Coal Mine Spoil Research Articles

Taxonomic and functional diversity along successional stages on post-coalmine spoil heaps

Coal is the most abundant fossil fuel in Europe, but the excavation of hard coal has covered large areas with disposed rock waste, and turned the natural habitats into disturbed novel ecosystems with harsh conditions differ in time and space. To examine the spontaneous complex successional gradient, we studied a large number of post coalmine heaps in Upper Silesia, which differ in vegetation type and age. Cluster analysis based on plant community composition (367 species in total) separated all surveyed plots on coal mining spoil heaps with herbaceous vegetation from Late Stage (LS) forests aged 14–56 years. Furthermore, the herbaceous vegetation was sub-grouped to three stages: Initial Stage (IS) aged 2–5 years, Early Stage (ES) aged 3–8 years and Mid-Stage (MS) aged 5–12 years. MS vegetation was characterised by the highest species richness and diversity (47 and 2.79) compared to ES (30 and 2.18) and IS (9 and 1.6), but higher species number and a similar diversity index occurred in LS (37 and 2.81). Functional diversity (FD) and community weighted mean (CWM) of nine functional traits showed higher (23.1) functional richness, higher (0.72) functional divergence, higher (4.5) functional dispersion, and higher value (24.4) of Rao’s quadratic entropy in LS compared to those calculated from the first three stages. Species at the initial successional stage (IS) were characterised by lower canopy height, seed mass, higher lateral spread, and specific leaf area (SLA). Additionally, the lowest (0.22 mg CO2 per hour per square metre) soil respiration (Sr) rate was recorded from IS compared to (0.53, 0.82 and 1.00) from ES, LS and MS, respectively. The soil water content (SWC) was the most important factor affecting the soil respiration, while the soil temperature (St) did not follow the well-studied relationship between soil respiration and soil temperature. Our spatial and temporal analyses illustrated changes in plant community assembly processes in the course of spontaneous vegetation succession on post coalmine spoil heaps. The importance of trait mediated abiotic filtration in community assembly in initial-, early-, and mid-stages of succession with an increase in competitive exclusion at the late successional stage was emphasized.

Delving into the diversity of genus Ironus Bastian, 1865 with special reference to Ironus dentifurcatus Argo & Heyns, 1972 (Ironidae: Enoplida), collected from coal mines

Summary In the exploration of nematode diversity within the coal mine spoil of Sonebhadra district, an isolate of Ironus dentifurcatus Argo & Heyns, 1972 was collected from the soil surrounding the roots of Prosopis juliflora. This study aims to unravel taxonomic intricacies of I. dentifurcatus through analysis of morphometric data, morphological characteristics utilising both light and scanning electron microscopy, and genetic scrutiny employing the SSU 18s rDNA gene marker. The study adds valuable information to the evolutionary history of I. dentifurcatus by constructing a comprehensive phylogenetic tree. This analysis is further augmented by an exploration of phylogeography and genetic divergence within the genus Ironus Bastian, 1865. The results reveal the genetic variability within the species of Ironus and the possible adaptative radiations in the group.

Exploring the influence of ground-dwelling ant bioturbation activity on physico-chemical, biological properties and heavy metal pollution in coal mine spoil

Coal mining activities increase the soil concentrations of heavy metals manifold thus impacting soil health and biodiversity. The understanding of the impact of bioturbation activities by ant colonies on soil in coal mine spoil site across different restoration ages is not studied. The study aimed to investigate the influence of bioturbation activities by two most common and distinct coal mine site inhabiting ant species (C. compressus and C. longipedem) at six different ages (2, 4, 6, 8, 10 and 12 years old) on the soil heavy metal concentrations of Fe, Zn, Mn, Cu, Ni, Pb, Cd and Cr, pH, OM, TC, TN, soil enzyme activity of DH, ACP, β-glucosidase and proteases properties of soil. Soil samples were collected from opencast coalmine spoils during October and November 2017. Reference (Ref.) soil samples (n=10 per site) were collected (from area adjacent to ant nest colony approximately 2–5 m distance) from a depth of 0–15 cm and ant nest debris soil of each ant species (n=10 per site) were collected from each site. Heavy metal pollution decreased and pH, OM, TC, TN and soil enzyme activity of DH, ACP, β-glucosidase and proteases of soil in both Ref. soil and ant nest debris soil increases with the increase of mine site restoration age. Our study revealed that different age of the mine spoil have more profound effects on the soil quality and heavy metal content. Contrary to our hypothesis, regression analysis did not support our notion that ant bioturbation activity directly accelerate heavy metal breakdown. Instead, our findings suggests that ant colonies prefer to construct their nest for the locations with lower heavy metal concentrations and higher enzyme activity and increase in soil porosity is a key factor behind the low heavy metal concentration in the nest debris soil.

Plant Species and Functional Diversity of Novel Forests Growing on Coal Mine Heaps Compared with Managed Coniferous and Deciduous Mixed Forests

(1): The Upper Silesia region of Poland is one of the most extensively altered regions of Europe due to human activity, especially coal mining. (2): We used cluster analysis to examine the floristic composition of three classified forest communities: forests developed on post-coal mine mineral heaps (HF), mixed deciduous forests (DECI), and managed secondary coniferous forests (CON). Vegetation data were collected from 44 randomly selected plots, and plant traits connected with persistence, dispersal, and regeneration were taken from commonly used plant trait databases. (3): Higher species richness, species diversity, and evenness (36, 2.7, and 0.76, respectively) were calculated for HF plots compared with those plots from DECI (22, 1.9, and 0.62) and CON (18, 2.0, and 0.71) plots. Higher functional richness (0.173, 0.76) and functional divergence were determined for HF compared with those calculated for DECI (FRic 0.090, FDiv 0.71) and CON (FRic 0.026, FDiv 0.69). In contrast, the substrate from HF forests had significantly lower soil respiration (0.76 mg-CO2 h/m2) compared with substrates from both CON and DECI forests (0.90 and 0.96 mg-CO2 h/m2, respectively); (4): A set of complex abiotic stresses which plants suffer from on coal mine spoil heaps shaped different patterns of taxonomic and functional diversity. These findings demonstrate the importance of investigating successional aspects and carbon dynamics of de novo forests which have developed on post-coal mine spoil heaps in urban industrial areas.

Assessment of factors determining the rate and direction of plant communities development on coal mining spoils (the case study of the Gorlovskoye anthracite deposit)

The aim of the study. Identification and assessment of specific succession processes on self-revegetating coal mining spoils of the Gorlovskoye anthracite deposit, as related to the abiotic factors. Location and time of the study. The coal mining spoils of the Gorlovskoye anthracite deposit (54.568880 NL, 83.588956 EL), Novosibirsk region, Iskitimsky district, June 2023. Methods. The properties of soil substrates in technogenic landscapes were determined by officially attested and widely used methods of soil analyses. In field conditions, soil hardness was measured with a penetrometer, then soil density was calculated from its values using the dependence function. Total carbon and nitrogen contents were determined using a Perkin Elmer 2400 Series II CHNS/O analyzer. Statistical processing of the data was carried out using cluster, principal components and Spearman's correlation analyses. Results. In the anthracite coal mining spoils in the forest-steppe conditions of West Siberia, the high content of physical clay and clay-producing rocks in the developing soils promotes predominantly herbaceous plant groups, whereas slope areas with a high content of stones benefits the growth of woody vegetation.

Possibility of spatial estimation of soil erosion using Revised Universal Soil Loss Equation model and generalized additive model in post‐hard coal mining spoil heap

AbstractRevegetation and plant cover establishment on coal mining heap areas are effective methods for reducing runoff and soil erosion. They are essential components for reestablishing ecosystems in ecologically vulnerable areas. Our study area covered the Upper Silesia coal region. The research focused on active and passive reclamation plots of the study area with different land covers, that is, woodland, grassland, forbland, and control plots. This study aimed to evaluate the spatial allotment of soil erosion in various reclamation techniques and land covers of a mining area using a combination of the Revised Universal Soil Loss Equation (RUSLE) model, geographic information systems, and regression modeling with generalized additive models. We demonstrated that the combination of different data analysis methods can be used to accurately predict soil degradation, even if not all factors used in the RUSLE model are wall‐to‐wall available. However, only sheet and rill erosions can be predicted using this model. The results demonstrated the spread of soil erosion over the post‐coal mining heaps, varying from 0.03 Mg/ha/year to 583.47 Mg/ha/year. The highest soil erosion rate was observed at the control site (bare rock without vegetation). Approximately 62.6% of the region remained in the safe zone, whereas approximately 1.4% of the area was classified as a very severe zone for erosion.

Heavy Metals in Soil and Plants During Revegetation of Coal Mine Spoil Tips and Surrounded Territories

Heavy Metals in Soil and Plants During Revegetation of Coal Mine Spoil Tips and Surrounded Territories

Functions of microarthropods in reclaimed mines spoil: A case study of Kathara Coalfield area of Jharkhand,India

Reclaimed mines spoil (RMS) is the byproduct of open-cast mining and an ecological footprint under twin stresses namely, anthropogenic and natural. The present paper measures the stresses in reclaimed coal mine spoils and has two sections – the first dealing with the experiments and their results, while the second section derives an ecological model from the experiment. An experiment was carried out (experimental years, 2006 – 2008) in reclaimed coal mine spoils (RMS) of Jharkhand. Four RMSs of different chrono sequences of plantations on the overburden dumps (OBD) were considered for the study. Data on soil arthropods along with other physical parameters were collected from a 1meter x 1meter grid of quadrate periodically. It was observed that the Shannon diversity index of younger RMS was higher than the 15- and 30-year-old RMS. Old age sites and forests had a higher Diversity Index. Simpson’s index was 0.0877, 0.889, 0.869, and 0.887 in four RMS sites, and 0.885, and 0.917 in the forest. Organisms in degraded systems are initially rudrals – create a functional system and establish as K-select species. It was observed that the system has stresses – homeostatic processes that keep a system in its original state, and other forces – resilience pulls them out of the status quo but in reclaimed mine spoils an additional force anthropogenic activities work synergistically with the forces of resilience that push the system towards non-equilibrium, which is critical for succession and ecesis. Based on findings and functional stresses in the system an ecological model was developed for ecesis that is operative in the system.

Bio-transfer and bioaccumulation patterns of heavy metals in mine site-inhabiting ants and grasshoppers, across mine site restoration chronosequence.

Soil is known to serve as a significant sink for heavy metals in coal mine sites, thus also influence the plant and other organisms of that area. Hence, the presence of heavy metals in coal mine soil is of concern to land managers. Insects occupy different trophic positions in the food chains, thus many insect species accumulate large amounts of heavy metals in their bodies and this is a matter of concern. In the present study, we investigated biotransfer and bioaccumulation of heavy metals from soil, grass species Cynodon dactylon, Vetiveria zizanioides, grasshopper species Gastrimargus africanus, Choroedocus robustus, ant species Cataglyphis longipedem and Camponotus compressus in six different ages (2, 4, 6, 8, 10 and 12 year old) of coal mine sites. Our study revealed that at some extent the heavy metal content and BAF patterns of heavy metals along different pathways (from soil to grass, soil to grasshoppers and from grass to grasshoppers) were not consistent and did not reflect the soil pollution status for all the metals, related to the mine spoil dump age. However, in contrast, ants successfully reflected a consistent pattern in the bioaccumulation of heavy metals via soil, thereby indicating the pollution status of the soil along with the restoration age of mine spoil dumps. Our study showed that ant species can successfully forecast the presence of heavy metals of coal mine spoils along with their restoration.

Changes in microbial community structure during the biooxidation of iron and inorganic/organic sulfur provide prediction of acid mine drainage from coal spoil

To thoroughly investigate the formation mechanism of acid mine drainage (AMD) from coal mine spoil, this study conducted microbial shake flask experiments on gangue possessing inorganic and organic sulfur to predict the future generation of AMD. The results revealed that microbial-mediated sulfur oxidation effectively lowered the pH of leachate and increased metal ion and sulfate concentrations. The oxidation of pyrite sulfur and thiophene sulfur contributed to 70 % and 30 % of the total acid production, respectively, highlighting the importance of both processes in coal mine acidification. The abundance and diversity of the microbial community increased, with “new” iron and sulfur oxidizing bacterial species during acidification, with “new” iron and sulfur oxidizing bacterial species, such as Sulfobacillus sp. and Acidibacillus sp., emerging and constituting approximately one-third of the bacterial population. These bacteria survived desiccation and proliferated faster than A. ferrooxidans YQ-N3 when conditions favored growth.

Carbon and nitrogen sequestration during primary succession in granodiorite quarries

AbstractStudies assessing the potential of mining areas for carbon sequestration focused mainly on areas after the extraction of energy raw materials, especially coal or oil shale, but little attention was paid to stone quarries and quarries of other non‐energy raw materials. We investigated carbon and nitrogen pools (stocks) along a chronosequence in the organic horizon and to a depth of 20 cm of the mineral soil in granodiorite quarries. We compared these pools and sequestration rates with other mining sites. The advantage of this study is that several differently aged quarries in a small area have the same rock chemistry and climate. Thus, the rate of pedogenesis is purely a function of time and vegetation. It is not affected by fossil organic matter or organic matter and nutrients in the topsoil used for reclamation. The vegetation succession tends towards tree cover dominated by Pine (Pinus sylvestris), Birch (Betula pendula), Willow (Salix caprea), Aspen (Populus tremula) and Alder (Alnus glutinosa). Analysis of soils from granodiorite quarries showed a natural accumulation of carbon and nitrogen in the soil to a depth of 20 cm during about 60 years of natural succession. The total soil organic carbon and nitrogen pools to a 20 cm depth average of 2482.4 g C m−2 and 179.1 g N m−2, respectively, in the oldest plots >50 years old. These values are for carbon 2.6 and nitrogen 2.4 times lower compared to pools in the same depth on control plots. Carbon and nitrogen stocks and sequestration rates are lower than in compared coal mining sites and spoils. The sequestration rates of the total sampled soil profile decreased with time from 57 g C m−2 year−1 and 4 g N m−2 year−1 for sites younger than 25 years to 46 g C m−2 year−1 and 3 g N m−2 year−1 for sites older than 50 years.

Soil recovery in a chronosequence of revegetated coal mine spoils in Colombian drylands: a view from the assessment of physical-chemical and biological properties

Characterizing changes in soil properties is essential to understand the effect of land rehabilitation practices and the mechanisms that drive such changes. The objective of this study was to evaluate the recovery of physical-chemical and biological properties of Technosols with increasing rehabilitation age in a chronosequence of dry forests (7, 10, and 21 years) in the El Cerrejón open-pit coal mine (La Guajira, Colombia). Based on previous studies that demonstrated a greater effect of surface change on the physicochemical properties of soils, composite samples taken at two depth levels (0–3 cm and 3–20 cm) were analyzed for each site. The studied properties improved over time, increasing significantly with respect to non-rehabilitated sites, mainly near the surface (0–3 cm). Particularly, after seven years, the increases in soil N content and soil P solution were significant (32% and 71%, respectively). The increased structural and functional development of the vegetation over time led to increased inputs of organic materials via fine litterfall. Overall, soil organic matter (SOM) ranged from 63 to 89% in the rehabilitated sites compared with a reference mature dry forest. Increased SOM is a key indicator of recovery in degraded mine spoils, as it has an outsized ability to influence other soil properties. This represents a positive result for the revegetation/restoration strategy applied at the El Cerrejón mine.

Lime slurry treatment of soils developing on abandoned coal mine spoil: Linking contaminant transport from the micrometer to pedon-scale

Historical and abandoned coal mine spoil continues to generate acid- and metal(loid)-rich porewaters and represents a geographically large and diffuse non-point source of contamination to local watersheds. A potentially inexpensive approach to treat these materials and soils developing on them is through the application of lime slurries, to neutralize acidity and encourage the (co)precipitation of metal(loids) with Fe(III)-(oxy)hydroxides, and potentially other metal-oxides and/or Ca-bearing phases. The efficacy of this approach was evaluated through parallel field application and laboratory-based flow-through column experiments. The field site is Huff Run sub-watershed 25 located in Tuscarawas County, Ohio and was chosen in part because it was previously classified as one of the most highly AMD-impacted sub-watersheds in the region. Two locations with historical spoil were chosen and suction lysimeters were installed at 25 and 75 cm depth to monitor porewater composition on two sides at the base of each pile. Half of each slope received seven lime slurry treatments from June through October of 2017. A suite of aqueous (ICP-OES, IC, and TOC-L) and solid phase geochemical and mineralogical approaches (quantitative SEM-EDS and synchrotron μ-XRF) were used to determine how composition, texture, morphology, and spatial distribution of mineral coatings differ in pre- and post-lime treated soils, and how that impacts the distribution and transport of trace metal(loid)s. Mine spoil porewater at site 1 was slightly less alkaline (pH ranging from 7.04 to 7.37) than at site 2 (ranging from 7.55 to 7.71), and average electrical conductivity values at site 1 (316–405 μS cm−1) were slightly lower than at site 2 (358–464 μS cm−1), although differences between the sites were not significant. Porewater pH and electrical conductivity in all lysimeters decreased over the course of the field season but there was no obvious response to lime treatment at either site or any depth. At site 1, both treatment and depth were significant factors affecting Ca, K, Ni, SO42−, and DOC concentrations while only treatment effects were significant for dissolved Al and Cu (p < 0.05). For all soils, there were no trends in metal concentration observed over time although DOC and SO42− decreased over the field season. Pedon-scale changes in metal porewater concentrations in response to treatment were linked to micrometer-scale changes in mineral surface coatings; specifically, higher concentrations of Ca, Fe, Mn, and Zn were observed in the coatings and no changes were observed in Fe redox speciation, whereas total S decreased likely due to oxidation of S in coal fragments. In contrast to the field experiment, the column experiments exhibited a much greater response in effluent composition with respect to lime treatment. The untreated columns had approximately an order of magnitude more H+ leached over the course of the experiment (p < 0.001) and resulted in greater Ca, Al, Cu, and DIC leached and less Mn, Zn, and SO42−. Soils treated with the lime slurry in the column experiments exhibited larger and thicker secondary Fe-coatings, including the addition of Fe-sulfates. Despite clear trends in the laboratory-based column experiment where the lime-to-soil ratio was higher, the effects were either muted or undetected in the field pilot project, suggesting that a higher application rate of lime in the field is needed to achieve a similar effect. This work provides evidence that a less alkaline lime slurry could be a practical and inexpensive method of treating coal mine spoil-impacted soils and represents an important step in linking laboratory-based remediation studies to implemented field-based studies.

Comparative assessment of soil properties and heavy metals indices at rehabilitated and non-rehabilitated sites in coal mine spoils

Comparative assessment of soil properties and heavy metals indices at rehabilitated and non-rehabilitated sites in coal mine spoils

In memoriam of Svetlana Vasilievna Shibareva (21.05.1953 – 25.05.2023)

The article provides information about the research activities of Svetlana Vasilievna Shibareva, candidate of biological sciences, the researcher at the laboratory of biogeocenology at the Institute of Soil Science and Agrochemistry of the SB RAS, briefly describing the main areas of her research such as carbon cycle, nitrogen and other elements in agrocenoses and on coal mining spoils, peat reserves and decomposition in the mires of West Siberia and Poland, as well as fractional and chemical composition of litter in the forest and grassland ecosystems of Siberia.

Community Level Physiological Profiling of Microbial Communities Influencing Mine Spoil Genesis in Chronosequence Coal Mine Overburden Spoil

Ecological restoration through mine spoil genesis should be dogmatic and the strategies involved a holistic approach, which emphasizes the role of microbial community composition that varies in accordance with the physiological and nutritional status of mine spoil profiles. This is because the patterns observed aboveground is being driven by the belowground diversity and processes. Thus, the relationship between microbial community structure and mine spoil genesis in chronosequence coal mine spoil has attracted considerable research attention. The occurrence of higher microbial diversity and difficulties in culturing microbes necessitate the use of a culture-independent approach through community-level physiological profiling based on the patterns of carbon source utilization using BIOLOG Ecoplate and thereby the functional diversity of microbial communities in different age series coal mine spoil was determined. The average well-color development exhibited an increasing trend with a minimum in OB0 (0.0640) and a maximum in OB15 (0.5060) over time. The patterns of substrate utilization (carbohydrates, carboxylic and ketonic acids, amino acids, polymers, amines, and amides) reflect the shift in microbial community composition in different age series coal mine spoil over time. Gradual increase in species richness and Shannon diversity index with the increase in age of mine spoil substantiated relatively higher microbial diversity reflecting the sign of mine spoil genesis. Principal component analysis and redundancy analysis based on the differential patterns of substrate utilization discriminate different age series coal mine spoil into independent clusters, which evaluated the broad-scale patterns of microbial community dynamics influencing the pace and progress of mine spoil genesis.

A Metagenomic Assessment of Soil Microbial Communities in a Coal Mine Spoil Dump Under Reclaimed Vegetation in La Guajira, Colombia

A Metagenomic Assessment of Soil Microbial Communities in a Coal Mine Spoil Dump Under Reclaimed Vegetation in La Guajira, Colombia

Trace Metal Enrichment in the Colloidal Fraction in Soils Developing on Abandoned Mine Spoils

The release of colloid-bound trace metals from abandoned coal mine spoils can potentially be a significant source of contamination during weathering. We examined the size-dependent enrichment of trace metals in mine spoil samples using centrifugation and acid extraction to compare metal loading in the bulk and colloid fractions. A combination of X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and focused ion beam (FIB) sectioning of selected colloids for transmission electron microscopy (TEM) analyses was used to determine the morphology and elemental and mineral composition at the micro- and nanoscales. In contrast to bulk soils, primary Fe-sulfides (up to 11%) and secondary Fe(III)-bearing phases (up to 5%) were a significant portion of the colloid mineralogy. Secondary Fe-(hydro)oxides and (hydroxy)sulfates were enriched with Mn, Ni, Cu, and Zn, and these metals showed stronger correlations with Fe in the colloid fraction (R2 of 0.58, 0.77, 0.94, and 0.81, respectively) than in the bulk fraction (R2 of 0.40, 0.09, 0.84, and 0.62, respectively), indicating that Fe-bearing colloids are likely major trace-metal-bearing phases. The results from this study will help to design better remediation projects for abandoned mine spoils to better account for a potentially underappreciated mode of contaminant transport.

Kinetic Indices of Enzyme Activity used as Sensitive Biomarkers to Monitor Mine Spoil Genesis in Chronosequence Coal Mine Overburden Spoil

Mine spoil genesis mostly focuses on careful consideration of enzyme activities and kinetics parameters toelucidate microbial mediated biotransformation and nutrient cycling including their link with the variationin physicochemical properties, microbial community dynamics and landscape ecology as the functionaldeterminants of ecosystem function. The relative distribution of microbial populations exhibited progressiveincrease in different age series coal mine overburden spoil over time. The kinetic parameters of amylase,invertase, protease, urease, phosphates and dehydrogenase activities were determined to assess the metabolicresponse in different age series coal mine spoil. Gradual increase in Vmax and decline in Km of enzymeactivities representing the quality and affinity of enzymes correlated well with the shift in microbialcommunity composition over time. Besides, the shift in catalytic efficiency (Vmax/Km) has greatersignificance as early and sensitive indicators of the changes in soil properties influencing microbialcommunity dynamics across the sites. The enzyme activity and kinetic parameters correlated well the changesin physicochemical properties over time across the sites. PCA and RDA analysis can able to discriminatesix different age series coal mine overburden spoil and nearby NF soil into independent clusters based onthe variability in physicochemical properties, microbial community structure, enzyme activities and kineticparameters. The study suggested that the kinetic indices of enzyme activities can be used as reliable ecologicalbiomarkers to monitor the progress of mine spoil genesis.

The effect of tree species on soil organic carbon recovery in a restoration project is associated with vegetation biomass: Evidence from the Pingshuo Mine reclaimed ecosystem, North China

AbstractVegetation and soil surveys were made within three mixed forests and four monoculture forests on opencast coal mine spoils in the Loess Plateau (China) to reveal the tree species effect on reclaimed mine soil (RMS) and carbon (C) sequestration. Results showed that tree biomass, annual litter biomass, and reserved litter biomass varied among forests, with Robinia pseudoacacia L.‐Pinus tabuliformis Carr. recording the highest tree biomass, leaf C, and leaf nitrogen (N) values. The greatest C and N contents in RMS were recorded in the R. pseudoacacia ‐ P. tabuliformis forest in both small macroaggregate (250–2000 μm) and large macroaggregate (&gt;2000 μm) fractions. However, no significant differences among forests were observed in microaggregate (53–250 μm) and silt+clay (&lt;53 μm) associate C and N. Significant positive correlations were observed among soil C and vegetation biomass and vegetation biomass associated C. It was in line with the C isotope analysis, which indicated that C flowed in the order: leaf→litter/root→soil macroaggregate→soil microaggregate/silt+clay. Moreover, negative correlations between soil C and soil δ15N in large and small macroaggregate fraction were recorded, indicating C sequestration in macroaggregate was potentially associated with soil N cycling. Overall, Tree species effect on soil C sequestration was derived from the amount and quality of the vegetation biomass and it was mediated by soil N cycling to some extent. R. pseudoacacia ‐ and P. tabuliformis mixed forest could be proposed as a favourable reclamation choice, due to these species prominent C sequestration ability.