Drought is a significant natural disaster in Ordos, exacerbating desertification and degrading grassland vegetation. Therefore, studying drought in this region is crucial for effective drought prevention, desertification control, and ecological restoration. In this study, we explored the spatiotemporal dynamics and trends of drought and analyzed the driving factors behind the spatial differentiation of DSI using a geographic detector model. The results show that evapotranspiration (ET) and the normalized difference vegetation index (NDVI) in the Ordos exhibit a significant increasing trend (P<0.05), with rates of 4.291 mm·a^-1 for ET and 0.004 a^-1 for NDVI. Additionally, the interannual variation of DSI also showed a significant increase, with a trend change rate of 0.089. ET and NDVI showed a spatial pattern, with lower values in the southwest and higher values in the northeast. Conversely, PET showed a spatial pattern of higher values in the southwest and lower values in the northeast. The DSI showed a dry spatial pattern in the west and a wet pattern in the east. The spatial differentiation of the DSI was primarily affected by five factors, such as air temperature, precipitation, land use type, soil type, and the digital elevation model (DEM), with q value exceeding 0.15, indicating these are the main driving factors of drought in the Ordos. Multiple factors interact to drive drought in Ordos, with four key combinations—temperature and DEM, precipitation and DEM, sunshine duration and DEM, and relative humidity and DEM. Among these, the combination of precipitation (0.156) and DEM (0.248) exerted the strongest influence on drought occurrence, with a q value of 0.389. This study can provide a scientific basis for ecological protection and drought management measures in the region.

In this study, we assess the characteristic bias in the diurnal precipitation forecasts from two models—CMA-SH9 and CMA-MESO—for hourly precipitation forecasts across four subregions in the Hedong Region of Gansu Province (the Gannan Plateau and the Longnan, Longdong, and Longzhong regions). These forecasts were assessed based on rainfall amount and frequency, using observed hourly precipitation data from 20 storm rainy days between May and September 2019-2021 in the same region. The results show the following: (1) Both models have similar forecasting abilities for precipitation amounts of ≥2.5 mm·h^-1 and ≥5 mm·h^-1 in the Gannan Plateau and the Longnan and Longdong regions. However, the CMA-MESO model facilitates easier precipitation forecasts of ≥5 mm·h^-1 in the Longzhong region than the CMA-SH9 model. (2) For rainfall ≥2.5 mm·h^-1, both models overestimate intensity during the day and underestimate it at night compared to observations, with significant deviations mostly occurring around the peak time of observed rainfall at night. The CMA-SH9 model generally outperforms the CMA-MESO model in predicting rainfall intensity in the Longzhong and Longdong regions most times of the day. In the Longnan region, the CMA-SH9 model performs better than the CMA-MESO model in predicting rainfall intensity at night but performs worse during the day. For rainfall ≥5 mm·h^-1, the CMA-SH9 model consistently predicts rainfall intensity better than the CMA-MESO model in the Longnan and Longdong regions, but worse in the Gannan Plateau, most of the time. (3) For rainfall ≥2.5 mm·h^-1, both models predict higher rainfall frequency during the day and lower frequency at night compared to observations, with significant deviations mostly occurring around the peak time of observed rainfall at night. The CMA-SH9 model mostly outperforms the CMA-MESO model in predicting rainfall frequency. For rainfall ≥5 mm·h^-1, both models underestimate rainfall frequency compared to observations in the Longnan, Longzhong, and Longdong regions, with the negative forecast deviation more pronounced around the peak time of observed rainfall at night. (4) Phase error are predominant across the four subregions for both models, while amplitude error was minimal.

The impact of surface O₃ on air quality in China has intensified, making it the primary pollutant for air quality management. As a gateway to Northwest China, Xinjiang has undergone rapid economic development, resulting in air quality issues, particularly in Urumqi and Kashgar. In this study, we analyzed the variation characteristics and potential sources of O₃ in these cities and employed a backward trajectory model to explore transmission paths, potential source areas, and influencing factors. The results indicated the following: (1) From 2015 to 2022, O₃ concentrations in Urumqi and Kashgar peaked in 2018, followed by a slight decrease and subsequent stabilization. O₃ concentrations showed significant seasonal variations, with the highest concentrations occurring in summer, alongside weekend effects and diurnal fluctuations. (2) Backward trajectory analysis revealed that from 2015 to 2022, airflow sources in Urumqi and Kashgar were similar, with long-distance airflows primarily originating from the western Central Asian region. Long-distance transport trajectories account for 31.86% of airflow trajectories in Urumqi, compared to 15.42% in Kashgar. Conversely, medium- and short-distance airflows mainly come from local sources, constituting 68.14% of the trajectories in Urumqi and 84.58% in Kashgar. (3) Urumqi and Kashgar encompass extensive potential source areas. In Urumqi, local sources are the primary contributors, while potential sources in Kashgar include both local and external origins. The range of high-value potential source areas expanded in 2022 compared to 2015.

Soil macropores are the main channels for soil moisture infiltration. Investigating their characteristics and influencing factors in the root zone of typical sand-fixing plants in the desert-oasis transition zone is crucial for regional ecological vegetation restoration and plant selection. In this study, we investigated the characteristics of soil macropores in the root zone of these plants in the middle reaches of the Heihe River desert-oasis transition zone through water penetration experiments. We analyzed the influencing factors of soil macropores and their impact on soil-saturated hydraulic conductivity. The results show the following: (1) The radius of soil macropores ranges from 0.5 to 1.6 mm, exceeding the minimum aeration pore radius of 0.3 mm. Soil moisture movement is mainly driven by gravitational water. The density of soil macropores in the root zone of sand-fixing plants in the transition zone decreases with increasing soil depth, characterized by a higher number of smaller pores and fewer larger pores. (2) Soil bulk density and other soil macropore indicators, except for the total number of macropores, showed a highly significant negative correlation. Conversely, saturated water content and other macroporosity indicators, except for the total number of macropores, exhibited a significant positive correlation. Additionally, organic matter content and various soil macropore indicators showed a highly significant positive correlation. (3) The saturated hydraulic conductivity of the soil ranged from 2.32 to 3.79 mm·min^-1. The variation in saturated hydraulic conductivity was determined by the soil macroporous volume ratio (82%), macroporous area ratio (68%), the fourth power of the average radius of macroporous space (79%), and the total number of macropores (43%). (4) Under the same habitat conditions in the study area, planting sand-fixing plants significantly improved the water infiltration ability of the soil compared to bare land. Among the three sand-fixing plants studied, their water infiltration abilities ranked as follows, from strongest to weakest: Haloxylon ammodendron, Calligonum mongolicum, and Nitraria sphaerocarpa.

In this study, we examined seven species suited to desert grasslands and analyzed the relationship between soil nutrients and nitrogen cycling in natural and artificial vegetation through field sampling and laboratory analysis. The results showed the following: (1) Salsola collina and Caragana korshinskii howed high nutrient content, which had a fixed effect on nutrients and was conducive to the restoration of nutrient content within the study area. Additionally, these species significantly increased the abundance of bac, AOA, AOB, nirS, nirK, nifH, and nosZ genes in the rhizosphere soil. (2) The abundance of the nifH gene was significantly correlated with soil nutrient levels. (3) The ecological restoration of soil in the study area is influenced by the combined effects of carbon and nitrogen, necessitating adjustments to the fertilization structure and improvements to the soil environment in the future. Overall, natural vegetation, such as Salsola collina, and artificial vegetation, such as Caragana korshinskii, outperformed other species in soil nutrient fixation and nitrogen cycling functional gene abundance, making them ideal for restoration in the study area. These findings provides valuable insights for selecting plant species in future ecological restoration of gravel-sand-mulched fields.

Phosphorus pollution is a significant concern in aquatic systems, as excessive accumulation can lead to eutrophication. The riparian zone, a vital transitional area between land and water, is crucial for mitigating phosphorous loss. Therefore, in this study, we investigated the forms and distribution characteristics of phosphorus in the sediments of the riparian zone along the Yellow River in Lanzhou using the SMT method and the Psenner classification extraction method. Additionally, we assessed the risk of phosphorus release using the balance concentration assessment method, single-factor analysis, and the bioavailable phosphorus pollution index. The results indicate that the average total phosphorus content in the sediments of the study area is relatively high, measuring 1240.07 mg∙kg^-1, with inorganic phosphorus as the dominant form, primarily calcium phosphorus. The phosphorus balance concentration in the sediments exceeds that of dissolved reactive phosphorus in the overlying water, indicating that the sediments act as a “phosphorus source” for the overlying water. Furthermore, evaluations of the single-factor pollution index and the bioavailable phosphorus pollution index reveal that while total phosphorus pollution in the area is primarily classified as heavy, the ecological pollution status of phosphorus in the Lanzhou section of the Yellow River is relatively good.

In this study, we analyzed meteorological data from 1980 to 2020, hydrological runoff data, and future climate models from CMIP6 in the Jinghe River Basin. The CMIP6 climate data was processed using the delta downscaling method and coupled with the Soil and Water Assessment Tool hydrological model to investigate the variations in blue-green water due to climate change in the basin. The results showed that under the SSP1-2.6 pathway, the blue-green water content in the study area exhibited an insignificant upward trend. Under the SSP3-7.0 pathway, the blue water content showed an insignificant downward trend, while the green water content showed a significant upward trend. Similarly, under the SSP5-8.5 pathway, the blue water content showed an insignificant downward trend, and the green water content also exhibited an insignificant upward trend. The average annual blue water volume under the three pathways decreased compared to the historical period, with annual averages of 128.8 mm, 117.2 mm, and 126 mm, respectively. Conversely, the average annual green water volume increased, recording values of 372.7 mm, 369.3 mm, and 372.1 mm, resulting in a green water coefficient higher than that of the historical period. The spatial distribution of blue-green water increased from northwest to southeast, with consistent spatial distribution characteristics across each pathway.

In this study, we explored the chemical control factors influencing groundwater and the causes of high-fluoride concentrations in the Irtysh River Basin plain, Xinjiang. In 2018, 70 groundwater samples were collected to analyze the spatial distribution characteristics of hydrochemical components and fluoride. The mechanisms behind the formation and enrichment of the high-fluoride water were also examined. Using an absolute factor analysis-multiple linear regression model (APCS-MLR), we quantitatively assessed the contributions of various factors to the hydrochemical components of groundwater in the basin. The results show the following: (1) The groundwater in the study area is generally neutral and slightly alkaline. The north of the Irtysh River is dominated by fresh water, while the south is dominated by brackish water. The rates of fluoride exceedance in the north and south of the Irtysh River are 27.91% and 44.44%, respectively. The primary chemical type of groundwater in both areas is HCO₃·SO₄-Na·Ca type. (2) The results of the SOM analysis suggest that fluoride may be derived from fluorine-containing minerals mixed with various elements. The APCS-MLR model indicates that the formation of groundwater chemical components in the study area is mainly affected by leaching enrichment (58.03%), groundwater pH (16.28%), and the primary geological environment (10.28%). (3) The primary factors influencing the formation of high-fluoride groundwater include mineral dissolution and precipitation, evaporation and concentration, rock weathering, and cation exchange. Additionally, the groundwater environment, climatic factors, topography, and human activities significantly contribute to the enrichment of high-fluoride groundwater.

To address the imbalance between the supply and demand of water resources and compensate for the shortage of freshwater resources, the use of brackish and saline water for irrigation has become crucial. Simultaneously, the effects of different sodium adsorption ratios (SAR) on cotton growth and yield can vary under the same degree of mineralization in irrigation water. Therefore, to further explore the effects of irrigation water mineralization and SAR on cotton, we established three mineralization treatments at 3 g·L^-1(T3), 5 g·L^-1(T5), and 7 g·L^-1(T7). Additionally, we designed three SAR treatments at 10 (mmol·L)^1/2(S10), 15 (mmol·L)^1/2(S15), and 20 (mmol·L)^1/2(S20). Local freshwater irrigation served as a control (CK). In total, 10 treatments were conducted in this experiment to examine the combined effects of irrigation water mineralization and SAR costress on soil salinity, cotton growth, plant ion accumulation, yield, and water use efficiency. The results indicated that soil salinity increased with higher irrigation water mineralization or SAR, initially rising before decreasing with increasing soil depth. Plant Na⁺ content increased with increasing irrigation water mineralization or SAR, with the interaction effect between these factors being highly significant. Conversely, plant K⁺, K⁺/Na⁺, and N content decreased as irrigation water mineralization or SAR increased. Additionally, plant height, stem thickness, leaf area index, and dry matter mass all showed a significant decreasing trend with increased irrigation water mineralization and SAR, with significant inhibition of dry matter accumulation observed. Irrigation water mineralization and SAR significantly affected the number of bolls per plant, boll weight, seed cotton yield, and water consumption (ET). Moreover, irrigation water SAR significantly affected water use efficiency (WUE). Compared to the CK treatment, yield and WUE increased by 3.27% and 1.09% in T3S10, 2.54% and 0.47% in T5S10, and 1.18% in T3S15, respectively. This increase indicated that moderately reducing the irrigation water SAR can help mitigate yield reduction in cotton due to increased mineralization. Different levels of mineralization and SAR in irrigation water increased the Na⁺ content in cotton plants while reduced K⁺ and N nutrient uptake, and increased the K⁺/Na⁺ ratio. Consequently, cotton plant height, stem thickness, leaf area, and dry matter accumulation gradually decreased as irrigation water mineralization or SAR increased. The number of bolls per plant and boll weight increased in the T3S10, T3S15, and T5S10 treatments compared to the CK treatment. In conclusion, using brackish water with an irrigation water mineralization of 3 g·L^-1 and SAR below 15 (mmol·L^-1)^1/2, or an irrigation water mineralization of 5 g·L^-1 with SAR below 10 (mmol·L^-1)^1/2, can ensure cotton yield. These findings provide a theoretical basis and reference for the efficient use of brackish water in Xinjiang and other extreme arid regions.

In this study, we aimed to clarify the spatial response of different vegetation drought indices to climate change in the Yellow River Basin. We selected the vegetation condition index (VCI), vegetation health index (VHI), and temperature vegetation drought index (TVDI), along with precipitation, temperature, and evapotranspiration data from 2003 to 2022. Using trend analysis, spatial path analysis, and multi-layer perceptron regression analysis, we examined the spatial and temporal variation characteristics of the three drought vegetation indices in the Yellow River Basin. Our findings reveal the direct, indirect, and overall effects of climatic factors on drought in the Yellow River Basin. The results show the following: (1) During the 20 years under study, VCI and VHI showed a fluctuating upward trend, while TVDI remained stable without significant increases or decreases. Spatially, the temperate-warm temperate boundary is delineated, revealing significant reductions in TVDI in the southeast and VHI in the northwest. (2) Precipitation has the strongest direct effect on VCI, while temperature exerts the most significant direct influence on TVDI. Additionally, the indirect effects of precipitation on TVDI and temperature on VHI are also substantial. TVDI is primarily inhibited by precipitation, while temperature predominantly enhances VCI and VHI. (3) The four drought indices exhibited a negative correlation with precipitation and temperature and a positive correlation with potential evapotranspiration. Potential evapotranspiration is the primary influencing factor for TVDI, while temperature is the main influencing factor for both VCI and VHI. Among these indices, the VHI is the most suitable for drought assessment in the Yellow River Basin. Our study offers a theoretical basis for vegetation drought assessment and management in the Yellow River Basin.

Shrub is an important part of forest community structure in Xinjiang wild fruit forest and plays an important role in maintaining ecosystem diversity and function. In this article, shrub communities of 4 wild fruit forest populations in JWTH, XHG, MHE and DXG were studied, then the species diversity and ecological niche of shrub were investigated by the means of sample plots (understory, forest gap, open space) and transversal lines (elevation lines between plots and wild fruit forest distribution). The results indicated that: (1) In the wild fruit forest: 110 species belonging to 26 genera and 18 families were found (see Annex 1 in the list), among which Rosaceae, Rosa and Cotoneaster are the dominant families and genera in the wild fruit forest; the areal-types of its families and genera are mainly distributed in the world and temperate zone; the important value accounts for a large proportion were Berberis (Berberis atrocarpa), Lonicera (Lonicera microphylla, Lonicera tatarica) and Rosa (Rosa beggeriana, Rosa laxa). There was no significant difference in shrub diversity coefficient among different habitats of the same wild fruit forest population, and the shrub diversity among populations gradually decreases from DXG, MHE, JWTH to XHG. (2) For the niche width, both B_L and B_S of B. atrocarpa in JWTH and MHE, L. microphylla in XHG were the largest, B_L of B. atrocarpa in DXG had the largest Levins niche width and B_S of Spiraea hypericifolia had the largest Shannon-Winner niche width. These species were widely distributed with strong ability of resource utilization and environmental adaptation. Ecological niche overlapped, <0.5 species pairs accounted for more than 50% of the total species pairs in wild fruit forest, and the similarity of environmental resources utilization was low, with weak competition between species. The shrubs of JWTH and MHE showed no significant negative association, while the shrubs of XHG and DXG showed no significant positive association, all of which were in the unstable early stage of succession. Conclusion: Xinjiang wild fruit forest was found with rich shrub species composition, the shrub species composition and diversity of different wild fruit forest populations were significantly different, the shrub population also was in an unstable state in the wild fruit forest ecosystem, which is closely related to the overall function of the wild fruit forest ecosystem.

Malus sieversii, a state-protected species and the progenitor of cultivated apples, is an important germplasm resource within the genus Malus. In this study, we aimed to compare the structural characteristics of chloroplast genomes across various populations of M. sieversii, clarify the lineage divergence pattern, and trace the evolutionary history of this species. We used the Illumina NovaSeq platform to conduct whole-genome sequencing of individuals from 16 different populations, with one sample representing each population. After conducting quality control on the sequencing data, we conducted genome assembly and functional annotation. Subsequently, we conducted a comprehensive structural analysis and lineage differentiation studies on the assembled genomes. The chloroplast genome length in M. sieversii ranged from 160195 to 160279 base pairs (bp), exhibiting a typical tetrad structure. In total, 131 genes were identified within the chloroplast genome, along with 48-58 long repeats and 93-101 simple sequence repeats. Notably, variations in the IR region between M. sieversii and other species in the genus were minimal, predominantly occurring in noncoding regions. Phylogenetic analysis revealed that M. sieversii clusters into three distinct lineages: lineage I, primarily occupying the eastern part of the distribution range, and lineages II and III, predominantly found in the west. The divergence time between lineages I and II was approximately 1.74 million years ago (Ma), while the divergence between lineages I, II, and III was around 2.28 Ma. These findings indicate that the lineage divergences of M. sieversii were significantly influenced by climate changes during the Quaternary period. Compared to internationally distributed populations, M. sieversii in China shows relatively low genetic diversity. Therefore, tailored conservation strategies should be implemented for M. sieversii across different regions, with particular emphasis on protecting genetically diverse populations in the Tacheng area.

In this study, we investigated the physiological responses of Pinus sylvestris var. mongolica seedlings to drought stress and subsequent rehydration. A pot experiment was conducted using 2-year-old seedlings subjected to five water treatments, including control (80%), light drought (40%), moderate drought (20%), severe drought (10%), and extremely severe drought (5%). We measured leaf water content, photosynthesis, chlorophyll fluorescence, leaf osmoregulatory substances, and antioxidant enzyme activity during drought and after rehydration. The results showed the following: (1) The physiological state of the seedlings was minimally affected by the light drought. The activities of superoxide dismutase and peroxidase peaked under moderate and severe drought stress, increasing by 25.26% and 38.8%, respectively. Conversely, the net photosynthetic rate, transpiration rate, and photochemical quenching coefficient under extremely severe drought stress decreased by 94.76%, 87.19%, and 72.35%, respectively, while the leaf malondialdehyde content was the highest in this condition. (2) The chlorophyll fluorescence and leaf proline content of the seedlings were restored to control levels after rehydration. However, the average photosynthetic indices of rehydrated leaves only returned to 28.51% after extremely severe drought stress. Additionally, leaf water use efficiency, soluble sugar content, and antioxidant enzyme activity were significantly higher than the control after rehydration (P<0.05). In conclusion, extremely severe drought stress primarily reduces photosynthetic ability and disrupts the cell membrane stability of Pinus sylvestris var. mongolica seedlings. Conversely, rehydration after moderate drought improves water utilization and the scavenging ability of reactive oxygen species, thereby improving drought resistance. This improved information provides theoretical insights for the efficient cultivation, management, and evaluation of drought resistance in the Pinus sylvestris var. mongolica plantation.

Understanding the response characteristics and influencing factors of land use change to habitat quality is essential for establishing a scientific basis for ecological protection in arid regions. In this study, we used land use data, the InVEST model, habitat contribution rate, and a geographic detector to evaluate the response and influencing factors of land use changes and habitat quality. Additionally, we predicted habitat quality for 2030. The results showed the following: (1) The land use types were dominated by unused land and grassland. The cultivated and construction land areas expanded by 10545 km² and 1170 km², respectively, while forest land, grassland, and unused land decreased. (2) The overall habitat quality was low and exhibited a continuous downward trend. Spatial distribution was high at the edges and low in the center. Additionally, habitat quality in grasslands adjacent to unused land decreased significantly, while overall habitat quality increased significantly. (3) The spatial distribution of habitat quality was primarily influenced by elevation, temperature, and precipitation, with the interaction between elevation and precipitation having the strongest impact on habitat quality in the watershed. (4) By 2030, the ecological protection scenario will offer significant advantages over the natural and economic development scenarios, improving habitat quality. In the future, ecological protection will primarily focus on preventing and controlling desert expansion and protecting grassland and water resources.

In this study, we investigated the spatiotemporal changes in vegetation greenness on the southern slopes of the Qilian Mountains and their responses to climate change and human activities. Utilizing the Google Earth Engine platform, we applied algorithms and remote sensing technologies to analyze these changes. By employing Sen’s trend analysis, the coefficient of variation, the Hurst index, ArcGIS spatial analysis, and multiple residual regression methods, we integrated multisource data products to comprehensively analyze the characteristics of vegetation greenness changes. Additionally, we assessed future trends and stability while thoroughly examining the influences of climate change and human activities. The results indicated the following: (1) From 2001 to 2020, vegetation greenness on the southern slope of the Qilian Mountains exhibited an overall upward trend, accompanied by significant spatial variations. Stability analysis revealed that the coefficient of variation ranged from 0 to 0.84, with a mean of 0.09, indicating that changes in vegetation greenness remained relatively stable and exhibited a positive trend. (2) Regarding influencing factors, both precipitation and temperature exhibited a positive correlation with vegetation greenness, with temperature showing a more pronounced effect. Notably, 95.7% of the study area passed the significance test, highlighting that temperature primarily drives changes in vegetation greenness. (3) Human activities have positively influenced changes in vegetation greenness. Overall, these changes result from the combined effects of climate change and human activities, with relative contribution rates of 36.68% for climate change and 63.32% for human activities. The higher contribution rate of human activities is closely linked to the implementation of ecological engineering initiatives.

A culvert is designed to manage water flow beneath an embankment. However, road culverts often encounter issues with sand accumulation, which disrupts flood flow and jeopardizes road safety. To identify wing wall types that reduce sediment accumulation in culverts, three models were developed—one-sided wall, eight-sided wall, and straight wall. Numerical simulations were conducted to analyze the characteristics of the outflow field and the sediment accumulation processes for each model. The results indicate the following: (1) The structure and velocity of the flow field in the culvert vary significantly based on the wing wall type. In cavities A and B, airflow primarily adheres to the upper wall of the culvert, while in cavity C, the airflow is accelerated. Overall, the velocity in the cavities is ranked as C>B>A. (2) The process of sediment accumulation in the culvert varies significantly based on the wing wall type. Wing walla A and B effectively guide airflow, leading to a high concentration of wind-sand flow within the culvert, making sand accumulation more likely. Conversely, wall C exhibits a weaker diversion ability, accumulating sand primarily at the culvert mouth and shoulder. As incoming wind speed increased, the sand transport capacity of the three culverts improved, with wall C showing the most significant increase, followed by wall B and wall A showing the least. (3) Wind direction also affects sediment accumulation in the culvert. As the oblique angle increased, sediment accumulation in cavities A and C also increased, while sediment accumulation in cavity B decreased. (4) The transport efficiency varies among different wing walls, with sand accumulation in the cavities ranked as A>B>C, while transport efficiency is ranked as C>B>A. Overall, wing wall C was most effective at reducing sand accumulation in the culvert.