the rate at which weathering occurs in these materials is unknown and methodologies need to be developed to assess this process.
The primary goal of this project is to determine which mine spoil (shale; brown weathered sandstone; gray unweathered sandstone; or a mixture of shale and sandstones) is most suitable for the rapid development of a soil medium capable of supporting plant life.
The objectives of this project are to:
- Assess the surface physical breakdown of geologic materials as a function of topographic changes and subsurface soil development,
- Evaluate the spatial distribution of naturally seeded plant material, and
- Assess the response of tree growth to geologic material weathering and soil genesis.