Assessment of Forest Ecosystem Development in Coal Mine Degraded Land by Using Integrated Mine Soil Quality Index (IMSQI): The Evidence from India

Research highlights: (1) Ecosystem development assessed in an afforested post-mining site. (2) Soil organic carbon (SOC) and total nitrogen (TN) stock reached close to the reference forest site after 25 years of afforestation. (3) Integrated mine soil quality index is developed to assess the reclamation success. Background and Objectives: Estimation of the mine soil quality is one of the most important criterions for evaluating the reclamation success and restoration of novel ecosystems of the post-industrial degraded lands. The aim of this long-term experiment was to investigate the influence of revegetation on Technosol (defined as anthropogenic soil resulted from reclamation of mine spoil materials) as the basic ecosystem development. Materials and Methods: A field study was carried out in the chronosequence afforested post-mining sites (5, 10, 25 years) and compared with natural forest site. We assessed the physicochemical properties and nutrient stock of mine soil and estimated general mine soil quality by using an integrated mine soil quality index (IMSQI). The studies were fully randomized in the chronosequence of afforested post-mining sites. Results: Nutrient dynamics and soil properties (physicochemical and biological) were recovered with the increase age of reclamation. Soil organic carbon (SOC) stock significantly increased from 9.11 Mg C ha−1 in 5 years to 41.37 Mg C ha−1 after 25 years of afforestation. Likewise, total nitrogen (TN) stock significantly increased from 1.06 Mg N ha−1 in 5 years to 4.45 Mg N ha−1 after 25 years of revegetation. Ecosystem carbon pool enhanced at a rate of 6.2 Mg C ha−1 year−1. A Principal Component Analysis (PCA)-based IMSQ index was employed to assess the reclamation success. The most influential properties controlling the health of reclaimed coal mine soil are fine earth fraction, moisture content, SOC and dehydrogenase activity. IMSQ index values are validated with vegetation characteristics. The estimated IMSQI ranged from 0.455 in 5-year-old (RMS5) to 0.746 in 25-year-old reclaimed dump (RMS25). Conclusions: A 25-year-old reclaimed dump having greater IMSQI (0.746) than reference forest soils (0.695) suggested the aptness of revegetation to retrieve soil quality and function in derelict mine land.

The formation of herbage cover in forty-year-old plantation of black locust on the reclaimed dump in the Western Donbass

The purpose of this paper is to study the formation of herbage cover in forty-year-old plantation of black locust (Robinia pseudoacacia L.), which has been growing under various forest growth conditions of artificial edaphotopes, which differed in stratigraphy and dumping depth on the reclaimed dump in the Western Donbass. The dump consisted of «empty» carefully planned mine rock; on its surface one-, two- and three-tiered structures of reclaimed land have been artificially formed. The maximum number of species in grass canopy of the black locust plantations has been recorded on technosol with typical chernozem. The formation of the grass canopy in plantations growing on technosol, consisted only of mine rock, the number of species depended on the power of edaphotope: with a decrease in dumping, a decrease in plant species has been observed. All studied variants are dominated by perennials. Under more favorable soil conditions, (variants 1 and 2) plants without vegetative movement dominate. With a decrease in the depth of dumping, the percentage of plants with slight vegetative movement increases. The representatives of plants with vegetative movement can be found under all forest growth conditions created on reclaimed lands. A specific trait of lithosol (variants 2, 3, 4) is an increase in mesoxerophytes, xerophytes and oligamegatrophs with a decrease in the power of dumping. Heliophytes predominate on studied variants with chernozem and loam with a dumping of one meter. Species partially demanding light have a significant advantage with the decrease in the power of dumping on lithosol variants with depth less than 0.6–0.3 meters. Among the coenomorphs, the dominance of ruderal and steppe complexes have been revealed. In the first case it is explained by the influence of anthropogenic factors (fire), –followed by the first stage of the restoration, namely colonization by weed plants; in the second case, it is caused by the influence of surrounding phytocenosis of undisturbed land and presence of herbal plants seeds from fertile soil level in pedosoil, which set the direction of succession towards the formation of zonal communities. Meadow and psammophytic coenotypes involved in the formation of flora indicate different types of forest growth conditions created by artificial soils.