Reclamation Age Research Articles

Influence of long-term ecological reclamation on carbon and nitrogen cycling in soil aggregates: The role of bacterial community structure and function

Understanding the influence of microbial taxa and functions on soil carbon (C) and nitrogen (N) cycling, particularly concerning soil aggregate sizes, is crucial for ecosystem management. This study examines the taxonomic and functional dynamics of soil bacterial communities within different aggregate sizes over time. Soil samples from a reclamation forest on the Loess Plateau in North China were collected across reclamation ages of 0, 3, 18, and 28 years. Soil aggregates were categorized into large macro-aggregates (>2000 μm), small macro-aggregates (250–2000 μm), and micro-aggregates (<250 μm) using a modified dry-sieving method. Soil aggregate stability, C and N concentrations, newly derived plant C, enzyme activities, bacterial communities, and functional genes in each aggregate fraction were systematically analyzed. There was a notable increase in soil aggregate stability and a higher proportion of large aggregates was found with increasing forest age. There were significant differences in bacterial community structures, particularly between micro-aggregates and large macro-aggregates and across different forest ages. Reclamation led to an increased abundance of copiotrophic bacterial taxa. Decreases in N-acquiring enzyme activity in micro-aggregates were contrasted by an increase in C, N, and phosphorus (P) acquisition activities in larger aggregates over time. Larger aggregates showed a faster recovery of C and N cycling genes accompanied by a significant enhancement in acetyl-CoA and ammonia oxidation processes, underscoring their importance in soil nutrient cycling. These results highlight the critical role of aggregate size in shaping microbial community structures and functions that influence soil C and N cycling during reclamation and provide new perspectives highlighting the significance of incorporating aggregate size considerations into soil management and reclamation strategies.

Soil erodibility results of revegetation using bitti plant at various ages reclamation of quarry a lime stone mine at Pt Semen Tonasa, Pangkep District, South Sulawesi

Background: Limestone mine reclamation carried out by PT Semen Tonasa is carried out periodically as an effort to restore land conditions in a sustainable manner. The reclamation was carried out in the form of revegetation using endemic plants, namely the bitti plant (Vitex cofassus R.) which grows a lot in the southern part of Sulawesi. This study aims to determine the erodibility of the soil in limestone mine reclamation land planted with bitti plants. Methods: The method used is the survey method by determining the location of soil samples using the purposive sampling method based on the reclamation age planted with bitti plants in 2019, 2015 and 2010 and determining the erodibility value using the formula according to Wischmerier and Smith (1978). Parameters used included soil texture, soil structure, organic matter, soil permeability, soil pH, and soil unit weight. Findings: The results of this study indicate that the erodibility of the soil in the limestone mine reclamation land planted with bitti plants is classified as high due to the high dust content which is influenced by the parent material. The results of this study indicate that the erodibility value of the land reclamation in 2019 was classified as moderately low to moderately high, the land reclamation in 2015 was classified as moderate to moderately high, and the land reclamation in 2010 was classified as moderate to high. Conclusion: The factor affecting the erodibility of the soil in the reclamation area is the M value (percentage of very fine silt and sand). Novelty/Originality of this Study: The novelty of this study lies in the examination of soil erodibility changes over different reclamation ages in a limestone mine using endemic bitti plants. This research highlights the unique relationship between reclamation age and soil properties, contributing valuable insights into effective land reclamation practices in tropical karst environments.

Effect of particle size distribution of sediments on development of polder soils in Japan

Abstract Purpose Polder soils develop from oceanic and lacustrine sediments covered with seawater, brackish water, and freshwater after artificial drainage. Because there are several concerns regarding the agricultural use of polder soils, soil genesis and properties have been considerably surveyed, mainly focusing on problematic soils developed from fine sediments. Although sediments have a wide range of particle size distributions due to different sedimentary conditions, particle size of parent materials have not been well addressed to understand the soil developmental process. In this study, Japanese polders with different reclamation ages and sedimentary conditions were surveyed to clarify the soil formation process and factors affecting pedogenesis. Materials and methods Soil samples were collected from 15 soil profiles in six Japanese polders under different land use types. Sedimentary conditions of polders were evaluated from particle size distributions using the hydrodynamic classification proposed by Pejrup (The triangular diagram used for classification of estuarine sediments: a new approach. Tide-influenced Sediment Environ Facies, pp 289–300, 1988). The major soil-forming factors of polders were extracted by principal component analysis (PCA) using general soil properties. Results and discussion Brackish lake and inner bay polders were characterized by calm hydrodynamic conditions comprising fine particles. Two polders reclaimed from a shallow inland sea were characterized by violent hydrodynamic conditions. Sandy sediments were also characteristic of immature soils reclaimed from a freshwater lake and an estuarine tidal flat. Soils on polders developed under calm hydrodynamic conditions enabled the accumulation of high total carbon content. The soil-forming process in the brackish bay oxidized pyrite, leading to an acidic soil reaction. Conversely, soils developed from sandy sediments were characterized by low iron content. The PCA extracted two factors explained by particle size and soil reaction relating to acidification and salt leaching. Conclusion Polder soils can be mainly discriminated by their particle size distributions, which are characterized by hydrodynamics under the sedimentary conditions, and the polder soil development is affected by water management in land uses after artificial drainage.

Studies on Soil Physical Quality of PT Coal Mine Reclamation Land, Sumber Bara Abadi, Kutai Kartanegara Regency, Indonesia

Evaluation of the physical quality of soil on coal mine reclaimed land is needed to monitor and evaluate reclamation activities aimed at restoring and improving soil quality. The results of the evaluation of the quality of the physical properties of the soil are presented as an index of the physical quality of the soil which can be used as input for taking further soil management actions. This research aims to determine the characteristics of the physical properties of the soil and assess the physical quality of the soil on coal mine reclaimed land as outlined in the soil physical quality index (IKFT). This research was carried out from August to November 2022 on the reclaimed coal mine land of PT. Sumber Bara Abadi, Sumber Sari Village, Sebulu District, Kutai Kartanegara Regency, East Kalimantan, Indonesia. The method used in this research was a survey. Determining the location of soil samples was carried out using a purposive method based on reclaimed land cover, reclamation age, and slope. Data analysis was carried out directly in the field and soil analysis in the soil laboratory of the Faculty of Agriculture, Mulawarman University. The assessment of the IKFT is carried out after the analysis of the physical characteristics of the soil has been determined. The IKFT is measured by following a three-step procedure, namely identification of indicator data sets, interpretation of indicators, and integration of all indicator scores into one overall IKFT value. The research results show that (1) the physical characteristics of the soil are: soil texture varies between clay, clay loam, and sandy clay loam; Soil porosity is classified as poor and good; stability of aggregate is classified as less stable aggregate to very stable; Soil permeability is relatively slow and moderate; bulk density is classified as medium and slightly dense; surface rocks are abundant; the depth of the solum is classified as shallow and medium; and (2) the physical quality of the soil on reclaimed coal mine land is classified as rather low and moderate with limiting factors including a large amount of surface rock, large bulk density, low solum depth, and low aggregate stability.

Capung (Ordo: Odonata) di Kawasan Reklamasi Bekas Tambang Timah, Belinyu, Bangka

Dragonflies are bioindicator insects that are known to be sensitive to the environment and their existence is influenced by habitat conditions. The potential of dragonflies as a bioindicator for the success of reclamation efforts for former tin mining on Bangka Island needs to be studied. This research aims to record the diversity of dragonflies and damselflies in reclaimed land covering an area of ±15.25 ha and aged ±16 years as one component to enrich the criteria for assessing the success of revegetation of ex-tin mining land. This research was conducted in the rainy season, January-March 2023. For three weeks, Schnabel's visual encounter survey (VES) and capture-mark-release-recapture (CMRR) methods were chosen to observe five transect lines, respectively non-revegetation areas, horticultural and fruit revegetation areas, oil palm revegetation areas, kolong with tilapia fish, and kolong with human activities. This research recorded 19 species of dragonflies and 6 species of damselflies, or around 6.5% of the dragonflies and 2.0% of the damselfly species on the island of Sumatra. The most dominant species are Neurothemis fluctuans and Ceriagrion cerinorubellum. The number of species and number of individual dragonflies is thought to be related to the age of reclamation, and has the potential to be an indicator of the success of ex-tin mining reclamation land. Keywords:“Area Type”; “Bangka”; “Bioindicator”; “Dragonfly”; “Ex-Mined Land Reclamation”

Long-term conventional cultivation after desert reclamation is not conducive to the improvement of soil carbon pool and nutrient stocks, a case study from northwest China

Reclamation in desert-oasis areas is effective for improving land productivity and ensuring food supply. However, the understanding of the sustainable productivity of soils under long-term conventional cultivation after desert reclamation is still poor. This study was conducted to determine soil structural properties, organic carbon stocks (SOCS) and nutrient stocks under four desert reclamation ages (0, 30, 60, and 100) in the arid region of northwest China, and evaluate the influence of long-term conventional cultivation on desert soil quality. The results indicated that soil structural stability index (SI) in topsoil improved after desert reclamation, but showed a slight downward trend after 60 years of cultivation, and farmland soil in the study area was still at serious risk of degradation (SI ≤ 5 %) overall. SOCS were enlarged by 4.2 times after desert reclamation, and nitrogen stocks (NS) and phosphorus stocks (PS) were increased by 1.2–6.5 times. However, the regression analysis showed that SOCS and NS in 0–40 cm soil layer and PS in topsoil stopped increasing after about 60-year conventional cultivation. Soil stoichiometry, pH and texture were the key factors affecting SOCS, NS and PS in oasis farmlands. In summary, our study emphasized that soil quality in arid areas was greatly improved after desert reclamation, however, long-term conventional agriculture management measures limited this improvement. Therefore, long-term conventional management of agricultural land in arid areas should introduce appropriate conservation measures to achieve sustainable soil productivity.

Stream Chemistry and Forest Recovery Assessment and Prediction Modeling in Coal-Mine-Affected Watersheds in Kentucky, USA

Kentucky is one of the largest coal-producing states; surface coal mining has led to changes in natural land cover, soil loss, and water quality. This study explored relationships between actively mined and reclaimed areas, vegetation change, and water quality parameters. The study site evaluated 58 watersheds with Landsat-derived variables (reclamation age and percentage of mining, reclaimed forest, and reclaimed woods) as well as topographic variables (such as elevation, slope, drainage density, and infiltration). Water samples were collected in spring (n = 9), summer (n = 14), and fall (n = 58) 2017 to study changes in water quality variables (SO42−, alkalinity, conductivity, Ca2+, Mg2+, Mn2+, Al3+, and Fe2+, Fe3+) in response to changes in land cover. Pearson correlation analyses indicated that conductivity has strong to very strong relationships with water quality variables related to coal mining (except Al3+, Fe2+, Fe3+, Mn2+, elevation, slope, and drainage density) and land cover variables. In addition, separate regression analyses were performed, with conductivity values based on samples collected in the fall. First, conductivity responses to mining percentage, reclamation age and topographic variables were examined (adjusted R2 = 0.818, p &lt; 0.01). Next, vegetation cover change parameters were added to the same model, which yielded slightly improved R2 (adjusted R2 = 0.826, p &lt; 0.01). Finally, reclamation age and mining percentages were used to explain the quantity of reclaimed forested areas as a percentage of watersheds. The model was significant (p &lt; 0.01), with an adjusted R2 value of 0.641. Results suggest that the quantity (area as a percentage) of reclaimed forests may be a predictor of the mining percentage and reclamation age. This study indicated that conductivity is a predictable water quality indicator that is highly associated with Coal-Mine-Related Stream Chemistry in areas where agriculture and urban development are limited. Water quality is not suitable for various purposes due to the presence of contaminants, especially in mined sites. These findings may help the scientific community and key state and federal agencies improve their understanding of water quality attributes in watersheds affected by coal mining, as well as refine land reclamation practices more effectively while such practices are in action.

Microbial composition and function in reclaimed mine sites along a reclamation chronosequence become increasingly similar to undisturbed reference sites

Mine reclamation historically focuses on enhancing plant coverage to improve below and aboveground ecology. However, there is a great need to study the role of soil microorganisms in mine reclamation, particularly long-term studies that track the succession of microbial communities. Here, we investigate the trajectory of microbial communities of mining sites reclaimed between three and 26 years. We used high-throughput amplicon sequencing to characterize the bacterial and fungal communities. We quantified how similar the reclaimed sites were to unmined, undisturbed reference sites and explored the trajectory of microbial communities along the reclamation chronosequence. We also examined the ecological processes that shape the assembly of bacterial communities. Finally, we investigated the functional potential of the microbial communities through metagenomic sequencing. Our results reveal that the reclamation age significantly impacted the community compositions of bacterial and fungal communities. As the reclamation age increases, bacterial and fungal communities become similar to the unmined, undisturbed reference site, suggesting a favorable succession in microbial communities. The bacterial community assembly was also significantly impacted by reclamation age and was primarily driven by stochastic processes, indicating a lesser influence of environmental properties on the bacterial community. Furthermore, our read-based metagenomic analysis showed that the microbial communities' functional potential increasingly became similar to the reference sites. Additionally, we found that the plant richness increased with the reclamation age. Overall, our study shows that both above- and belowground ecological properties of reclaimed mine sites trend towards undisturbed sites with increasing reclamation age. Further, it demonstrates the importance of microbial genomics in tracking the trajectory of ecosystem reclamation.

Diversity of soil mesofauna at various ages of post-tin mining reclamation land on Bangka Island

Soil mesofauna can be used as an indicator of soil fertility on post-tin mining reclamation land. The diversity of soil mesofauna depends on climatic conditions and soil characteristics at its habitat. The purpose of this study were to determine the diversity of soil mesofauna at various ages of post-tin mining reclamation on Bangka Island and to determine the relationship of soil mesofauna diversity at various ages of post-tin mining reclamation land on Bangka Island with the soil characteristics. This research was carried out in January-March 2021 in reclamation land with different ages (2 years, 4 years, 6 years and 26 years) and forest site as control (comparison data). The method used is a survey method and sampling with a stratified random sampling method using pifall trap. The results showed that the diversity of soil mesofauna in reclamation aged 2 years, 4 years and 6 years, and control forest was in the medium category while the 26 years old reclamation land indicated as low diversity. The age of reclamation affects the soil mesofauna’s diversity index, the higher the age of reclamation land have higher diversity index, except for the 26 years old reclamation. The soil mesofauna diversity index has a very high correlation with soil and air moisture, a very low correlation with air temperature, a moderate correlation between air temperature and soil pH, while the C-organic content is opposite or negatively correlated with the diversity index and evenness index of the soil mesofauna.

Increasing reclamation ages drive shifts in carbon and nitrogen stoichiometry and natural isotopes from leaf-litter-root-soil continuum in a reclamation ecosystem, North China

Increasing reclamation ages drive shifts in carbon and nitrogen stoichiometry and natural isotopes from leaf-litter-root-soil continuum in a reclamation ecosystem, North China

Effects of Cd addition on soil phosphorus mineralization in reclaimed coastal wetlands along a 100-year reclamation chronosequence in the Pearl River Estuary (China)

The relationship between Cd and soil phosphatase activity has been given some concerns due to serious soil Cd contamination. However, the effects of high-risk Cd pollution on the soil phosphorus mineralization process are still kept unclear in reclaimed coastal wetlands. Here, we investigated the impacts of Cd additions at three levels on phosphorus mineralization and phosphatase activities in reclaimed coastal wetland soils with different reclamation ages (e.g., 100-year, 40-year, and 10-year) in the Pearl River Estuary by a 40-day laboratory incubation experiment. The results showed that lower soil phosphatase activity was observed in the reclaimed wetlands with longer reclamation age, which led to the lower increase in cumulative net phosphorus mineralization and Occluded P. High Cd exposure facilitated the phosphatase activities and phosphorus mineralization through the promotion of Occluded P and Al/Fe-P contents in the 100-year and 10-year reclaimed wetland soils, respectively. The addition of the low-dose of Cd to the soil inhibited phosphorus mineralization in the middle of incubation in 40-year reclaimed wetland soils, while the high-dose Cd addition had little effect. The findings of this work indicate that the older reclaimed wetlands might have lower phosphorus mineralization potentials, while higher Cd pollution might lead to soil phosphorus loss by improving phosphorus mineralization in reclaimed coastal wetlands.

Do the Reclaimed Fungal Communities Succeed Toward the Original Structure in Eco-Fragile Regions of Coal Mining Disturbances? A Case Study in North China Loess-Aeolian Sand Area.

Mining activity has caused serious environmental damage, particularly for soil ecosystems. How the soil fungal community evolves in mine reclamation and what are the succession patterns of molecular ecological networks still needs to be studied in depth. We used high-throughput sequencing to explore the changes in soil fungal communities, molecular ecological networks, and interactions with soil environmental factors in five different ages (the including control group) during 14 years of reclamation in eco-fragile mines. The results showed that the abundance and diversity of soil fungi after 14 years of reclamation were close to, but still lower than, those in the undisturbed control area, but the dominant phylum was Ascomycota. Soil nitrate-N, C/N ratio, pH, and water content significantly affected the fungal community with increasing reclamation ages. Moreover, we found that Mortierellomycota, despite its high relative abundance, had little significant connectivity with other species in the molecular ecological network. Fungal molecular ecological networks evolve with increasing ages of reclamation, with larger modules, more positive connections, and tighter networks, forming large modules of more than 60 nodes by age 9. The large modules were composed mainly of Ascomycota and Basidiomycota, which can form mycorrhiza with plant roots, and are not only capable of degrading pollution but are also “encouraged” by most (more than 64%) physicochemical factors in the soil environment. The results can provide a basis for scientific mine ecological restoration, especially for eco-fragile regions.

BIRD DIVERSITY ON RECLAIMED NICKEL MINE-LAND IN KOLAKA DISTRICT SOUTHEAST SULAWESI

Nickel mining is one of open type mining having a high risk on environment. Birds are often used as indicators of habitat change in reclaimed mine-land. The objectives of this study were (1) to identify bird species; (2) to compare bird communities; (3) to predict biotic and abiotic factors that affect bird communities in mining reclamation land according to the age of reclamation, and natural forest in nickel mining area. This research was conducted on reclaimed land in 2006, 2007, 2008, 2009. The composition of bird species is described based on family, endemicity and feeding guild. Bird data were analyzed using Shannon index, Jacknife index, and Sorensen community similarity. Estimation of environmental factors is calculated using multiple regression analysis. This study discovered 41 bird species from 23 family classified into 7 guilds. There were 17 Sulawesi endemic species, and one of them is categorized as vulnerable by IUCN (Rhabdotorrhinus exarhatus). The highest species richness and diversity was found in year 2006 reclamation land (34 species, S = 44, H '= 3,08). The highest similarity analysis of bird communities was in 2006 reclaimed land and natural forest (Cn = 0,79). Based on the results of multiple regression analysis, 3 variables significantly affect the presence of birds (the insect abundance, number of tree species, and the closest perpendicular distance to the river). The presence of birds is influenced by food sources (insects, fruit) and the presence of water. The composition of bird species approached natural conditions with increasing age of reclaimed land. &#x0D; &#x0D; Key words: bird, community, diversity, mine, reclamation

Soil Carbon Sequestration in Novel Ecosystems at Post-Mine Sites—A New Insight into the Determination of Key Factors in the Restoration of Terrestrial Ecosystems

Mining activities are one of the main causes of land degradation around the world and reduce the quality of the surrounding ecosystems. Restoration approaches using different vegetations and reclamation methods have been implemented to address this issue. In this review, paper, different studies focusing on the effect of the restoration of mining sites on the accumulation of soil organic carbon (SOC) were analyzed. SOC in reclaimed mining soil (RMS) increased considerably after various restoration efforts were implemented. The amount of SOC accumulated in RMS was mostly influenced by the restoration age, vegetation type, and substrate or type of reclamation used. From the scientific papers analyzed, we found that SOC accumulation increases with restoration age; however, vegetation type and reclamation have varied effects. According to the review, the restoration of mine sites with vegetation resulted in a rate of SOC accumulation ranging from 0.37 to 5.68 Mg SOC ha−1 year−1. Climate conditions influenced the type of vegetation used for restoration. Regrading, liming, NPK fertilization, and seeding a mix of legumes and grasses were the most efficient reclamation techniques. Additionally, the use of grass and legume better facilitates the early accumulation of SOC compared with afforestation. Thus, the selection of appropriate tree species composition, reclamation treatments, and restoration age are the key factors for a high SOC accumulation rate.

SOIL CHARACTERISTICS AND MICROBIAL RESPONSES IN POST-MINE RECLAMATION AREAS IN A TYPICAL RESOURCE-BASED CITY, CHINA

Mining activities worldwide have resulted in soil nutrient loss, which pose risks to crop and environmental health. We investigated the effects of post-mine reclamation activities on soil physicochemical properties and microbial communities based on 16S rRNA sequencing and the further statistical analysis in the coal base in Peixian city, China. The results revealed significant differences in soil microbial relative abundance between reclamation and reference soils. Proteobacteria was the most abundant phyla in all seven mine sites regardless of reclamation age while considerable differences were found in microbial community structure at other levels among different sites. Notebly, Gammaproteobacteria, member of the phylum Proteobacteria, had relatively high abundance in most sites. Furthermore, Kendall’s tau-b correlation heatmap revealed that potentially toxic elements and other physicochemical properties play vital roles in microbial community composition.

Shift in archaeal community along a soil profile in coastal wheat‐maize rotation fields of different reclamation ages

AbstractCoastal mudflats reclamation activities show a strong influence on soil properties and microbial community activity, which drive soil carbon and nitrogen cycling. Studies have found there is a shift of bacterial community with reclamation time. However, effects of reclamation time on the soil archaeal community are still largely unknown. Here, we determined soil properties and archaeal community in the soil profiles (0–15, 15–30, 30–45 cm) of different reclaimed sites with different reclamation ages (R12: 12‐year; R38: 38‐year; R68: 68‐year; R100: 100‐year) in Rudong County, Jiangsu, China. Soil archaeal communities were identified via Illumina high‐throughput sequencing. Soil archaeal communities were dominated by two phyla, the Crenarchaeota (82.1–93.3%) and Thermoplasmatota (4.2–17.9%), which are associated with nitrogen cycle (Nitrosopumilaceae, Nitrososphaeraceae, and Nitrosotaleaceae) and organic carbon metabolism (Marine_Group_II), respectively. Ammonia oxidizing archaea showed a divergent response to the reclamation, i.e. Nitrosotaleaceae increased with reclamation time whereas Nitrosopumilaceae showed a decreasing trend. Soil total carbon, total nitrogen, pH, EC, C:N ratio, NO3−‐N content, soil moisture, depth, and reclamation age determined archaeal community distribution in our reclaimed sites. Our findings suggest that both reclamation time and soil depth significantly shaped the archaeal community composition, and then in turn modulated soil carbon and nitrogen cycling in the reclaimed mudflats.

Soil profile rather than reclamation time drives the mudflat soil microbial community in the wheat-maize rotation system of Nantong, China

Conversion of coastal mudflats to agricultural soil is one of the most important land use practices in Eastern China. However, effects of soil profile and reclamation time on soil microbial community, which play an important role in soil nutrient cycling, are still poorly documented. Soil profile (0–15 cm, 15–30 cm, 30–45 cm) samples were collected from four sites with different reclamation ages (R12: 12 years, R38: 38 years, R68: 68 years, R100: 100 years) in Rudong County, Nantong, Jiangsu, China. Soil bacterial communities were determined via Illumina 16S rRNA gene high-throughput sequencing. Soil electrical conductivity (EC) responded more rapidly to reclamation time than soil pH. Soil total carbon and nitrogen increased with increasing reclamation age. Soil available nutrients (ammonium, nitrate, dissolved organic carbon, and available phosphorus) were affected by the agricultural practice and did not show a unanimous tendency between different reclaimed sites. Proteobacteria, Acidobacteriota, and Bacteroidota dominated the bacterial community across different sites and soil profiles. However, Methylomirabilota- and Nitrospirota-associated species, which are involved in nitrogen cycling, increased with increasing soil depth. Canonical correspondence analysis (CCA) showed that bacterial community was grouped by soil depth and also significantly affected by soil pH, EC, and reclaimed time. Moreover, co-occurrence network analysis showed a potential role of low abundant phyla besides dominant phyla in stabilizing the bacterial community, and the connection between soil properties and bacterial amplicon sequence variant (ASV) numbers would shift along soil profiles. Reclamation time of the coastal mudflats is not the only reason for the shift of bacterial community. Here, we found soil profile had a strong influence on soil bacterial composition in the coastal reclaimed wheat-maize rotation soils.

Characterization and prediction of soil organic matter content in reclaimed mine soil using visible and near-infrared diffuse spectroscopy

An accurate determination of the soil organic matter (SOM) levels present in reclaimed mine soil is necessary to evaluate the success of the ecological reclamation of mines. Visible and near-infrared diffuse spectroscopy is a fast and efficient method for collecting data for soil management during the reclamation of soil removed from mines. In this work, we used spectroscopy to characterize and estimate the SOM of lands from different reclamation years after coal mining in semi-arid grasslands of North China. Our goals were: (1) to explore the SOM characteristics and the spectra of reclaimed mine soil with different reclamation ages, and (2) to establish a reliable and accurate SOM prediction model by comparing support vector machine (SVM), partial least-squares regression (PLSR), and random forest (RF) modeling methods by determining the optimal preprocessing method and input spectral region. The results showed that spectral characteristics are useful indicators for understanding progressive SOM changes in the topsoil at different reclamation ages. RF is a more appropriate method for assessing the performance of a selected spectral region and provides more accurate results with a root mean square error (RMSE) of 4.34 g·kg−1 between predicted and observed SOM values. This study provides an alternative method that uses spectroscopy to estimate reclaimed soil conditions for the environmental monitoring of mining sites.

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.

Yearling proportion correlates with habitat structure in a boreal forest landbird community.

Landbird vital rates, such as productivity and adult survivorship, can be estimated by modeling mist-netting capture data. The proportion in which an adult breeding bird is 1 year of age (a “yearling”), however, has been studied only minimally in a few landbird species. Here we relate yearling proportion to habitat-structure covariates, including reclamation age, in a boreal forest landbird community. Data were collected at 35 constant-effort mist-netting stations over a 6-year period, and consisted of 12,714 captures of adults, of 29 landbird species, including 4,943 captures of yearlings. Accuracy of age determination (yearling or older) was assessed based on recapture data and error rates were estimated at a mean of 8.1% (range 0.0–19.4%) among the 29 species, with 20 species showing age-error rates <10%. The estimated mean yearling proportion was 0.407, ranging from 0.178 to 0.613 among species. Remote-sensed Enhanced Vegetation Index (EVI), a measure of habitat greenness, was positively correlated with age since reclamation up to 20 years, at which time it became comparable to that of natural stations. The probability of capturing a yearling for species associated with mature forest was lower at stations with higher EVI and the opposite was the case for species favoring successional habitats. These results suggest that yearling birds are being excluded from preferred breeding habitats by older birds through despotism and/or that yearlings are simply selecting poorer habitat due to lack of breeding experience or other factors. This dynamic appears to be operating in multiple species within this forest landbird community. Captured yearlings may also be “floaters”, or non-breeding individuals not holding territories. However, presuming that yearlings show lower reproductive success whether floating or not, our results suggest that stations with high yearling proportions could be located within sink as opposed to source habitats. Overall, we infer that yearling proportion may become an important vital-rate measure of habitat quality and reclamation efforts, when combined with indices of population size, productivity, reproductive condition and survivorship.