Aerodynamic roughness （Z0） and friction velocity （u* ） reflect the interaction between underlying surface properties and the atmosphere， and vegetation plays an important role in regulating Z0 and u* . This experiment was conducted by planting vegetation（Astragalus adsurgens）in the field， setting up four vegetation coverage and three vegetation layouts， and using a mobile wind tunnel for field experiments. The experimental results showed that： （1） As the input wind speed increases， there is a negative correlation between Z0 and u*， that is， as u* increases， Z0 shows a linear decreasing trend； Under the same input wind speed， as vegetation coverage increases， there is a positive correlation between Z0 and u*， which conforms to the logarithmic function form. （2） Z0 follows a logarithmic function variation pattern with vegetation coverage， and as vegetation coverage increases， there is a threshold phenomenon in Z0. （3）The size of Z0 with different vegetation layouts is in the order of two rows>cross layout>one row. （4） From the perspective of aerodynamics， it is proposed that Astragalus adsurgens vegetation coverage is 30%， and its wind erosion prevention efficiency is strong when the layout is two rows and one belt.
To study the windproof effect of double-row nylon sand-blocking net-grass square combination， wind tunnel experiments of double-row nylon sand-blocking net-grass square lattice with porosity of 40%， 45%， and 55% were carried out， and the contours of wind acceleration rate， windproof efficacy， and wind contour indexes were investigated under the three kinds of wind speeds， namely， 6， 10 m·s-1 and 14 m·s-1. The results show that： （1） Under different wind speed conditions， the windproof effect of double-row nylon sand-blocking net-grass combination decreases significantly with the increase of the incoming wind speed. （2） The windproof effect of the combined use of double-row nylon sand-blocking net-grass squares using a porosity of 40% is relatively better， whereas the windproof effect is relatively poorer when using a porosity of 45%， and the worst is found in the case of the windproof effect of porosity of 55%. （3） There is a cumulation of windproof effects in the combined application of double-row nylon sand-blocking net-grass squares. Therefore， it is recommended that a 40% porosity double-row nylon sand-blocking net-grass square grid be used in combination with practical applications to obtain the best wind protection effect.
Saline soil in arid regions is important land resources in China， and their improvement and utilization are an important element in promoting the green and sustainable development of China， which is related to national food security and ecological safety. Microorganisms， as an important part of soil ecosystem， play an important role in the improvement and management of saline soils and improving the salt tolerance of plants. Intensive study on soil microbial diversity， community structure and functional characteristics in arid saline soils and the related factors can provide important microbial references for the restoration and ecological reconstruction of saline soil in arid regions. The paper organized the overview of saline soil in arid regions， analyzed the characteristics of microbial diversity， community structure and ecological function in saline soils， elaborated the related factors of saline environment on soil microbial communities， and put forward the problems in microbial research in arid saline soil and the future development direction. This review can provide references for the development and utilization of saline soil and microbial resources management in arid regions in China.
Aeolian-fluvial interaction is an important geomorphic process in arid and semi-arid areas. The interaction between wind and water power is causal and promoting and has significant spatio-temporal variation characteristics. Under its action， a unique landform landscape， riparian dune， is formed， which is different from the dune landform formed by a single wind accumulation. Taking Wudinghe River Basin in Mu Us Sandy Land as a research area， based on remote sensing image interpretation and other methods， the dynamic geomorphological changes of the interaction between river channels and dunes are studied. The results show that： （1） The vegetation coverage in the Wudinghe River Basin in the Mu Us Sandy Land has recovered well during 1990-2020， and the riparian dunes have gradually solidified， showing the transformation from mobile dunes to semi-fixed dunes and from semi-fixed dunes to fixed dunes. （2） The river channel affects the continuity of the distribution of sand dunes， which makes them fragmented， and also blocks the movement of sand dunes and the transmission of some coarse particle size sand. （3） The geomorphologic pattern of riparian dunes in typical reaches is distributed in a band centered on the river channel， and moving dunes， semi-fixed dunes and fixed dunes are successively distributed along the distance from the river channel. The angle between wind direction and river direction affects the form and distribution of riparian dunes by influencing the mode and intensity of aeolian-fluvial interaction. （4） Riparian dune geomorphic system and river hydrological system maintain a dynamic equilibrium state through the water supply relationship， but excessive human activities may break their thresholds， resulting in increased desertification degree and deterioration of river hydrological conditions.
In this study， the evaluation of the sand control efficiency of the reed bundle sand control system in the gobi region of Milan section of Golmud-Korla Railway， Southern Xinjiang， China was carried out through field observation and numerical simulation. The results show that the sand-control systems consisting of two reed bundle fences and a 40 m long belt of large reed checkerboard （4 m×4 m×0.8 m） have a good effect on controlling damages caused by the gobi wind-blown sand. The maximum windproof efficiency （wind speed attenuation ratio） in the range of 2-14H （H， fence height， 2 m） after a single row reed bundle sand fence reached 86%， and the sand blocking efficiency （attenuation ratio of sand flux） ranged between 91.8% and 96.8%. The maximum wind protection efficiency of the double-row sand fence was almost unchangeable， and the sand blocking efficiency increased to 98%， while the sand blocking efficiency increased to 99.7% as wind-blown sand flux flowing over the belt of large reed checkerboard. Moreover， as the wind-blown sand flux flowed over the sand control system， the average particle size was significantly reduced from 240 μm to 72-109 μm， and the sorting tended to become better. The measured and simulated results show that the sand control system composed of two reed-bundle sand fences with 50% porosity and two large reed-bundle grids （4 m×4 m×0.8 m） can play a good role in sand control， the project cost is relatively low， and the protection system can be applied to the control of sand damage in the gobi wind area of Golmud-Korla Railway.
Compared to other terrestrial ecosystems， desert steppe transition zone ecosystems are highly vulnerable and exhibit heightened sensitivity to climate change. Therefore， long-term protection and attention is important. In this study， Hanggin Banner at the edge of Hobq Desert in Inner Mongolia was selected as the research area. Utilizing the Google Earth Engine （GEE） remote sensing cloud computing platform， we analyzed the vegetation change trends in Hanggin Banner by employing the Normalized Difference Vegetation Index （NDVI） from the MOD13Q1 series dataset during 2000-2020. Additionally， we monitored the vegetation evolution pattern using Fraction Vegetation Coverage （FVC） derived from a binary the study period. This analysis was supplemented by spatial transfer matrix and barycentric migration models to elucidate changes in NDVI characteristics within Hanggin Banner. Furthermore， annual precipitation average annual temperature data were utilized to investigate correlations with vegetation normalization index trends in Hanggin Banner. The results indicated the following： （1） Overall， there was a gradual increase in vegetation in the region， with an average annual change rate of 0.0021， demonstrating significant improvement. The vegetation cover was higher in the southeast and lower in the northwest. （2） From 2000 to 2020， Hanggin Banner witnessed considerable enhancement in vegetation coverage， with medium vegetation covering more than 50% of the total area. While low vegetation coverage decreased significantly by 62.35%， there was a slight decrease of 36.39% in high vegetation coverage. However， other grades experienced an increase in their respective coverages， particularly high vegetation which saw a remarkable rise of 150.12%. Moreover， areas with high and medium vegetative coverage tended to expand from north to south while those with medium and low vegetative coverage expanded. （3） There were distinct regional variations observed regarding the partial correlation between NDVI and climate factors. At an inter-annual scale， precipitation had a more pronounced impact on vegetation changes， and the correlation coefficient R reach 0.8 with NDVI， thus indicating that precipitation serves as the primary driving force behind changes in NDVI.
Urban agglomerations are strategic highlands for participating in global competition， important carriers of China's new urbanization， growth poles for high-quality regional development， and also the most prominent areas for spatial expansion. However， due to the underlying influence of the spatial structure of urban agglomerations， there is a certain degree of heterogeneity in their expansion patterns and forms. On the basis of defining the spatial structure of urban agglomerations， this paper systematically studied the patterns and forms of spatial expansion in the Lanzhou-Xining urban agglomeration and the Ningxia Yellow River urban agglomeration using nighttime light data. The results showed that： （1） Both urban agglomerations were mainly characterized by marginal expansion， with enclave expansion as a supplement. From 2011 to 2015， the enclave style expansion of the LXUA was higher than that of the NXUA. From 2016 to 2020， the enclave style expansion of the NXUA was outstanding. Implying that dual core-dual province urban agglomerations prefer to seek new development space in different locations （spatial discontinuity）， while single core urban agglomerations prefer spatial sprawl （spatial continuity）. Filling expansion is generally insufficient， indicating a weak trend of spatial integration in urban agglomerations. （2） The NP and FRAC-AM of the LXUA are higher than those of the NXUA， indicating that the expansion of the dual core dual province urban agglomeration is more obvious and the form is more complex； The COHENSION， AI， and PD indices of the LXUA are lower than those of the NXUA， indicating a higher degree of fragmentation and more prominent spatial dispersion in the dual core dual province urban agglomeration. The NP and PD indices of the two major urban agglomerations are increasing， while the FRAC-AM index decreases， while AI and COHENSION first increase and then decrease， showing a certain degree of convergence. However， the change rate of the dual core dual provincial urban agglomeration is relatively fast， indicating the distribution characteristics of the dual core and cross provincial regions. In fact， it reduces patch density， inhibits patch aggregation， and widens patch separation， which is not conducive to the optimization of the spatial structure of the urban agglomeration.
The "14th Five-Year Plan" of China proposed to include the Loess Plateau as a key area in the ecological protection and restoration of the Yellow River， implementing integrated watershed management on an appropriate basis. As a typical vulnerable basin in the Loess Plateau， the study of its spatial and temporal changes in habitat quality is of great significance for promoting the improvement of regional ecological environment quality. This study evaluated and predicted the spatiotemporal evolution characteristics of habitat quality in the Wuding River basin at both the whole basin and sub-basin scales， and explored the driving factors of spatial differentiation in habitat quality. The results showed that： （1） During 2000-2020， the proportion of forests and grasslands in the Wuding River basin increased by 11.73%， the area of construction land more than doubled compared to 2000， and the proportion of unused land decreased by 8.46%. During 2020-2050， the land use change situation is expected to remain consistent with the period from 2000 to 2020， but the intensity of change will gradually decrease. （2） During 2000-2020， the habitat quality in the Wuding River basin increased over time， showing a small upward trend overall. During 2020-2050， the growth rate of habitat quality will slow down， and the intensity of change will also weaken， indicating a generally positive development. （3） Land use is the dominant factor driving habitat quality， followed by NDVI and soil type. The study results can provide reference for biodiversity conservation， natural environment protection， and sustainable development in the basin.
The characteristics of wind regime and sediment transport potential are crucial for characterizing the wind energy environment in desert areas and studying aeolian sand movement. The wind patterns and sediment transport potential of the Ten Tributaries in the Yellow River Basin were investigated by analyzing meteorological station data from 2018 to 2022， aiming to understand their energy characteristics and environmental impacts. The results show that： （1） There is minimal variation in wind velocity between 2018 and 2022， with an annual mean wind speed of 3.17 m?s-1 and a yearly average sand-driving wind speed of 6.28 m?s-1. The polarization pattern of sand-driving winds across different seasons is evident， with the highest frequency occurring during spring， while inter-monthly wind speeds exhibit significant fluctuations due to seasonal changes. （2） The intensity of wind energy varies， with higher intensity observed towards the western regions and lower intensity towards the eastern areas in the Ten Tributaries， due to the influence of topography and elevation. Prevailing sand-driving winds predominantly originate from westerly and northerly directions across different temporal scales. （3） Based on the sediment transport potential， the Ten Tributaries are classified as having a moderate overall wind energy environment. The western region， which is located in close proximity to the Hobq Desert， falls within the high wind energy region； the central region falls within the moderate wind energy region； and the eastern region falls within the low wind energy region. The characteristics of sediment transport potential vary across different time scales； however， the overall direction of resultant sediment transport potential consistently remains oriented towards the southeast （SE） and south-southeast （SSE）， ensuring sufficient momentum for sediments to enter the channel. Therefore， it is suggested that spring should be considered the key control period for wind-blown sand， and the western region near the source of sand should be regarded as the key control area.
In recent years， various counties in the Zoige Basin have taken measures such as setting checkerboard sand barriers and planting shrubs to control desertification， and many wandering dunes have been fixed. To explore the changes of grain size characteristics of sand dune surface sediments under the influence of sand-fixing vegetation， surface samples were collected before and after sand dune control on the left bank of the Yellow River in Maqu County， Zoige Basin， and the relevant data were compared and analyzed. The results show： （1） After vegetation fixation， the proportion of silt and clay components increased from 1.3% to 9.9%， and the mean particle size decreased from 181.9 μm to 162.0 μm. The grain size components of surface sediments became finer， the sorting of dunes became worse， the skewness changed from near symmetry to very positive skewness， and the kurtosis changed from medium to very narrow. （2） The frequency distribution curve has a secondary peak， and the probability accumulation curve has a sub-component in the suspension section. The overall change from two-stage to three-stage， the particle size of the suspension component becomes finer， and the proportion of the saltation component content decreases from 99% to 87%-88%. （3） Under the combined action of wheat straw grid and sand-fixing vegetation， the effect of desertification control is remarkable， but the local environment of desertification land will also affect the effect of sand control. Therefore， it is necessary to carry out sand control work according to local conditions， pay attention to the dynamic changes of the control area， and timely take measures to adjust.
Taking 57 prefecture level and above cities in the Yellow River Basin as the research object， this paper measures the ecological level of industrial structure from 2010 to 2019 from the three dimensions of industrial structure rationalization， optimization and sustainability， clarifies its spatiotemporal evolution pattern， and reveals the sources and contributions of the spatial differences of the urban ecological industrial structure in the Yellow River Basin by applying the Dagum Gini coefficient decomposition method， based on which the influencing factors of the ecological industrial structure are dissected by the spatial Dubin model. The results showed that： （1） From 2010 to 2019， the overall development of the ecological development of urban industrial structure tended to be better， with an average annual growth rate of 1.55%， and the fluctuating trend of the ecological level of urban industrial structure in the downstream， midstream and upstream was basically consistent with the whole. （2） The spatial differentiation of cities was obvious， with high-value areas mainly concentrated in the downstream areas and low-value areas mostly located in the middle and upper reaches， and the overall evolution of "downstream-upstream" gradient was characterized by a decreasing gradient. （3） The spatial difference of urban ecological industrial structure was gradually narrowing， with an average annual decline rate of 2.47%， The intensity of transvariation was the main source of spatial difference， with an average annual contribution rate of 46.45%. The spatial correlation of areas with similar levels of ecological industrial structure decreased， and the phenomenon of spatial aggregation was weakened. （4） The financial development level and consumption structure upgrading level had positive promoting effects on the urban ecological industrial structure， while government regulation level， industrial agglomeration level and urbanization level had negative hindering effects. Meanwhile， consumption structure upgrading level had an obvious positive spillover effect， while government regulation level and industrial agglomeration level had negative spillover effects.
The Hexi inland river basin is located in arid and semi-arid regions with fragile ecosystems， and there is significant importance in studying the dynamic changes in vegetation cover and its driving factors for understanding the interaction between vegetation and ecosystems. This study uses the mean NDVI during the growing season as the vegetation cover index， employs slope trend analysis and coefficient of variation to analyze the changes in vegetation cover in the Hexi inland river basin from 2000 to 2020， and explores the effects of natural and anthropogenic factors on the spatial differentiation of vegetation using the Geodetector model. The results indicate that： （1） During 2000-2020， the vegetation cover in the Hexi inland river basin exhibited a generally rising trend with fluctuations， having a growth rate of 0.001·a-1， characterized by a spatial distribution of lower in the northwest and higher in the southeast， decreasing from east to west. （2） Between 2000 and 2020， in most parts of the basin， the vegetation cover remained relatively constant. The areas with increased vegetation cover constituted 35.27% and those with decreased cover constituted 10.91%. （3） The Hexi inland river basin exhibits strong spatiotemporal variability in vegetation cover， with the coefficient of variation ranging from 0.011 to 1.530. The majority of regions demonstrate high stability， with low stability areas primarily focused in the middle and upper reaches of the basin. （4） Natural factors play a leading role， with substantial impacts from evapotranspiration， vegetation types， precipitation， and soil types. Among human factors， land use type emerges as a primary influencer. Revealing the long-term vegetation evolution patterns and characteristics in the Hexi inland river basin offers valuable insights for ecological preservation and soil and water conservation in the region.
Geological relics are an important part of the tourism resource supply system in the Yellow River Basin. The average nearest neighbor， kernel density estimation and spatial autocorrelation are used to explore the spatial distribution pattern of 1 481 important geological relics in the Yellow River Basin， and on the basis of which an evaluation index system for the development potential of geotourism in the Yellow River Basin is established， and with the help of entropy weight-TOPSIS model， the potential of geotourism development of the Yellow River Basin is deeply explored. The results show that： （1） The important geological relics in the Yellow River Basin are clustered， but there are significant differences in the degree of clustering of different types and grades of geological relics. （2） The geological relics in the Yellow River Basin as a whole show a pattern of "dense in the middle reaches， sparse in the upper and lower reaches， one main and two sub-mains， and a band-like extension"， and the Shanxi-Henan border zone in the middle and lower reaches of the Yellow River is the absolute core distribution area of geological relics. （3） The distribution trend of positively correlated agglomeration is obvious on the global scale， but the spatial correlation characteristics of geological relics of different types and grades differ significantly in local space. （4） The spatial differentiation and polarization distribution trend of the development potential of geotourism in the Yellow River Basin is obvious， with the number of cities with high potential and higher potential being relatively small， and the number of cities with low potential and lower potential accounting for 46.09%， and a gradient decreasing in the spatial distribution of geotourism potential from downstream to upstream， and a gradient increasing from downstream to upstream.
The study focuses on the high-quality development of ecotourism in the Yellow River Basin， which investigates nine provinces（regions）within the basin from 2017 to 2021. Specifically， the analysis employs Entropy-Weighted TOPSIS method， standard deviation ellipse and fuzzy set to analyze the spatial evolution and optimization path. The findings are as follows： The high-quality development level of ecotourism in the Yellow River Basin ranges from 0.026 and 0.867， which indicates considerable regional disparities. The spatial agglomeration in the direction of Northeast-Southwest is obvious， and the pulling effect of the southwestern region on the high-quality development of tourism in the Yellow River Basin is gradually increasing； Over the study period， the centre of gravity of high-quality development of ecotourism in the Yellow River Basin is moved in a south-westerly direction gradually， concentrated in the spatial range at 111.75°-111.16°E and 36.02°-35.53°N. The centre of gravity shows slight movement， covering 91.47 km in five years； and ecological environment protection is considered a necessary condition for realizing the high-quality development of ecological tourism in the Yellow River Basin. There are three kinds of condition： market-ecological governance， resource-service-ecological governance， and resource-service-ecological governance-market.
Taking the West Route of the South to North Water Diversion Project as the background，based on the optimization of water-land relationship， aim at coordinating human-land relationship， Be directed against “changing low water and high ground to high water， low ground for remolding” and “high water consumption and diversion of Taohe River to east are proposed” use schemes： And in terms of ecological safety， food security， clean energy， and steady development of social economy， the eco-economic and social effects of the water use scheme are analyzed. Under this scheme， the cooperation between Yellow River natural channels and artificial artesian channels can improve the water-land relationship of middle and upper reaches of the Yellow River. Then over 100 000 square kilometers of eco-economic functional area integrated with landscape， forest， farmland， lake， grass， sand and ice will appear in a barren area locating at the intersection of Gansu， Qinghai， Ningxia and Inner Mongolia. It can provide water resources support to further consolidate the ecological safety barrier in northwest， ensure the national food security， promote the development and utilization of clean energy， steady development of regional social economy， and plays a role in strengthening the bones and waist in the Silk Road Economic Belt.
The Gobi Desert is a region known for its frequent sandstorms， and is one of the key sources of sandstorms in East Asia. The Tibet Plateau is adjacent to the two major sand source regions of East Asia and South Asia， and is one of the most sensitive regions to climate change in the world. However， the transmission path and mechanism of the Gobi Desert dust to the Tibet Plateau are still unclear. Based on the regional air quality mode WRF-Chem， FNL reanalysis data and the HYSPLIT backward trajectory model， a strong dust event in April of 2020 was used to explore the dust transmission path and transmission mechanism from the Gobi Desert to the Tibet Plateau. The results showed that during this dust event， the east and north slopes of the Tibet Plateau were important channels for dust transmission from the Gobi Desert to the Tibet Plateau. Affected by the circulation situation and the high terrain， the dust transmission efficiency on the north slope of the Tibet Plateau is greater than that on the east slope， while the vertical movement of dust on the east slope is stronger than that on the north slope. The 500 hPa cyclone system east of the Ural Mountains and the Mongolian cyclone jointly control the middle and high latitudes and affect the dust transport process. With the eastward movement of the mid-high latitude cyclone systems， the 500 hPa Xinjiang ridge was destroyed， and the short-wave trough over the Tibet Plateau began to be established. The low layer convergent circulation in front of the short-wave trough is conducive to the maintenance of the 700 hPa closed low pressure， which promotes the northerly wind on the northern slope of the Tibet Plateau， and is conducive to the transport of dust from the northern slope to the plateau. The downward transmission of the 200 hPa upper-level jet stream caused the near-ground easterly wind to prevail in the Hexi Corridor， which was conducive to the transport of the Gobi Desert dust to the plateau. This circulation situation constitutes a favorable wind field for dust transmission from the Gobi Desert from the eastern slope to the Tibet Plateau. The research results further improve the transmission path of the Gobi Desert dust， and provide scientific support for the study of the weather and climate change of the dust influence on the Qinghai-Tibet Plateau and its surrounding areas.
Clarifying the coupling relationship between urbanization and water ecological environment and its influencing factors has great significance for promoting the ecological protection and high-quality development of the Yellow River Basin. Based on the analysis of the coupling mechanism between new urbanization and water ecological environment， this paper analyses the spatial and temporal pattern of the coupling between the two systems and its driving factors by using the coupling coordination degree and spatial econometric model. The main conclusions are as follows： （1） From 2006 to 2021， the coupling coordination degree between new urbanization and water ecological environment in the Yellow River Basin had improved steadily but were overall low， which had risen from the stage of near imbalance to the stage of primary coordinated in general. Meanwhile， the coupling coordination degree of the downstream is greater than that of the middle reaches and upstream. （2） The coupling coordination degree has a significant spatial spillover effect， and the influence strength of the spatial spillover effect from high to low is the lower， middle and upper reaches of the Yellow River respectively. （3） Local government capacity has a positive promotion on the local coupling coordination but a negative spillover effect on that of neighboring cities； Local population agglomeration and environmental regulation negatively affect its own coupling coordination； Capital accumulation positively influences the coupling coordination of the whole study area through positive spillover effect， while with a negative influence in the downstream； The level of industrialization hinders the coupling coordination development in the whole basin through negative spillover effect； The open and innovative economy has positive impact and spillover effect only on the middle reaches. Differentiated strategies should be adopted to promote the coupling coordination development of new urbanization and water ecological environment across the Yellow River Basin.
To clarify the laws and evolution characteristics of territorial spatial differentiation is the basis and premise for improving governance capacity and building a balanced development pattern of territorial spatial pattern. Based on the theory of production-living-ecological spaces， the land use data from 1995 to 2020 are used to analyze the characteristics of the territorial spatial evolution characteristics of Lanzhou-Xining urban agglomeration by using the methods of land spatial transfer matrix， standard deviation ellipse， nuclear density analysis， comparative advantage index. The results show that： （1） The horizontal regional difference and vertical gradient differentiation of territorial space are obvious in the Lanzhou-Xining urban agglomeration. The ecological space occupied the absolute dominant position， and the production and living spaces are together in the medium altitude of Lanzhou-Xining urban agglomeration； （2） The territorial spatial conversion speed of Lanzhou-Xining urban agglomeration is accelerated， and the largest conversion proportion comes from the production space to living space， which indicates that the interaction between the two types of spaces is obvious. The downtown areas of Lanzhou and Xining， Lanzhou New Area and Linxia city are the conversion hotspot； （3） The production space and living space are distributed from northwest to southeast， and the ecological space is evenly distributed from east to west. The distribution patterns and expansion mode of production-living-ecological spaces are quite different. The shift distance of the gravity center of the living space is the largest， the production space is multi-core diffusion， and the fragmentation trend of the ecological space is enhanced. From the scale of towns， six types of optimal zoning of territorial space are identified， and zoning guidance strategies are proposed to promote the balanced and coordinated development of territorial space in Lanzhou-Xining urban agglomeration.
In this paper， the wind-sand environment wind tunnel simulation was used to measure the sand transport volume， wind-sand flow structure and particle size characteristics of the near-surface wind-sand flow in the gobi under different wind speeds and different gravel coverages. The variation law of gravel coverage on the bed surface under different wind speeds was analyzed to reveal the wind-sand movement on the gobi surface and its influence on the change of gravel coverage on the underlying surface. The results show that： （1） The bed gravel coverage is divided into low and high coverage with 12% as the boundary. Under low gravel coverage and high wind speed （18-24 m·s-1）， the surface sediment transport volume of gobi changes obviously with wind speed， and the inflection point of sediment transport curve appears as " elephant trunk " effect. With the increase of wind speed， the inflection point moves up， and the smaller the gravel coverage， the greater the curvature of sediment transport profile. Compared with high wind speed， the change of surface sediment transport volume of gobi under low wind speed （6-18 m·s-1） is not obvious， indicating that the change of sediment transport volume under low gravel coverage is mainly controlled by wind speed， and high gravel coverage has an inhibitory effect on wind sand flow. （2） With the increase of gravel coverage on the bed surface， the frequency distribution curve of sediment transport particle size has a downward trend. The gravel coverage has little effect on the frequency distribution of sediment transport particles， which shows a single peak distribution and only affects the mass percentage of the peak value of the curve. It shows that when the wind speed is constant， the particle size distribution of sediment transport particles in wind-blown sand flow is less affected by gravel coverage. （3） In the process of wind-sand movement， the gravel coverage of gobi bed increases linearly with the increase of wind speed， and there is a strong linear correlation between them. The variation of different coverage under high wind speed is greater than that under low wind speed.
Studying the spatial and temporal response characteristics of evapotranspiration to soil water content aids in comprehending regional hydrological cycle processes. The 8-day， monthly， and annual variation characteristics and corresponding relationship between evapotranspiration and soil water content in Qinghai Lake Basin were investigated from 2016 to 2020 by remote sensing data and spatial analysis， mathematical and statistical methods of ArcGIS， which would reveal the spatial and temporal response. The results indicated that： （1） From 2016 to 2020， the average evapotranspiration and soil water content in the Qinghai Lake Basin were 494.45 mm and 0.34 m3·m-3， respectively. The 8-day， monthly， and annual evapotranspiration showed an increasing-then-decreasing trend， while the soil water content showed the increasing-decreasing-increasing-decreasing， increase-steady-decrease and comparable stable characteristics. （2） The average evapotranspiration across all time scales generally decreased from the northeast to the southwest of Qinghai Lake Basin. Additionally， the average soil water content increased from the lakeshore to the perimeter of the watershed and from the valley to the sides. （3） There is a temporal synergism between evapotranspiration and soil water content during the 1st-185th days （January-June） and the 241st-365th days （September-December）， which is stronger than that during the 185th-241th days （July-August）. This synergism during the non-growing season is also stronger than the growing season， and stronger in 2016-2018 than in 2018-2020. Additionally， spatial synergies were found to be stronger in the northeast of Shaliu River Basin and Haergai River Basin and the eastern shore of Qinghai Lake than in other areas. （4） The correlation coefficients between evapotranspiration and soil water content were calculated at different temporal scales. The coefficients were 0.61， 0.69， 0.36 and 0.24 for the 8-day， monthly， non-growing season and growing season scales， respectively. The spatial result showed significant positive correlations， indicating that the temporal response of evapotranspiration to soil water content was stronger at the monthly and 8-day scales. In addition， the results showed that evapotranspiration increased with the increase of soil water content in different time. The results of this study can provide theoretical reference for understanding the hydrological cycle process， water balance and water resources management in Qinghai Lake Basin.
The relationship between biodiversity and ecosystem multifunctionality is the new hotpot of international ecological research. Ants are of the social insects that harbors the greatest number of individuals in terrestrial ecosystems， and have many ecosystem functionality. However， the ant diversity plays the basic roles in the maintenance of soil ecosystem function， but it is always neglected in ecological research on arid desert ecosystems. Focusing on the relationship between ant biodiversity and ecosystem multifunctionality in arid ecosystems， ant acts as “ecosystem engineering” that indicates significant effects on soil structure， soil physical-chemical properties， and soil nutrient and energy flow. Then， the interaction of ant and soil biota is observed to be the forcing drivers for the distribution of soil microbiology and soil arthropods. There is also a cascade relation of ants and soil arthropods that is one of the deterministic factors of soil food web. Nevertheless， the ant itself acted as the dominant taxa in soil ecosystems can play implications on soil functionality. In summary， ants acted as “ecosystem engineering” and played important role in soil physical-chemical properties and soil functions. There is a “bottom-up” effect and “top-down” effect of ants on soil biology. The trophic relations of ants to soil biology were the key point of the formation and maintenance of soil biodiversity， and were an important foundation of soil ecosystem functionality. In semiarid and arid regions， the nest-building activities of ants created anthills and had strong effects on soil conditions and soil biodiversity. The ant diversity and its effect on soil biodiversity played important implications on soil multifunctionality， which provided a key basis for ecological restoration of arid ecosystems， ecosystem services and its multiserviceability.
The vegetation optical depth （VOD）， as a crucial indicator reflecting surface biomass and vegetation water content， plays a vital role in accurately characterizing the changes in VOD under the context of large-scale vegetation restoration on the Loess Plateau. This is crucial for scientifically assessing the benefits of ecological engineering. This study， using X-band VODCA data， employs various methods including trend analysis， partial correlation analysis， and residual analysis to scrutinize the spatiotemporal variations of vegetation optical depth （VOD） on the Loess Plateau from 2003 to 2018. The research quantifies the respective contributions of climatic factors and human activities to the fluctuations in vegetation optical depth. The result indicates that： （1） The VOD on the Loess Plateau showed a significant increasing trend during the period of 2003-2018， with a growth rate of 0.28%/10a （P<0.01）. Moreover， the growth rate in autumn surpassed that in spring and summer， reaching 0.32% /10a （P<0.01）. （2） In terms of spatial distribution， there was a significantly increasing trend in VOD across 69.7% of the Loess Plateau， while the VOD decrease was observed in only 5.4% of the area， primarily concentrated in the northern part of Inner Mongolia and western Ordos. （3） In the Loess Plateau， the VOD showed a significant positive correlation with precipitation and solar radiation， mainly distributed in the western semi-arid grassland region. Conversely， negatively correlated regions were predominantly distributed in the gully areas in the southern part of Gansu Province. （4） Regression analysis reveals that the relative contributions of temperature， precipitation， radiation， and human activities to VOD are 45.74%， 2.09%， 38.20%， and 13.97%， respectively. Notably， the impact of human activities is progressively growing， encompassing 88.4% of the study area with an increasing trend. The comprehensive results of this study reveal the dynamic features of VOD changes on the Loess Plateau， offering a scientific basis for estimating vegetation carbon storage and supporting sustainable management in the context of ecological restoration on the Loess Plateau.
The Horqin Sandy Land is the largest semi-fixed sandy land in northern China. Tracing its material sources is of great importance to understand the formation and evolution of deserts and reconstruct the migration paths of fragments. Therefore， the composition of fine particles （<63 μm and <11 μm） of eolian sand in the Horqin Sandy Land was analyzed by petrology， elemental geochemistry， Sr-Nd isotope， TIMA automatic mineral identification and U-Pb dating of detrite zircon. The material composition of the Horqin Sandy Land was characterized and its provenance was quantitatively constrained. The geochemical indicators show that the Horqin Sandy land has experienced low chemical weathering and fractional recycling degree. The heavy mineral assemblages are mainly ilmenite， epidote， zircon， garnet， magnetite + hematite limonite， which together with the discriminant diagram of geochemical motherrock indicate that the sediments in the Horqin Sandy Land are mainly derived from medium acid magmatic mother rocks. Further constrained by Sr-Nd isotopes， the main source areas are the southern margin of the Central Asian orogenic belt and the northern margin of the North China Craton， and a small amount of dust originates from the northern border desert of China. The U-Pb ages of detrital zircons in sandy land are mainly from Mesozoic to Late Paleozoic （200-600 Ma） and Paleoproterozoic （1 518-2 000 Ma and 2 200-2 600 Ma）. The comparison with the zircon age spectrum of the potential source area shows that the fine particles in the Horqin Sandy Land contain both near-source material from the Greater Khingan Mountains in the southern margin of the Central Asian orogenic belt by wind and river transport， and ancient bedrock from the Yanshan Mountains in the northern margin of the North China Craton by river transport. Quantitative provenance results of inverse Monte Carlo model show that the Central Asian orogenic belt contributes 53.7% and the North China Craton contributes 46.3%. The synergistic effect of wind and river explains the formation of fine particles of wind-sand in the Horqin Sandy Land.
The management of soil salinization along the Yellow River section of Ulan Buh Desert is of great significance to guarantee the ecological security of the Yellow River Basin and realize high-quality development. Based on the traditional and geostatistical analysis methods， this paper analyzed the spatial differentiation characteristics of soil water and salinity， as well as the causes of soil salinization along the Yellow River section of Ulan Buh Desert based on the results of soil water and salinity surveys at 45 sampling sites along the Yellow River section of Ulan Buh Desert. The results showed that the soil water salt content along the Yellow River section of Ulan Buh Desert showed a trend of increasing gradually from west to east and from south to north， with non-saline soils accounting for 41.37% of the total area of the area， lightly， moderately， and severely saline soils accounting for 34.11%， 10.56%， and 8.74% of the total area of the area， respectively. Extremely saline soils appeared near Bayanmuren Sumu， which accounted for 5.22% of the total area of the area. Saline soils were dominated by sulfate saline soils （46.67%） and chloride saline soils （53.33%）. Soil texture had the most significant effects on soil salinity， followed by soil total carbon content and water content. Climatic drought， sparse precipitation， Yellow River diversion for irrigation and groundwater table elevation were the main reasons of soil salinization along the Yellow River section of the Ulaanbuhe Desert.
Dryland area is substantial， and the drylands exhibit great sensitivity to global climate change. Nitrogen， which composed of various nitrogen forms， is generally considered the second most limiting resource in desert ecosystems. However， it remains unclear how different levels of aridity affect the spatial distribution of soil nitrogen. Based on data of inorganic nitrogen， organic nitrogen， and total nitrogen from 54 sampling points in the northwest desert region of China， and coupled with climate and environmental data， we explored the spatial variations in nitrogen components under different levels of aridity and the driving factors. Our results indicated a distinct aridity threshold （0.87） for the spatial variations in soil nitrogen along the aridity gradient， meaning an abrupt change in response to aridity. Near the threshold， soil total nitrogen， organic nitrogen content， and the ratio of organic to inorganic nitrogen exhibited rapid increases， while nitrate nitrogen content showed a rapid decrease. Before and after the aridity threshold， both total nitrogen and organic nitrogen content significantly decreased with increasing aridity. In the 0-10 cm soil layer， soil total nitrogen and organic nitrogen content gradually increased with soil depth. The increase in aridity directly or indirectly affected the spatial variation oin nitrogen components through soil water content （SWC）， electrical conductivity （EC）， and pH. The study revealed the impacts of aridity on soil nitrogen balance， which are beneficial for prediction on the response of soil nutrients to environmental changes in drylands， and provide crucial support for making scientifically effective environmental decisions.
The C exchange processes dominated by biological crusts， an important surface cover in arid desert soil， at the background of the intensified climatic change is of vital importance to access C balance at the regional and even global scale. Despite how desert crustal C exchange responds to climatic change have received many attentions， the effects of warming and changes of precipitation as well as their interactions remain unclear. To evaluate the extent of C exchange of desert crustal soils in response to climatic change， two typical types of crustal （moss- and algal- dominated crusts） soils in the southeastern edge of the Tengger Desert were selected， and their gross primary productivity （GPP）， ecosystem respiration （ER） and net ecosystem exchange （NEE） were monitored in field with stimulated warming and five precipitation gradients （2， 5， 8， 13， and 20 mm）.The results showed that： （1） warming only significantly affected daily NEE of moss-dominated crustal soil， precipitation significantly affected daily GPP， ER and NEE of moss- and algal-dominated crustal soil， and there was no interactions between warming and precipitation. （2） Across the five precipitation gradients， warming averagely reduced 20.8% of accumulative GPP and increased 9.9% of accumulative ER， leading to an increase in accumulative NEE by 102% on average for moss-dominated crustal soil. However， warming averagely enhanced 264% of accumulative GPP and increased 24.2% of accumulative ER， with a neutral effects on NEE for algal-dominated crustal soil. （3）ER and NEE of moss-dominated crustal soil were positively and negatively correlated to air temperature and soil moisture， respectively， while NEE of algal-dominated crustal soil was not associated with air temperature and soil moisture under warming. These results suggest climatic change might stimulate C immobilization of moss-dominated crustal soil， while its effects on algal-dominated crustal soil were negligible in the desert region. Accordingly， the distinct responses of C exchange for different crustal soils to climatic warming and precipitation should be taken in consideration when we predict the balance of carbon budget in desert ecosystems.
Aeolian sand activities threaten highway safety operation in Wuhai-Maqen Highway （G1816） in Tengger Desert. The characteristics of wind conditions， grain size and near-surface（0-2 m）horizontal dust flux in typical section of protection system were investigated. The results show that the average annual wind speed is 3.13 m·s-1， the average annual sand driving wind speed is 7.66 m·s-1， the frequency of sand driving wind is 17.6%， and the direction of sand driving wind is mainly W-NNW， E and S. The annual sand drift potential is 187.57 VU， the resultant sand drift potential is 78.6 VU， the direction of resultant sand drift potential is 135°， and the RDP/DP is 0.419， which belongs to the low wind energy environment and blunt bimodal wind condition with moderate wind direction variability. The spatial difference of horizontal sand and dust flux in the protection system is significant， and the horizontal sand and dust flux decreased by 99% from moving dune observation point to straw checkerboard barriers observation point near the road upwind， and it also decreased by 93.6% from moving dune observation point to checkerboard barriers observation point near road downwind. The surface sediment in the protection system is mainly consist of medium sand and fine sand， and the particle size of sand and dust at different heights gradually becomes finer from the outside to the inside of the protection system.
Compared to traditional Salixpsammophila sand barriers which should be manually inserted one by one， brush shaped S.psammophila sand barriers use mechanical weaving to form bottle brush barriers， which have a shape similar to horse resistance. This kind of barriers are easy to construct and have good stability after setup. Wind tunnel experiments were conducted to study sand fixation function of a brush shaped sand barrier made from S.psammophila branches. The results show that： （1） The wind speed slightly decreases in front of the first row of barrier， and increases significantly at position of the first， the second and the forth row of barrier. After pass through each row barriers， wind speed reduced greatly and formed deceleration zone. （2） The sand surface directly below the barrier often exhibits erosion effect. The erosion phenomenon is the most severe right under the first row barrier， and excavation occurs with time lapse. Between the sand barriers， the sand surface showed a state of accumulation， the first checkerboard accumulated the most severe， followed by a decrease in the degree of accumulation. （3） After setting up the barrier， the structure of the wind-sand flow exhibits a complex exponential decline curve. The sediment collection at wind speeds of 8 m·s-1， 12 m·s-1， 16 m·s-1， and 20 m·s-1 decreased by 86.8%， 81.6%， 53.4%， and 67.8%， respectively. This indicates that the brush shaped sand barrier has good sand fixation performance. Due to the disturbance of barriers， sand material drifts upwards， resulting in an increase in the amount of sand collected at the sand inlet above a height of 10-14 cm.
Morphological evolution features can reflect the adaptive strategy of plants to environmental changes. To understand the morphological variations of mosses in adapting to arid sandy area environment， we select three moss species （Bryum argenteum，Didymodon vinealis and Syntrichia caninervis） in the artificial stabilized sand vegetation area on the southestern edge of the Tengger Desert. Using the method of “space replacing time”， we analyzed the morphological and quantitative characteristics of mosses at for levels： leaf， individual， population， and community， in different vegetation age zones （35， 41 and 66 years）. The result revealed certain differences in the morphological traits of the three moss species at the study levels as the vegetation age increased. Specifically， D. vinealis exhibiteda continuous decrease in leaf area， awns， and plant height， while S. caninervis and B. argenteum showed non-continuous variations. The patterns of variation may be to resource competition within and between species. Nevertheless， considering the overall morphological traits， mosses in the artificially stabilized sand vegetation area of the Tengger Desert generally undergo an evolutionary trend from smaller stem-leaf shoots with higher density to larger stem-leaf shoots with low density during the process of ecosystem restoration. This study provides insights into the morphological adaptation strategies of mosses during ecosystem restoration and serves as a scientific basis for species selection of mosses in ecosystem restoration.
Helan Mountain is the boundary between deserts and desert grasslands in China. Desert grasslands are distributed on the alluvial fan at its eastern foot， playing a positive role in maintaining ecosystem stability. Research is conducted on the spatiotemporal changes in fraction vegetation coverage （FVC）， and the main factors affecting vegetation coverage changes are analyzed. This study utilized Landsat satellite remote sensing data and inverted the vegetation coverage of desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains from 2001 to 2020 based on a pixel binary model. The spatial pattern and spatiotemporal variation characteristics were analyzed， and the driving factors were analyzed using Sen+Mann Kendall trend analysis， Hurst index， and parameter optimal geographic detector model. The results indicate that： （1） FVC shows a trend of "higher in the northwest and lower in the southeast" in space， mainly characterized by extremely low vegetation coverage and low vegetation coverage. The average annual FVC is 33.38%， and the overall vegetation coverage is at a relatively low level. （2） From 2001 to 2020， FVC showed a significant increase trend （P<0.01）， with an average annual growth rate of 0.25%. Overall， the northwest and southeast showed an improvement trend， with the improved area accounting for 93.24% of the total vegetation coverage area； The average coefficient of variation of vegetation coverage is 0.394， which is relatively stable overall. The eastern and central regions show the most drastic changes in space， with significant spatial differences. （3） The anti sustainability of vegetation coverage in the study area is strong， with an average Hurst index of 0.495， and 44.77% of the areas are greater than 0.5； From a spatial distribution perspective， the Hurst index is higher in the southern and western parts of the study area， indicating a higher sustainability of vegetation change， while the Hurst index is lower in the eastern and northern parts， indicating a lower sustainability of vegetation change. （4） The annual precipitation and land use type are the main factors affecting the spatial distribution of vegetation coverage in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountain. The interaction detection table shows that the impact of next year's precipitation on vegetation coverage is enhanced after the superposition of other factors， while the impact of topography and slope orientation on vegetation coverage is significantly enhanced； Risk detection indicates that each driving factor has an appropriate range of impacts on vegetation growth in the study area. This study helps to reveal the driving mechanisms of different factors on vegetation changes in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains.
Establishing a reasonable assessment system for ecological environment vulnerability is very important to the high-quality development of ecological environments. This work collects Landsat 5/9 image， topography， soil， meteorological and socioeconomic data to assess ecological vulnerability by the CRITIC objective weighting method， then investigates spatiotemporal changes and its influence factors using transition matrix method and obstacle degree model in Tianshui city with a key position in water source conservation， soil and water conservation， and ecological security barriers. The result shows that the ecological vulnerability in Tianshui city presented a pattern of high in the north and low in the south， and generally decreased during 2000-2022. Except for Wushan and north-central part of Gangu with no change of extremely vulnerable areas， most area in Tianshui city had been transformed from extremely vulnerable areas to severely or moderately vulnerable areas. However， some areas surrounding the urban districts had been changed from moderately vulnerable areas to severely or extremely vulnerable areas due to urbanization. In 2022， bare soil， land use types， and precipitation are dominated factors for decreasing of extremely vulnerable areas. In order to effectively reduce the areas of extremely vulnerable areas in Tianshui city， the capabilities of planting tree and grass， artificial weather modification， and irrigation capacity should be improved continuously in line with the local conditions in future.
