Evaluation of Growth and Survival of Hardwood Trees on Brown and Gray Sandstone

Abstract

Deciduous forests in the Appalachian region have been greatly disrupted due to surface coal mining since the 1930's. After the passage of the Surface Mining Control and Reclamation Act (SMCRA) in 1977, coal mine operators began planting a variety of grasses and legumes as a fast and economical way to re-establish a permanent vegetative cover in order to meet erosion and site stabilization requirements. However, soil compaction and competitive forage species have arrested the re-colonization of native hardwood tree species on these reclaimed sites. In an effort to evaluate tree growth on selected spoils and determine the effects of compaction, three 2.8-ha experimental plots were established at Catenary Coal's Samples Mine in Kanawha County, West Virginia. Two plots were constructed of weathered brown sandstone and the third plot was constructed of un-weathered gray sandstone. Half of each plot was compacted while the other half was non-compacted. Each plot was hydroseeded with a low competition herbaceous cover and planted with eleven hardwood tree species. Soil chemical properties and tree growth have been measured each year since 2005. After eight growing seasons, average tree volume index was nearly ten times greater for trees grown in the brown sandstone treatments, 3853 cm 3 , compared to 407 cm 3 in gray sandstone. Trees growing on compacted treatments had a lower mean volume index, 2281 cm³, than trees growing on non-compacted treatments, 3899 cm³. Average pH of brown sandstone was 5.2 to 5.7 while gray sandstone was 7.9. The gray sandstone has continued to resist breakdown and had much lower fines content (40%) compared to brown sandstone (70%), which influenced nutrient and water-holding capacity. After eight years, brown sandstone showed significantly greater tree growth and survival, and is a more suitable topsoil substitute than gray sandstone on this site.