Mine reclamation practices under the Surface Mining Control and Reclamation Act of 1979 often resulted in minimal natural succession due to changes in soil physical characteristics. As part of the reclamation process, industrial rollers were used to compact the soil, and grasses were seeded to stop nutrient runoff and prevent further pollution downstream. Although this brought herbaceous plants back to the sites, the resulting soil conditions made it nearly impossible to grow larger woody plants due to high soil bulk density and an inability to spread roots. To counteract this problem, new methods are designed to reverse reclamation effects on soil bulk density by soil ripping – dragging large shanks sunk one meter into the ground in a 2x2 meter grid pattern, followed by tree-planting at rip intersections. To assess the effectiveness of soil ripping at two former mines managed by Cuyahoga Valley National Park, we measured near-surface soil bulk density in non-ripped areas, within rips, and at cross-rips. Additionally, we measured profile bulk density at depths between 0cm and 60cm in ripped and non-ripped areas.
Results/Conclusions
Approximately one year after soil ripping to reduce soil compaction, both of the mines we studied showed higher bulk densities of surface soil in the rips than in the non-rips, in contrast to our expectations. However, at depths between 20cm and 60cm, the bulk densities were lower in the rips than in the non-rips. This suggests that, immediately after ripping, soils were lower in bulk density, but erosion washed fine clay particles into the surface of the rips. Although the near-surface soil may have increased bulk density one year after ripping, the deeper, less dense soils in the rips could better support the root growth of woody plants. Future research will assess root growth of several hundred native trees that have been planted in the legacy mine site to aid in succession to a natural forested area. Although soil ripping only appeared to have the desired effect at depths below 20cm, we hope that this will have a lasting positive effect on the root penetration by our trees.