Litterfall, litter decomposition and nutrient release in five exotic plant species planted on coal mine spoils

Litterfall, leaf litter decomposition and nutrient dynamics (N, P, K and Ca) were studied for four years in old plantations of five exotic plant species namely Acacia auriculiformis, Cassia siamea, Casuarina equisetifolia, Eucalyptus hybrid and Gravelia pteridifolia growing on coal mine spoil. Maximum litterfall on mine spoil was found during cooler and drier seasons than in to the hotter and moist. Total litterfall was maximum for G. pteridifolia and minimum for C. siamea. Litter of different plant species showed variations in their decomposition. The mean relative decomposition rate was maximum in the rainy season and minimum during summer, The concentrations of N and P increased, whereas K and Ca decreased in decomposing litter with increasing retrieval days. Mass loss was negatively correlated with N and P concentrations, whereas the same was positively correlated with K and Ca. Maximum litter decomposition rate was recorded for C. siamea, whereas G. pteridifolia showed the slowest decomposition rate. The plant species A. auriculiformis, E. hybrid and C. equisetifolia were found to be most suitable for planting on mine spoils as these have led to the most balanced nutrient cycling with both moderate litter deposition and decomposition rates.