Ecological restoration of coal mine spoils by certain indegenous woody plantations in a dry tropical region, India

This study focuses on the ecological aspects of rehabilitation of coal mine spoil through dense plantations of selected woody species. On the basis of ecological and economic potential, four species were selected for plantations: Albizia lebbeck, A. procera, Tectona grandis and Dendrocalamus strictus. The objective of the present study was to quantify growth, biomass, net primary production (NPP) and nutrient dynamics in the plantations and to assess the impact of plantations on restoration of biological fertility. Growth in height and diameter, accumulation of biomass and NPP in different tree components and herb layer, N and P deposition and release were measured up to 6 yr of age for A. lebbeck, A. procera, and T. grandis and up to 5 yr of age for D. strictus. Impact of these plantations on the soil redevelopment was monitored as indicated by chemical characteristics such as nutrient concentrations, accumulation of organic C and total N, levels of mineral N and PO₄^--P, and rate of N-mineralization. Result showed that biomass accretion, and nutrient storage increased with age of plantations on mine spoils but varied between species. In plantations, net production and root foraging efficiencies were interdependent but varied among species, NPP and nutrient uptake were limited by nutrient supply rate. Redevelopment of soil biological fertility on mine spoil was strongly integrated with vegetation growth and nutrient cycling tended to become tighter with age of plantation.Kew words: ecological restoration; coal mine spoil; biomass; NPP; Albizia lebbeck; Albizia procera; Tectona grandis; Dendrocalamus strictus; nutrie; soil redevelopment.