A geospatial analysis of coal mine overburden reclamation: Land use, carbon stock, biomass, and soil genesis in chronosequence plantations

Abstract

Coal remains a pivotal energy source, meeting 27 % of global energy demand and 70 % of India's energy requirements. However, coal mining significantly disrupts land use, necessitating effective reclamation strategies. This study examines the repercussions of coal mining on land use disruption and assesses the benefits of revegetation on structural attributes, biomass, carbon sequestration, and soil restoration in central India. Utilizing Landsat 9 satellite imagery, we characterized land use and vegetation dynamics, employing the Normalized Difference Vegetation Index (NDVI) to classify five distinct age sequence classes with median ages of 5, 10, 20, 30, and 40 years. Results indicated a decrease in tree density from 1408 to 588 trees per hectare as plantations aged from 5 to 40 years, while the basal area increased from 5.88 to 28.25 m² per hectare. Notably, values in 40-year-old stands approached those of natural forests. Key novelties include the identification of a strong correlation between spectral vegetation indices (SVIs) and soil quality indicators, providing a remote-sensing-based framework for monitoring ecological restoration. Both total standing biomass and carbon stock exhibited significant (p ≤ 0.05) increases with plantation age, ranging from 10.25 to 66.41 Mg ha⁻¹ and 5.16 to 32.74 Mg ha⁻¹, respectively. Soil carbon content decreased with depth, with values ranging from 7.68 to 18.98 Mg ha⁻¹ at 0–20 cm depth, and soil nitrogen values spanning 82.66 to 216.08 kg ha⁻¹. These findings underscore the necessity of site-specific management strategies that integrate technological, ecological, and economic considerations to advance ecological restoration and align with the Sustainable Development Goals by 2030.