Evaluation of Reforestation Efforts on Two Reclaimed Surface Mines in West Virginia

Evaluation of Reforestation Efforts on Two Reclaimed Surface Mines in West Virginia Curtis A. DeLong Coal mining has disturbed approximately 2.4 million hectares (6 million acres) since 1930 in the United States. West Virginia is located in the Eastern Coal Region where surface mining has disturbed large areas of eastern deciduous forest. As coal operators and land owners are moving toward restoring forests on mined lands, techniques are being developed and tested to increase tree survival and growth to ensure disturbed land is converted back to forest in a timely fashion. To aid in successful reforestation, the Office of Surface Mining Reclamation and Enforcement adopted reclamation techniques called the Forestry Reclamation Approach which provides recommendations on substrate selection, grading, ground covers, tree species selection, and proper tree planting. This study was implemented to provide additional scientific data on the implementation of these techniques especially related to substrate selection. Studies were conducted at Catenary Coal’s Samples mine in Kanawha County, WV and ICG Eastern, LLC’s Birch River mine in Webster County, WV. Both of these sites have been surface mined for coal and reclaimed using either Commercial Forestry or Forestry post mining land uses. Following FRA guidelines, demonstration plots were constructed at both locations; 2005 at the Samples mine and 2007 at Birch River. Demonstration plots at the Samples mine had treatments of substrate (brown vs. gray), depth of substrate (1.2 m vs. 1.5 m), and compaction (compacted vs. noncompacted), while plots at Birch River had treatments of substrate (brown vs. gray), bark mulch (with vs. without), and hydroseeding (with vs. without). After final construction of the plots, a mixture of hardwood trees was planted at both sites. The objectives of this research were to assess physical and chemical properties of mine soils after three years at ICG and five years at Samples, and to determine tree volume and survival in various treatment combinations. Gray sandstone substrates at both sites had high pH ranging from 7.7 to 8.3 while brown substrates pH ranged from 4.4 to 5.4, which were consistent throughout the study at both sites. After five years at Samples, there were only a few significant changes in soil properties and extractable element concentrations. Electrical conductivity decreased in all treatment combinations with the exception of the 1.2 m brown sandstone noncompacted (4B-NC) with totals ranging from 0.10 to 0.53 dS m and decreases ranging from 0.10 to 0.40 dS m. Extractable potassium concentrations ranged from 0.17 to 0.20 cmolc kg in 2005 and 0.05 to 0.10 cmolc kg in 2009 with significant decreases in all treatment combinations. After five growing seasons at Samples, the average survival across all tree species was 66% with an average volume of 1328 cm. No significant differences were found for total tree survival between substrate, compaction and depth treatments. Survival by species ranged from 50% for white pine to 77% for black locust. Trees in the brown sandstone substrates had significantly greater volume at 1840 cm compared to 176 cm in the gray sandstone. Black locust significantly outperformed all other species with a volume of 7361 cm while the species with the next closest volume was black cherry at 998 cm. After three years at Birch River, the gray sandstone treatments and treatments with bark mulch had a soil pH of 7.2 to 8.0, while brown sandstone treatments without bark mulch had a soil pH of 4.6 and 4.9. Electrical conductivity was significantly higher in treatments that received bark mulch. After three growing seasons at Birch River, average tree survival across all species was 69% and there were no tree survival differences between substrate, bark mulch, or hydroseeding. Average survival across all trees in all treatment combinations ranged from 41% for sycamore to 85% for sugar maple. Trees planted in brown sandstone had significantly greater volume of 313 cm compared to gray sandstone at 100 cm. Black locust outperformed all other tree species with a volume of 806 cm with the next closest species being tulip poplar at 319 cm. In a separate study at Samples, four bulk density measurement techniques were used to determine bulk density in five substrates (four sandstone mine soils and one unmined native forest soil) and comparisons for accuracy and in-field efficiency were made among the four techniques. The techniques used were the frame apparatus, polyurethane foam, radiation, and sand-cone techniques. Bulk density measurements ranged from 1.35 to 1.76 g cm for the four measurement techniques. Bulk density in the unmined native forest soil was significantly lower than the four sandstone substrates and no significant differences were found among the four sandstone substrates. The unmined native forest soil had a bulk density that was approximately 38 to 43% lower than the sandstone substrates. Bulk density ranged from 1.05 to 1.84 g cm in the five substrates. The bulk density determined by the sand-cone technique was significantly lower than the other three determination techniques and no significant differences were found among the frame, polyurethane foam, and radiation techniques. The sand-cone technique produced a bulk density that was approximately 18 to 23% lower than the other techniques used. Significantly different in-field efficiency times were recorded for each of the four determination techniques. The radiation technique had the greatest in-field efficiency (345 s) while the frame had the lowest (1605 s) with the polyurethane foam and sand-cone techniques being intermediate between the two (612 and 837 s).