The development of reclaimed mine soils is normally spatially heterogeneous, making the fine management and utilization of reclaimed mined lands difficult. Soil nutrient grading can provide a scientific basis for the precise regulation of soil nutrients, but few related studies are available in reclaimed mined areas. This study aimed to quantify the spatiotemporal variations in soil nutrient grades under different land-use types in a reclaimed mined area on the Loess Plateau, China. The study area was graded by four soil nutrients (soil available potassium (SAK), soil available phosphorus (SAP), soil total nitrogen (STN), and soil organic matter (SOM)), and the variation features of soil nutrient grades in the initial stage of reclamation under four land-use types (i.e., cultivated land, grassland, forestland, and barren land) were systematically characterized by geostatistical analysis, pedodiversity analysis, and correspondence analysis. The results show that during the initial five years after reclamation, the soil nutrient grades of most reclaimed areas increased from Grade V and VI to Grade I–IV, while the improvements were significantly heterogeneous. Notably, the four land-use types had distinct variation characteristics. The barren land had the lowest SAP level, whereas it had the highest proportion, and medium–high grades of SAK, STN, and SOM (88.3, 100.0, and 100.0%, respectively). In terms of quantitative structure, it had the lowest richness index ($S^{\prime }$, 2.5) and Shannon’s entropy index ($H^{\prime }$, 0.7) and the highest evenness index ($E^{\prime }$, 0.8). These results suggest that the barren land had relatively high and balanced nutrients, with the highest homogeneity among the four land-use types. The grassland had considerable improvement in all nutrients (especially SAP; 95.6% of the area had high SAP grades); however, its improvement was the most heterogeneous ($S^{\prime }$ = 4.5, $E^{\prime }$ = 0.7). As the second-most heterogeneous land-use type ($S^{\prime }$ = 4.0, $E^{\prime }$ = 0.8), the forestland had relatively low STN, SAP, and SAK levels due to high nutrient uptake and storage by tree species, but it had the highest proportion of area that reached high SOM grades (36.4%) and medium to high SOM grades (100.0%) due to its high community productivity. The cultivated land, which received fertilization for an additional three years, was the most imbalanced in terms of nutrients. It had the highest proportion of area that reached high SAP grades (98.0%); in contrast, its area proportions of low-grade SAK and SOM (69.0 and 32.9%, respectively) were the highest among the four land-use types. Based on the above comprehensive characterization of soil nutrient grade variation, guidance was given for fine management of reclaimed mined land and the optimization of reclamation measures.

Climatic impact on re-established ecosystems at reclaimed mined lands may have changed. However, little knowledge is available about the difference in vegetation–climate relationships between reclaimed and unmined lands. In this study, ecological responses to climatic variability on reclaimed and neighbouring unmined lands were estimated using remote-sensing data at the Pingshuo Mega coal mine, one of the largest coal mines with long-term reclamation history in China. Time-series MODIS enhanced vegetation index (EVI) data and meteorological data from 1997 to 2017 were collected. Results show significantly different vegetation–climate relationships between reclaimed and unmined lands. First, the accumulation periods of all climatic variables were much longer on reclaimed mining lands. Second, vegetation on reclaimed lands responded to variabilities in temperature, rainfall, air humidity, and wind speed, while undisturbed vegetation only responded to variabilities of temperature and air humidity. Third, climatic variability made a much higher contribution to EVI variation on reclaimed land (20.0–46.5%) than on unmined land (0.7–1.7%). These differences were primarily caused by limited ecosystem resilience, and changed site hydrology and microclimate on reclaimed land. Thus, this study demonstrates that the legacy effects of surface mining can critically change on-site vegetation–climate relationships, which impacts the structure, functions, and stability of reclaimed ecosystems. Vegetation–climate relationships of reclaimed ecosystems deserve further research, and remote-sensing vegetation data are an effective source for relevant studies.

Topsoil is required to be stripped and reused to maintain land productivity in mining and construction activities. However, as a great threat to unprotected soil, wind erosion on topsoil replacement sites has not received enough research attention, which hinders the efficient implementation of wind erosion control measures in the right time and place on a national scale. This study aims to evaluate wind erosion on unprotected topsoil replacement sites (WEUTRS) in mainland China, examining its spatiotemporal pattern and demonstrating its significance for the relevant research and industry. The WEUTRS was calculated by the Revised Wind Erosion Equation with meteorological data (1988–2017) and raster data of soil properties. The results showed a strong spatiotemporal heterogeneity of WEUTRS. The highest (>300 kg m⁻²) and the lowest (<0.5 kg m⁻²) WEUTRS appeared in Northwest and Central Southern China, respectively. The most drastic temporal change through the year was in Northwest China (as high as 335.4 kg m⁻² on the example site), followed by Qinghai–Tibet Plateau and Shandong Province. By contrast, almost no temporal changes happened in Central Southern China. The ratio of monthly WEUTRS to respread the topsoil mass (R_w) in Northwest China and Mongolia Plateau reached 10% or more in specific months, and less than 0.1% in most of Southern China. The WEUTRS quantification could be applied to the wind erosion control on topsoil replacement sites on both a national scale and a regional scale. The spatiotemporal pattern of WEUTRS may be a scientific basis for a nationwide or regionwide differentiated policy on the wind erosion control on topsoil replacement sites for policy makers, as well as the reference to the proper working schedule and the control measures for local mining and construction projects for management authorities and practitioners.

China has implemented extensive land restoration programs and now leads the world in artificial forest area. However, such plantations often face degradation, largely due to soil nutrient deficiency. In contrast, near-natural restoration tends to result in better soil quality, ecosystem integrity, and stability. This study focuses on three near-naturally restored sites on the Loess Plateau—a critical part of China’s National Ecological Security Barrier System, which has undergone substantial ecological restoration in recent decades. Using soil stoichiometry to assess nutrient balance and land sustainability, we investigated two forest types (Betula platyphylla, BP; Larix principis-rupprechtii, LP) and a mixed shrubland (Ostryopsis davidiana and Cotoneaster multiflorus, OD–CM). Soil profiles were sampled at 20 cm intervals from the surface to bedrock. We measured soil carbon (C), nitrogen (N), and phosphorus (P) contents, along with key environmental factors. The results show the following: (1) The two forest lands exhibited similar C and N levels, which were 1.23–1.26 and 1.40–1.51 times higher, respectively, than those in the shrubland. (2) Lower C/N (BP: 25.05; LP: 23.46) and higher N/P (BP: 4.83; LP: 5.00) in the forest lands indicated lower nitrogen limitation versus the shrubland (C/N: 28.55; N/P: 3.44). (3) Key influencing factors varied across land restoration types, indicating that the vegetation community’s composition mediates nutrient cycling through nutrient uptake and litter input. (4) Relative to plantations in the same region, near-naturally restored lands had 3.47–5.64 times higher C content and 1.51–2.51 times higher N content. Moreover, near-natural communities exhibited higher C/N (21.68–30.56) and C/P (85.92–132.97) compared to plantations (C/N: 8.8–13.1; C/P: 9.16–31.2), reflecting more efficient nitrogen and phosphorus utilization. Thus, near-natural land restoration enhances soil carbon sequestration, nitrogen fixation, and nutrient use efficiency on the Loess Plateau, supporting its promotion as a superior land management strategy for enhancing land sustainability and ecosystem services in this area.

In regions where severe topographic constraints coincide with intensive human activity, the mechanisms underlying landscape ecological risk (LER) and its spatial differentiation remain poorly understood. In particular, the nonlinear responses and threshold effects arising from the combined influence of complex natural gradients, urban expansion, and policy interventions have not been adequately characterized, limiting effective regional ecological management and policy formulation. Taking the Taiyuan section of the Fen River Basin as the study area, this study constructed an LER index using land-use data for 2014, 2019, and 2024. Landscape metrics and spatial autocorrelation analyses were used to characterize the spatiotemporal evolution of LER, and a LightGBM-SHAP model with spatial block cross-validation was employed to identify the nonlinear effects of natural and socioeconomic drivers. A four-quadrant zoning framework integrating current risk state and driver sensitivity was then developed. The results showed that: (1) LER followed a fluctuating trajectory, rising from 2014 to 2019 and declining from 2019 to 2024, with evident spatial differentiation. Low- and relatively low-risk zones dominated about 71% of the area, while medium- to high-risk zones clustered mainly in the northeast, south, and parts of the northwest; high-risk agglomerations gradually contracted. (2) LER was driven by both natural and socioeconomic factors, with natural factors playing the stronger role. Slope, NDVI, elevation, and GDP were the key drivers. (3) The effects of these drivers were strongly nonlinear: slope increased risk at 5–13° but reduced it above 13°; NDVI displayed an inverted U-shaped relationship, with the strongest positive contribution at 0.60–0.75.; and elevation shifted from a positive to negative contribution near 1200 m. Based on these results, the framework coupling risk state and driver sensitivity delineated differentiated management units, providing fine-scale spatial guidance for ecological protection, restoration, and development control in topographically constrained river-valley basins.