ABSTRACT
Reclamation of surface mined sites to forests is a preferred post-mining land use option, but performance of planted trees on such sites is variable. American chestnut (Castanea dentata (Marsh.) Borkh.) is a threatened forest tree in the eastern USA that may become an important species option for mine reclamation. Chestnut restoration using backcross hybrids that incorporate blight resistance may be targeted to the Appalachian coal mining region, which corresponds closely with the species' native range. Thus, it is important to understand how chestnut hybrids perform relative to progenitors on reclamation sites to develop restoration prescriptions. Seeds of parents and three backcross generations of chestnut (100% American, 100% Chinese, and BC1F3, BC2F3, and BC3F2 hybrids) were planted into mine soils in West Virginia, USA with shelter treatments. Survival for all stock types was 44% after 8 years (American 39%, Chinese 77%, BC1F3 40%, BC2F3 28%, and BC3F2 35%). Height for all stock types was 33 cm after 8 years (American 28 cm, Chinese 67 cm, BC1F3 30 cm, BC2F3 21 cm, and BC3F2 20 cm). At another site a year later, seedlings of the chestnut stock types were planted into brown (pH 4.6) or gray sandstone (pH 6.3) mine soils and seedling survival across all stock types was 58% after 7 years. Chinese had the highest survival at 82%, while the others ranged from 38 to 66%. Height was 63 cm for all stock types after 7 years. More advanced backcross hybrids (BC2F3 and BC3F2) had the lowest vigor ratings at both sites after 7-8 years. Our results indicate that surface mines in Appalachia may provide a land base for planting blight-resistant chestnuts, although Chinese chestnut outperformed American chestnut and later generation backcross hybrids. As blight-resistant chestnuts establish and spread after planting, chestnut trees may become a component of the forest canopy again and possibly occupy its former niche, but their spread may alter future forest stand dynamics.
ABSTRACT
Each year surface mining in Appalachia disrupts large areas of forested land. The Surface Mining Control and Reclamation Act requires coal mine operators to establish a permanent vegetative cover after mining, and current practice emphasizes soil compaction and planting of competitive forage grasses to stabilize the site and control erosion. These practices hinder recolonization of native hardwood trees on these reclaimed sites. Recently reclamation scientists and regulators have encouraged re-establishment of hardwood forests on surface mined land through careful selection and placement of rooting media and proper selection and planting of herbaceous and tree species. To evaluate the effect of rooting media and soil amendments, a 2.8-ha experimental plot was established, with half of the plot being constructed of weathered brown sandstone and half constructed of unweathered gray sandstone. Bark mulch was applied to an area covering both sandstone types, and the ends of the plot were hydroseeded with a tree-compatible herbaceous seed mix, resulting in eight soil treatments. Twelve hardwood tree species were planted, and soil chemical properties and tree growth were measured annually from 2007 to 2012. After six growing seasons, average tree volume index was higher for trees grown on brown sandstone (5333 cm) compared with gray sandstone (3031 cm). Trees planted in mulch outperformed trees on nonmulched treatments (volume index of 6187 cm vs. 4194 cm). Hydroseeding with a tree-compatible mix produced greater ground cover (35 vs. 15%) and resulted in greater tree volume index than nonhydroseed areas (5809 vs. 3403 cm). Soil chemical properties were improved by mulch and improved tree growth, especially on gray sandstone. The average pH of brown sandstone was 5.0 to 5.4, and gray sandstone averaged pH 6.9 to 7.7. The mulch treatment on gray sandstone resulted in tree growth similar to brown sandstone alone and with mulch. After 6 yr, tree growth on brown sandstone was about double the tree growth on gray sandstone, and mulch was a successful amendment to improve tree growth.
