Abstract
Purpose Surface coal mining operations generate large quantities of mine-waste that are disposed in land-raised ‘mine-waste dumps’, which are generally unstable, nutrient deficient and unsuitable for creating ecological structure and functions. The natural recovery of disturbed ecosystems is a long-term process extending to decades. The purpose of the present work is to explore the restoration opportunities using a scientific revegetation approach for re-establishment of ecological services and mine dump stabilisation in selected Indian mining wasteland. Methods A 18 year re-vegetation study was undertaken into the Indian coalmine spoils to understand the process of ecosystem development, with an ecological and geotechnical perspective. This long-term investigation examined (i) the physico-chemical properties of soil/mine spoil following standard methods; (ii) screened suitable plant species for restoration; (iii) assessed the impact of revegetation on mine dump slope stability by measuring the dump geometry using an electron distance meter (EDM), numerical simulations and in-situ shear jack test; and (iv) basic ecological services that were achieved in two different spoil heaps located in Jharia, formerly comprising native grassland and forest, some 20 km apart. Results The results clearly indicated that leguminous plants significantly enhanced spoil stability from 4 to 18 years after re-vegetation. Following, considerable quantities of organic carbon were stored in the mine spoil, with increases of 125–250% and by 82–282% being recorded at 6 and 18 years, respectively. Similarly, C in below ground biomass (BGB) increased by 380–945%, and 300–993%; C in plant biomass by 194–345% and 392–695% and 214–429% and 73–662%; and C in soil microbial biomass (MBC) by 157–372 kg ha –1 and 121–292 kg ha –1 . The factor of safety (FOS) was significantly enhanced from 1.4 to 1.6 and 1.9 after 6 and 18 years of plantation on dump slope, respectively. Further, the ecological services were considerably enhanced by increased soil carbon stock, soil nutrient, microbial biomass, reduced soil runoff and wildlife movement. Conclusion Long-term monitoring following a scientific re-vegetation approach can assess ecosystem recovery and the re-establishment of ecological services in damaged ecosystems from mining. The physico-chemical and biological properties of re-vegetated mine spoils helps to assess the critical indicators for mine spoil dump stabilisation and ecosystem recovery. These indicators can be used to elucidate the geotechnical and ecological engineering processes pertinent for mine spoil and degraded ecosystem management.