On the basis of field survey， Ground-penetrating radar （GPR） was used to detect the internal structure of vegetation linear dunes in the southeastern Gurbantunggut Desert， and radar facies image information was obtained. Combined with regional natural geography and morphological characteristics， the evolution model of vegetation linear dunes internal structure was preliminarily discussed. The results indicate that： （1） GPR reveals the shallow （3-5 m） structure information below the dune surface， which can identify high-angle dipping， convex and wedge cross-bedding in the middle-upper part of dunes and crest， and sub-horizontal to low-angle dipping bedding in interdunes and the middle-lower part of dunes， which reflects the strong wind erosion and deposition activity in the upper part of dune， and the accretion in the middle-lower parts of dune wings and interdunes. （2） From desert edge to the center， the shallow sedimentary structure assemblage of dune slope changes from asymmetrical to symmetrical， the dune cross-section morphology showed the same variation， but no evidence of lateral dune migration have been found. （3） According to different scale dune structure sequence， the evolution mode could be divided into four stages： shrub dunes， shadow shrub dunes， longitudinal dune chains and vegetation linear dunes. With the continuous merging and integration of overlapping shrub dunes， the width and height of linear dunes increase， frequent wind activity at the dune crest， and the types of high-angle dipping， convex and wedge cross-bedding increase. （4） The causes of massive bedding （below 3-5 m， not hit the bottom） and GPR signal attenuation should be further verified. Besides， to systematic clarify the evolution process of vegetation linear dunes in study area， it is necessary to supplement more GPR data and chronology study.

The operational agricultural drought monitoring system is a powerful tool for monitoring and predicting agricultural drought， as well as agricultural risk assessment and prevention. In order to better promote the development of the operationalization of agricultural drought monitoring， we systematically reviewed four types of commonly used drought indices based on meteorological variables， soil moisture， vegetation status and multivariate， and analyzed the characteristics of operational agricultural drought monitoring systems in the United States， China， Europe and the United Nations Food and Agriculture Organization， etc. in detail， and discussed the problems existing in operational agricultural drought monitoring systems. For example， the quality and fusion of data are unstable， the construction of the comprehensive drought index is uncertain， the temporal resolution of monitoring needs to be improved， and the hydrological conditions and the growth process of crops are not considered. Looking forward to the future， the operational agricultural drought monitoring system should develop further from using multi-source data to monitor drought， considering regional spatial and temporal differences and the accumulation and lag between different indicators when constructing comprehensive indicators， strengthening the role of machine and deep learning in the construction of comprehensive indices， developing daily time-scale monitoring of drought to deal with the occurrence of flash drought events， strengthening the role of crop growth process models and advanced technical means in drought monitoring.

Plant diversity is the basis for ecosystem structure and function， and climate change has had a profound impact on it， even a serious threat. The decrease or loss of plant diversity necessarily affects the stability of ecosystem structure and function， lead to serious ecological， economic and social consequences. Studies have shown that the response of plant diversity to climate change is controlled by the dynamic balance of temperature and water. This research systematically introduced the effects of climate warming and precipitation pattern change on plant diversity. In this report， the impacts of climate change on plant diversity in different ecosystems， community types and scales （global， regional and local scale） are analyzed and the main factors that influence the difference were summarized. We also propose research hotspots and directions for future plant diversity research in different environmental conditions.

Grain size analysis is one of the main methods to study the process of aeolian sand landform. The analysis of sand dune grain size characteristics can not only reflect the source and power of sand dunes， but also reflect the changes of the terrain to the movement of the sand flow. This paper analyzes the grain size characteristics of the surface sediments of the mobile dunes in different geomorphological positions in the Pengqu Basin of Tibet. The results show that： （1） Surface sediments on mobile dunes in Pengqu basin are mainly divided into medium sand （46.51%） and fine sand （40.52%）， followed by coarse sand （5.87%） and very fine sand （5.87%）， and the content of clay （0.37%） and silt sand is the least （0.85%） . The average grain of surface sediments on mobile dunes is in the range of 1.41-2.32 Φ， and the skewness is in the range of 0.01-0.24 . In general， the kurtosis range is 0.98-1.80， and the sorting coefficient is in the range of 0.45-0.79 Φ. （2） The grain size composition of different geomorphic units （river floodplain-river terrace-hillside） gradually becomes finer； the frequency distribution curve gradually becomes higher and steeper， and the probability accumulation curves from southwest to northeast along the dominant wind direction change from two-stage to one-stage， the slope gradually increases， and the sortability gradually becomes better. （3） The surface sediments of the flowing sand dunes from the floodplain to the high-level terraces of the river become finer with increasing altitude， and the particle size from the slope to the top of the slope becomes coarser with the increase in altitude， but the sorting becomes better， indicating the sand materials of the sand dunes on the hillside and the sand dunes on the terrace come from different river sections of riverbed or floodplain. The research results can provide a scientific basis for the prevention and control of desertification in different areas in the study area.

In arid and semi aird region of China, precipitation between irrigation plantation region and non-irrigation plantation region is 150-200mm in the monsoon climatic region and 100-150mm in the Mediterranean climatic region. In the area where precipiation is less than their limit precipitation, non-irrigation plantation should be carried out; where the groundwater table is lower than 4-6m it suits to plant trees and lower than 5-10m for xeric shrubs(dwarf trees). Mineral content of groundwater is less than 3g/l. for salt-avoiding trees and 3-8g/l. for salt-avoiding shrubs.

The problem of land desertification in northwest region of China is serious and the ecological environment is severe. It is of great significance to clarify the spatio-temporal variation characteristics and driving factors of vegetation cover in this area for ecological environment protection. In this study， MOD13A3 products in this area were used as the data source to obtain the NDVI sequence set from 2000 to 2019 through the maximum value synthesis method. Trend analysis， anomaly analysis， Hurst index， geographic detector， correlation analysis and residue analysis were used to analyze the spatiotemporal variation characteristics and impact factors of vegetation cover in the study area. The results showed that ：（1） In recent 20 years， the vegetation coverage in the study area showed an overall growth trend， with an increase rate of 0.0027·a^-1 and an average NDVI of 0.252. However， the growth rate of the Yellow River basin area （0.0062·a^-1） is higher than that of the semi-arid grassland area （0.0026·a^-1） and inland arid area （0.0018·a^-1）. （2） The vegetation coverage in the study area is on the rise， accounting for 55.77% of the total area， while the degraded area accounts for 3.76% of the total area. The increased land use types were mainly tillage， forest and grassland. The area with sustainable change trend of vegetation cover accounted for 31.87% of the total area， the sustainable improvement （17.04%） was greater than the sustainable degradation （1.27%）， and the growth and sustainable growth of the Yellow River basin area were the best. （3） The main contributing factors that affect the spatial distribution of vegetation cover are precipitation， temperature， sunshine and relative humidity in order of influence， but the influence degree of each sub-region is slightly different. The spatial distribution of arid areas in the Yellow River basin and inland is most affected by precipitation， and the semi-arid grassland is most affected by sunshine. （4） Vegetation cover changes is mainly driven by natural factors and human activities， and natural factors on the growth of vegetation role in promoting are greater than human activity， and natural factors on vegetation cover change in the rate of contribution are higher. The results of this study can provide reference for assessing the ecological environment change under the background of climate change in northwest China.

As a very serious problem to China, desertification distributes widely, occupies a very large area, and earns a high, serious level of hazard. During the past decades, a certain amount of achievements had been obtained in desertification control, but the desertified land was still restored in some local regions, and meanwhile, desertification has been expanding rapidly as a whole and the trend seems worsening. Now desertification control is facing severe situations in China. Drought is the basic background condition for development of desertification, while unreasonable human activities resulting from fast increasing of population and backward mode of production and management, such as over-reclamation, over-grazing, unrestricted cutting, squandered water resources and indiscriminate mining, are the main causes of rapid wide-spreading of present desertification in China. Desertified land should be tackled in a comprehensive way that combines prevention, amelioration and exploitation. And what's more, in order to speed up desertification control, the government should formulate a preferential policy for desertification areas.

We collected and measured aeolian sand samples from the Mu Us Sandy Land and the Hobq Sand Sea of northern China. The data of grain sizes show that aeolian sands in the eastern and western Mu Us Sandy Land are quite different. The aeolian sands in the western Mu Us Sandy Land are much finer and better sorted compared with those in the eastern Mu Us Sandy Land. Aeolian sands in the Hobq Sand Sea show similar grain size characteristics to those of the western Mu Us Sandy Land. We conclude that the initial grain sizes of source materials could be the main factors for the regional variations across these aeolian environments. Local detritus act as an important provenance for aoelian sands of Mu Us Sandy Land and Hobq Sand Sea， and its contribution varies regionally. Influenced by complicated provenances and mixed transportation by winds and rivers， the values of mean grain size （M_z） and sorting coefficient （σ） do not show obviously spatial variations which would be associated with the prevailing wind directions in the study areas.

The Yellow River Basin is an important part of ecological security strategy in China， and it is a sensitive area of climate change and a vulnerable area of ecological environment. This paper mainly analyzes and reviews the latest research progress on the characteristics， impacts， causes and countermeasures of climate change in the Yellow River Basin： （1） In recent 60 years， the temperature shows an upward trend， with an average warming rate of 0.30 ℃ per decade， and the trend of temperature rise is the most significant in winter and the smallest in summer. The precipitation in the upstream increased， while that in the middle-stream and lower-stream decreased significantly. （2） In recent years， under the joint influence of climate change and human activities， a series of problems have appeared in the Yellow River Basin， such as the reduction of runoff， the degradation of glaciers and frozen soil， the improvement of vegetation coverage， the increase of soil erosion in the ecological fragile areas of upstream and sand-producing areas of the middle-stream. The impact of climatic change on the crops is not only of advantageous aspects but also of disadvantageous， and the pets and diseases increase. The climate warming and the increase of extreme events have brought great challenges to the safe preservation of cultural heritage. （3） The evolution process of climate system in the Yellow River Basin is not only affected by its own internal power and heat， but also by external forcing factors such as atmospheric circulation， sea surface temperature and Qinghai Tibet Plateau. The change of atmospheric composition and land use/cover caused by human activities is an important factor affecting the local climate. （4） In the future， the temperature will still show an upward trend， the precipitation fluctuation will increase， and extreme weather events will occur more frequently in the Yellow River Basin. It is necessary and urgent to take adaptive measures to deal with climate change. These measures mainly include strengthening the scientific research on the impact of climate change and extreme events， improving the ability of forecasting and early warning of extreme weather events， establishing a disaster forecasting and early warning system integrating meteorology， hydrology， ecology， numerical prediction， prevention and control， strengthening the management， allocation and effective utilization of water resources， strengthening the protection of ecological environment， formulating scientific and reasonable agricultural development strategy， and promoting the high-quality development of the Yellow River Basin.

Non-structural carbohydrates （NSC） played a fundamental role in plant growth， reproduction， defense and survival. To explore the effects of N and P addition on NSC of Lycium ruthenicum，a field manipulation experiment combined three nutrient supply levels （Low， Medium， High） and three N：P supply ratios （5∶1， 15∶1， 45∶1） was conducted on three-year-old L. ruthenicum. The results indicated that： （1） Soluble sugar was the major contributor to the total NSC in different organs， starch accounts for about 37.3%. On average， the concentrations of NSC in different organs followed the order of： coarse roots & fine roots>leaves>current-year>one-year& two-year branches. The concentrations of soluble sugar， starch and the ratio of soluble sugar to starch followed the order of coarse roots & fine roots>leaves>current-year branches>one-year branches>two-year branches； fine roots>coarse roots>two-year branches>one-year branches>leaves & current-year branches； leaves>current-year branches>coarse>one-year branches>two-year branches>fine roots respectively. （2） Changes in soluble sugar，starch and NSC concentrations in different organs of L. ruthenicum. reflected significant interactions between N∶P supply ratios and supply levels. When the N∶P supply ratios was 5∶1， the NSC concentrations of leaves and branches was higher under high supply level， when the N∶P was 15∶1， the NSC and its components concentrations of leaves，current-year and one-year branches in the low supply level is significantly higher than the high supply level， when the N∶P was 45∶1， the NSC concentrations of leaves，one-year and two-year branches in high level of supply is significantly higher than low supply level. N∶P supply ratios and supply level had no significant effect on root soluble sugar concentrations. （3） The NSC concentrations of one-year branches reached the maximum value （5.05% DW） before germination and dropped to the lowest value （3.79% DW） during the shoot growth period； NSC concentrations of two-year branches decreased before germination （4.23% DW） and reached the maximum value in the foliage period （4.33% DW）. （4） The NSC concentrations of coarse roots was negatively correlated with NSC concentrations of leaves、one and two-year branches； NSC concentrations of current-year branches was positively correlated with NSC concentrations of leaves and starch content of two-year branches； soluble sugar concentrations of one-year branches was negatively correlated with that of two-year branches； starch concentrations of two-year branches was negatively correlated with starch and NSC concentrations of coarse roots.When compared the impact of N and P addition on NSC concentrations of vegetative organs of L. ruthenicum， the results showed obvious organ difference adapted to N and P supply condition by adjusting accumulate and distribute NSC in different organs. Choosing to store more NSC in root system can enhance carbon balance and survivability in a nutrient-restricted environment， and also provide greater flexibility for the interaction with the non-biological environment.

Google Earth engine （GEE） is the most advanced platform for analysis and visualization of geographic big data， which makes remote sensing monitoring surface vegetation break through the limitations of data acquisition， local storage and low processing efficiency. Based on GEE cloud platform to calculate the NDVI of Landsat series satellite images， this paper studied the spatial and temporal variation of NDVI in Minqin oasis from 1987 to 2019， analyzed and predicted the variation trend of NDVI in Minqin oasis through unvariable linear trend analysis， stability analysis and Hurst index. The results shows that： （1） From 1987 to 2019， the annual average NDVI value of Minqin Oasis increased from 0.172 to 0.230 at the speed of 4.6%?（10a）^-1， and the multi-year average value was 0.244， showing an upward trend in 1989-2007 and 2010-2016， and a downward trend in 1987-1989， 2007-2010 and 2016-2019. During the year， NDVI ranged from -0.017 to 0.333， and the highest value was from April to October every year. In terms of spatial changes， NDVI in the periphery of the oasis has increased obviously， and the oasis has expanded to desert. （2） From 1987 to 2019， most areas of NDVI in Minqin Oasis remained basically unchanged. The periphery of the oasis in dam region and Quanshan region， the south of the lake region and Qingtu Lake showed an increasing trend. The urban area of Minqin County in the middle of the dam region and the edge of the oasis in the north of the lake region showed a decreasing trend. Basically unchanged， increasing and decreasing areas account for 81.90%， 16.25% and 1.85% of the total area respectively. （3） From 1987 to 2019， the areas with high NDVI change stability in Minqin oasis are mainly located in the southeast of the dam region， the east of Quanshan region and the north of the lake region； the regions with high volatility are mainly located in the periphery of the oasis in dam region and Quanshan region， the south of the lake region and Qingtu lake. （4） Hurst index shows that the trend of NDVI change in most areas of Minqin Oasis remains unchanged in the future. In the periphery of the oasis in the dam region and Quanshan region， in the north of the lake region and in Qingtu Lake， NDVI is likely to increase. In the middle of minqin County and the north of the lake region， NDVI is likely to decrease. The areas of NDVI basically unchanged， increased and decreased accounted for 71.62%， 12.96% and 15.42%， respectively.

The 10 years period of “Culture Revolution” from 1966 to 1976 had hindered the practice on prevention and control of aeolian desertification and the development of desert science to a certain degree. Nonetheless， relied on the foundation laid over the past decade， the science， technology and engineering teams from all levels of national to provincial and local carried on with scientific research， technological development and engineering implementation， field long-term observations and experiments， laboratory sample analysis and data statistics， blowing sand wind tunnel experiment， summary of results and writing of papers and monographs， etc. These efforts had obtained a batch of achievements， in which some of typical progress can be expressed as follows. （1） The construction and application of blowing sand wind tunnel created the pioneering work of wind tunnel experiment for prevention and control of aeolian desertification and research on law of wind-blown sand movement in China. （2） Some new results have been made in process and prevention of wind-sand disaster to the desert railway by systematically conducted on engineering technology experiments and theoretical research. （3） The work exchange meeting on desert control research of Chinese Academy of Sciences had successfully held in Lanzhou in March of 1975， which timely concluded and presented the theoretical and practical achievements and levels. （4） Systematically summarized the results of scientific investigations， observations， experiments， research， and practice， so that many scientific papers have been published as well as a series of monographs compiled and edited. There were some encouraged results of exploration and innovation on the distribution and general characteristics of deserts， causes of desert formation， source of sand material rising right on the spot， feature of wind-blown sand movement， formation and evolution mechanism of sand dunes in China and the development of aeolian geomorphology， morphological characteristics and movement patterns of sand dunes， regionalization of aeolian geomorphology and several landform issues for preventing blown sand disaster in the Taklamakan Desert. Other system summary results also delivered such as the management of farmland wind-blown sand disaster， railway's prevention and control of wind-blown sand damage， desert railway engineering construction as well as the successful experiences and effective measures from the Xinjiang， Gansu and Inner Mongolia Autonomous Region. All of the achievements and progress promoted the theoretical exploration and systematic composition of desert science in China.

The arid and semi-arid regions cover more than half of China's land area， which are sensitive to global climate change and human activities with fragile ecological environment. Extreme climate events are frequent and strong in those regions， where the climate anomalies are not only modulated by the internal atmospheric variability， but also affected by the underlying surfaces such as sea surface temperature， sea ice and snow cover. These physical factors play a key role in the climate anomalies in arid and semi-arid regions. This article systematically reviews and sorts out the effects of these physical factors on climate anomalies in arid and semi-arid regions of China. Studies have shown that atmospheric teleconnection is an internal influencing factor of climate anomalies， and the circulation anomalies caused by its phase transition will cause climate anomalies in arid and semi-arid regions by regulating the position of jet stream， planetary wave activity， blocking intensity， and the location of trough-ridge. Sea surface temperature affects the climate anomalies in arid and semi-arid regions by influencing the intensity of monsoon and Walker circulation and the location of western Pacific subtropical high， in the meantime stimulating the response of atmospheric Rossby waves. Moreover， snow cover changes the thermal conditions of the underlying surfaces such as surface radiation and soil temperature and humidity through the albedo effect and hydrological effect， and then has a significant effect on the temperature and precipitation in arid and semi-arid regions by diabatic heating or changing atmospheric baroclinicity. On the basis of summarizing the existing research progresses and achievements， the paper points out that the synergistic mechanism among different factors and the contribution of each factor to the climate anomalies in the arid and semi-arid regions of China still need further research.

Soil moisture regulates the landing-surface-atmosphere interaction process， which is an important factor affecting the exchange of water and energy in the soil-plant-atmosphere continuum. Soil moisture is also a key factor affecting the hydrological， biological and biochemical processes of ecosystems and is an indispensable component of terrestrial ecosystems. This paper briefly reviews the monitoring at point and surface scale and analysis methods about soil moisture， systematically described the research progress of soil moisture in arid and semi-arid region， and put forward the prospect of soil moisture research based on the present research progress in arid and semi-arid region. All this is in order to promote in-depth understanding and accurately predict the ecological and hydrological effects of soil moisture changes in arid and semi-arid areas， and lay a theoretical foundation for the formulation of scientific and reasonable water resources management scheme in arid and semi-arid areas.

Biological soil crusts （BSCs） is a complex of microorganism， cyanobacteria， lichen and moss that occur on or within top few centimeters of the soil surface. BSCs usually distributes in the dryland regions， and is an organizing principle in drylands. As the pioneers occurred in the desert ecosystems， BSCs can improve the stability of sand surface， fix carbon and nitrogen， increase soil fertility， and maintain soil moisture. In addition， BSCs plays a crucial role in the restoration of degraded soil surface. This article introduced the biological mechanism to fix sand through the ecological relationships between species replacements and the changes in ways of sand grain binding. The local dominant species （such as Microcoleus vaginatus， Syntichia caninevis and Bryum argenteum） in the field are recommended for the BSCs rehabilitation. Mass cultivation can be attained via the steps from species isolation in the laboratory to factory production in greenhouse， thus proving abundant inoculum for field growth. We also explored the species composition， physical and chemical assistance models during the field inoculation， and suggested that we need assess the growth according to surface stability， soil nutrient and species diversity of artificial BSCs. Last， we introduced the developments in sand fixation though artificial BSCs in China， and the experiences and challenges of BSCs rehabilitation. Our reviews suggest that artificial BSCs rehabilitation is a prospecting option for the ecological restoration.

Through investigating and analyzing the effects of overgrazing on the community type, coverage, biomass of pasture vegetation and characteristics of soil, it is showed that overgrazing leads to some very serious environmental problems, which in return exerts adverse effects on animal husbandry. Overgrazing causes grassland deterioration and soil erosion, especially in spring, the damage of overgrazing is the most serious. The changeability and easy to deterioration of pasture ecosystem determine that grazing leads to a series of problems, even causes some serious problems such as salinization or alkalinization, hungriness and drying in deep soil. This paper points out that content of saline-alkaline in soil, vegetation coverage, moisture in deep soil, humidity of subaerial air and its content of atomy should be monitored, which are the bases to establish some rational developmental plans and supervisory measures, it is very necessary for ecological and environmental improvement and long-range development of animal husbandry.

The succession of sand-binding forest impacts the construction effect of sand fixation forest. With the method of substituting time with space, the artificial sand-binding forests afforested for 5, 15 and 25 years at the southern edge of Tengger Desert were selected as a success stage series, and the adjacent mobile sand dune and native vegetation habitat were took as the reference sites to reveal the ecological mechanism of the succession of artificial sand-binding forests from the aspects of ecological hydrology, soil seed bank and soil-vegetation corresponding relationship, which provided theoretical basis for the construction, protection and restoration of regional artificial sand-binding vegetation. The results showed that during the successional process of artificial sand-binding forest of Hedysarum scoparium in the southern edge of Tengger Desert, the artificial population of H. scoparium, pioneer plants Agriophyllum squarrosum and Artemisia sphaerocephala declined gradually, and the natural dominant species changed from annual herbs to semi shrubs, then to semi shrubs and perennial herbs. After 25 years, a relatively stable near natural sand-binding vegetation similar to the zonal vegetation up to 50% was formed, which showed a trend of grassland desertification succession. During the successional process of artificial sand-binding forest, the topsoil water holding capacity increased continually, reaching 3.4 times of that of the mobile sand dunes after 25 years, which resulted in the shallow distribution of soil moisture and the drought of the deep soil, driving the decline of the deep root plants and the development of the shallow root herbs. A. squarrosum and A. sphaerocephala in the soil seed bank decreased rapidly and disappeared after 25 years; A. ordosica continued to increase and Stipa breviflora appeared after 25 years, which was more than 50% similar to the aboveground vegetation composition, driving the artificial sand-binding forest to A. ordosica vegetation with perennial herbs. With the succession of artificial sand-binding forest, soil bulk density continued to decrease, clay, silt, organic matter and total nitrogen continued to increase, which was closely related to the community and species composition of artificial sand-binding forest, and determined the succession stage and species composition of sand-binding forest. Obviously, sand fixation and afforestation is a necessary measure for ecological restoration of the desertified land in arid areas, which starts and accelerates the restoration and succession of natural vegetation. However, the zonal vegetation and soil habitat conditions should be fully considered in sand fixation and afforestation, so as to establish stable near natural vegetation quickly.

Sabina vulgaris is the dominant sand-binding shrub species in the Mu Us Sandy Land. The widely distributed biological soil crusts （BSCs） in Sabina vulgaris community are of great significance to maintain the stability of desert ecosystem. Bacteria are an important part and play important roles in maintaining the structure and function of BSCs. However， the changes of diversity and composition of the bacterial communities with the development of BSCs are not fully understood. In this study， Illumina sequencing was used to analyze bacterial communities’ diversity and composition of four different developmental stages of BSCs （microbial， algae， lichen and moss crusts） and bare sand in Sabina vulgaris community in the Mu Us Sandy Land， and to explore the main environmental factors influencing bacterial community structure. Results showed that in the Mu Us Sandy Land， the diversity of bacterial communities significantly increased with the development of BSCs （P<0.05）， and reached the highest value in the moss crusts. Bacterial communities of BSCs were dominated by the phyla of Proteobacteria， Actinobacteria， Cyanobacteria and Acidobacteria， as their relative abundance accounted for more than 78% of the total bacterial abundance in different developmental stages of BSCs. Bacterial community compositions significantly changed with the development of BSCs. In particular， the relative abundance of Proteobacteria and Firmicutes， which belonged to the oligotrophic bacteria in stress resistance， significantly decreased from bare sand to moss crusts， whereas the relative abundance of Actinobacteria， Acidobacteria， Bacteroidetes and Chloroflexi， which belonged to the eutrophic bacteria， significantly increased. The relative abundance of Cyanobacteria in algae crusts was significantly higher than that in other developmental stages （P<0.05）. The change of bacterial community composition indicated that the community ecological function changed with the development of BSCs， from increasing the stability of soil surface by promoting soil particle cementation to promoting the material circulation of the ecosystem by promoting carbon and nitrogen fixation and litter decomposition. Bacterial communities were sensitive indicators of soil water and nutrient changes during the development of BSCs. Mantel test showed that the bacterial community structure in BSCs was affected by soil water content， total carbon， organic carbon， total nitrogen， nitrate nitrogen and total phosphorus content.

Desert pavement is a surface layer with closely packed gravel that insets in a thin fine-grained vesicular soil horizon， and is important for the stability of the desert ecosystem. Based on the data of the field investigation and situ soil water infiltration in the northern desert of Linze Oasis in the Hexi Corridor， the characteristics of desert pavement and its influence on water infiltration are analyzed in this study. The results show that： （1） desert pavement is 0.50 cm thick with 4.61 mm size gravel， and its surface gravel coverage average 52.7%. （2） Compared to the soil profile below the desert clast， the mass water content of pavement is lower and 0.3%， but the gravel content of pavement is higher and 41.64%， with the declining trend from hill to oasis. Except for Sample 2， the bulk density in upper soil profile （0-5 cm） with pavement clast is higher than it in lower soil profile （5-50 cm）. （3） desert pavement can constrain the water infiltration， the steady-state infiltration increases from 2.35 mm·min^-1 to 3.69 mm·min^-1 when the pavement clast removed. （4） Steady-state infiltration of desert pavement has a significantly negative correlation with thickness and gravel content of pavement clast， a significantly positive correlation with gravel coverage and mass water content of pavement clast， and a positive correlation with grave size of pavement clast. This study is helpful to understand the hydrologic effect of desert pavement.

The southwestern region is one of the areas where drought disasters frequently occur in China. Under the background of global warming， the frequency and degree of droughts have increased， posing threats to agricultural production and water security. The Palmer drought Severity Index （PDSI） and the self-calibrating Palmer Drought Severity Index （sc_PDSI）， which was developed based on PDSI have been widely used as mature ones. In this paper， the correspondence between soil species and available water holding capacity （AWC） included in the soil AWC geospatial model was used to inverse the high resolution AWC distribution in the southwest region. And the monthly mean temperature， as well as the monthly cumulative precipitation data of 70 stations in Southwest China were also used to calculate the PDSI index and sc_PDSI Index. Further comparative analysis of time-varying characteristics of the two indexes themselves and the statistical distribution properties， as well as the discussion of the applicability of both drought indexes in the Southwest area drought monitoring， were also included. The results show that： （1） Both PDSI and sc_PDSI reflect the “drought trend” of Southwest area during 1965-2010， but PDSI is of greater fluctuation amplitude； （2） There’s ‘tail’ phenomenon in PDSI frequency distribution， showing that the frequency of extreme drought / moist event it monitored is higher than that of severe drought / wet event， while the frequency distribution of sc_PDSI is closer to normal distribution； （3） The monitoring results of the two indexes during the 2009/2010 drought event in southwest area show that， to a certain extent， sc_PDSI is superior to PDSI in the monitoring of drought area and drought level， and is more consistent with soil moisture results， while PDSI is more likely to over-estimate the drought； （4） Although in general sc_PDSI adjusts PDSI to some extent， which makes sc_PDSI as superior， there’s no adjustment in the specific area（tropical monsoon climate）. So area factor should be taken into account in any application of these indexes.

The Yellow River Basin is an important ecological region in China， and it is of great significance to explore the spatio-temporal variation characteristics of biodiversity in this basin for regional ecological protection and restoration. In this study， the InVEST model is used to evaluate the habitat quality of the Yellow River Basin from 2000 to 2018， combined with the spatial autocorrelation model to explore its temporal and spatial changes characteristics. The driving factors of spatial differentiation characteristics of habitat quality are analyzed by using the single factor detection and interactive detection methods of geographic detectors. The results show that： from 2000 to 2018， the average habitat quality index of the Yellow River Basin was 0.631， with a decline rate of 0.16%， and the habitat quality index was high in the west and low in the east. The habitat quality index of the Yellow River Basin exhibits a highly positive spatial correlation characteristic， which shows that the similar values of habitat quality gather in space. The low-value areas of habitat quality are mainly concentrated in the lower reaches of the Yellow River Basin， Guanzhong Plain and Fenhe Valley， while the high-value areas of habitat quality are mainly concentrated in the Qinghai-Tibet Plateau in the upper reaches of the Yellow River. Land use cover type is the most important driving factor for the spatial differentiation of habitat quality， with q value of 0.5560. Moreover， the interaction between any two driving factors on spatial differentiation of habitat quality is greater than that of one driving factor alone， and the interaction factors between land use cover types and temperature， elevation， rainfall， slope and NDVI are all greater than 0.5.

Due to the differences in historic culture， thinking model and research process， the research perspectives， research content， and research methods of desert tourism at home and abroad are significantly diversified. This paper systematically sorts out the research results of desert tourism at home and abroad. In terms of research perspective， ecological environment， economics and sociology are the starting points for domestic scholars to analyze the desert tourism resource development value， tourism market demand， environmental carrying capacity and other key issues. Foreign scholars， with a wide range of research perspectives， mainly analyze the value of resources based on geomorphology and archeology， analyze the impact on local communities according to anthropology and ethnology， and analyze the distribution characteristics of passenger flow from the perspective of climatology. In terms of research content， desert studies at home and abroad are focused on tourism resource development， sustainable development of scenic spots， tourist behavior characteristics， etc. However， foreign tourists also pay attention to exploring tourist destination evolution patterns and characteristics of tourist source places. In terms of research methods， qualitative research is mostly adopted by domestic scholars. Quantitative research is mainly used for indicator system building， models， and questionnaires. Quantitative research is the main research method for foreign scholars， who obtain information mainly from field surveys and questionnaires for quantitative data modeling， regional comparison discussion and typical case analysis.

Based on the MODIS NDVI vegetation index and meteorological data sets， and by utilizing the methods of Ensemble Empirical Mode Decomposition， trend analysis， and Random Forest Regression， this paper analyzes the spatiotemporal changes in vegetation coverage in the Yellow River Basin from 2001 to 2020 and discusses the driving factors behind the changes. The analysis produced the following findings. （1） The spatial averaged NDVI showed a significant increasing trend across the Yellow River Basin from 2001 to 2020， with a growth rate of 0.055/10a （P<0.05）. The regional growth rates of different land cover types are significantly different. Among them， the growth rate of the conversion of farmland to forest （grass） region is the fastest， followed by the agricultural land region， and the natural vegetation region. （2） Spatially， areas with increased vegetation coverage are mainly distributed in the Loess Plateau of northern Shaanxi， southeastern Gansu Province， the Hetao Plain of Inner Mongolia Autonomous Region， and in other areas where the Sloping Land Conversion Program is implemented. Meanwhile， areas with significant decline in vegetation coverage are mainly concentrated in the Guanzhong Plain urban agglomerations， the Huanghuaihai Plain， and the Qinghai-Tibet Plateau. （3） Regression analysis results show that the overall impact factors such as temperature， carbon dioxide concentration， and precipitation positively promote vegetation growth and the absolute contribution rate will decrease sequentially， while factors such as atmospheric vapor pressure deficit and radiation generally inhibit vegetation growth. The findings of this study provide a reference for assessing the comprehensive impact of climate change on vegetation cover changes across the Yellow River Basin.

According to the requirement from the First National Conference on Combating Desert in November， 1958， the Chinese Academy of Sciences organized rapidly the Scientific Investigation Team for Combating Deserts （SITCD， CAS） in the January， 1959 and carried out fieldwork soon， which was the maximal national desert comprehensive survey up to now with the widest areas， the most complete majors， the most diverse team members， and the most concentrated campaigns. This paper， as the pioneering part （1） of the practice on prevention and control of aeolian desertification and the development of desert science in China for 70 years， briefly retrospect the results and experience from a smaller scale desert survey in 1957 and 1958， which was cooperative implemented by Chinese Academy of Sciences and Academy of Sciences of the USSR， and talk over the achievement and positive impacts from the desert comprehensive survey of the Scientific Investigation Team for Combating Deserts， Chinese Academy of Sciences in 1959. Based on the references and available data， every Investigation Team Branch for different desert and Gobi in Northern China had reported the progression of field-survey and the analysis and research mostly focused on the distribution of deserts/Gobi， different genetic types， sand material source area， hazards of sand blown， desert control measures， socioeconomic status， agriculture， forestry， and animal husbandry production. We also specially discus and praise highly the followings milestone events such as （1） the pioneering and development of desert science is the practiced paragon of “task promoting subject development”， （2） “national demand is our first choice” radiated the scientist’s enthusiasm and dedication spirit during 1950s， （3） professional selection and prominent contribution of 8 distinguished scientists， and （4） the international cooperation assisted development of desert science in China.

The Second National Conference on Combating Desert had been held in September， 1959 in Urumqi， which further to demonstrate the attention and expectation from the state's responsibility for prevention and control of aeolian desertification. In the years that followed， the Scientific Investigation Team for Combating Deserts， CAS and relevant provincial （autonomous region） departments carried out a more systematic investigation， experiment， research and practice. This paper focus on following three parts： （1） Based on the experimental investigations in the filed fixed station and semi-fixed station to comprehensive control of the desert， the author discusses some progress and function in the selection and introduction of plant species for moving dune fixing and optimal allocation， the mechanical sand fixation， the moving dune's moisture state and its stabilization and afforestation， the transpiration intensity of the major psammophytes， the process of soil formation in the fixed quicksand area and the dune soil microorganisms， etc. （2） Based on the research results of several major scientific and technological issues in prevention and control of aeolian desertification， the author discusses some main progress and function in the cause of the desert， the relationship between moving regular pattern of sand dune and wind prevention and sand-fixation， the assessment of aircraft seeding， the vegetation types and their evolution law in desert， the psammophytes characteristics， rational use of grassland in desert， the classification of the Gobi Desert and its transformation and utilization， water resources and their utilization， etc. （3） The author expounds briefly the process and the achievements of prevention and control of aeolian desertification during the establishment of the People's Republic of China （PRC） from 1949 to 1965，which affirmed the research objectives， formed the spirit of pioneering dedication and effective research method， and formed preliminarily in theory， practice， team and platform of the desert science. Thus laid the foundation and conditions for the start-up and pioneering of China Desert Science， so that let it enter the development period smoothly.

The soil erosion in China was characterized by various types and complicated processes. It is of great significance to accurately quantify the temporal variation and spatial patterns of soil wind erosion and water erosion intensity in watersheds， to identify regional dominant erosion types for reasonable arrangement of soil and water conservation measures. This study quantified the temporal and spatial patterns and evolution of soil wind erosion and water erosion intensity in the Yellow River Basin from 2000 to 2020 combined remote sensing monitoring， field survey， and model simulation， revealed soil erosion type area， and its significance to zoning control of soil erosion. The results showed that： （1） The intensity of soil wind erosion and water erosion in the region showed a downward trend as a whole， while the wind erosion and water erosion showed a fluctuation and continuous decrease， respectively. In the past 20 years， the modulus of soil wind erosion and soil water erosion have respectively decreased at a rate of 18.88 t·km^-2·a^-1 and 34.98 t·km^-2·a^-1. （2） The type zones dominated by soil wind erosion and soil water erosion accounted for 16.35% and 83.65% of the total land area of the region， respectively， and the overall performance of soil erosion type zoning from north to south was the transition from soil wind erosion to water erosion. The areas dominated by soil wind erosion were distributed in the upper reaches of the main stream of the Yellow River and the Ordos inland flow area， accounting for 41.53% and 28.57% of the area of soil wind erosion area， respectively. Moderate erosion intensity of soil wind erosion accounted for the largest proportion， 24.72%. The areas dominated by soil water erosion were distributed in the middle reaches of the Yellow River （25.04%）， the Wei River-Yiluo River system （22.06%）， the source water system of the Yellow River （18.60%）， the upper reaches of the Yellow River （15.49%）， Huangshui-Taohe River System （13.35%）. Soil water erosion was mainly micro-erosion intensity， accounting for 49.30% of the soil water erosion area， and light （17.28%）， moderate （14.98%） and strong erosion intensity （11.95%） were widely staggered. （3） Desertification control project and soil and water conservation engineering made soil erosion modulus and erosion intensity decrease significantly in areas with strong wind and water erosion. According to the zoning characteristics of soil erosion types， the measures of vegetation restoration and agricultural oases in the soil wind erosion area were discussed. Agricultural cultivation measures， forest and grass measures and engineering measures are used to protect and control soil water erosion areas， in order to provide scientific guidance for the high-quality development of the ecosystem in the Yellow River Basin.

The global environment has undergone profound changes since the industrial revolution. Due to the poor stability， anti-interference and self-recovery abilities of ecosystems， global change has led to the decline of natural resource supply capacity， land degradation， biodiversity reduction， frequent disasters， and increased ecosystem risks in ecologically vulnerable regions. Therefore， it is urgent to implement researches on global change risk in ecologically vulnerable regions. This study mainly summarized the researches on the risk sources and the impact of global change on ecologically vulnerable areas of China， as well as the response to global change. The study then put forward the future strategies for global change to promote the in-depth understanding of the response of ecosystem to global change and improve the ability to cope with global change in typically and ecologically vulnerable regions of China. The risk of global change in ecologically vulnerable regions comes from the impact of environmental change on complex systems of natural， social， and economic. Global change has a great impact on the ecosystem of ecologically vulnerable regions， with climate change as the main symbol and human activities as the main driving force. Global change causes extreme climate events， frequent disasters， land degradation， the reduction of vegetation productivity and biodiversity， the melting of glaciers and frozen soil， and the change of water resources pattern， which may intensify under the continuous impact of global change in the future. However， the implementation of ecological construction project has significantly improved the ecological environment. In the future， we should strengthen the researches on the coupling of natural， social， and economic systems， the monitoring of resources and environmental factors， and the risk assessment and early warning of global change.

The agro-pastoral ecotone in northern China， a typical region sensitive to interaction between climate and human beings， has always been undergoing wind erosion and soil degradation. At present， the wind erosion model is one of the most effective methods to obtain the regional potential wind erosion. In this study， the regional versions of Revised Wind Erosion Equation （RWEQ） and Wind Erosion Prediction System （WEPS） were used to evaluate the potential wind erosion at the agro-pastoral ecotone in northern China during 2000-2012. The results demonstrate that the magnitudes of average potential wind erosion were different while the spatial distribution， interannual decreasing trend and seasonal distribution of potential wind erosion were similar between the RWEQ and WEPS. It is found that wind speed， soil moisture and land use change have an impact on soil wind erosion by the analysis of the spatial correlation between wind speed， soil moisture and wind erosion modulus， and the influence of land use change on fluctuation of wind erosion amount. The observed wind erosion data are closely related to the values predicted by RWEQ （R²=0.45， P<0.01） and WEPS （R²=0.57， P<0.01）. The Nash （Sutcliffe efficiency coefficient） of WEPS model （NSC=0.54） is higher than that of RWEQ model （NSC=0.27）. Both RWEQ model and WEPS model can objectively predict the soil wind erosion of the APEC， and the prediction accuracy of WEPS model is better.

Wind regime is one of the most important factors affecting the development of aeolian landforms. For wind-accumulated landforms （e.g.dunes）， wind also determines the dune types partly. In order to explore the relationship between aeolian landforms and wind， we analyzed the wind pattern in different regions of the Haerteng River for a whole year. The results show that the mean wind speed is 2.78 m·s^-1， and the sand-driving wind mainly occurs in spring and summer with a speed of 7.78 m·s^-1， and the average duration of sand-driving wind events is 4.1 h. Annual drift potential range from 122 to 254 VU， which generally belongs to the intermediate-low wind environment and the index of directional variability （RDP/DP） is mostly intermediate from 0.51 to 0.58. Regional wind regime is different and the western part is intermediate wind environment while central and eastern are low. From the west to the east， the dune types transform from simple （e.g. dome and barchan dunes） to complex （e.g. reticulate and star dunes） with the variation of wind direction and the dune morphology is consistent with wind pattern. Dunes move generally from west to east along the direction of sediment transport. Combined with wind regime and dune distribution， it is speculated that the aeolian landforms of the basin are formed by weathered debris from the eastern mountain that undergo river transportation and wind modification. This study is of great significance for comprehensive understanding the law of regional wind-sand landform differentiation and the relationship between wind regime and sand dunes. It also can provide basic data for further study about the interaction and evolution of dunes.

The grain-size characteristics of sediments are the key indicators that reflect the sediment sources and the sedimentary environment. The diversity of granular analysis methods restricts the systematic integration and analysis of multi-source data. Based on three groups of aeolian sediment samples (a total of 222), the grain-size parameters including Average Grain-Size (M_z), Sorting-Coefficient (σ), Skewness (SK), and Kurtosis(K_g) are calculated by Folk-Word Graphical-Method, McManus Moment and Friedman Moment Methods. The results show that the linear correlativity of M_z and σ, respectively obtained by the Graphical-Method and the Moment-Method, is prominent in the three groups of samples，which is not related to the sedimentary environment. SK and K_g obtained by the three calculation methods are basically not correlated and non-interchangeable, which is closely related to the differences of sedimentary environment and the morphology of frequency curve of grain-size. Statistically, the numerical significance of K_g should be contrary to that of σ, i.e. negative correlation. Therefore, the Friedman Moment-Method is more applicable. In the process of granularity analysis, we should fully consider the differences in different calculation methods and establish corresponding qualitative grading standards.

The characteristics of regional sandstorms in Northwest of China from 2000 to 2020 were analyzed using ground observation data， and based on climatic dynamic factors， temperature， precipitation and NDVI data to analyse the causes of regional sandstorms changes in Northwest of China. The study results show that from 2000 to 2020， the annual total number of days of regional sandstorms in Northwest of China showed a fluctuating downward trend， and there were two high （low） frequency periods. Spring is the season of high incidence of regional sandstorms， of which the total number of days in April is the highest， reaching 47 days. Compared with the first ten days and the middle ten days of the month， regional sandstorms are more likely to occur in the last ten days of each spring months. The Tarim Basin in southern Xinjiang and central-western Inner Mongolia and the Hexi in Gansu are frequent areas of regional sandstorms in Northwest of China with total number of days more than 10 days， and the total number of days in most other places of Northwest of China is less than 8 days. The area index and intensity index of the polar vortex in the northern hemisphere and the polar vortex intensity index in Asia have a significant positive correlation with the number of days of regional sandstorms. The transition of the northern hemisphere polar vortex from an expansion period to a contraction period and the weakening of its intensity are important climatic dynamic factors for the reduction of regional sandstorms in Northwest of China. The annual （spring） precipitation and average NDVI in Northwest of China are significantly negatively correlated with the number of days of regional sandstorms. In the past 21 years， the climate in most parts of the northwest region has tended to be warm and humid， and the vegetation cover has improved as the main trend. The transformation is conducive to the shrinkage of the desertified area and reduces the occurrence of non-imported sandstorms.

The concept of "a living community of mountains， rivers， forests， farmlands， lakes， grasslands and sandylands" points out a new direction for the management of ecological environment in sandy land， but what research should be carried out in sandy land is a new topic. Based on the challenges faced by ecological construction， this paper discusses the directions and key issues of ecological management in Horqin Sandy Land from the perspective of integrated management of mountains， rivers， forests， farmlands， lakes， grasslands and sandylands.

The restoration and reconstruction of reasonable vegetation coverage and soil habitat， and the maintenance of ecosystem stability and sustainable development are important objectives of desertification land govern in arid and semi-arid regions. As an effective and economical environmental protection material for water conservation， soil improvement and plant growth， eco-mat has been widely used in desertification control. The study on the influence of eco-mat laying on sand fixation and soil temperature and humidity can provide theoretical basis for wind prevention， sand fixation and vegetation construction in sandy area. This paper takes sand dunes covered by different eco-mats and mobile sand dunes （control area） in the southeast edge of Tengger Desert as the research object， to analyze the influence rule of eco-mat laying on wind-sand flow， soil temperature and soil moisture. The results indicated that eco-mats significantly increased the soil surface roughness of quicksand and decreased the sediment transport. The surface roughness of eco-mats experimental plots for pin shape laying with grass seed， pin shape laying without grass seed， strip shape laying with grass seed， strip shape laying without grass seed was 45， 22， 29 and 15 times as much as that of the surface layer of quicksand， the surface sediment transport for 0 to 20 cm was reduced by 90.57%， 87.14%， 88.14%， and 86.71% compared to quicksand， respectively. When the temperature was low， the soil temperature of 0-20 cm layer under eco-mats coverage was lower than that of quicksand， the result was opposite when the soil temperature wad high. Eco-mats laying increased the soil moisture content of 0-100 cm layer， only the value of 0-20 cm layer was lower than the quicksand， the soil moisture content of 40-60 cm， 60-80 cm and 80-100 cm was 1.61， 1.28 and 1.83 times of that of quicksand， respectively. Eco-mats coverage plays an important role in increasing surface roughness， reducing sediment transport， heat preservation， reducing evaporation， and maintaining soil moisture， which provides favorable conditions for the survival and growth of vegetation in sandy areas.

Water use efficiency （WUE） is a key proxy for linking carbon and water exchange processes in terrestrial ecosystems. Understanding the spatial-temporal variations in WUE helps to evaluate the adaptability of vegetation to local environmental conditions. This study estimated the vegetation WUE in the Mu Us Desert during 2001-2016 using remote-sensing data and meteorological observations. Carbon sequestration （i.e.， net primary productivity， NPP） was estimated based on the Carnegie-Ames-Stanford Approach （CASA） model， while water consumption （i.e.， evapotranspiration， ET） was obtained from the MODIS product. The spatial-temporal patterns of WUE and their responses to meteorological factors were investigated by trend analysis and correlation analysis， respectively. The results showed that： （1） the mean annual WUE across the Mu Us Desert was 0.62 gC·mm^-1·m^-2 with a trend of decrease from the east to the west， and among different vegetation types， the values of WUE ranked in the order of cultivated vegetation>shrub>meadow>steppe>desert； （2） WUE increased at the rate of 0.009 gC·mm^-1·m^-2·yr^-1 during the study period， especially significantly in eastern， and the increase in WUE mainly attributed to the rapid rise in NPP； and （3） the relationships between WUE and meteorological factors followed a sequence of solar radiation， precipitation， wind speed， and air temperature from strong to weak， and there were relatively insignificant relationships between WUE and meteorological factors in the western part of the Mu Us Desert. The study highlight that the revegetation programs implemented in the Mu Us Desert have achieved good outputs that both NPP and WUE have increased since 2001， which contributed to the improvement of local ecological environment； however， in the central and western part of the Mu Us Desert with poor condition of water and heat， the mismatch between revegetation magnitude and water should be paid more attention.

Dusty weather is an extreme weather phenomenon that occurs frequently in the northern China. It leads to a turbidity of the air and a sharp decline in visibility， causing adverse effects on various aspects of human society. Dust aerosols transported into the atmosphere by strong winds also have a significant impact on weather and climate by modulating atmospheric radiation budget and cloud microphysics. Accurate identification and forecasting of dusty weather are of great significance in ecological protection and climate change mitigation. This paper provides a comprehensive review of recent research on methods for identifying and forecasting dust events. Important methods are described in detail， and their advantages and disadvantages are analyzed and compared. Finally， this paper summarizes the research achievements related to the identification and forecasting of dusty weather and proposes valuable future research directions.

China has achieved remarkable prevention and control effects of aeolian desertification in northern China， and has shown an overall reversal trend since 2000. The Yellow River Basin is an important barrier to national ecological security， and its aeolian desertification prevention and control is a key link in consolidating the foundation for high-quality development of the basin. Based on the background of the overall reversal of aeolian desertification in northern China since 2000. The aeolian desertification process in the Yellow River Basin from 2000 to 2020 was discussed in this study， and the dominant factor which driving the dynamics of aeolian desertification in the basin and their relative contributions were analyzed using the quantitative method. The results showed that： （1） The aeolian desertification land in the Yellow River Basin mainly consisted of moderate and severe aeolian desertification lands， and was concentrated in the middle and upper reaches of the Yellow River Basin. From 2000 to 2020， the total aeolian desertification land decreased by 7 529 km² （5.6%） in the Yellow River Basin. In detail， the serious aeolian desertification land continued to decrease by 47.1%， while the increasing trend of the slight， moderate， and severe aeolian desertification lands slowed down significantly after 2010. （2） In space， the aeolian desertification land was mainly distributed in the middle and upper reaches of the Yellow River Basin， and the total aeolian desertification land further shrank to the upper reaches of the Yellow River Basin from 2000 to 2020. The reversed aeolian desertification land with a large distribution area of 2020， 35 542 km² （26.5%）， and the developed aeolian desertification with a scattered distribution area of 2 823 km² （2.1%） was mainly concentrated in the Hobq Desert， Mu Us Sandy Land， and the source area of the Yellow River. The reversal or development of aeolian desertification was dominated by the transfer to the aeolian desertification land with a lighter or a higher desertification degree， and the transfer has also slowed down significantly after 2010. （3） The area jointly driven by climate change and human activities accounted for 89.67% of the aeolian desertification dynamic area of the Yellow River Basin from 2000 to 2020， and that driven by individual climate change or individual human activities only accounted for 7.30% and 3.03%， respectively. The relative contribution of human activities （54.91%） was generally higher than that of climate change （45.09%）， but this relative contribution of human activities decreased with the increase of the relative contribution of climate change in different periods. This work can provide a decision-making basis and reference for the key desertification control in the ecological protection and high-quality development strategy of the Yellow River Basin， and can also provide significant theoretical support for realizing the high-quality development of the Yellow River basin.

Human activities and climate change have caused the seagrass ecosystem to degrade and lose at an alarming rate， forming a large "submarine desert" area， leading to the loss of ecosystem service function. In recent years， because of the rising concerns on marine resources by governments， the restoration of the seagrass ecosystem has entered a new historical stage. Nevertheless， there are fewer cases of successful restoration of degraded seagrass ecosystems. Therefore， it is time to present the theories of restoration ecology to guide the practice of seagrass restoration. Under the circumstances， this study systematically discusses the significance， difficulties， and problems of seagrass restoration， elaborates the interaction and complexity of the effects of human activities and climate change on the seagrass ecosystem， integrates research methods at different scales， and proposes targeted seagrass ecosystem restoration strategies. This study contributes to constructing the seagrass ecosystem restoration theoretical system and provides academic guidance for seagrass ecosystem restoration.

Vegetation in the Otingdag Sandy Land plays an important role in maintaining the desert-grassland ecosystem stability， promoting ecological security of the Beijing-Tianjin-Hebei region. Due to different water conditions， the vegetation in the Otingdag Sandy Land has obvious zonality from the east to the west， and the species composition and community structure are obviously different. On the basis of field survey， the vegetation types of the Otingdag Sandy Land under different precipitation conditions were classified， and the species composition and diversity characteristics of the community under different water conditions were analyzed. The results showed that： （1） There were abundant vegetation types in the Otingdag Sandy Land， including 5 vegetation type groups， 12 vegetation （sub） types and 27 vegetation groups， which has obvious zonal characteristics. （2） There are 256 species of vascular plants in 46 families， 149 genera， and more than 75% of them are herbaceous plants. （3） The community diversity varies greatly from east to west. The dominant families in the middle and east side are Asteraceae， Poaceae， Fabaceae， while the dominant families in the west side are Amaranthaceae， Poaceae. The results can provide basic data for vegetation protection and utilization in the Otingdag Sandy Land.

China， especially the arid and semi-arid regions of northern China， is one of the leading contributors in global greening， and ecological projects has been thought as the main causal factors. As a key desertification-combating actions， the impacts of desertification control on vegetation temporal dynamics have not been fully clarified. This study analyzed the differences of temporal dynamics of normalized difference vegetation index （NDVI） and its influencing factors between desertification vegetation and its adjacent zonal vegetation in arid regions of northern China. The results showed that： （1） Desertification in the study region initially expanded， peaked in 2000， and then reversed， implying desertification control worked after 2000. （2） During 1982-2021， NDVI in 44.5% of the study area significantly increased， while 5.8% of the study area experienced a notable reduction， suggesting a generally greening. The greening primarily occurred in the Hetao Plains， Horqin Sandy Land， Kubuqi， Mu Us Sandy Land， Southern Xinjiang， Junggar Basin and the Tianshan Mountains. More area in desertified areas （45.7%） showed remarkable increase than their adjacent zonal vegetation （41.7%）. （3） Notably， the increasing rate after 2000 （0.0055 a^-1） markedly greater than that of pre-2000 （0.0036 a^-1）. Moreover， larger increasing rate was found in desertified areas after 2000 but in adjacent zonal vegetation before 2000. （4） Precipitation and specific humidity were the dominant factors in both the desertification and their adjacent zonal vegetation， with wind speed exerting a more significant influence in some natural units. The correlation coefficient of NDVI with moisture was lower in desertified areas compared with their adjacent zonal vegetation， whereas wind speed exhibited a stronger correlation. Our results will provide a scientific foundation to evaluate desertification control effectiveness in the past and improve related measures in the future.

Taking 66 cities in the Yellow River Basin as the research object， and selecting 34 indicators from new development philosophy to construct a high-quality development index system， the entropy method was used to calculate the high-quality development level of the Yellow River Basin， and the high-quality development level and the average growth volume and average growth rate of the high-quality development level are used as variables to analyze spatial correlation and pattern evolution characteristics of high-quality development in the Yellow River Basin from 2000 to 2020 by ways of ESDA. The result shows that：（1）Similar high-quality development levels cities in the Yellow River Basin had spatial correlation during the study period， and the high-quality development levels increased amid fluctuations， and the development tended to be balanced. （2） From 2000 to 2015， the average growth volume and average growth rate of high-quality development in the Yellow River Basin had significant spatial correlations， the evolution characteristics tended to shift from strong agglomerations to weak ones and to strong ones， cities with similar growth were close to each other； but in 2015-2020， cities with similar growth were randomly distributed and spatially uncorrelated. （3） The spatial pattern of high-quality development average growth volume and average growth rate changed greatly， with high-value regions migration from the east to middle and then to the west. The number of high-value regions was greater than the number of low-value regions， and the overall high-quality development speed of the Yellow River Basin was relatively fast. Average growth volume hot and cold areas changed from a relative dispersion to a centralized distribution one and then to a decentralized layout one， and the average growth rate of similar cities evolved from relatively scattered to concentrated and contiguous one， and different levels of hot and cold spots were distributed in layers.（4）Regions with relatively weaker development foundations displayed a higher growth rate， and urban agglomerations were still key areas to drive high-quality development in the Yellow River Basin. In the future， we should adhere to the new development philosophy， innovate the urban agglomeration cooperation model， and promote the high-quality integrated development of the Yellow River Basin.