Evaluation of tree growth and chemical, physical and biochemical soil properties of two reclaimed surface mines in West Virginia

Advancements in technology and coal mining methods have accelerated the disturbance of valuable contiguous deciduous forests in the Appalachian region. In many instances, mountaintop mining has converted large expanses of forested mountaintops to rolling pasture and hay land that have been left abandoned to revert to shrub land dominated by invasive nonnative species. Due to excessive soil compaction and heavy herbaceous cover, natural plant community succession from planted grasslands to hardwood forests is slow. Recently, efforts are being made to re-establish hardwood forests on mined land through careful spoil and amendment selection, and placement and planting of appropriate herbaceous and tree species. In order to evaluate tree growth and survival on selected spoils with various amendments, two study areas were established on two mountaintop mines in West Virginia. The oldest study area is Catenary Coal\u27s Samples Mine in Kanawha County, WV, where three 2.8-hectare demonstration plots were established in 2005. Two plots were comprised of oxidized (brown) sandstone and one of un-oxidized (gray) sandstone. Half of all plots were tracked in to produce a smooth compacted surface. Care was taken to leave the other half of the plot relatively uncompact, producing a rough uneven surface. The study area was planted with a variety of hardwood tree species, mainly oaks, sugar maple and black cherry, on 2.4-m centers. Soil chemical properties and tree volume index and survival were evaluated for seven years. Substrate type had a significant effect on tree volume index with brown sandstone consistently outperforming gray sandstone. Of the eleven tree species planted, dogwood, black cherry, and red and white oak gave the highest growth index. Compaction did not have a significant effect on tree volume index. In 2011, pH, fines, Fe, P, and Zn where all significantly higher in gray sandstone. Differences were found for electrical conductivity and all extractable elements between 2005 and 2011. Aluminum was significantly lower in brown sandstone. Compaction had no effect on soil properties.;The second study area was a 3-ha demonstration plot created at Arch Coal\u27s Birch River mine near Cowen, WV. The plot is comprised of two exclusive areas of brown and gray sandstone substrates. Approximately one third of each was amended with bark mulch and/or hydroseeded with fertilizer and low growing non-competitive herbaceous species, creating a total of eight treatments. The study area was planted with a variety of hardwood tree species, mainly oaks, sugar maple and black cherry, on 2.4-m centers. Soil chemical properties and tree survival and growth were evaluated for four years beginning in 2007. Using a model approach and Akaike\u27s Information Criterion (AIC) to analyze tree and soil data, sandstone type and mulch had the highest empirical support for influencing tree volume index and soil chemical properties. No strong empirical support was found for any of our pre-selected models for predicting or inferring tree survival. Like the Catenary study, tree volume index on brown sandstone at Birch River was consistently higher than gray. After four years, hydroseeding had no effect on tree volume index, survival or soil chemical properties. Mulch application had the ability to improve tree growth in both sandstone types and had a strong influence on soil chemical properties.;In addition, soil organic carbon (SOC), microbial biomass carbon (MBC), total combustible nitrogen (TCN), potentially mineralizable nitrogen (PMN) was also measured for soil samples of the Birch River study area. Substrate had no effect on these properties. Hydroseed application had a significant effect on MBC and TMN. Both of these biochemical properties were higher in the hydroseed application treatment