Changes in ecosystem carbon pool and soil CO₂ flux following post-mine reclamation in dry tropical environment, India

Open strip mining of coal results in loss of natural carbon (C) sink and increased emission of CO₂ into the atmosphere. A field study was carried out at five revegetated coal mine lands (7, 8, 9, 10 and 11years) to assess the impact of the reclamation on soil properties, accretion of soil organic C (SOC) and nitrogen (N) stock, changes in ecosystem C pool and soil CO₂ flux. We estimated the presence of C in the tree biomass, soils, litter and microbial biomass to determine the total C sequestration potential of the post mining reclaimed land. To determine the C sequestration of the reclaimed ecosystem, soil CO₂ flux was measured along with the CO₂ sequestration. Reclaimed mine soil (RMS) fertility increased along the age of reclamation and decreases with the soil depths that may be attributed to the change in mine soils characteristics and plant growth. After 7 to 11years of reclamation, SOC and N stocks increased two times. SOC sequestration (1.71MgCha^-1year^-1) and total ecosystem C pool (3.72MgCha^-1year^-1) increased with the age of reclamation (CO₂ equivalent: 13.63MgCO₂ha^-1year^-1). After 11years of reclamation, soil CO₂ flux (2.36±0.95μmolm^-2s^-1) was found four times higher than the natural forest soils (Shorea robusta Gaertn. F). The study shows that reclaimed mine land can act as a source/sink of CO₂ in the terrestrial ecosystem and plays an important role to offset increased emission of CO₂ in the atmosphere.