Search Results (121)

Understanding the impacts of climate change on species’ geographic distributions is fundamental for biodiversity conservation and resource management. As a key plant group for ecological restoration and windbreak and sand fixation in arid and semi-arid ares in China’s Three Northern Regions (Northeast, North, and Northwest China), Caragana spp. exhibit distribution patterns whose regulatory mechanisms by environmental factors remain unclear, with a long-term lack of climatic explanations influencing their spatial distribution. This study integrated 2373 occurrence records of 44 Caragana species in China’s Three Northern Regions with four major environmental variable categories. Using the Biomod2 ensemble model, current and future climate scenario-based suitable habitats for Caragana spp. were predicted. This study innovatively combined quantitative analyses with Kira’s thermal indexes (warmth index, coldness index) and Wenduo Xu’s humidity index (HI) to elucidate species-specific relationships between distribution patterns and hydrothermal climatic constraints. The main results showed that (1) compared to other environmental factors, climate is the key factor affecting the distribution of Caragana spp. (2) The current distribution centroid of Caragana spp. is located in Alxa Left Banner, Inner Mongolia. In future scenarios, the majority of centroids will shift toward lower latitudes. (3) The suitable habitats for Caragana spp. will expand overall under future climate scenarios. High-stress scenarios exhibit greater spatial changes than low-stress scenarios. (4) Hydrothermal requirements varied significantly among species in China’s Three Northern Regions, and 44 Caragana species can be classified into five distinct types based on warmth index (WI) and humidity index (HI). The research findings will provide critical practical guidance for ecological initiatives such as the Three-North Shelterbelt Program and the restoration and management of degraded ecosystems in arid and semi-arid regions under global climate change. Full article

Arid and semi-arid regions serve as crucial ecological barriers in China, making the spatiotemporal evolution of their ecological environmental quality (EEQ) scientifically significant. This study developed a Modified Remote Sensing Ecological Index (MRSEI) by innovatively integrating the Comprehensive Salinity Indicator (CSI) into the Remote Sensing Ecological Index (RSEI) and applied it to systematically evaluate the spatiotemporal evolution of EEQ (2014–2023) in Yinchuan City, a typical arid region of northwest China along the upper Yellow River. The study revealed the spatiotemporal evolution patterns through the Theil–Sen (T-S) estimator and Mann–Kendall (M-K) test, and adopted the Light Gradient Boosting Machine (LightGBM) combined with the Shapley Additive Explanation (SHAP) to quantify the contributions of ten natural and anthropogenic driving factors. The results suggest that (1) the MRSEI outperformed the RSEI, showing 0.41% higher entropy and 5.63% greater contrast, better characterizing the arid region’s heterogeneity. (2) The EEQ showed marked spatial heterogeneity. High-quality areas are concentrated in the Helan Mountains and the integrated urban/rural development demonstration zone, while the core functional zone of the provincial capital, the Helan Mountains ecological corridor, and the eastern eco-economic pilot zone showed lower EEQ. (3) A total of 87.92% of the area (7609.23 km²) remained stable with no significant changes. Notably, degraded areas (934.52 km², 10.80%) exceeded improved zones (111.04 km², 1.28%), demonstrating an overall ecological deterioration trend. (4) This study applied LightGBM with SHAP to analyze the driving factors of EEQ. The results demonstrated that Land Use/Land Cover (LULC) was the predominant driver, contributing 41.52%, followed by the Digital Elevation Model (DEM, 18.26%) and Net Primary Productivity (NPP, 12.63%). This study offers a novel framework for arid ecological monitoring, supporting evidence-based conservation and sustainable development in the Yellow River Basin. Full article

The arid and semi-arid regions of Northwest China, as major agricultural production zones, have long faced dual challenges: increasing water resource pressure and severe supply–demand imbalances caused by the expansion of cultivated land. The crop water footprint, an effective indicator for quantifying agricultural water use, plays a crucial role in supporting sustainable development in the region. This study adopted a multi-scale spatiotemporal analysis framework, combining the CROPWAT model with Geographic Information System (GIS) techniques to investigate the spatiotemporal evolution of crop water footprints in Northwest China from 2000 to 2020. The Logarithmic Mean Divisia Index (LMDI) model was used to analyze spatial variations in the driving forces. A multidimensional evaluation system—encompassing structural, economic, ecological, and sustainability dimensions—was established to comprehensively assess agricultural water resource utilization in the region. Results indicated that the crop water footprint in Northwest China followed a “decline-increase-decline” trend, it increased from 90.97 billion m³ in 2000 to a peak of 133.49 billion m³ in 2017, before declining to 129.30 billion m³ in 2020. The center of the crop water footprint gradually shifted northward—from northern Qinghai to southern Inner Mongolia—mainly due to rapid farmland expansion and increasing water consumption in northern areas. Policy and institutional effect, together with economic development effect, were identified as the primary drivers, contributing 49% in total. Although reliance on blue water has decreased, the region continues to experience moderate water pressure, with sustainable use achieved in only half of the study years. Water scarcity remains a pressing concern. This study offers a theoretical basis and policy recommendations to enhance water use efficiency, develop effective management strategies, and promote sustainable water resource utilization in Northwest China. Full article

Aerosol optical properties and radiative forcing critically influence Earth’s climate, particularly in semi-arid regions. This study investigates these properties in Yinchuan, Northwest China, focusing on aerosol optical depth (AOD), single-scattering albedo (SSA), Ångström Index, and direct radiative forcing (DRF) using 2023 CE-318 sun photometer data, HYSPLIT trajectory analysis, and the SBDART model. Spring AOD peaks at 0.58 ± 0.15 (500 nm) due to desert dust, with coarse-mode particles dominating, while summer SSA reaches 0.94, driven by fine-mode aerosols. Internal mixing of dust and anthropogenic aerosols significantly alters DRF through enhanced absorption, with spring surface DRF at −101 ± 22W m⁻² indicating strong cooling and internal mixing increasing atmospheric DRF to 52.25W m⁻². These findings elucidate dust–anthropogenic interactions’ impact on optical properties and radiative forcing, offering critical observations for semi-arid climate research. Full article

Nitraria tangutorum (Zygophyllaceae) is an ecologically and economically valuable shrub, locally dominant in the arid and semi-arid deserts of northwest China owing to its exceptional drought resistance and salt tolerance. In this study, environmental variable importance was evaluated within the MaxEnt model using percent-contribution metrics, based on 154 distribution records of N. tangutorum and 14 bioclimatic and soil-related environmental variables. We identified the five key variables of N. tangutorum distribution as follows: Precipitation of the Wettest Quarter (Bio16), Topsoil Sodicity (T_esp), Topsoil Electroconductibility (T_ece), Topsoil Car-bonate or lime content (T_CACO₃), and Precipitation of the Driest Month (Bio14). The constructed MaxEnt model was then used to project the potential distribution areas of N. tangutorum under the four Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) for both current climate conditions and future climate conditions (2050s and 2090s). The results indicate that, under present-day conditions, high-suitability areas occur primarily in Xinjiang, Gansu, Qinghai, Inner Mongolia, and Ningxia; in future climate scenarios, the suitable habitat for N. tangutorum is anticipated to shrink by the 2050s but is expected to gradually recover by the 2090s. As time progresses, the suitable habitat areas will generally expand towards higher latitude regions. These findings demonstrate N. tangutorum’s strong adaptive potential to climate change and provide a scientific basis for its targeted introduction, cultivation, and long-term management in desert restoration and ecological rehabilitation projects. Full article

The span of pile foundations beneath metro depots typically ranges from 10 to 20 m, exhibiting a notably large span. This structural characteristic results in the pile foundations bearing a more concentrated upper load, while the interstitial soil between the piles bears minimal force. Concurrently, global climate change and enhanced urban greening initiatives have led to a significant increase in rainfall in northwest China, a region traditionally characterized by arid and semi-arid conditions. This climatic shift has precipitated a continuous rise in groundwater levels. Furthermore, the extensive distribution of collapsible loess in this region exacerbates the situation, as the rising groundwater levels induce loess collapse, thereby adversely affecting the mechanical behavior of the pile foundations. In light of these factors, this study utilized the pile foundations of a metro depot in Xi’an as a prototype to conduct static load model tests under conditions of rising groundwater levels. The experimental results reveal that the load–settlement curve of the pile foundations in the absence of groundwater exhibited a steep decline with distinct three-stage characteristics, and the ultimate bearing capacity was determined to be 5 kN. When the groundwater level is situated below the loess stratum, the settlement of both the pile foundations and the foundation soil, as well as the axial force, skin friction, and pile tip force, remains relatively stable. However, when the groundwater level rises to the loess stratum, there is a significant increase in the settlement of the pile foundations and foundation soil. Negative skin friction emerges along the pile shaft, and the bearing type of the pile foundation transitions gradually from a friction pile to an end-bearing pile. The influence range of the pile foundation on the settlement of the foundation soil is approximately three times the pile diameter. Full article

This study combines field experiments and numerical analysis using the HYDRUS model to investigate the impact of water table depths on evaporation processes in semi-arid regions with shallow groundwater. Two lysimeters with different water table depths were set up in the Ordos Basin, Northwest China, and instrumented with multi-depth soil moisture and temperature sensors. The experimental data were used to calibrate and validate numerical models that simulated both non-isothermal and isothermal flows. The results reveal that groundwater levels significantly influence the evaporation rate, dictating the position of the evaporation front and zero-flux plane. Isothermal models underestimated cumulative evaporation by 14.7% and 44.2% for the shallow and deep-water table lysimeters, respectively, while non-isothermal models produced more accurate results with 0.95% overestimation and 5.2% underestimation. The study demonstrates that incorporating both water and heat transport into numerical models enhances the accuracy of evaporation estimates under varying groundwater conditions. Furthermore, the findings show that when the evaporation front occurs near the surface, liquid water flux dominates, whereas water vapor flux plays a crucial role when the evaporation front is located below the surface. These results offer valuable insights for refining water management strategies and models in agricultural and ecological systems of semi-arid areas, underscoring the critical role of considering soil moisture and temperature dynamics, along with groundwater levels, in accurately quantifying evaporation for improved resource management. Full article

Revegetation in arid and semi-arid regions is a pivotal strategy for mitigating desertification and controlling soil erosion by enhancing carbon storage in woody biomass and mitigating wind-induced erosion. Despite its recognized importance, a critical gap remains in understanding how biomass carbon is distributed across different plant compartments (leaves, stems, litter, and roots) and how this distribution influences soil carbon dynamics. In this study, we examined carbon allocation between aboveground (shoot and litterfall) and belowground (coarse and fine roots) components, as well as the composition and vertical distribution of soil carbon in three 20-year-old shrub plantations—Salix psammophila, Corethrodendron fruticosum, and Artemisia desertorum—in northwest China. Total biomass and litter carbon storage were highest in the S. psammophila plantation (3689.29 g m⁻²), followed by C. fruticosum (1462.83 g m⁻²) and A. desertorum (761.61 g m⁻²). In contrast, soil carbon storage at a 1 m depth was greatest in A. desertorum (12,831.18 g m⁻²), followed by C. fruticosum (7349.24 g m⁻²) and S. psammophila (5375.80 g m⁻²). Notably, A. desertorum also exhibited the highest proportions of stable soil organic carbon (heavy-fraction) and soil inorganic carbon, while S. psammophila had the lowest. Across all plantations, belowground biomass carbon and light-fraction soil organic carbon displayed distinct vertical distributions, while heavy-fraction soil organic carbon and soil inorganic carbon did not show significant spatial patterns. A strong correlation was found between soil carbon fractions and microbial biomass carbon and nitrogen, suggesting that microbial communities were key drivers of soil carbon stabilization and turnover. These findings underscore the importance of litter composition, root traits, and microbial activity in determining soil carbon accumulation following shrub revegetation. The study highlights the need to investigate species-specific mechanisms, such as rhizodeposition dynamics and microbial necromass stabilization, to elucidate carbon redistribution pathways in semi-arid ecosystems. Full article

This paper addresses the dual challenges of food security and sustainable development by examining the balance between arable land quality and economic development. Coordinating and optimizing development models is essential for achieving sustainable agricultural and economic progress. The North Slope Economic Belt of Tianshan Mountain (UANST), a semi-arid agriculturalpastoral transition zone in northwest China, exemplifies a coupled human environment system where global sustainability targets confront regional development imperatives. Focusing on seven cities and counties within the UANST, this study employs information sensitivity indicators to quantitatively select evaluation metrics. It provides a comprehensive analysis of the current state of the coupling and coordination degree (CCD) between arable land quality and economic development in the region. Using a system dynamics model (SDM), four scenario models were developed to predict and analyze the interaction between cultivated land quality and economic development on the North Slope of Tianshan. The study proposes a model to improve coordination between cultivated land quality and economic development. The key findings are as follows: (1) “preliminary screening + information sensitivity analysis” method identified 12 arable land quality evaluation indicators and 11 economic development evaluation indicators for the North Slope Economic Belt of Tianshan. (2) The coupling coordination between arable land quality and economic development in the seven counties and cities improved from 0.469 to 0.663, reflecting a transition from “marginal imbalance” to “primary coordination”. By 2021, all regions had reached the initial stage of coordinated development. (3) Among the development models analyzed, the coordinated development model achieved the highest coupling coordination score (0.9136). This model also demonstrated lower carbon dioxide emissions and reduced water resource consumption, alleviating environmental pressures and offering an optimal solution for regional coordinated development. Full article

The Weining Plain is in the semi-arid northwest region of China, with groundwater as its main source for various purposes. This research provided a detailed investigation into the groundwater exploitation status in the Weining Plain, analyzed the groundwater quality for different purposes, and estimated the groundwater recharges using water budget analysis with end member mixing analysis. The entropy water quality index was applied to assess the overall quality of drinking water, and the industrial water quality index and several agricultural water quality indicators were used for the assessment of groundwater quality for industrial and agricultural uses. The findings showed that the groundwater recharge in the research area primarily comes from irrigation infiltration and leakage of the irrigation canal system which account for approximately 50–60% of the total groundwater recharge. The overall drinking water quality is poor, with over 80% being of moderate to poor quality and requiring treatment. A large proportion of the groundwater in the research area is suitable for irrigation. However, groundwater has a corrosive effect on boilers, and there is a high risk of boiler scaling and foaming. Only 12.41% of the water samples have good water quality for industrial use, and the treatment of the water quality for industrial uses is needed. This study can help local decision-makers understand the availability of groundwater resources in the Weining Plain and manage groundwater resources reasonably. Full article

Maize production in the arid and semi-arid regions of northwest China is limited by water scarcity, while the abundance of brackish water highlights the opportunity for its effective and sustainable utilization. A 2-year field experiment (2022–2023) was conducted in the Shiyang River Basin to investigate the impacts of deficit irrigation with brackish water on soil moisture, salinity, temperature, crop growth index, yield, and water productivity. Six treatments were implemented, consisting of two irrigation levels (W1: 75%I, W2: 100%I) and three water quality gradients (S0: 0.7 g L⁻¹, S1: 3.7 g L⁻¹, S2: 5.7 g L⁻¹ in 2022 and 7.7 g L⁻¹ in 2023). Results indicated that brackish irrigation (except S0) increased soil salinity, keeping the soil water storage at higher levels, while decreased maize yield, and water productivity (WP). Compared with full irrigation at the same salinity level, deficit irrigation decreased soil salinity, keeping the soil water storage at lower levels, while increasing soil temperature, which led to lower maize yield but resulted in higher WP. Path analysis of soil hydrothermal salinity and crop growth indicators demonstrated that soil salinity changes play a crucial role in determining maize plant height and yield. S0W2 (100% irrigation, 0.7 g L⁻¹) achieved the highest maize yield, with S0W1 yielding 5.15% less. However, the water productivity (WP) of S0W1 was 17.66% higher than that of S0W2. Therefore, considering the combined factors of maize yield, water productivity, and water-saving benefits, the use of S0W1 (75% irrigation, 0.7 g L⁻¹) is recommended. Full article

In the transitional region between agriculture and livestock rearing in northern China, planting forage crops in rows among fruit trees as feed in orchards represents an effective strategy for enhancing the ecological environment while addressing the increasing demand for livestock feed. Nonetheless, the impact of short-term mowing of cover forage crops for livestock feed on the quality of soil remains unclear. A two-year field experiment was conducted in Ziziphus jujuba cv. “Lingwuchangzao” orchards located in Lingwu County, Ningxia Hui Autonomous Region, in arid and semi-arid Northwest China. The experiment consisted of four treatments: (A) clean tillage (CK), (B) plantation with Lolium perenne (LP), (C) plantation with Trifolium repens (TR), and (D) plantation with Vicia villosa (VV).The results showed that short-term intercropping of forage crops may lead to a reduction in most soil nutrients in Z. jujuba cv. “Lingwuchangzao” orchards, particularly in the 0–20 cm soil layer. However, intercropping with TR can mitigate this declining trend and may even enhance nutrient levels within the 0–40 cm depth. Furthermore, intercropping of forage crops had a more pronounced effect on the α-diversity of fungal communities than on bacterial communities. This practice also altered the relative abundance of bacterial genera such as Sphingomonas, Bacillus, and Flavobacterium in the 20–40 cm depth and dominant fungal genera Fusarium and Mortierella in the 0–20 cm soil layer. The effects of soil physicochemical properties on bacterial communities were more significant than those on fungal communities.These results indicate that the short-term intercropping of forage crops in Z. jujuba cv. “Lingwuchangzao” orchards in arid and semi-arid Northwest China have varying impacts depending on the type of forage crop used. Full article

Water scarcity hinders sustainable agriculture in arid and semi-arid regions. This study investigated the combined effects of trickle irrigation and biochar application on sugar beet cultivation in northwest China’s arid and semi-arid regions, addressing challenges of water scarcity. Three-year field experiments were conducted using plastic film mulch, four irrigation levels based on crop evapotranspiration (0.6–1.2 ETc), and four biochar application rates (0–30 t ha⁻¹). Results showed that biochar application increased sugar beet germination rates by 7.2–24.5% and enhanced relative chlorophyll content by 3.1–22.1%. Optimal combinations of irrigation and biochar significantly improved growth indices and yield, with maximum values observed under the highest irrigation (1.2 ETc) and 10 t ha⁻¹ biochar treatment. However, the 1.0 ETc irrigation treatment with 10 t ha⁻¹ biochar demonstrated superior water use efficiency (14.8% higher), sustainable yield index (1.1% higher), and economic benefits (1.4% higher) compared to the highest irrigation treatment. Considering growth, yield, quality, water use efficiency, sustainability, and economic factors, an irrigation level of 1.0 ETc combined with a biochar application rate of 10 t ha⁻¹ is recommended for sugar beet cultivation in Xinjiang. This study provides valuable insights and practical strategies for water conservation, high yield, and quality improvement in sugar beet cultivation under arid and semi-arid conditions, contributing to sustainable agricultural practices in water-scarce regions. Full article

As one of the countries with the most severe extreme climate disasters in the world, it is of great significance for China to scientifically understand the characteristics of extreme precipitation. The artificial neural network near-real-time dynamic infrared rainfall rate satellite precipitation data (PDIR-Now) is a global, long-term resource with diverse spatial resolutions, rich temporal scales, and broad spatiotemporal coverage, providing an important data source for the study of extreme precipitation. But its applicability and accuracy still need to be evaluated in specific applications. Based on the observation data of 824 surface meteorological stations in China, the correlation coefficient (R), relative deviation (RB), root mean square error (RMSE), and relative root mean square error (RRMSE) of quantitative statistical indicators were used to evaluate the annual maximum daily precipitation of PDIR-Now from 2000 to 2016 in this study, in order to explore the ability of PDIR-Now satellite precipitation products to monitor extreme precipitation in Chinese mainland. The results show that from the perspective of long-term series, the annual maximum daily precipitation of PDIR-Now has a good ability to monitor extreme precipitation across the country, and the R exceeds 0.6 in 65% of the years. The RMSE of different years is generally distributed between 40 and 60 mm, and in terms of time characteristics, the error of each year is relatively stable and does not fluctuate greatly with dry precipitation or abundant years. From the perspective of spatial characteristics, the distribution of RMSE is very regional, with the RMSE in the Qinghai–Tibet Plateau and Northwest China basically in the range of 0~20 mm, the Yunnan–Guizhou Plateau, the Sichuan Basin, Northeast China, and the central part of the study area in the range of 20~50 mm, and the RMSE in a few stations in the southeast coast greater than 80 mm. The RRMSE distribution of most sites is between 0 and 0.6, and the RRMSE distribution of a few sites is between 0.6 and 1.5. Generally, higher RRMSE values and larger errors are observed in the northwest and southeast coastal regions. Overall, PDIR-Now captures the regional characteristics of extreme precipitation in the study area, but it is underestimated in the wet season in humid and semi-humid regions and overestimated in the dry season in arid and semi-arid regions. Full article

Soil salinity and water deficit are important challenges for sustainable agricultural development in arid and semi-arid regions. While soil salinity and water deficits may result in lower crop yields, they may improve crop quality. The quantitative relationship between water–salt stress, crop yield, and quality is key to achieving stable yield and enhanced quality through the coordinated regulation of soil water and salt. The interaction between soil salinity and deficit irrigation on tomato quality needs to be further understood, and the model simulating the response of tomato quality to deficit irrigation under simulated soil salinity needs to be further optimized. In this study, a two-year experiment was conducted in northwest China consisting of combinations of three soil salinity levels (0 g, 3 g, and 5 g mixed salt added to 1000 g air-dried soil, respectively) and four water regimes relative to the field capacity (θ_f) (W0, W1, W2, and W3 refer to 95% θ_f, 80% θ_f, 70% θ_f, and 60% θ_f as the upper limit of soil water content, respectively). The responses of plant stem water potential (φ), fruit osmotic potential (φ_π), fruit Na⁺ content, fruit fresh weight, fruit water content, total soluble solids (TSS), lycopene (Ly), soluble sugars content (SSC), and color index (CI) to the degree of water deficit and the stage of water deficit were analyzed under soil salinity. The results show that both soil salinity and water deficit significantly reduced φ, but there is no significant interaction. TSS, SSC, and CI are all significantly affected by soil salinity, degree of water deficit, and stage of water deficit, and there is a significant interaction between the degree of water deficit and soil salinity. Fruit fresh weight, TSS, Ly, SSC, and CI are all strongly correlated with φ, and the straight lines of regression of each index with φ are significantly affected by soil salinity content. Soil salinity significantly increased the Na⁺ content in the fruit, and water deficit significantly enhanced the effect of soil salinity on the Na⁺ content of tomato fruit. A functional model to simulate fruit quality was developed based on the response of fruit quality parameters to φ and the effect of fruit Na⁺ accumulation under the compound effect of soil salinity and water deficit. The validation results of the model show that this function model effectively simulates tomato fruit quality under the combined effects of soil salinity and water deficit, providing a theoretical basis for soil water–salt management in arid and semi-arid regions. Full article