An evaluation of the effects of rehabilitation practiced in coal mining spoils in Korea: 2. An evaluation based on the physicochemical properties of soil

Abstract

The effectiveness of rehabilitation programs for coal mining spoils in Samcheok, Jeongsun, and Mungyung were evaluated based on the physicochemical properties of soil in the rehabilitated areas. These spoils were reclaimed by introducing plants such as black locust (Robinia pseudoacacia), pitch pine (Pinus rigida), birch (Betula platyphylla var. japonica), alder (Alnus hirsuta), bush clover (Lespedeza cyrtobotrya), and grass (Lolium perenne) in planting beds covered with forest soil. In the surface soil, the pH, organic matter, total N, available P, and exchangeable Ca showed significant changes over the years after reclamation. The pH and exchangeable Ca content decreased exponentially over time, whereas organic matter increased linearly and total N and available P increased exponentially. Changes in the physicochemical properties of subsurface soils displayed a different pattern. There were significant changes over time in the organic matter, available P, and exchangeable Ca and Mg contents of the soil. Organic matter increased logarithmically with years since rehabilitation and available P increased exponentially. Meanwhile, exchangeable Ca decreased exponentially, and Mg decreased logarithmically. The changes in the subsurface soil were not as dramatic as those in the surface soil. This result suggests that the ameliorating effects of the establishment and growth of plants more pronounced on the surface soil layer. Stand ordination data showed different relationships with time since rehabilitation in the early and later stages of the rehabilitation process. In the early stages of rehabilitation, stands tended to be arranged in the order of reclamation age. However, in the later stages, there was not a clear relationship between reclamation age and vegetation characteristics. This result suggests that soil amelioration is required for the early stages, after which an autogenic effect becomes more prominent as the vegetation becomes better established.