Search Results (168)

Geochemical proxies in coastal sediments are widely applied to reconstruct past climatic and environmental changes, yet their sensitivity to climate versus localized depositional processes remains debated in dynamic land–sea interfaces. Here, we present major, trace, and rare earth element (REE) data from two Holocene sediment cores (QX01 and QX02) from the western coast of Bohai Bay to decouple provenance, weathering, and hydrodynamic controls. Provenance-sensitive trace element ratios (La/Sc and Th/Sc) and REE fractionation patterns indicate exceptional source stability dominated by the Yellow River and adjacent cratonic catchments throughout the Holocene, eliminating provenance shifts as a confounding variable. Since ~8 ka, an overarching upward increase in raw chemical index of alteration (CIA), accompanied by increasing Al/Si ratios and grain sizes, broadly aligned with the warm and humid Holocene Climate Optimum. Crucially, a highly significant linear relationship between grain size, Al/Si and CIA (R² > 0.78) demonstrates that raw CIA variations were decisively modulated by sea-level-driven hydrodynamic sorting during the Holocene transgression, which shifted the depositional setting from high-energy fluvial regimes to low-energy marine settings, preferentially trapping fine-grained, clay-hosted aluminosilicates with inherently high CIA values. During the late Holocene (~5 ka to present), stabilizing sea-level conditions shifted the raw records into an elevated plateau punctuated by high-frequency fluctuations and localized geochemical anomalies, reflecting a dynamic interface sensitive to episodic fluvial floods or tidal/storm reworking that periodically introduced coarser, quartz-rich detritus. The resulting sorting-corrected CIA_C removes the transgressive clay-trapping artifact and reveals a broad, subdued weathering plateau between ~8 ka and 4 ka BP, consisting with previous Chinese Loess Plateau weathering intensity. These findings highlight that in dynamic marginal-marine sinks, raw silicate weathering indices reflect physical sorting overprints, and hydrodynamic detrending is essential to extract genuine continental paleoclimate signals. Full article

The Chinese Loess Plateau is a vast semi-arid landscape that has experienced substantial vegetation recovery through afforestation since the late twentieth century, altering the regional carbon cycle and contributing to China’s carbon neutrality efforts. However, large-scale quantification of carbon storage (CS) remains challenging in this heterogeneous and erosion-prone landscape. In this study, the PLUS land-use simulation model was coupled with an InVEST-based carbon storage accounting framework, and multi-source remote sensing and field survey data were integrated to quantify historical carbon storage from 1980 to 2020 and predict carbon storage in 2040 under three future land-use scenarios: natural development (ND), cultivated land protection (CLP), and ecological protection (EP). The results showed that NDVI exhibited a distinct southeast-to-northwest gradient, with peak values (>0.8) in the southeastern tablelands, where CS reached 10.27 ± 4.20 kg C m⁻². Carbon storage increased from 1980 to 2020, primarily due to afforestation, with higher CS in the humid southeastern plateau and lower CS in the arid northwest. Scenario simulation showed that CS maintained a baseline level of 7.07 ± 3.81 kg C m⁻² under the ND scenario, increased slightly to 7.08 ± 3.77 kg C m⁻² under the CLP scenario, and reached the highest value of 7.10 ± 3.80 kg C m⁻² under the EP scenario. SEM-based mechanism analysis indicated that topography exerted the strongest direct influence on CS, followed by vegetation, climate, and socioeconomic factors. These findings suggest that water availability and topographic constraints strongly regulate CS in semi-arid regions, while land-use policy can still modify CS through scenario-dependent land-use change. Full article

Vegetation restoration is widely used to combat soil erosion on the Chinese Loess Plateau, where intense rainfall and steep slopes make this region one of the most eroded areas in the world. However, the effectiveness of strip grass cover (Vc) in reducing erosion under varying rainfall and topographic conditions remains insufficiently quantified. In this research, based on indoor simulated rainfall experiments in a soil tank, we investigated the erosion characteristics of slopes under six Vc levels (0%, 20%, 30%, 40%, 50%, and 60%), three rainfall intensities (RI) (1.33, 1.67, and 2.0 mm·min⁻¹), and four slope gradients (SG) (10°, 15°, 20°, and 25°), and quantified the effects of Vc on slope erosion processes. Runoff and sediment reduction effects by Vc ranged from 3.5% to 62.6% and from 15.2% to 99.1%, respectively. An exponential decay in erosion rate was observed with increasing Vc, whereas runoff velocity initially decreased and then increased as the Vc increased. By integrating RI, SG, and Vc, the average runoff rate and erosion rate models accurately simulate erosion processes on Vc slopes. These findings provide laboratory-based evidence that Vc substantially reduces slope erosion, and support the development of empirical models for predicting runoff and erosion under the tested conditions. Full article

Forest stand composition can regulate soil nutrient cycling by altering aggregate formation, nutrient partitioning and microbial extracellular enzyme activity. Here, we examined pure Pinus tabuliformis forest (YS), pure Quercus acutissima forest (ML) and mixed coniferous–broadleaved forest (HJ) in the Ziwuling forest region of the Chinese Loess Plateau. Soil aggregate composition, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and extracellular enzyme activities were quantified across different aggregate-size fractions in the 0–100 cm soil profile. Except for the >5 mm aggregate fraction, the proportions of all other aggregate-size classes followed the order ML > HJ > YS, with ML and HJ showing increases of 19.94%–66.98% and 8.76%–35.01%, respectively, relative to YS. Mixed forest significantly promoted SOC content, with SOC contents 46.9% and 76.1% higher than those in YS and ML, respectively. In contrast, TN content was highest in YS and was 20.3% higher than that in HJ, whereas TP showed only small differences among forest types. SOC and TN were mainly enriched in smaller aggregate fractions, accounting for 49.7%–79.1% and 44.7%–81.3% of their total stocks, respectively, while TP was preferentially associated with larger aggregates, accounting for 54.9%–82.1%. Compared with YS, HJ increased EG, LAP, NAG and ACP activities by 42.2%, 14.9%, 18.0% and 42.5%, respectively. Compared with ML, HJ also showed generally higher extracellular enzyme activities, indicating that mixed forest favored the enhancement of most enzyme-mediated nutrient acquisition processes. Overall, forest stand type regulated extracellular enzyme activity by reshaping soil aggregate composition and aggregate-associated nutrient distribution. These findings help improve our understanding of aggregate-associated nutrient cycling processes in restored forest soils on the Loess Plateau and may provide a reference for future comparative studies on restoration effects among different forest types. Full article

Traditional Chinese brick-and-stone archways are not merely architectural products shaped by geographical constraints; they also embody a highly rational structural logic. Drawing on the unique earthen environment of the Loess Plateau and the region’s traditions of brick-and-stone construction, the Jinzhong region of China has developed a distinct system of archways. Consequently, to deconstruct the mechanical wisdom inherent in the traditional building techniques of the Jinzhong region, this study selected residential buildings in Qi County and Pingyao, as well as Qing Dynasty (1636–1912 AD) official architecture, as case studies. Through field investigations into the masonry techniques of three typical vault forms—the single-centre arch, the double-centre arch, and the four-centre arch—the study revealed their evolutionary characteristics in terms of geometric form. Static numerical simulation analysis was conducted using the Abaqus CAE 2025 (Dassault Systèmes, Vélizy-Villacoublay, France) platform. The study found that, under a simulated surface load of 0.027 N/mm², different arch profiles exhibited significant quantitative mechanical differences, and their stress distributions and deformation thresholds showed distinct scenario-specific tendencies. The results show that, compared to a semicircular arch, the official double-centred arch reduces maximum displacement by approximately 20%, and the maximum principal stress decreased from 1.35 MPa to 1.215 MPa, effectively mitigating the risk of cracking at the arch crown. With this high sectional stiffness and displacement-constraining capability, it supports the high load requirements of defensive city fortifications. Compared to the Pingyao gentle-type four-centre arch, its maximum displacement increased by only about 10%, and the maximum principal stress rose by only about 8%. Therefore, given similar mechanical performance but considering construction feasibility, the official double-centred arch was selected for the construction of defensive city fortifications. Furthermore, although the stress concentration at the corners (arch feet) of the Pingyao gentle-curved four-centred arch is approximately 4.8% higher than that of the pointed four-centred arch, its spatial utilization is improved by 15–20%; This geometric trade-off achieved through composite curvature maximizes interior clear space while maintaining structural stability, aligning with the functional requirements of guyao architecture for large-span living spaces. Meanwhile, the semicircular vaults of Qi County demonstrate universal value in low-load residential door and window components due to their low construction threshold. These quantitative data and qualitative observations indicate that the evolution of traditional forms is not merely an esthetic pursuit, but rather a precise optimization of structural performance within the constraints of material strength. This coupled relationship between “geometric form, load-bearing mechanism and usage context” confirms the inherent principles of resource efficiency and performance balance within traditional building systems. The quantitative assessment framework established in this study provides scientific guidance, grounded in construction logic, for the preventive conservation and precise reinforcement strategies of historic masonry structures. Full article

Runoff on the Chinese Loess Plateau has declined substantially over recent decades, but the relative roles of climate change and non-climatic disturbance remain debated. Here, we provide a robust regional attribution of runoff reduction across 14 major catchments during 1961–2009 by integrating seven Budyko-based climate elasticity methods with long-term hydro-meteorological analysis and change-point detection. Across the region, runoff and runoff coefficients decreased markedly, while evapotranspiration and leaf area index increased, indicating a widespread reduction in catchment water yield. Runoff showed consistently greater sensitivity to precipitation than to potential evapotranspiration, highlighting precipitation as the primary climatic control on runoff variability. However, the Budyko-based climatic component explained only part of the observed runoff decline, and the residual component not explained by annual precipitation and potential evapotranspiration was large in many catchments, with estimated contributions generally exceeding 50% and reaching more than 80% in several basins. Independent evidence, including vegetation greening, the expansion of ecological engineering measures, and increasing anthropogenic water demand, suggests that this residual was at least partly associated with human disturbance, although other non-Budyko climatic and hydrological processes may also contribute. These results indicate that annual precipitation and potential evapotranspiration alone cannot explain runoff decline across much of the Loess Plateau and underscore the need to jointly consider climatic forcing, land surface alteration, and direct human water use in regional water management. Full article

Soil erosion and nutrient loss degrade the soil resource base and water quality in dryland agricultural landscapes, yet optimal design of vegetation buffers for soil conservation under intensifying rainfall remains poorly quantified, particularly for nutrient retention. This study is novel in integrating event-scale rainfall-simulation experiments, Bayesian hierarchical modelling, Causal Forest analysis, and WEPP simulations to quantify how the sequential addition of biocrusts and grasses to shrub buffers shifts density thresholds for runoff, soil loss, and nutrient export across varying rainfall intensities. Experiments were conducted across a continuous shrub-density gradient (0–11,429 plants ha⁻¹) representing three configurations: shrub monoculture, shrub-biocrust, and shrub-biocrust-grass on agricultural hillslopes of the Chinese Loess Plateau. Runoff, soil loss, and exports of total nitrogen (TN) and total phosphorus (TP) were measured. Results demonstrate three main findings. First, multilayer shrub–biocrust–grass buffers exhibited lower soil loss than monocultures. Posterior estimates indicate reductions from approximately 3.8 t ha⁻¹ at moderate monoculture density to below 1.0 t ha⁻¹ at lower planting densities, with 94% of the highest-density intervals reflecting uncertainty in these estimates. Second, Causal Forest analysis reveals a functional separation of controls: rainfall intensity dominates soil loss (88% importance) and runoff (84%), whereas nutrient retention responds more strongly to buffer structure and density management. Third, WEPP simulations across rainfall intensities (50–180 mm h⁻¹) and slopes (10–30%) identify an optimal multilayer buffer density of 3800–5700 plants ha⁻¹, which delivers robust multifunctional benefits with 50–67% lower planting requirements than conventional high-density monocultures. These findings demonstrate that multilayer vegetation buffers enhance soil retention and reduce nitrogen and phosphorus losses from hillslopes, sustaining the soil resource base and protecting water quality in dryland agricultural landscapes. The integrated modelling framework provides transferable, evidence-based density recommendations for climate-resilient soil conservation in similar dryland regions. Full article

Soil erosion remains a critical ecological challenge on China’s Loess Plateau (LP), where fragile geomorphology and intensive human activities jointly amplify land degradation risks. As land-use and land-cover change (LUCC) is a primary determinant of erosion processes, clarifying the nexus between land patterns and erosion intensity is essential for formulating effective conservation strategies. This study integrates the Chinese Soil Loss Equation (CSLE) with the Patch-generating Land Use Simulation (PLUS) model to analyze the spatiotemporal dynamics of soil erosion from 2000 to 2020 and project future patterns for 2060 under five scenarios: Natural Development (ND), Ecological Protection (EP), Economic Development (ED), Cropland Protection (CP), and Planning Guidance (PG). Results indicate a fluctuating decline in LP soil erosion during 2000–2020, marked by a transition toward predominantly slight erosion (~70% of the total area), while high-intensity erosion remained concentrated in central and western cropland and grassland. Scenario projections reveal pronounced divergence in erosion outcomes. The EP scenario, characterized by sustained vegetation expansion, demonstrated the highest efficacy in erosion mitigation. Conversely, the ED scenario exhibited the most severe erosion risk due to urban expansion into ecological areas. The PG scenario effectively reconciled the trade-offs between ecological conservation and socioeconomic demands, maintaining a balanced erosion control performance. In the context of global climate change, the complexity of soil and water conservation governance is expected to intensify. This study suggests that future efforts should focus on scientifically guiding the evolution of land-use patterns through sustainable spatial planning. Furthermore, targeted engineering and biological conservation measures must bae implemented for high-risk land categories to ensure the long-term stability of the regional ecological security barrier. Full article

Land use change profoundly impacts the trade-offs and synergies among ecosystem services in ecologically fragile watersheds. Optimizing land use patterns based on ecological function zoning is an important approach to coordinate multiple ecosystem services and promote sustainable watershed management. This study focuses on the Wuding River Basin within the Chinese Loess Plateau, using Self-Organizing Map, multi-objective genetic algorithms, and the Future Land-Use Simulation model to explore land use optimization schemes. The results show that the windbreak and sand fixation service in the Wuding River Basin presents a spatial pattern of higher values in the northwest and lower values in the southeast, while the other six services exhibit a pattern of higher values in the east and lower values in the west. Based on the ecosystem service cluster characteristics, the basin can be divided into soil and water conservation zones, habitat conservation zones, and ecologically fragile zones. The trade-offs and synergies between ecosystem services within different zones differ significantly, with the trade-off between food supply, soil conservation, and habitat quality being particularly prominent. After optimization, the food supply and soil conservation in the soil and water conservation zones increased by an average of 0.63 × 10⁴ t and 1.94 × 10⁵ t, respectively. The food supply in the habitat conservation zones increased by 0.11 × 10⁴ t, while habitat quality remained stable. In the ecologically fragile area, water production and carbon sequestration services increased by an average of 0.26 × 10⁴ t and 0.58 × 10⁵ t, respectively. During the optimization process, the reasonable allocation of grassland and unused land played a key role in balancing service conflicts. This study provides a scientific basis for coordinating trade-offs in watershed ecosystem services and achieving land use optimization management through the framework of service clusters, functional zones, and multi-objective optimization. Full article

Research on the evolutionary patterns and propagation mechanisms of different drought types is of great significance for regional water resources management and the prevention and control of agricultural drought risks. Taking the arid region in the western Chinese Loess Plateau as the study area, this paper systematically revealed the spatiotemporal variation characteristics, propagation lag time and conditional probability of meteorological and agricultural droughts based on the monthly Standardized Precipitation Evapotranspiration Index (SPEI) and self-calibrating Palmer Drought Severity Index (scPDSI) during 1985–2022 by comprehensively adopting the Mann–Kendall trend test, Sen’s slope estimation, run theory, drought frequency analysis, as well as the Copula function and event-matching method. The results showed that during the study period, meteorological drought (characterized by SPEI) exhibited an insignificant intensification overall, while agricultural drought (characterized by scPDSI) presented a significant mitigation at the monthly scale. The maximum occurrence frequency of agricultural drought reached 70.39%, which was significantly higher than that of meteorological drought (38.82%); in addition, agricultural drought featured a longer average duration and greater severity, with a spatial pattern of higher in the northwest and lower in the southeast in the study area. The average propagation lag time of drought derived from the Copula function was 1.41 months, versus 2.19 months obtained by the event-matching method. When meteorological drought reached the moderate level (SPEI < −1.0), it was likely to trigger agricultural drought of mild or higher severity. The research findings can provide a scientific reference for formulating differentiated drought prevention strategies in the arid region of the western Loess Plateau, China. Full article

This study conducts a landslide deformation assessment in Tianshui, Gansu Province, on the Chinese Loess Plateau, utilizing the Small Baseline Subset InSAR (SBAS-InSAR) method integrated with velocity direction conversion and Z-score clustering. The Chinese Loess Plateau is one of the most landslide-prone regions in China due to frequent rains, strong topographical gradients and severe soil erosion. By constructing subsets of interferograms, SBAS-InSAR can mitigate the influence of decorrelation to a certain extent, making it a highly effective technique for monitoring regional surface deformation and identifying landslides. To overcome the limitations of the satellite’s one-dimensional Line-of-Sight (LOS) measurements and the challenge of distinguishing true landslide signals from noise, two optimization strategies were implemented. First, LOS velocities were projected onto the local steepest slope direction, assuming translational movement parallel to the slope. Second, a Z-score clustering algorithm was employed to aggregate measurement points with consistent kinematic signatures, enhancing identification robustness, with a slight trade-off in spatial completeness. Based on 205 Sentinel-1 Single-Look Complex (SLC) images acquired from 2014 to 2024, the integrated workflow identified 69 “active, very slow” and 63 “active, extremely slow” landslides. These results were validated through high-resolution historical optical imagery. Time series analysis reveals that creep deformation in this region is highly sensitive to seasonal rainfall patterns. This study demonstrates that the SBAS-InSAR post-processing framework provides a cost-effective, millimeter-scale solution for updating landslide inventories and supporting regional risk management and early warning systems in loess-covered terrains, with the exception of densely forested areas. Full article

Increased atmospheric nitrogen (N) deposition alters the formation and stability of soil organic carbon (SOC) in fragile ecosystems. While biochar (BC) amendment represents a promising strategy for augmenting soil carbon sequestration, its impact on the stability of the SOC pool under high N deposition remains unclear. In this study, we conducted a two-year field trial with three replicates to investigate the effects of combined N (0 and 9 g N·m⁻²·yr⁻¹) and BC (0, 20, and 40 t·ha⁻¹) addition on the stability of the SOC pool in restored grasslands on the Loess Plateau. We assessed SOC pool stability by examining the influence of soil microbial carbon utilization efficiency (CUE), metabolic constraints, and community composition on the content of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). The results indicate that in comparison to the control treatment (N0BC0), the addition of both high N (N9BC0) and BC (N0BC20 and N0BC40) significantly promoted the accumulation of POC by 15.78%, 9.87%, and 11.05%, respectively. Conversely, the content of MAOC was suppressed under the N9BC0 (−10.64%) and N0BC40 (−8.29%) treatments. However, the combination of high N and BC treatments resulted in increased levels of SOC, POC, and MAOC, while simultaneously reducing the MAOC/POC ratio, with all parameters reaching their peak under the N9BC40 treatment. Meanwhile, high N and BC additions led to differences in bacterial community structure, increased CUE, and enzyme vector angle. Notably, high N shifted the dominant factor of BC on MAOC/POC from physicochemical properties to biological factors. Microbes drive CUE to influence changes in MAOC by adapting to metabolic limitations and stoichiometric imbalances. In contrast, POC is primarily influenced by physicochemical properties. Overall, high additions of N and BC have been shown to reduce the stability of SOC by promoting the accumulation of POC. However, an addition rate of 40 t·ha⁻¹ of BC was found to be more effective in mitigating the negative impacts of high N addition on MAOC. This strategy can serve as an effective management approach for enhancing SOC sequestration in vulnerable regions of the Loess Plateau. Full article

Aeolian deposits are globally recognized as sensitive recorders of Quaternary climate and environmental change, exemplified by the continuous loess sequences of the Chinese Loess Plateau in northern China, which document paleoclimatic and paleoenvironmental evolution since the Miocene. However, such deposits have rarely been confirmed in low-latitude inland regions of southern China. Here we present systematic evidence of aeolian deposition in a low-latitude environment, namely at the Xinlipoding (XLPD) Paleolithic site, situated between the Bose and Bubing Basins in Guangxi, southern China. Using optically stimulated luminescence (OSL), geochemical, and grain-size analyses, we investigate 100 cm thick yellow-brown sandy loam exposed on the hillside of the Bubing Basin. OSL dating constrains its accumulation between 25.3 ± 1.5 ka and 2.7 ± 0.1 ka, spanning the Last Glacial Maximum (LGM) to the late Holocene. Geochemical signatures indicate that the sediments were primarily derived from a nearby terrace in the Bose and Bubing Basins. Grain-size end-member modeling further reveals a mixed alluvial-aeolian origin, comprising both windblown and reworked loess. These findings demonstrate that aeolian dust deposition persisted even in the humid subtropical low-latitude regions of China, recording continuous dust input across glacial–interglacial cycles. The XLPD section thus provides a valuable framework for reconstructing late quaternary environmental change and extends the spatial reach of global aeolian deposition into previously underrecognized regions. Importantly, it also offers a crucial paleoenvironmental context for human occupation in the Bubing Basin from the LGM through the late Holocene. Full article

The Wushan Loess, situated in the Yangtze Three Gorges region of China, represents the southernmost aeolian loess deposit in China and provides critical insights into Late Pleistocene paleoenvironmental conditions and East Asian monsoon dynamics. Despite its significance, the genesis and provenance of this unique loess deposit remain controversial. This study employs an integrated multi-proxy approach combining detrital zircon U-Pb geochronology, optically stimulated luminescence (OSL) dating, and detailed grain size analysis to systematically investigate the provenance and depositional mechanisms of the Wushan Loess. Three representative loess–paleosol profiles (Gaotang-GT, Badong-BD, and Zigui-ZG) were analyzed, yielding 17 OSL ages, 729 grain size measurements, and approximately 420 analyses per profile were conducted, yielding 1189 valid ages (GT 406, BD 391, ZG 402). OSL chronology constrains the deposition period to 18–103 ka (Marine Isotope Stages 2–5), coinciding with enhanced East Asian winter monsoon activity during the Last Glacial period. Grain size analysis reveals a dominant silt fraction (modal size: 20–25 μm) characteristic of aeolian transport, with coarse silt (20–63 μm) averaging 47.1% and fine silt (<20 μm) averaging 44.2% of the sediments. Detrital zircon U-Pb age spectra exhibit consistent major peaks at 200–220 Ma, 450–500 Ma, 720–780 Ma, and 1800–1850 Ma across all profiles. Kernel Density Estimation (KDE) and Multi-Dimensional Scaling (MDS) analyses indicate a mixed provenance model. Non-negative least squares (NNLS) unmixing confirms this quantitative source apportionment., dominated by proximal contributions from the upper Yangtze River basin (including the Three Gorges area and Sichuan Basin, ~65%–70%), supplemented by distal dust input from the Loess Plateau and northern Chinese deserts (~30%–35%). This study establishes for the first time a proximal-dominated provenance model for the Wushan Loess, providing new evidence for understanding southern Chinese loess formation mechanisms and Late Pleistocene East Asian monsoon evolution. Full article

Understanding the effectiveness of engineering measures in mitigating surface erosion is crucial for sustainable land management. However, studies explicitly quantifying the combined effects of large-scale engineering measures and environmental factors remain limited. In this study, multisource remote sensing data were integrated with interpretable machine learning to quantify and analyze the regional influence of erosion control measures. We constructed a comprehensive indicator system encompassing spectral, textural, and topographic variables derived from high-resolution satellite imagery and DEM data. To address model transparency and enhance the interpretability of the results, we employed an interpretable machine learning framework capable of both accurate prediction and explicit attribution of feature importance. The results indicate that the implementation of engineering measures substantially reduces erosion intensity across the study area. Spatial heterogeneity in erosion mitigation effectiveness was closely associated with the distribution patterns of engineering measures and site-specific environmental conditions. Basins with a high proportion of check dams showed average elevation gains of up to 2.5 m compared with those without check dams, and terraces contributed to elevation increases of ~1.9 m in typical loess hilly regions. The interpretable machine learning model achieved R² = 0.62 at Basin 1 (average area ~100 km²) and R² = 0.73 at Basin 2 (~600 km²), demonstrating reliable predictive capability. The findings not only validate the role of engineering interventions in erosion mitigation but also provide a transparent analytical framework that connects remote sensing analytics with process-based geomorphological understanding. Full article