Long-term Effects of Rock Type on Appalachian Coal Mine Soil Properties.

Rock-derived overburden material is used as a topsoil substitute for reclamation of Appalachian coal mines. We evaluated five mixtures ( = 4 each) of sandstone (SS) and siltstone (SiS) overburden as topsoil substitutes for 25+ years to quantify changes in mine soil properties. The study area was planted only to tall fescue [ (Schreb.)], but over 50 herbaceous species invaded over time. Standing biomass was highest in early years (5.2-9.3 Mg ha in 1983) and was strongly affected by rock type (SS > SiS), declined significantly by 1989 (1.5-2.4 Mg ha), and then increased again (2×) by 2008. However, there was no long-term rock type effect on standing biomass. Rock fragments and texture differed after 26 yr, with fewer rock fragments in the SS-dominated mixtures (53 vs. 77% in SiS) and lower sand and higher clay in the SiS-dominated mixtures. Soil pH initially ranged from 5.45 (SS) to 7.45 (SiS), dropped for several years, increased in all SiS mixes, and then slowly declined again to 5.65 (SS) to 6.46 (SiS) over the final 15 yr. Total N, organic matter, and cation exchange capacity increased with time, and extractable P decreased. Chemical weathering was most apparent initially, but physical weathering of rock fragments and changes in texture continued throughout the study period. Influences of original rock mixtures remained apparent after 25+ yr in both physical and chemical properties of these mine soils, which remained much coarser than local native soils but were higher in pH, exchangeable cations, and extractable P.

Ripping improves tree survival and growth on unused reclaimed mined lands.

There is renewed interest in re-establishing trees on 0.6 million ha of mining-disturbed lands in the Appalachian mountains of Eastern United States. Many coal-mined lands reclaimed to meet requirements of US federal law have thick herbaceous vegetation and compacted soils which impede tree establishment. Mitigation practices were applied on three mine sites and evaluated for success in enabling planted trees to become established. Eastern white pine (Pinus strobus), hybrid poplar (Populus deltoids × Populus trichocarpa), and mixed Appalachian hardwoods were established using weed control only and weed control with subsoil ripping. Trees were measured in October of 2008 after 5 years of growth. Subsoil ripping increased mixed hardwood survival from 43 to 71%, hybrid poplar biomass index from 1.51 to 8.97 Mg ha(-1), and Eastern white pine biomass index from 0.10 to 0.32 Mg ha(-1). When restoring trees to unused mined sites, subsoil ripping can aid survival and growth to an extent that will result in a valuable forest.

Restoring forests and associated ecosystem services on appalachian coal surface mines.

Surface coal mining in Appalachia has caused extensive replacement of forest with non-forested land cover, much of which is unmanaged and unproductive. Although forested ecosystems are valued by society for both marketable products and ecosystem services, forests have not been restored on most Appalachian mined lands because traditional reclamation practices, encouraged by regulatory policies, created conditions poorly suited for reforestation. Reclamation scientists have studied productive forests growing on older mine sites, established forest vegetation experimentally on recent mines, and identified mine reclamation practices that encourage forest vegetation re-establishment. Based on these findings, they developed a Forestry Reclamation Approach (FRA) that can be employed by coal mining firms to restore forest vegetation. Scientists and mine regulators, working collaboratively, have communicated the FRA to the coal industry and to regulatory enforcement personnel. Today, the FRA is used routinely by many coal mining firms, and thousands of mined hectares have been reclaimed to restore productive mine soils and planted with native forest trees. Reclamation of coal mines using the FRA is expected to restore these lands' capabilities to provide forest-based ecosystem services, such as wood production, atmospheric carbon sequestration, wildlife habitat, watershed protection, and water quality protection to a greater extent than conventional reclamation practices.

Hardwood seedling growth on different mine spoil types with and without topsoil amendment.

The goal of many owners of reclaimed mined land in the Appalachian region is to restore the diverse native hardwood forest for environmental, economic, and cultural reasons. However, native hardwoods often grow poorly on mined sites because they are planted in unsuitable spoils devoid of native topsoil. In a greenhouse experiment, we examined the suitability of four growth media available for use on many mined sites in the central Appalachians-forest topsoil (FT), weathered sandstone (WS), unweathered sandstone (US), and unweathered shale (UH)-as well as the effects of topsoil amendment (none vs. amended) on the growth of three native hardwood species: Fraxinus americana, Quercus rubra, and Liriodendron tulipifera. A 4 x 2 x 3 factorial greenhouse experiment was conducted with planted 1-yr-old seedlings. Tree growth, foliar nutrients, and soil properties were measured and characterized. The WS was the spoil most conducive to growth for F. americana and Q. rubra. Liriodendron tulipifera did not respond to any treatments. Tree growth was highly correlated with mineralizable soil nitrogen and extractable soil phosphorus. Topsoil amendment significantly increased growth on the UH but not on the US or WS. Topsoil amendment increased the number of native herbaceous plants growing in the pots and improved foliar nutrient content in F. americana and L. tulipifera. Many properties of the WS, such as pH, microbial activity, and water availability, more closely approximated the control soil than the US or UH. This study showed that trees are sensitive to spoil type and that certain spoil types that are conducive to good growth of native trees should be used during the reclamation process, particularly if forest topsoil is not applied. Forest topsoil amendment improved tree growth on some spoil materials, improved tree nutrition, and helped restore the native soil organisms and plants that were present before mining.

Variation in root density along stream banks.

While it is recognized that vegetation plays a significant role in stream bank stabilization, the effects are not fully quantified. The study goal was to determine the type and density of vegetation that provides the greatest protection against stream bank erosion by determining the density of roots in stream banks. To quantify the density of roots along alluvial stream banks, 25 field sites in the Appalachian Mountains were sampled. The riparian buffers varied from short turfgrass to mature riparian forests, representing a range of vegetation types. Root length density (RLD) with depth and aboveground vegetation density were measured. The sites were divided into forested and herbaceous groups and differences in root density were evaluated. At the herbaceous sites, very fine roots (diameter < 0.5 mm) were most common and more than 75% of all roots were concentrated in the upper 30 cm of the stream bank. Under forested vegetation, fine roots (0.5 mm < diameter < 2.0 mm) were more common throughout the bank profile, with 55% of all roots in the top 30 cm. In the top 30 cm of the bank, herbaceous sites had significantly greater overall RLD than forested sites (alpha = 0.01). While there were no significant differences in total RLD below 30 cm, forested sites had significantly greater concentrations of fine roots, as compared with herbaceous sites (alpha = 0.01). As research has shown that erosion resistance has a direct relationship with fine root density, forested vegetation may provide better protection against stream bank erosion.