Changes in Ecosystem Carbon Following Afforestation of Post-Mining Sites- A Case Study from Raniganj Coalfield, India

Abstract:

The concept of changes in ecosystem dynamics of carbon (C) as a function of soil and vegetation developments at post-mining sites is of interest because of its prospective function in mitigating increasing global C-cycle. Forestry reclamation approaches (FRA) for post-mining sites can significantly enhance C storage in minesoils and established species; however the mechanism that not widely assessed to predict changes in ecosystem functions. A chronosequence post-mining sites (2-years, 5-years, 9-years, 15-years and 21-years old reclaimed afforested minesoils at Raniganj Coalfield, India) were investigated to: (i) quantify the amount of soil C accumulating in developing ecosystem; (ii) examine several physiochemical properties and biological processes that govern the rate of C-sequestration; (iii) identify the relationships between C-sequestration and soil properties, and (iv) develop a soil quality index by principal component analysis (PCA). From changes in ecosystem C perspective, although soil organic carbon (Corg) was less in newly developed ecosystem in comparisons to older one (21-years). However, rate of soil C-accumulation was greater (2.6 Mg C ha^-1yr^-1) in newly formed minesoil ecosystem. The overall microbial indices, dehydrogenase activities (DHA-15.7 µg^-1TPF g^-1 24 hrs^-1); microbial biomass carbon (MBC-368 mg C kg^-1); and rates of soil CO₂ flux (15 μmol CO₂ m^-2 s^-1) were found highest in older minesoils in comparisons to younger minesoils. PCA showed that three PCs with eigenvalues > 1 explained 74.5% of the total variance in the soil properties. The first PC is mostly characterized by soil nutritional and biological properties; second PC by physical properties and showed a positive correlation with soil C-accumulation and changes in plant species diversity. The present study showed that changes in ecosystem C and nutrients are direct function of enhanced and established forest land use managements.