Carbon storage in coal mine spoil by Dalbergia sissoo Roxb.

Abstract

Terrestrial carbon storage in the form of biomass and soil organic carbon stock is one of the important tools to combat climate change. Carbon sequestration by trees on coal mine spoil is of significance in view of the huge quantities of carbon emission associated with energy extraction from coal. Dalbergia sissoo is one of the timber yielding trees normally used for reclamation of mine spoil. Biomass and soil organic carbon stocks under D. sissoo growing on different aged (2 to 16years) coal mine spoils were evaluated. Tree height, diameter at breast height, and biomass weight of D. sissoo increased with age of reclamation. Biomass carbon stock of 16years old D. sissoo in reclaimed mine spoil amounts to 50.8t/ha, which is about 80% of a similar stand in forest ecosystem. In line with biomass C stock, soil organic carbon stock also increased with time (1.19t/ha in 2years to 9.82t/ha in 16years). Biomass carbon stock increased exponentially with time, whereas soil organic carbon stock increased linearly. A sharp increase in biomass C stock was observed after 10years of reclamation. Chemical analysis and pyrolysis data showed that D. sissoo leaf litter and other plant parts could significantly contribute to soil carbon stock. Establishment of D. sissoo on the mine spoils augmented the soil carbon stock and ameliorated physical, chemical and biological parameters of the mine spoil. These improvements in the soil quality parameters could further enhance the biomass productivity. Principal component analysis revealed that soil organic C, microbial biomass carbon and available nutrients are key factors influencing the overall quality of the mine spoil and biomass carbon stock. Thus, while reclaiming mine spoils, management practices could be focused to improve soil organic C and nutrients.