Impact of habitat heterogeneity on plant community pattern in Gurbantunggut Desert

This paper reports a geomorphologic landscape investigation, vegetationsurvey and soil sampling at 14 sites across the Gurbantunggut Desert between87°37′09″-88°24′04″E and 44°14′04″-45°41′52″N. The study encountered 8 species of lowtrees and shrubs, 5 of perennial herbs, 8 of annual plants and 48 of ephemeral and ephemeroidplants. These species of plants represent one-third of the species found in the GurbantunggutDesert, and their communities make up a large proportion of desert vegetation with great landscapesignificance. In the investigation we found that the plant communities are accordingly succeededwith the spatial variation of macro-ecoenvironment. Using Principal Component Analysis (PCA) andCorrelation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandysoil's physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc.only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation.Meanwhile, the impact of microhabitat on the plant community pattern with an antagonisticinteraction made vegetation's eco-distribution in a temporary equilibrium.

Distribution of ephemeral plants and their significance in dune stabilization in Gurbantunggut Desert

Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation, describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes, analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert. Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.

Spatial heterogeneity for grain size distribution of eolian sand soil on longitudinal dunes in the southern Gurbantunggut Desert

The grain size composition, distribution characteristics and spatial variation of eolian sand soil on distinct positions across two longitudinal dunes and interdune areas were studied by means of conventional grain size analysis and geostatistical methods. In the study, 184 samples of eolian sand soil from the 0-30cm layer were systemically collected and measured from two longitudinal dunes and interdunes in the southern Gurbantunggut Desert. The results show that the dominant grain sizes are fine and very fine sands, and the differences of grain size compositions between the distinct geomorphologic positions are significant. The contents of clay and silt are highest on the interdune areas and lowest on the crests, and higher on the leeward slopes than on the windward slopes. The contents of very fine and fine sands are highest on the windward slopes and lowest on the crests. The contents of medium, coarse and very coarse sands are lowest on the interdune lands, and highest on the crests, and are identical on the two slopes. The coarser sizes (phi(1)) and mean sizes (Mz) for eolian sand soil all have a varying tendency from fine to coarse sizes with interdune area -> leeward slope -> windward slope -> crest, and the sorting (sigma) are poorly to well sorted. The results of geostatistical analysis reveal that phi(1), Mz and a values are moderately to strongly spatially autocorrelated. The values of the spatially correlated ranges are phi(1) < sigma < Mz. The spatial variation for these grain size parameters is significant across the longitudinal dune landscape. From the crests towards the bottom of the slope, there is a varying gradient of zonal distribution, and the gradient values on the leeward slopes are larger than sites on the windward slopes.

Characteristics of soil seed banks at different geomorphic positions within the longitudinal sand dunes of the Gurbantunggut Desert, China

Understanding the characteristics of soil seed banks in sand dunes is crucial to stabilize the dune systems and maintain the plant populations in deserts. In this study, we conducted a survey investigation in the field and a seed germination experiment in the laboratory to explore the characteristics of soil seed banks at various geomorphic positions of longitudinal sand dunes in the Gurbantunggut Desert, China. Totally, 17 plant species belonging to 17 genera and 9 families were identified in soil seed banks, and 35 plant species belonging to 34 genera and 17 families were identified in aboveground vegetation. Plant species richness in soil seed banks decreased with increasing soil depth. The highest species richness was presented in the upper slope of the windward slope and the lowest species richness was presented in the base of the windward slope. There was no significant difference in seed density of soil seed banks among the examined seven geomorphic positions. The highest seed density occurred in the lower slope of the leeward slope while the lowest occurred in the crest. Moreover, seed density decreased with increasing soil depth, being the highest in the upper soil layer （0-2 cm）. For both soil seed banks and aboveground vegetation, there was no significant difference in Simpson＇s diversity index among the seven geomorphic positions; however, Shannon-Wiener diversity index and Pielou＇s evenness index showed significant differences among the seven geomorphic positions. Those results showed that although there was no significant difference in seed density of soil seed banks among the seven geomorphic positions, the geomorphic positions significantly affected the species richness, diversity and distribution of soil seed banks. Therefore, understanding the characteristics of soil seed banks at different geomorphic positions of sand dunes is essential to vegetation restoration or reestablishment. Furthermore, the Jaccard＇s similarity coefficients of plant species between soil seed banks and aboveground vegetation at the seven geomorphic positions were low, suggesting that vegetation restoration or reestablishment processes should be promoted through adding seeds to surface layers.

Effects of spring-summer grazing on longitudinal dune surface in southern Gurbantunggut Desert

Intensive grazing in spring-summer has been responsible for environmental degradation of the Gurbantunggut Desert in recent years. The coverage of plants and biological crusts, sand surface stability and physicochemical characteristics of soil on the dune surface were conducted in 2002 （winter grazing） and 2005 （spring-summer grazing）. The results showed that over 80% of the total area of the dune surface was covered by well-developed biological crusts and plants in 2002, when the interdune and middle to lower part of dune slopes were stabilized and only the crest had 10-40 m wide mobile belt. Affected by spring-summer grazing in 2005, over 80% of the total cover of biological crust was destructed and the plant coverage only reached 1/5 of that in 2002, especially the ephemeral plant cover had a great change. The value of sand transport potential in 2005 only reached 1/3 of that in 2002, but the total surface activity in 2005 was 1.6 times stronger than that in 2002. Meanwhile the mobile area began to expand from the dune top to the whole dune surface following spring-summer grazing. Compared with 2002, medium sand content of the dune surface soil increased by 13.9%, while that of fine and very fine sands decreased by 7.4% and 8.0% respectively in 2005 and the soil organic matter in 2005 was only about 1/2 of that in 2002. It is obvious that the presence of snow cover and frozen soil in winter could avoid the surface structure destruction in winter, while spring-summer grazing made excessive damage to biologic crusts and ephemeral plants. Spring is the main windy season in Gurbantunggut Desert and therefore intensive activity of dune surface occurred following spring-summer grazing, which led to a great loss of fine sand and organic matter. It can be seen that grazing season have a significant influence on the sustainable development of the desert ecosystem in Northwest China.

Dynamics of arbuscular mycorrhizal fungi associated with desert ephemeral plants in Gurbantunggut Desert

Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal （AM） fungi, however, little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems. The dynamics of AM fungi with desert ephemerals were examined to determine the effects of host plant life stages on the development of AM fungi. Mean colonization of ephemeral annual plants was 45% lower than that of ephemeral perennial plants. The colonizations were much higher in the early part of the growing season than in later parts, peaking at flowering times. The phenology of AM fungi in root systems varied among different ephem- erals. The density of AM fungal spores increased with the development of ephemeral annual plants, reached its maximum at flowering times, and then plateaued about 20 days after the aboveground senescence. A significant positive correlation was found between AM fungi spore density and biomass of ephemeral annual plants. The life cycles of AM fungi associated with desert ephemerals were very shod, being about 60-70 days. Soil temperature and water content had no direct influence on the development of AM fungal spores. We concluded that the development of AM fungi was in response to desert ephemeral phenology and life history strategy.

Competition,spatial pattern,and regeneration of Haloxylon ammodendron and Haloxylon persicum communities in the Gurbantunggut Desert,Northwest China

Competition,spatial pattern,and regeneration are important factors affecting community composition,structure,and dynamics.In this study,we surveyed 300 quadrats from three dunes(i.e.,fixed dunes,semifixed dunes,and mobile dunes)in the Gurbantunggut Desert,Northwest China,from late May to early June in 2021.The intraspecific and interspecific competition,spatial pattern,and regeneration of Haloxylon ammodendron and Haloxylon persicum were studied using the Hegyi competition index and point pattern analysis methods.The results showed that the optimal competition distance of the objective tree in the H.ammodendron and H.persicum communities was 6 m.The intraspecific and interspecific competition of H.ammodendron was the greatest in fixed dunes,while the competition intensity of H.persicum in semifixed dunes and mobile dunes was greater than that in fixed dunes.The order of competition intensity of the two populations was seedlings>saplings>adults,and the competition intensity gradually decreased with the increase in plant diameter.The spatial distribution pattern of the three life stages of H.ammodendron and H.persicum was random,and there were no correlations between seedlings and saplings,adults and saplings,and seedlings and adults.The density of regenerated seedlings and saplings of H.ammodendron in the three dunes followed the order of fixed dunes>semifixed dunes>mobile dunes,and that of H.persicum in the three dunes followed the order of mobile dunes>semifixed dunes>fixed dunes.Therefore,when artificially planting H.ammodendron and H.persicum for sand control,the planting interval should be 6 m,and seedlings should be planted next to adults to minimize the competition between plants,which can promote the renewal of H.ammodendron and H.persicum and the stabilization of the ecosystem.

Spatio-temporal variation of soil moisture in a fixed dune at the southern edge of the Gurbantunggut Desert in Xinjiang, China

Soil moisture is critical for vegetation growth in deserts.However,detailed data regarding the soil moisture distribution in space and time in the Gurbantunggut Desert of China have not yet been reported.In this study,we conducted a series of in situ observation experiments in a fixed sand dune at the southern edge of the Gurbantunggut Desert from February 2014 to October 2016,to explore the spatio-temporal variation of soil moisture content,investigate the impact of Haloxylon ammodendron(C.A.Mey.)Bungeon soil moisture content in its root zone,and examine the factors influencing the soil moisture spatial pattern.One-way analysis of variance,least significant difference tests and correlation analysis were used to analyze the data.The results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods,namely,a moisturegaining period,a moisture-losing period and a moisture-stable period.According to the temporal and spatial variability,the 0–400 cm soil profile could be divided into two layers:an active layer with moderate variability and a stable layer with weak variability.The temporal variability was larger than the spatial variability in the active layer,and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative height and mainly followed the order of interdune area>west and east slopes>slope top.The mean profile soil moisture content in the root zone of dead H.ammodendron individuals was significantly higher than that in the root zones of adult and young individuals,while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant difference.The spatial pattern of soil moisture was attributable to the combined effects of snowfall,vegetation and soil texture,whereas the effects of rainfall and evaporation were not significant.The findings may offer a foundation for the management of sandy soil moisture and vegetation restoration in arid areas.

Study on the Land Reclamation of Oilfield of Gurbantunggut Desert in Junggar Basin

The exploration and development of oilfield results in damages to land resources. Along with the further development of petroleum in the Gurbantunggut Desert, the fragile ecological environment and land resource was suffering much more damage. Vegetation degradation and desertification become more prominent. In response to the damage to the fragile ecological environment and oilfield in the Gurbantunggut Desert, limit condition method was used to evaluate the suitability of land reclamation suitability. Results suggested that the main restraining factors for land reclamation were soil condition and water resources. Based on the effect and shortage of oilfield in the Gurbantunggut Desert Oilfield, the reclamation of oilfield in the Gurbantunggut desert was discussed.

Distribution of plant species and species-soil relationship in the east central Gurbantunggut Desert, China

The distribution of plant species and relationships between species and soil factors in the east central part of Gurbantunggut Desert was studied to provide more insight into the flora and determine differences in vegetation across various parts of the desert. Two-way Cluster Analysis showed that the vegetation in the area could be divided into three groups, the first group was dominated by the shrub species, Ephedra przewalskii and the grass species, Carex physodes mainly in areas of flat grounds and gentle slopes; the second group was dominated by C. physodes, Artemisia songorica and A. xerophytica mainly on the slope of sand dunes and the third group was dominated by the shrub species, Haloxylon persicum mainly on the top of sand dunes. There was no difference in plant density between Groups 1 and 2 but there was a significant decrease in Group 3. Soil water under vegetation Group 3 was much lower than that in the other two groups at all soil depths. The EC, organic matter, total P and soluble Na, Ca and Mg varied very similarly with soil water. Canonical corre- spondence analysis （CCA） satisfactorily assessed the species-soil relations in the area. The distribution of plant species was strongly correlated with the soil factors of water content, organic matter, EC and nutrients. The variations in species occurrence explained by the three CCA axes were about 70%, indicating that some explanatory site variables may exist outside our studied parameters. Soil texture is suggested to be included in future studies to improve the explanation of CCA.

Chlorophytes of biological soil crusts in Gurbantunggut Desert,Xinjiang Autonomous Region,China

In this paper,chlorophytes collected from 253 biological soil crust samples in Gurbantunggut Desert in Xinjiang Autonomous Region,China were studied by field investigation and microscopical observation in lab.The flora composition,ecological distribution of chlorophytes in the desert and dynamic changes of species composition of chlorophytes in different developing stages of biological soil crusts are preliminarily analyzed.Results showed that there were 26 species belonging to 14 genera and 10 families,in which unicellular chlorophytes were dominant.There existed some differences in distribution of varied sand dune positions.The taxa of chlorophytes in leeward of sand dunes are most abundant,but the taxa in windward,interdune and the top of sand dunes reduced gradually.Chlorophytes were mainly distributed within the crust and the taxa of chlorophytes decrease obviously under the crust.In the devel-oping stages of the biological soil crust,species diversity of chlorophytes changed a little,but species composition pre-sented some differences.Chlorococcum humicola,Chlorella vulgaris,Chlamydomonas ovalis and Chlamydomonas sp.nearly existed in all developing stages of biological crusts.In several former stages of the biological soil crust there were spherical chlorophytes and filamentous ones.When moss crust formed,filamentous chlorophytes disappeared,such as Microspora and Ulothrix.

Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang

Eolian loess is widely distributed on the various geomorphic surfaces between 700-2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuy-ama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be -0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at -0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous

Respondence and feedback of modern sand deserts to climate change ——A case study in Gurbantunggut Desert

The research on the respondence and feedback of modern sand deserts to the climate change is an important component part in the studies on the global climate change. Deserts respond to the climate change, meanwhile, they affect the climate with their feedback of peculiar environment during the respondence. Many researches on desert climate have been carried out at home and abroad. However, there is little research on the respondence and feedback of modern fixed, semi-fixed and mobile deserts in arid areas to the climate change, in which the factor analysis as well as the parameter changing effects is especially the difficult problem all along. In this note, the parameters of the respondence and feedback of Gurbantunggut Desert to the climate change are measured and analyzed, some variable parameters of water-heat exchange are obtained, and a numerical model of desertification is developed according to a series of climate change of about 40 years and the variable relations of meteorological and physical

Responses of ephemeral plant germination and growth to water and heat conditions in the southern part of Gurbantunggut Desert

在 Gurbantunggut 沙漠的南部的部分的短暂植物系统地从 2002 ～ 2004 被监视，气象学的数据和土壤潮湿在一样的时期期间被分析。结果证明短暂植物萌芽和生长对水和热状况的变化敏感。超过 0 的每日的温度的时间 ?????????

Arbuscular mycorrhizal associations in the Gurbantunggut Desert

在位于 Xinjiang 的 Gurbantunggut 沙漠的植物，中国是改编的干旱种类并且在通常滋养穷人的土壤成长。调查在沙漠被进行决定与合适的荒芜的植物联系的 arbuscular mycorrhizal (AM ) 地位从 annuals 和 perennials 的 11 个家庭的 to23 种类。从所有植物的根为决定 mycorrhizal 殖民的地位和程度的内部、外部的 hyphae，泡和 coils/arbuscules 的存在被检验。调查的植物种类，(61%) 14 被发现形成 AMassociations，(22%) 5 是可能的 AM 开拓殖民地于种类，并且 4 是 non-my-corrhizal 植物。形成 AM 的 annuals 和灌木的 Theproportions 分别地是比 perennials 和植物的那些显著地低的。孢子密度在根地区的土壤每 20 g 从 5 ～ 21 变化了。在 3 个类的上午 14 点 fungaltaxa 被孤立并且识别了其 10 属于血管球， 3 到 Acaulospora， and1 到 Archaeospora。血管球是在识别的所有类的主导的类。G。deser-ticola 和 G.etunicatum 是最普通的税一孤立与 77.4% 和 74.8% 的出现频率，并且相对许多 14.4% 和 15.5% 分别地。

Temporal-spatial dynamics of distribution patterns of microorganism relating to biological soil crusts in the Gurbantunggut Desert

生物土壤外壳用作贡献沙固定的一个重要生物因素。这研究被进行在关于地点的外壳中调查微生物的时间空间的可变性，沙沙丘和季节的土壤层。在苔藓主导的内部沙丘的区域，更高的土壤营养素和水集中是可能的维持微生物引起的活动。细菌显示出解决和生长的最高的能力在在春天和秋天内部沙丘。土壤水内容在内部沙丘的区域在土壤外壳中到达了最高的价值，特别在春天。放线菌和真菌的数量的变化基本上在沙沙丘的不同地点显示出一致趋势。与加深土壤层，因为环境因素在春天和秋天波动，每个微生物组的数量的垂直分发显示出不同特征。在不同微生物组之中，细菌是占优势的，在在所有的春天和秋天的放线菌下一个和真菌最少玷污层(020 厘米) 。细菌和土壤水内容的比例比在在所有土壤层(020 厘米) 的秋天的那些在春天是更高的。没有一致趋势在放线菌和真菌被发现。结果证明微生物的数量是显著地积极的与有机物内容相关，土壤水满意的、全部的 N，全部的 P，可得到的 P，可得到的 K， pH，电的传导性，全部的盐内容，过氧化氢酶， urease，磷酸酶和碱的磷酸酶。

Damage and recovery of the Gurbantunggut Desert vegetation following engineering activities

The fragile ecological environment of the Gurbantunggut Desert is damaged/disturbedby human activities relating to the development of oil-gas resources and the constructions of de-sert road and great engineering in the Jungger Basin. It was mainly represented: soil compaction,vegetation cleaning, burial of vegetation, oil polluting, and soil disturbance. With investigation andexperiment, we found that when the way and intensity of engineering activities disturbing theeco-environment does not make its ecological stability disintegrated, the desert vegetation has acapacity of natural recovery. To speed and strengthen the process of vegetation recovery efficientassistant measurements, including stabilizing mobile sands promptly and sowing seeds of shruband herb plants in good time will be needed.

Abiotic contribution to total soil CO_2 flux across a broad range of land-cover types in a desert region

As an important component of ecosystem carbon（C） budgets, soil carbon dioxide（CO2） flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence showing that the abiotic component can be important in total soil CO2 flux（R（total））, its relative importance has never been systematically assessed. In this study, after comparative measurements of CO2 fluxes on sterilized and natural soils, the R（total） was partitioned into biotic flux（R（biotic）） and abiotic flux（R（abiotic）） across a broad range of land-cover types（including eight sampling sites： cotton field, hops field, halophyte garden, alkaline land, reservoir edge, native saline desert, dune crest and interdune lowland） in Gurbantunggut Desert, Xinjiang, China. The relative contribution of R（abiotic） to R（total）, as well as the temperature dependency and predominant factors for R（total）, R（biotic） and R（abiotic）, were analyzed. Results showed that R（abiotic） always contributed to R（total） for all of the eight sampling sites, but the degree or magnitude of contribution varied greatly. Specifically, the ratio of R（abiotic） to R（total） was very low in cotton field and hops field and very high in alkaline land and dune crest. Statistically, the ratio of R（abiotic） to R（total） logarithmically increased with decreasing R（biotic）, suggesting that R（abiotic） strongly affected R（total） when R（biotic） was low. This pattern confirms that soil CO2 flux is predominated by biotic processes in most soils, but abiotic processes can also be dominant when biotic processes are weak. On a diurnal basis, R（abiotic） cannot result in net gain or net loss of CO2, but its effect on transient CO2 flux was significant. Temperature dependency of R（total） varied among the eight sampling sites and was determined by the predominant processes（abiotic or biotic） of CO2 flux. Specifically, R（biotic） was driven by soil temperature while R（abiotic） was regulated by the change in soil temperature（ΔT）. Namely, declining temperature（ΔT0） resulted in positive R（abiotic）（i.e., CO2 released from soil）. Without recognition of R（abiotic）, R（biotic） would be overestimated for the daytime and underestimated for the nighttime. Although R（abiotic） may not change the sum or the net value of daily soil CO2 exchange and may not directly constitute a C sink, it can significantly alter the transient apparent soil CO2 flux, either in magnitude or in temperature dependency. Thus, recognizing the fact that abiotic component in R（total） exists widely in soils has widespread consequences for the understanding of C cycling.

Impacts of snow on seed germination are independent of seed traits and plant ecological characteristics in a temperate desert of Central Asia

Seed germination profoundly impacts plant community composition within the plant life cycle.Snow is an important source of water for seed germination in the temperate deserts of Central Asia.Understanding how seed germination responds to variations in snow cover in relation to seed traits and plant ecological characteristics can help predict plant community sustainability and stability in Central Asia under a scenario climate change.This study investigated the seed germination of 35 plant species common to the Gurbantunggut Desert in Central Asia under the three snow treatments:(1)snow addition;(2)ambient snow;and(3)snow removal.Two-way analysis of variance(ANOVA)tests were performed to assess interactions among the impacts of snow treatments,seed traits and plant ecological characteristics on seed germination.Phylogenetic generalized least-squares(PGLS)model was used to test the relationships between seed traits and seed germination.The results demonstrated that snow variations had no significant impacts on seed germination overall.Seed germination under the snow addition treatment was similar with that under the ambient snow treatment,irrespective of seed traits and plant ecological characteristics.Snow removal only had negative impacts on seed germination for certain groups of seed traits and plant ecological characteristics.Seed mass positively affected seed germination,showing a linear increase of arcsin square root-transformed seed germination with log-transformed seed mass.Seed shape also profoundly impacted seed germination,with a higher germination percentage for elongated and flat seeds.Seed germination differed under different plant life forms,with semi-shrub species showing a significantly higher germination percentage.Most importantly,although snow treatments,seed traits and plant ecological characteristics had no interactive effects on seed germination overall,some negative impacts from the snow removal treatment were detected when seeds were categorized on the basis of seed mass and shape.This result suggests that variations of snow cover may change plant community composition in this temperate desert due to their impacts on seed germination.

Water-use efficiency in response to simulated increasing precipitation in a temperate desert ecosystem of Xinjiang, China

Water-use efficiency（WUE） is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE. Here, we analyzed the responses of leaf WUE, ecosystem carbon and water exchanges, ecosystem WUE, and plant community composition changes under normal conditions and also under extra 15% or 30% increases in annual precipitation in a temperate desert ecosystem of Xinjiang, China. We found that leaf WUE and ecosystem WUE showed inconsistent responses to increasing precipitation. Leaf WUE consistently decreased as precipitation increased. By contrast, the responses of the ecosystem WUE to increasing precipitation are different in different precipitation regimes： increasing by 33.9% in the wet year（i.e., the normal precipitation years）and decreasing by 4.1% in the dry year when the precipitation was about 30% less than that in the wet year.We systematically assessed the herbaceous community dynamics, community composition, and vegetation coverage to explain the responses of ecosystem WUE, and found that the between-year discrepancy in ecosystem WUE was consistent with the extent to which plant biomass was stimulated by the increase in precipitation. Although there was no change in the relative significance of ephemerals in the plant community, its greater overall plant biomass drove an increased ecosystem WUE under the conditions of increasing precipitation in 2011. However, the slight increase in plant biomass exerted no significant effect on ecosystem WUE in 2012. Our findings suggest that an alteration in the dominant species in this plant community can induce a shift in the carbon-and water-based economics of desert ecosystems.