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Precipitation is the major cause of yield variation in rainfed agriculture production on the Loess Plateau. Overfertilization is economically and environmentally undesirable. Optimizing nitrogen management based on fallow season precipitation is crucial for enhancing crop water use efficiency and achieving high yields in dryland/rainfed farming systems, considering the economic and environmental drawbacks of overfertilization and the uncertainty of crop yield and N input returns under high rainfall variability. Therefore, this study establishes a reference range that characterizes different wheat cultivation year types based on 37 years of fallow season precipitation data. The reference range for describing years as normal (220.7–346.2 mm), dry (< 220.7 mm), or wet (> 346.2 mm) is based on a 37-year precipitation record. At the same time, an 8 year field experiment (A randomized block design) was conducted using 7 N rates(0, 90, 120, 150, 180, 210, 240 kg N ha-1 to explore the prediction of PF on optimal N input for higher yield and water use efficiency (WUE). Optimum nitrogen (N) rates varied with the precipitation factor, being 150, 150–180, and 210 kg ha− 1 during dry, normal, and wet years respectively. Maximizing yield and water use efficiency (WUE) through optimized N input was primarily attributed to an increase in spike number per hectare. A non-linear regression analysis revealed a positive correlation between yield and precipitation frequency (PF), with an increase in yield ranging from 1.6 to 15 kg ha-1 for every mm increment in PF. Furthermore, the study demonstrated that an increase of 1% in the ratio of PF to total precipitation resulted in a significant yield gain of 46 kg ha-1.And as "drought at sowing" effects on yield were more adverse than "drought in growing season" effects in dryland systems, our results indicate that adjusting N fertilizer inputs based on summer rainfall variation could enhance wheat yield and WUE in the rainfed farming system. Thus, our results indicate that adjusting N fertilizer inputs based on seasonal variation in summer rainfall could enhance wheat yield and WUE in the rain-fed farming system. [ABSTRACT FROM AUTHOR]

The northwest region of China's loess plateau is an important area for wind power development. However, the unclear understanding of the evolution mechanism of the near-ground atmospheric boundary layer (ABL), which is influenced by its unique geomorphological features, has compromised the safety and stability of wind turbine operations. To address this challenge, wind tunnel experiments were conducted to investigate the mean and turbulent characteristics of wake flow generated by mountains in the loess plateau. The results indicate that the terrain significantly affects both the average velocity deficit and turbulence intensity distribution within the wake. Specifically, topographic features dominate turbulent energy transfer and modulate coherent structures in the inertial subrange. Additionally, the scale of these features enhances turbulence energy input at corresponding scales in the fluctuating wind speed spectrum, leading to a non-decaying energy interval within the inertial subregion. [ABSTRACT FROM AUTHOR]

Since the 21st century, large-scale afforestation projects on the Loess Plateau have resulted in significant vegetation greening, contributing to ecosystem restoration and enhanced soil conservation. However, these efforts have also led to soil aridification, declining groundwater levels, and reduced terrestrial water storage. These negative consequences are primarily attributed to increases in evapotranspiration (ET), which has augmented water consumption. Despite these findings, the underlying mechanisms driving ET variations remain contentious due to the complex interplay of multiple factors. In this study, we employed a logical attribution method, which attributes vegetation changes predominantly to anthropogenic activities (e.g., reforestation or land-use changes), while directly linking changes in climatic factors (e.g., temperature and precipitation) to climate change. We separately examined the contributions of long-term trends and interannual variability in ET to reveal distinct driving forces. Between 2000 and 2022, approximately 80% of areas showing significant changes in ET and its components were directly influenced by vegetation greening, particularly in the central part of the Loess Plateau, where restoration efforts were most prominent. In contrast, only around 20% of these changes were attributable to climate change and other factors. After removing long-term trends, interannual variations in ET were found to be more closely associated with climatic factors (temperature and precipitation), especially in arid and semi-arid regions. This indicates that climate is the dominant factor driving interannual variations in ET across the Loess Plateau. Our findings contribute to a deeper understanding of the water cycle dynamics in the context of large-scale vegetation restoration on the Loess Plateau. These insights provide a scientific foundation for policymakers to evaluate the environmental impacts and potential water-related risks associated with ecological restoration projects. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to explore the temporal and spatial variation characteristics of ecosystem carbon sink in the Loess Plateau, and to provide a scientific basis for in-depth analysis of scientific assessment of ecosystem carbon sequestration capacity and formulation of strategies to cope with climate change. [Methods] Based on the existing long-term series of remote sensing products, topography and soil properties, linear trend analysis and geodetectors were used to calculate the net ecosystem productivity (NEP) of the Loess Plateau from 2000 to 2022, and to analyze the spatial and temporal changes of NEP and its influencing factors. [Results] (1) The average value of NEP in the Loess Plateau from 2000 to 2022 was 33.44 gC/m². The current level of NEP in the Loess Plateau in 2022 was 39.9 gC/m², and the total annual carbon sink reached 25.40 Tg C. The interannual variation of NEP showed a significant increase and gradually stabilized. The overall growth rate was 0.70 gC/(m² · a), with an annual increase of 0.45 Tg C, among which Shanxi Province and Shaanxi Province contributed the most. Although the forest vegetation in the Loess Plateau has the highest carbon sink capacity (NEP) and sink enhancement capacity (NEP trend), due to the large area of grassland, the total carbon sink and sink enhancement contribution of grassland are higher than those of forest. Compared with grassland, farmland and bare land, grassland-shrub, farmland- forest-grass, bare land-forest-grass and other ecological restoration projects can increase the carbon sink capacity of original surface coverage by 83.2%, 14.0% and 81.1%, and increase the carbon sink capacity by 5.6%, 15.8% and 127.7%. Among the single influencing factors, NDVI, as a vegetation biomass index, is the main factor driving the spatial and temporal dynamic changes of NEP in the Loess Plateau ecosystem. However, the interaction between NDVI and rainfall, NDVI and soil bulk density on NEP spatial differentiation and NEP trend changes can not be ignored. [Conclusion] Combined with the comprehensive consideration of climate characteristics and soil conditions, a series of ecological restoration measures such as adjusting land use structure and increasing plant coverage can effectively improve the carbon sink capacity of the Loess Plateau ecosystem. [ABSTRACT FROM AUTHOR]

[Objective] Soil moisture plays a vital role in influencing vegetation recovery, particularly in the loess plateau gully erosion region, where hydrological processes are highly responsive to the combined effects of climate, vegetation, and topography. The aims of this study are to understand the spatiotemporal distribution characteristics of soil moisture at the watershed scale, and to advance ecological construction efforts. [Methods] This research investigated the artificial afforestation watershed in Caijiachuan, Jixian County, Shanxi Province, based on the soil moisture positioning monitoring platform. By conducting watershed-scale field positioning monitoring and employing various geostatistical analysis methods, we systematically gathered soil moisture datasets of growing season in the afforested watershed in 2023. Employing diverse interpolation techniques, we analyzed the spatiotemporal variations of soil moisture at the small watershed scale. [Results] The small watershed-scale soil moisture changes were highly responsive to rainfall, showcasing distinct vertical stratification characteristics. The soil moisture content in the Caijiachuan afforestation watershed was categorized into three layers: the active soil moisture layer (0-10 cm), the sub-active soil moisture layer (10-80 cm), and the soil moisture regulation layer (80-180 cm). The sub-active soil moisture layer exhibited the highest coefficient of variation, while the soil moisture regulation layer had the lowest variation coefficient. The active soil moisture layer was predominantly influenced by climate, the sub-active layer served as the primary layer for vegetation water absorption, and the regulation layer primarily functions as a water storage layer. In terms of interpolation method selection, the inverse distance weighting method yielded the most accurate results for the spatial distribution of soil moisture within the watershed, with a Nash coefficient of 0.64 and a root mean square error of 3.22, establishing it as the preferred interpolation method among the four considered. Upon stratifying the soil in the Caijiachuan afforestation watershed into three layers and conducting interpolation analysis, It was observed that the sub-active soil moisture layer had the highest water content, while the active soil moisture layer had the lowest water content. [Conclusion] The spatial distribution of water in the study area is influenced by many factors such as topography, precipitation and vegetation, and the spatial distribution of water is generally characterized by high in the southeast and low in the northwest. [ABSTRACT FROM AUTHOR]

The Loess Plateau is one of the most severely affected regions by soil erosion in the world, with a fragile ecological environment. Vegetation plays a key role in the region's ecological restoration and protection. This study employs the Geographical Detector (Geodetector) model to quantitatively assess the impact of natural and human factors, such as temperature, precipitation, soil type, and land use, on vegetation growth. It aims to reveal the characteristics and driving mechanisms of vegetation cover changes on the Loess Plateau over the past 26 years. The results indicate that from 1995 to 2020, the vegetation coverage on the Loess Plateau shows an increasing trend, with a fitted slope of 0.01021 and an R2 of 0.96466. The Geodetector indicates that the factors with the greatest impact on vegetation cover in the Loess Plateau are temperature, precipitation, soil type, and land use. The highest average vegetation coverage is achieved when the temperature is between −4.8 and 2 °C or 12 and 16 °C, precipitation is between 630.64 and 935.51 mm, the soil type is leaching soil, and the land use type is forest. And the interaction between all factors has a greater effect on the vegetation cover than any single factor alone. This study reveals the factors influencing vegetation growth on the Loess Plateau, as well as their types and ranges, providing a scientific basis and guidance for improving vegetation coverage in this region. [ABSTRACT FROM AUTHOR]

Soil degradation and erosion pose significant threats to agricultural sustainability in fragile ecosystems, such as the Loess Plateau in northern China. This study examines the long-term impacts of fertilization regimes and land-use systems on soil health, focusing on soil aggregate stability, fertility, and crop productivity. Six treatment combinations were evaluated in our study, including three continuous alfalfa fields (AL-CK, AL-P, and AL-NPM) and three continuous wheat fields (WH-NPM, WH-NP, and WH-P), each representing a combination of land use and three fertilization treatments: (1) no fertilization (CK), (2) inorganic fertilization (120 kg ha−1 N, 60 kg ha−1 P-NP), and (3) a combination of organic and inorganic fertilization (75 t ha−1 cow manure-NPM). Soil samples were collected from three depths (0–10 cm, 10–20 cm, and 20–30 cm) to assess physical and chemical properties. We evaluated the long-term effects of different fertilization treatments on soil stability, fertility, and crop yield to explore the interactions among soil's physical and chemical properties under two land-use types and to assess the effectiveness of combined organic and inorganic fertilization strategies in improving soil health and mitigating erosion in vulnerable landscapes. The study revealed significant depth-specific variations with surface layers (0–10 cm) showing the greatest improvement under NPM treatments, particularly in continuous alfalfa fields, which exhibited higher soil fertility, improved soil structure, and crop yield. In contrast, continuous wheat fields with minimal fertilization demonstrated significantly lower soil quality and productivity. Using the combination of mineral fertilizers and organic amendments, such as cow manure, proved to be the most effective strategy for significantly enhancing nutrient availability and overall soil health. Partial Least Squares Modeling (PLS-M) and Mantel analysis highlighted the critical role of fertilization management in maintaining soil quality, boosting crop productivity, and mitigating erosion in high-risk areas. This study emphasizes the importance of integrated nutrient management for sustainable land use and soil conservation in erosion-prone regions. [ABSTRACT FROM AUTHOR]

To investigate the impacts of vegetation change on deep soil water recharge, it is essential to identify the sources of deep soil water and deep drainage. The combination of stable and radioactive water isotopes is an effective method for studying deep vadose zones, though it has been rarely applied in complex gully areas. In this study, we measured δ2H, δ18O, and 3H in soil water under long-term natural grassland and C. korshinskii on the same slope. Both natural grassland and C. korshinskii plots received deep soil water from rainfall during the rainy season; however, the replenishment thresholds for soil water at depths of 2–10.4 m differed between the two vegetation types, corresponding to rainfall intensities of ≥20 mm and ≥50 mm, respectively. Following the conversion of natural grassland to C. korshinskii vegetation, the rate of soil water storage deficit increased by 46.4 mm yr−1, and deep drainage shifted from 39.6 mm yr−1 to 0 mm yr−1. Deep-rooted vegetation significantly depletes soil water to meet transpiration demands, thus hindering rainfall recharge. These findings have important implications for water and land resource management, especially in areas undergoing significant vegetation changes. [ABSTRACT FROM AUTHOR]

Vegetation greening resulting from ecological engineering efforts has statistically contributed to environmental improvement, through enhancing ecosystem effectiveness remains a challenge. Nevertheless, there has been a notable lack of research dedicated to enhancing vegetation resilience and restoration potential by mitigating vegetation browning in watersheds within arid and semi-arid regions. This study fills that gap by identifying the spatial heterogeneity in ecological resilience using statistical analyses and an exponential decay approach. It then evaluates the potential for ecological restoration by optimizing ecosystem structures in browning areas based on resilience and reference state. The key findings included the following: (1) With a narrower interquartile range, kNDVI values from 2015 to 2023 demonstrated notable increases as compared to 2000–2014. The northern and eastern sub-watersheds showed greater vegetation restoration, but the southern regions showed less resilience. (2) Vegetation resilience in the majority of sub-watersheds was concentrated at moderate levels, and the number of grids with strong positive tendencies decreased, according to the analysis of grid trends. (3) Fifteen reference states were established for browning areas based on the current natural conditions. The larger restoration potential ratio showed notable differences in sub-watershed restoration, indicating opportunities for improvement. Extreme vegetation degradation demonstrated little potential for restoration in resource-poor areas. This study provides valuable insights into integrating resilience and restoration potential into ecological restoration practices, advancing the application of ecological engineering strategies. [ABSTRACT FROM AUTHOR]

On the Loess Plateau, vast farmlands have suffered from severe land degradation and soil erosion. Afforestation and natural vegetation restoration are two main methods for ecological restoration on the degraded farmland in the last few decades. Previous studies have mainly investigated the effects of the two methods on soil organic carbon (SOC). However, few studies have focused on the influence of the two methods on soil inorganic carbon (SIC), which is the fundamental component of the local soil carbon pool. On the Loess Plateau, we measured SOC and SIC stocks, and the stable carbon isotope values of SOC and SIC (δ13C-SOC and δ13C-SIC) within 0–100 cm depth in an artificial forestland (Robinia pseudoacacia, 27 years) and a neighboring abandoned farmland (Poa annua and Bothriochloa ischaemum, 27 years). The results showed that SOC and SIC stocks at 0–100 cm in forestland were 23.43 Mg ha−1 and 16.89 Mg ha−1 higher than the abandoned farmland, respectively. The δ13C-SOC in topsoil was significantly (p < 0.05) lower than the subsoil in both lands. The δ13C-SIC in forestland was significantly (p < 0.05) lower than in abandoned farmland. The results indicated that afforestation is more suitable to conserve soil carbon than natural vegetation restoration on degraded farmland on the Loess Plateau. The forestland generated more pedogenic inorganic carbon than the abandoned farmland causing the difference in SIC stock between the two lands. Our findings highlight the importance of SIC, and the SIC may be more important than SOC in sequestrating soil carbon following vegetation restoration on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Mulching practices have demonstrated the potential to increase crop yields and resource utilization efficiency. However, the response of different crops with various growth stages to different mulching practices remains unclear, particularly in the rainfed agroecosystem. Therefore, a two-year field experiment (2013–2015) of different crops (wheat, maize, and potato) was conducted to evaluate the effects of three different mulching treatments: straw strip mulching (SM), plastic film mulching (PM), and conventional planting without mulching as the control (CK), on soil moisture and temperature, evapotranspiration (ET), water use efficiency (WUE), crop yield and economic benefits on the Loess Plateau. The results indicated that both mulching practices significantly increased the soil water content (SM: 4.3% and PM: 3.6%) compared to CK. However, the effects on soil temperature varied between mulching practices, PM increased soil temperature by 4.9% compared to CK, while SM decreased it by 6.3%. The improved soil hydrothermal conditions, characterized by favorable temperatures and higher soil water status would lead to a higher crop daily growth rate (5.3–49.8%), as well as greater dry matter accumulation (4.7–36.7%). Furthermore, mulching practice (SM and PM) has a significant influence on crop yield and its components of various crops, as well as WUE. The mean grain yield of SM and PM was, respectively, increased by 11.4% and 27.1% for winter wheat, compared to CK, 1.8% and 24.3% for spring maize, and 23.0% and 13.9% for potato, respectively. Compared to CK, PM yielded a higher net economic benefit and WUE for winter wheat and spring maize, while SM presented the best economic benefit and WUE for potato. In conclusion, a comprehensive analysis of crop yield, economic benefits, and resource utilization efficiency suggests that straw strip mulching for potato is a more sustainable environmentally friendly mulching practice, recommended for rainfed farming systems on the Loess Plateau and areas with similar climatic conditions. [ABSTRACT FROM AUTHOR]

In recent decades, China has collected extensive strong-motion data from the Loess Plateau, which is valuable for understanding the dynamic characteristics of loess sites and the effects of site conditions on seismic motions. The horizontal-to-vertical Fourier spectrum ratio (HVSR) and the horizontal-to-vertical velocity response spectrum ratio (VRSR) are widely used to study site dynamics. This study analyzes strong-motion data from the Loess Plateau to identify key features of the HVSR and VRSR curves. The results show that these spectral ratio curves effectively capture the dynamic behaviors of loess sites, minimizing the influences of earthquake magnitude and propagation path. While the spectral ratio peaks are less affected by magnitude, epicentral distance, and focal depth, they are significantly influenced by site conditions. Conversely, the dominant periods estimated from these curves are strongly influenced by magnitude, epicentral distance, and focal depth. For sites located on the Loess Plateau, the average amplification factor is approximately 3, with a mean predominant period of 0.4 s. These results provide valuable insights into the dynamic characteristics of loess sites and have practical implications for seismic design in the region. [ABSTRACT FROM AUTHOR]

Abstract The position of landslides on a slope plays a crucial role in determining landslide susceptibility and the likelihood of landslide debris interacting with the fluvial system. Most studies primarily focus on shallow landslides in the bedrock weathering zone or large-scale bedrock landslides, but the relevant work about the location and connectivity to channels of loess landslides is limited despite their potential to provide insights into slope stability and material transport in loess regions. In this study, we explored differences in landslide location and connectivity to channels between 2013 Mw5.9 Minxian earthquake-induced (EQ) landslides and 2013 Tianshui rainfall-induced (RF) landslides in the Loess Plateau area, China. The result shows that more than 37% of EQ landslides occur in the vicinity of ridges and ~ 30% are concentrated near river channels. Landslide locations of the Minxian earthquake not only occur in ridge crest areas but also exhibit clustering near the channels. We attribute the former cluster to seismic shaking along the ridge crest, and the latter cluster to dynamic changes in pore pressure within saturated lower hillslopes due to nearly a month of rainfall prior to the Minxian earthquake. Compared to EQ landslides, RF landslides are more evenly distributed across slopes. However, due to heavy rainfall and river erosion, landslides are more concentrated in the middle and lower slope areas, especially near the river channels. Moreover, the connectivity of landslides to channels indicates that RF landslides exhibit stronger connectivity with river channels compared to EQ landslides, which may be related to the concentration of EQ landslides near ridge areas. Furthermore, due to the smaller scale of EQ landslides compared to RF landslides, larger landslides are more likely to be located closer to river channels. This may contribute to the lower observed connectivity index between EQ landslides and river channels.

The natural environment of the Gansu-Qinghai region in northwest China exhibits spatial variation, resulting in distinct adaptive strategies among populations in different geographical areas. In this study, we analyzed the diachronic trend and regional variations in caries prevalence among 10 different middle and late-Holocene groups by examining dental caries data to explore the correlation between different adaptation strategies and caries frequency. Frequency data was used to compare dental caries between populations, and the Chi-square test was employed to detect statistical differences. A multidisciplinary approach was employed to investigate the relationship between these changes and the adaptive strategies adopted by the populations in this region. The result shows that there was a gradual increase in caries prevalence over time in eastern Gansu, which corresponded with development of millet farming and social hierarchy. In the Hexi Corridor, caries prevalence exhibited fluctuations attributable to climate variability, human migration, and regime change. The research proposes that changes in adaptive strategies due to various social and environmental factors are reflected in human teeth, while also presenting a novel endeavor of aggregating a large, multisite bioarchaeological dataset in order to investigate the interactions between Holocene populations and palaeoenvironments in northwest China.

[Objective] The aims of this study are to investigate the spatial and temporal characteristics of meteorological drought and its influencing factors in the Loess Plateau region, and to provide scientific support for drought monitoring, dry-crop agricultural food production, water resource management and ecological restoration construction in this region. [Methods] Based on the day-by-day meteorological data of 119 stations in the Loess Plateau region from 1957 to 2019, the daily-scale potential evapotranspiration (PET) and standardized precipitation evapotranspiration index (SPEI) were calculated using the FAO Penman-Monteith formula. Theil-Sen Median slope estimation and Mann-Kendall trend analysis were used to explore the distribution characteristics and trends of the number of drought days, the number and intensity of drought events. Meanwhile, Pearson correlation coefficient was used to analyze the relationship between meteorological factors and drought indicators. The impact of human activities on meteorological drought was explored in combination with the land use type transfer matrix. [Results] (1) The daily-scale SPEI was more accurate than the monthly-scale SPEI in identifying the number of drought days, the number of drought events and intensity. (2) The number of drought events increased in the northwestern part of the Loess Plateau from 1957 to 2019, and the intensity of drought in most regions showed an increasing trend, with the number of days of different types of droughts decreasing. (3) There was a clear trend of drying in the southeastern and northwestern regions of the Loess Plateau, while the northern and southern regions show a trend of wetting. (4) There was a moderate correlation between meteorological factors and drought indicators, and the land use/surface cover affected meteorological droughts to a certain extent in the Loess Plateau region. [Conclusions] Meteorological drought in the Loess Plateau region is influenced by both climatic factors and human activities, and its spatial and temporal changes are characterized by complexity. The results of the study can provide an important scientific basis for drought monitoring and management in this region. [ABSTRACT FROM AUTHOR]

[Objective] Converting slopes into terraces is a crucial soil and water conservation and agricultural measure on the Loess Plateau. Understanding the impact of terraced walls on soil water is conducive to preserving soil water and enhancing terrace productivity. [Methods] Soil samples were collected from different locations on typical artificial high-slope terraces (terraced wall height of 5 meters) on the Loess Plateau to measure soil water content and soil physical and chemical properties. The spatial distribution characteristics and influencing factors of soil water were analyzed. [Results] The results showed that as the distance from the terraced wall increased, the soil water storage in the 0-300 cm soil layer increased significantly from 15.9 mm to 328.6 mm. The evaporation from the terraced wall decreased gradually from 318.0 mm to 83.4 mm. When the terrace width was 300 cm, the evaporation from the terraced wall could account for 33% to 38% of the soil water storage. The depth of the soil layer and the distance from the terraced wall were the main factors influencing soil water content, while the correlation between soil particle composition as well as organic matter content and soil water content was low. [Conclusion] Lateral evaporation caused by the terraced walls on the Loess Plateau significantly affects the distribution of soil moisture, leading to a reduction in soil water on the side adjacent to the walls. Appropriate measures should be taken in terrace maintenance and management to reduce soil water loss due to evaporation from the terraced walls.

Abstract Land use change can significantly alter the proportion of soil aggregates, thereby influencing aggregate stability and distribution of soil organic carbon (SOC). However, there is minimal research on the variations in the distribution of soil aggregates, aggregate stability, and SOC in soil aggregates following land use change from farmland (FL) to forest and grassland in the Loess Plateau region of China. Select six land use patterns (farmland (FL), abandoned cropland (ACL), Medicago sativa (MS), natural grassland (NG), Picea asperata Mast. (PA), Platycladus orientalis (L.) Franco (PO)) on the Loess Plateau in China and collect undisturbed soil samples. These six land use patterns have similar geographical characteristics. The distribution of aggregates and the aggregate-associated SOC contents under the six land use patterns were measured at the 0–10 cm, 10–30 cm and 30–50 cm depths. The results showed that forestland and grasslands converted from FL significantly increased the aggregates (> 5 mm) content, mean weight diameter (MWD), and geometric mean diameter (GMD) but decreased the aggregates ( 5 mm, 2–5 mm, 1–2 mm, 0.5–1 mm, 0.25–0.5 mm, and

The interaction and feedback between soil and vegetation will promote the restoration of damaged mine ecosystems towards a virtuous cycle, especially in surface mine dump site reclamation areas. However, the lack of understanding of the correlation and mutual feedback mechanism between vegetation restoration and soil functions limits the scientific formulation of vegetation reconstruction strategies for surface mine dump sites. This study aims to reveal the trade-off and synergistic relationship between vegetation succession and soil system functions during the vegetation restoration process. Using methods such as field surveys, high-throughput sequencing, and resilience assessment models, four reclamation areas with different reclamation timings were selected in the Heidaigou surface coal mine on the Loess Plateau, and a resilience assessment model and trade-off synergy were constructed for five plant restoration types: grassland, shrub, coniferous forest, broad-leaved forest and mixed forest. The results show that: ① compared with bare land, the recovery degree of soil indicators is 30%−80% and the vegetation index recovery degree is 20%−75% after 8−30 a of restoration. ② The recovery rate of soil nutrient conservation and ecological carbon sink functions of grassland and shrubs peaked at 15 a, and the recovery rate of coniferous forest, broadleaf forest and mixed forest peaked at 25 a. The recovery degree of the soil system is mixed forest > grassland > coniferous forest > broadleaf forest > shrubs, and the vegetation system recovery is mixed forest > broadleaf forest > coniferous forest > grassland > shrubs. ③ In terms of the overall trend, the functional resilience of grassland, shrub and broad-leaved forest vegetation and soil systems is mainly in a trade-off relationship, while coniferous forest and mixed forest are mainly in a synergistic relationship. It concludes that the vegetation restoration significantly improves the physical, chemical, biological properties and vegetation community characteristics of the reclaimed soil, the reclamation years significantly affects the recovery elasticity and rate of the soil-vegetation system in the surface mine area of the Loess Plateau, China. As the reclamation years increase, there is a trade-off relationship between soil-vegetation system indicators. The research results confirm that different vegetation types have temporal characteristics in improving the resilience of the soil-vegetation system. Therefore, it is recommended to appropriately adjust the vegetation clustering strategy, allocate vegetation types in a timely manner, and fully coordinate the relationship between various soil functions to optimize the surface mine ecology of the Loess Plateau. The study provides a scientific basis for the restoration planning and management of disturbed surface mine.

Land use change can significantly alter the proportion of soil aggregates, thereby influencing aggregate stability and distribution of soil organic carbon (SOC). However, there is minimal research on the variations in the distribution of soil aggregates, aggregate stability, and SOC in soil aggregates following land use change from farmland (FL) to forest and grassland in the Loess Plateau region of China. Select six land use patterns (farmland (FL), abandoned cropland (ACL), Medicago sativa (MS), natural grassland (NG), Picea asperata Mast. (PA), Platycladus orientalis (L.) Franco (PO)) on the Loess Plateau in China and collect undisturbed soil samples. These six land use patterns have similar geographical characteristics. The distribution of aggregates and the aggregate-associated SOC contents under the six land use patterns were measured at the 0–10 cm, 10–30 cm and 30–50 cm depths. The results showed that forestland and grasslands converted from FL significantly increased the aggregates (> 5 mm) content, mean weight diameter (MWD), and geometric mean diameter (GMD) but decreased the aggregates (< 0.25 mm) content. Compared with FL, the values at the 0–50 cm depth under PA, NG, MS, PO and ACL increased by 473.71–732.55%, 283.98–724.60%, 179.06–634.12%, 142.31–413.50% and 110.25–213.34%, respectively, for MWD and by 244.04–607.77%, 141.68–666.67%, 52.39–483.33%, 50.49–214.43%, and 35.23–64.29%, respectively, for GMD. Land use patterns and soil aggregate size had obvious influences on SOC content, SOC content in soil and aggregates decreased under ACL. In other forestland and grasslands, The SOC content in bulk soil, > 5 mm, 2–5 mm, 1–2 mm, 0.5–1 mm, 0.25–0.5 mm, and < 0.25 mm aggregates at the 0–50 cm depth after afforestation increased by 20.75–125.87%, 14.50–163.64%, − 11.86–118.18%, 9.65–150.95%, 38.28–126.49%, 51.26–165.87% and − 15.59–163.37%, respectively, Compared to FL. The contributions of different aggregates particle sizes to the increase in SOC content in bulk soil were 104.74%, 7.86%, 4.76%, 6.23%, 5.37%, and − 21.97%, respectively. MWD and GMD were positively correlated with SOC content in aggregates (1 mm), SOC content in bulk soil and aggregates. Although SOC content in bulk soil and different aggregates particle sizes under NG and PA were significantly higher that than under MS and PO, the soil macroaggregate content, MWD, and GMD under PO and NG were higher than that under PA and MS. These findings suggest that converted FL into PO and NG significantly improved soil structure and also increased SOC content. Therefore, in the process of transforming land use patterns on the Loess Plateau, the proportion of forest land and grassland should be appropriately increased to improve soil carbon storage and quality. The results of this study provides a theoretical basis and scientific basis for the scientific evaluation and understanding of soil organic carbon accumulation and distribution under different land use patterns in the Loess Plateau region of China. [ABSTRACT FROM AUTHOR]

The Loess Plateau (LP) in China is an ecologically fragile region that has long faced challenges such as soil erosion, water shortages, and land degradation. The spatial and temporal variations in ecological environment quality on the LP from 2000 to 2020 were analyzed using the Remote Sensing Ecological Index (RSEI) on the Google Earth Engine (GEE) platform. The Sen, Mann–Kendall, and Hurst exponent analyses were used to examine the spatial variation trends over the past 20 years, while Geodetector identified key factors influencing RSEI changes and their interactions. The results indicate that (1) RSEI effectively represents the ecological and environmental quality of the LP, with 47% of the study area's annual mean RSEI values over the 20-year period classified as moderate, ranging from 0.017 to 0.815. (2) Ecological quality trends showed improvement in 72% of the area, with a 90% overall increase, but 84% of these trends are not likely to continue. (3) Key factors influencing RSEI changes during abrupt change years included precipitation, land use/land cover, and soil sediment content, with precipitation and topography emerging as primary influences on ecological quality. Although natural factors largely drive ecological changes, human activities also exert both positive and negative effects. This study underscores the importance of sustainable ecological management and provides policy insights for advancing ecological civilization on the LP, contributing to the achievement of the Sustainable Development Goals (SDGs). [ABSTRACT FROM AUTHOR]