The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary fades can be identified in this set of arid red beds: mudstones of the plaza and intracontin...The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary fades can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha, aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third-order sequences. Based on the cyclicity in stratigraphic records, 5 third-order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second-order tectonic sequence. The primary feature of these third-order sequences is of an upward-fining sedimentary succession formed by a succession of 'coarse sediments of the alluvial system-fine sediments of the lake system'. The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela-2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.展开更多
The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shr...The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shrub and the inter-shrub sites. Microbial biomasses as well as basal respiration were found to be significantly greater in the soil samples taken beneath the Z. duraosura shrubs than from the inter-shrub sampling sites, with no differences between the two sampling layers （0-10 and 10-20 cm） throughout the study period. However, seasonal changes were observed due to autumn dew formation, which significantly affected microbial biomass and basal respiration in the upper-layer inter-shrub locations. The calculated metabolic coefficient （qCO2） revealed significant differences between the two sampling sites as well as between the two soil layers, elucidating the abiotic effect between the sites throughout the study period. The substrate availability index was found to significantly demonstrate the differences between the two sites, elucidating the significant contribution of Z. duraosura in food source availability and in moderating harsh abiotic components. The importance of basal microbial parameters and the derived indices as tools demonstrated the importance and need for basic knowledge in understanding plant-soil interactions determined by an unpredictable and harsh desert environment.展开更多
Climate change is expected to alter the frequency and intensity of drying-rewetting cycles,impacting water availability and consequently soil nutrient availability.However,the effects of these fluctuations on the chem...Climate change is expected to alter the frequency and intensity of drying-rewetting cycles,impacting water availability and consequently soil nutrient availability.However,the effects of these fluctuations on the chemical speciation and bioavailability of phosphorus(P)in soil remain uncertain,both in the presence of desert species and in their absence.We conducted a pot experiment involving bare soil(absence of plants)and two desert species(Alhagi sparsifolia and Calligonum mongolicum)to determine the short-term impacts of drought(no water supply),drying-rewetting 1(D-RW1,high frequency of low water inputs),and drying-rewetting 2(D-RW2,low frequency of high water inputs)on soil Hedley P pools,plant P concentration,and plant biomass accumulation.Results demonstrated that the presence of plants significantly increased soil labile P and organic P(Po)concentrations by 60%–150%and 1%–68%,respectively,compared to the absence of plants.Both D-RW1 and D-RW2 treatments significantly increased soil dissolved organic carbon concentration by 2%–35%relative to the drought treatment.Moreover,in the presence of A.sparsifolia,soil resin-extractable P and NaHCO_(3)-extractable inorganic P(Pi)concentrations in the D-RW1 treatment significantly increased by 31%and 75%,respectively,when compared to the drought treatment,with the NaHCO_(3)-and NaOH-extractable Po concentrations in the D-RW2 treatment rising by 14%and 32%,respectively.Furthermore,the D-RW2 treatment significantly increased leaf P concentration and plant biomass compared to the D-RW1 and drought treatments.Overall,compared to the drought treatment,frequent low-intensity drying-rewetting cycles enhanced soil Pi turnover,whereas infrequent high-intensity drying-rewetting cycles increased Po turnover and P bioavailability.These findings will inform better water management strategies for desertification restoration in hyper-arid desert ecosystems.展开更多
Root system architecture has often been overlooked in plant research despite its critical role in plant adaptation to environmental conditions.This study focused on the root system architecture of the desert shrub Rea...Root system architecture has often been overlooked in plant research despite its critical role in plant adaptation to environmental conditions.This study focused on the root system architecture of the desert shrub Reaumuria soongorica in the Alxa steppe desert,Northwest China.Plant samples were collected during May-September 2019.Using excavation methods,in situ measurements,and root scanning techniques,we analyzed the root distribution,topology,and branching patterns of R.soongorica across an age sequence of 7-51 a.Additionally,we investigated the allometric relationships of root collar diameter with total coarse root length,biomass,and topological parameters.The results showed that the roots of R.soongorica were predominantly concentrated in shallow soil layers(10-50 cm),with lateral root branching and biomass allocation increasing with shrub age.The root topology exhibited a herringbone-like structure,with average topological and modified topological indices of 0.89 and 0.96,respectively,both of which adjusted with shrub age.The root system displayed a self-similar branching pattern,maintaining a constant cross-sectional area ratio of 1.13 before and after branching,deviating from the area-preserving rule.These adaptive traits allow R.soongorica to efficiently expand its nutrient acquisition zone,minimize internal competition,and optimize resource uptake from the upper soil layers.Furthermore,significant linear relationships were observed between log10-transformed root collar diameter and log10-transformed total coarse root length,biomass,and topological parameters.These findings advance non-destructive approaches for studying root characteristics and contribute to the development of root-related models.Besides,this study provides new insights into the adaptive strategies of R.soongorica under extreme drought conditions,offering valuable guidance for species selection and cultivation in desert restoration efforts.展开更多
Amid global climate change, rising levels of nitrogen(N) deposition have attracted considerable attention for their potential effects on the carbon cycle of terrestrial ecosystems. The desert steppes are a crucial yet...Amid global climate change, rising levels of nitrogen(N) deposition have attracted considerable attention for their potential effects on the carbon cycle of terrestrial ecosystems. The desert steppes are a crucial yet vulnerable ecosystem in arid areas, but their response to the combination of N addition and precipitation(a crucial factor in arid areas) remains underexplored. This study systematically explored the impact of N addition and precipitation on net ecosystem exchange(NEE) in a desert steppe in northern China. Specifically, we conducted a 2-a experiment from 2022 to 2023 with eight N addition treatments in the Urat desert steppe of Inner Mongolia Autonomous Region, China, to examine changes in NEE and explore its driving factors. The structural equation model(SEM) and multiple regression model were applied to determine the relationship of NEE with plant community characteristics and soil physical-chemical properties. Statistical results showed that N addition has no significant effect on NEE.However, it has a significant impact on the functional traits of desert steppe plant communities. SEM results further revealed that N addition has no significant effect on NEE in the desert steppe, whereas annual precipitation can influence NEE variations. The multiple regression model analysis indicated that plant functional traits play an important role in explaining the changes in NEE, accounting for 62.15% of the variation in NEE. In addition, plant height, as an important plant functional trait indicator, shows stronger reliability in predicting the changes in NEE and becomes a more promising predictor. These findings provide valuable insights into the complex ecological mechanisms governing plant community responses to precipitation and nutrient availability in the arid desert steppes, contributing to the improved monitoring and prediction of desert steppe ecosystem responses to global climate change.展开更多
Desert shrubs are indispensable in maintaining ecological stability by reducing soil erosion,enhancing water retention,and boosting soil fertility,which are critical factors in mitigating desertification processes.Due...Desert shrubs are indispensable in maintaining ecological stability by reducing soil erosion,enhancing water retention,and boosting soil fertility,which are critical factors in mitigating desertification processes.Due to the complex topography,variable climate,and challenges in field surveys in desert regions,this paper proposes YOLO-Desert-Shrub(YOLO-DS),a detection method for identifying desert shrubs in UAV remote sensing images based on an enhanced YOLOv8n framework.This method accurately identifying shrub species,locations,and coverage.To address the issue of small individual plants dominating the dataset,the SPDconv convolution module is introduced in the Backbone and Neck layers of the YOLOv8n model,replacing conventional convolutions.This structural optimization mitigates information degradation in fine-grained data while strengthening discriminative feature capture across spatial scales within desert shrub datasets.Furthermore,a structured state-space model is integrated into the main network,and the MambaLayer is designed to dynamically extract and refine shrub-specific features from remote sensing images,effectively filtering out background noise and irrelevant interference to enhance feature representation.Benchmark evaluations reveal the YOLO-DS framework attains 79.56%mAP40weight,demonstrating 2.2%absolute gain versus the baseline YOLOv8n architecture,with statistically significant advantages over contemporary detectors in cross-validation trials.The predicted plant coverage exhibits strong consistency with manually measured coverage,with a coefficient of determination(R^(2))of 0.9148 and a Root Mean Square Error(RMSE)of1.8266%.The proposed UAV-based remote sensing method utilizing the YOLO-DS effectively identify and locate desert shrubs,monitor canopy sizes and distribution,and provide technical support for automated desert shrub monitoring.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the ...Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the size and composition of belowground bud banks and their response to environmental factors in the desert steppe zone remain poorly understood,challenging desertification control efforts in arid desert areas.This study examined the density and vertical distribution of horizontal and vertical rhizome buds of a rhizomatous legume herb Sophora alopecuroides L.,its population characteristics,and soil physical-chemical properties in three habitats(interdune lowland(IL),flat sandy land(FSL),and desert steppe(DS))in a desert steppe zone,northern China.Our findings revealed that:(1)total and horizontal rhizome bud densities of S.alopecuroides differed significantly among the three habitats(P<0.05),with the largest total rhizome bud density(177 buds/m2)in IL and the smallest(63 buds/m2)in DS;(2)horizontal rhizome buds distributed in the deep soil layer were dominant in IL,while vertical rhizome buds in the top soil layer were predominant in DS;and(3)soil coarse sand,nutrient content,and population density were the primary factors affecting bud bank density of S.alopecuroides.Specifically,horizontal rhizome buds were dependent largely on soil coarse sand content,and vertical rhizome buds tended to be more related to soil organic matter content and population density.Our results indicated that horizontal rhizome buds were more important in IL with frequent aeolian disturbance,whereas vertical rhizome buds were more important in DS with abundant water and nutrient resources.The plastic responses and survival strategies of S.alopecuroides bud bank to different habitats provide valuable information for the effective implementation of desertification control measures and the management of desert steppe ecosystems.展开更多
Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section...Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section of the Wuhai-Maqin Expressway as a case study,employing CFD numerical simulation methods to calculate and analyze the wind-sand flow field distribution characteristics in different longitudinal slope sections.The results show that:(1)Along with the direction of the incoming flow,the windward and leeward slope toes of the embankment are low-wind-speed zones,with the wind speed at the leeward slope toe being even lower.The higher the embankment,the larger the low-wind-speed zone at the windward and leeward slope toes.As the longitudinal slope increases,the extent of the lowwind-speed zone at the same location along the route also increases.(2)Along the route direction,the wind speed at the windward and leeward slope toes decreases as embankment height increases.At the embankment toe,sand particles are transported from the top to the bottom of the longitudinal slope,and the greater the longitudinal slope,the stronger the transport effect.(3)Along the route direction,the sand accumulation around the embankment gradually gathers toward the bottom of the longitudinal slope as the slope increases.When the longitudinal slope is 3%and 4%,the trend of sand accumulation moving from the windward side at the end of the route to the leeward side at the start of the route is more significant.When the longitudinal slope is less than or equal to 3%,severe sand accumulation within the embankment range is reduced by 86.4%or more compared to when the slope is 4%.(4)Under the same longitudinal slope,the higher the embankment height,the smaller its transport rate.When the embankment height is the same,the greater the longitudinal slope,the greater the embankment transport rate.展开更多
Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the ...Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field ob- servation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows： 1） The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were ap- proximately 33%-100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0-31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 q）, were finer than those （2.15 q）） outside the system. In addition, wind velocities basically followed a loga- rithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2） There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90-22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51-15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.展开更多
Due to large deserts on Earth surface a thorough understanding of climate change, landscape evolution and geomorphological processes having occurred in deserts is crucial for Earth System Science. The landscapes in de...Due to large deserts on Earth surface a thorough understanding of climate change, landscape evolution and geomorphological processes having occurred in deserts is crucial for Earth System Science. The landscapes in deserts are, however, diverse and different over the globe with regard to their geomorphological nature, human activities and geological histories. In the last decades a great number of efforts have been put to the investigation of the initial timing of the occurrence of arid climate, e. g. in northwestern China. Silty sediments in the downwind directions have been used to deduce the histories of deserts. In general, there is a lack of knowledge about processes and landscapes in Chinese drylands between the initial Miocene silt sedimentation at desert margins and the late Quaternary multiple occurrences of wetter climate with assumed large lakes in many of the deserts in northern China. The geomorphological concept of three primary triggering factors, i.e., the sediment supply, sediment availability and transport capacity of wind, and additionally the underground geology need to be fully considered for a better understanding of the environmental histories of sand seas which should not be viewed as equivalent for deserts because sand seas cover between 〈 1% and ca. 45% of the desert areas in various continents dependent on a complex interaction between various processes of both exogenous and endogenous origins.展开更多
Desert mosses, which are important stabilizers in desert ecosystems, are distributed patchily under and between shrubs. Mosses differ from vascular plants in the ways they take up nutrients. Clarifying their distribut...Desert mosses, which are important stabilizers in desert ecosystems, are distributed patchily under and between shrubs. Mosses differ from vascular plants in the ways they take up nutrients. Clarifying their distribution with ecological stoichiometry may be useful in explaining their mechanisms of living in different microhabitats. In this study, Syntrichia caninervis, the dominant moss species of moss crusts in the Gurbantunggut Desert, China, was selected to examine the study of stoichiometric characteristics in three microhabitats(under living shrubs, under dead shrubs and in exposed ground). The stoichiometry and enzyme activity of rhizosphere soil were analyzed. The plant function in the above-ground and below-ground parts of S. caninervis is significantly different, so the stoichiometry of the above-ground and below-ground parts might also be different. Results showed that carbon(C), nitrogen(N) and phosphorus(P) contents in the below-ground parts of S. caninervis were significantly lower than those in the above-ground parts. The highest N and P contents of the two parts were found under living shrubs and the lowest under dead shrubs. The C contents of the two parts did not differ significantly among the three microhabitats. In contrast, the ratios of C:N and C:P in the below-ground parts were higher than those in the above-ground parts in all microhabitats, with significant differences in the microhabitats of exposed ground and under living shrubs. There was an increasing trend in soil organic carbon(SOC), soil total nitrogen(STN), soil available phosphorous(SAP), and C:P and N:P ratios from exposed ground to under living shrubs and to under dead shrubs. No significant differences were found in soil total phosphorous(STP) and soil available nitrogen(SAN), or in ratios of C:N and SAN:SAP. Higher soil urease(SUE) and soil nitrate reductase(SNR) activities were found in soil under dead shrubs, while higher soil sucrase(STC) and soil β-glucosidase(SBG) activities were respectively found in exposed ground and under living shrubs. Soil alkaline phosphatase(AKP) activity reached its lowest value under dead shrubs, and there was no significant difference between the microhabitats of exposed ground and under living shrubs. Results indicated that the photosynthesis-related C of S. caninervis remained stable under the three microhabitats while N and P were mediated by the microhabitats. The growth strategy of S. caninervis varied in different microhabitats because of the different energy cycles and nutrient balances. The changes of stoichiometry in soil were not mirrored in the moss. We conclude that microhabitat could change the growth strategy of moss and nutrients cycling of moss patches.展开更多
Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatiotemporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversi...Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatiotemporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversity, providing diverse microhabitats tightly interweaving with resource partitioning. Determination of a ＂scale unit＂ to help understand ecological processes has become one of the important and most debatable problems in recent years. A fieldwork was carried out in the northern Negev Desert highland, Israel to determine the influence of fine-scale landscape patch moisture heterogeneity on biogeochemical variables and microbial activity linkage in a desert ecosystem. The results showed that the spatio-temporal patchiness of soil moisture to which we attribute influential properties, was found to become more heterogenic with the decrease in soil moisture availability （from 8.2 to 0.4 g kg^-1） toward the hot, dry seasons, with coefficient of variation （CV） change amounting to 66.9%. Spatio-temporal distribution of organic matter （OM） and total soluble nitrogen （TSN） was found to be relatively uniformly distributed throughout the wet seasons （winter and spring）, with increase of relatively high heterogeneity toward the dry seasons （from 0.25% to 2.17% for OM, and from 0 to 10.2 mg kg^-1 for TSN） with CV of 47.4% and 99.7% for OM and TSN, respectively. Different spatio-temporal landscape patterns were obtained for Ca （CV = 44.6%）, K （CV = 34.4%）, and Na （CV = 92%） ions throughout the study period. CO2 evolution （CV = 48.6%） was found to be of lower heterogeneity （varying between 2 and 39 g CO2-C g^-1 dry soil h^-1） in the moist seasons, e.g., winter and spring, with lower values of respiration coupled with high heterogeneity of Na^＋ and low levels of TSN and organic matter content, and with more homogeneity in the dry seasons （varying between 1 and 50 g CO2-C g^-1 dry soil h^-1）. Our results elucidate the heterogeneity and complexity of desert system habitats affecting soil biota activity.展开更多
As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway ...As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway enables the Highway itself to operate properly and creates enormous socio-economic benefits. However, due to delivery time pressure, the sand-controlling system was built in a haste. Lack of studies on sand-controlling system brought deficiencies on design and construction of the sand-controlling system. And with the lapse of time, troubles such as sand deposition on the roadbeds and erosion on roadsides came to surface and caused more serious problems for the traffic routes[1.2]. This paper discusses two forms of the sand-controlling system-the upright fence and the send-covered sand barrier, then analyzes the general benefits of the sandcontrolling system along the Desert Highway.展开更多
Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photos...Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.展开更多
Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to d...Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to date.This research describes an oasis protective system in the southeastern border of the Tengger Desert.The system consists of a sand barrier belt,a shrub and herbaceous plant belt,and a farmland shelter belt.The system was compared to a bare dunes area as the control zone.The study investigated windproof effect,sediment transport,and erosion through field observations.Results showed that the roughness of the shrub and herbaceous plant belt,farmland shelter belt,and sand barrier belt were increased compared with bare dunes.The shrub and herbaceous plant belt provided the highest windproof effect values for the same wind velocity measurement height,and the windproof effect values for different protective belts were as follows:shrub and herbaceous plant belt>farmland shelter belt>sand barrier belt.The sand barrier belt provided effective wind and sand control at heights from 0 to 50 cm above the ground.The total sediment transport for each protective belt is as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.The sediment transport decreased exponentially as the height increased.In the bare dunes and protective systems,the sediment transport is mainly within 30 cm of the ground surface.The wind erosion intensity for this protective system was as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.This research offers quantitative evidence for how oasis protective systems can effectively intercept sand and prevent erosion in oases.The results of this study can be applied in similar regions.展开更多
Shrub is an important factor on structuring ground arthropod communities in desert ecosystems. In this study, in order to determine how shrubs and their species influence ground arthropod distribution patterns in a sa...Shrub is an important factor on structuring ground arthropod communities in desert ecosystems. In this study, in order to determine how shrubs and their species influence ground arthropod distribution patterns in a sandy desert scrubland dominated by two different shrub species, Calligonum mongolicum and Nitraria sphaerocarpa, the ground arthropods were sampled with pitfall traps during spring, summer and autumn. At the community level, total arthropod abundance was shown to be significantly higher under shrubs than in intershrub bare areas in spring; similar patterns occurred in terms of the richness of arthropod groups in the spring and over three seasons, suggesting season-specific shrub presence effects on arthropod activity. In addition, more arthropods were found under N. sphaerocarpa shrubs than under C. rnongolicum shrubs in autumn, suggesting season-specific effects of shrub species of arthropod activity, whereas more arthropods taxa were captured under C. mongoIicum than N. sphaerocarpa. At the trophic group level, the abundances of predator and herbivore arthropods were significantly greater under shrubs than in intershrub bare habitats, whereas herbivore arthropods were more abundant under N. sphaerocarpa than C. rnongolicum, and an opposite rule was detected for predator arthropods At the family level, the mean abundances of Carabidae, Curculionidae, Gnaphosidae and Lycosidae were significantly higher in the shrub microhabitats than in the intershrub bare habitat, there was no significant difference between habitats on the mean abundances of Formicidae and Tenebrionidae. The study results suggested that shrub presence and shrub species variation are important determinants of ground arthropod assemblages in this desert ecosystem, but the responses of ar- thropods differed among trophic and taxonomic groups.展开更多
Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap...Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.展开更多
Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou...Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.展开更多
[Objective] To establish drought resistance evaluation index system of desert shrubs,and provide scientific support for selecting quality tree species.[Method] Taking 2-year-old seedlings of 12 desert shrubs in Ulan B...[Objective] To establish drought resistance evaluation index system of desert shrubs,and provide scientific support for selecting quality tree species.[Method] Taking 2-year-old seedlings of 12 desert shrubs in Ulan Buh Desert ecosystem as the test materials,7 water physiological indexes were tested,principal component analysis and cluster analysis were applied to explore drought resistance of the shrubs.[Results](a) Water potential of Ephedra distachya Linn.,Nitraia tangutorum Bobr.,Caragana korshinski Kom.was lower than that of the other 9 species;bound water content(V_a) and bound water/free water ratio(V_a/V_s) of Zygophyl um xanthoxylon Maxim.was 64.20% and 3.3,higher than the others';transpiration rate of Atraphaxis bracteata A.Los.,Nitraia tangutorum Bobr.and Tamarix elongata Ldb.was significantly lower than the others';constant weight time of Haloxylon ammodendron(C.A.Mey.) Bunge and Ephedra distachya Linn.was the longest(144 h);residual moisture content of Ammopiptanthus mongolicus Maxim.was the highest(44.80%).(b) Water potential,bound water/free water(V_a/V_s),residual moisture content,bound water,constant weight time,and transpiration rate had great impact on drought resistance of plant,and the accumulative variance contribution rate achieved 87.59%.[Conclusion] According to the drought resistance,the 12 species were classified into 3 categories,namely shrubs with strong drought resistance(Ephedra distachya Linn.),shrubs with moderate drought resistance(Haloxylon ammodendron(C.A.Mey.) Bunge,Nitraia tangutorum Bobr.,and Zygophyllum xanthoxylon Maxim.);shrubs with poor drought resistance(Hedysarunn scoparium Fisch,Hedysarum mongolicum Turcz.,Tamarix elongata Ldb.,Caragana korshinskii Kom.,Ammopiptanthus mongolicus Maxim.,Atraphaxis bracteata A.Los.,Cal igonum mongolicum Mattei.,and Caragana microphylla Lam.).展开更多
基金This study was supported by the Ministry of Sciences and Technology of China(2001CB209100),
文摘The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary fades can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha, aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third-order sequences. Based on the cyclicity in stratigraphic records, 5 third-order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second-order tectonic sequence. The primary feature of these third-order sequences is of an upward-fining sedimentary succession formed by a succession of 'coarse sediments of the alluvial system-fine sediments of the lake system'. The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela-2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.
文摘The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shrub and the inter-shrub sites. Microbial biomasses as well as basal respiration were found to be significantly greater in the soil samples taken beneath the Z. duraosura shrubs than from the inter-shrub sampling sites, with no differences between the two sampling layers （0-10 and 10-20 cm） throughout the study period. However, seasonal changes were observed due to autumn dew formation, which significantly affected microbial biomass and basal respiration in the upper-layer inter-shrub locations. The calculated metabolic coefficient （qCO2） revealed significant differences between the two sampling sites as well as between the two soil layers, elucidating the abiotic effect between the sites throughout the study period. The substrate availability index was found to significantly demonstrate the differences between the two sites, elucidating the significant contribution of Z. duraosura in food source availability and in moderating harsh abiotic components. The importance of basal microbial parameters and the derived indices as tools demonstrated the importance and need for basic knowledge in understanding plant-soil interactions determined by an unpredictable and harsh desert environment.
基金supported by the National Natural Science Foundation of China (Nos. 42271071, 42207163,and 32250410301)the Postdoctoral Fellowship Program of China (No. GZC20232964)+5 种基金the “Tianchi Talents” Introduction Program, Xinjiang, China, the Ministry of Science and Technology, China (Nos. QN2022045005L and WGXZ2023078L)the National Key Research and Development Project of China (No. 2022YFF1302504)Josep PENUELAS and Jordi SARDANS were funded by the Spanish Government grants PID2020115770RB-I, TED2021132627 B-I00, and PID2022-140808NB-I00funded by the Ministry of Science and Innovation (MCIN) and the Agencia Espa?ola de Investigación (AEI), Spainsupported by the European Union’s Next Generation EU/PRTR program, the Fundación Ramón Areces grant CIVP20A6621Spain, and the Catalan Government grant SGR 2021–1333, Spain
文摘Climate change is expected to alter the frequency and intensity of drying-rewetting cycles,impacting water availability and consequently soil nutrient availability.However,the effects of these fluctuations on the chemical speciation and bioavailability of phosphorus(P)in soil remain uncertain,both in the presence of desert species and in their absence.We conducted a pot experiment involving bare soil(absence of plants)and two desert species(Alhagi sparsifolia and Calligonum mongolicum)to determine the short-term impacts of drought(no water supply),drying-rewetting 1(D-RW1,high frequency of low water inputs),and drying-rewetting 2(D-RW2,low frequency of high water inputs)on soil Hedley P pools,plant P concentration,and plant biomass accumulation.Results demonstrated that the presence of plants significantly increased soil labile P and organic P(Po)concentrations by 60%–150%and 1%–68%,respectively,compared to the absence of plants.Both D-RW1 and D-RW2 treatments significantly increased soil dissolved organic carbon concentration by 2%–35%relative to the drought treatment.Moreover,in the presence of A.sparsifolia,soil resin-extractable P and NaHCO_(3)-extractable inorganic P(Pi)concentrations in the D-RW1 treatment significantly increased by 31%and 75%,respectively,when compared to the drought treatment,with the NaHCO_(3)-and NaOH-extractable Po concentrations in the D-RW2 treatment rising by 14%and 32%,respectively.Furthermore,the D-RW2 treatment significantly increased leaf P concentration and plant biomass compared to the D-RW1 and drought treatments.Overall,compared to the drought treatment,frequent low-intensity drying-rewetting cycles enhanced soil Pi turnover,whereas infrequent high-intensity drying-rewetting cycles increased Po turnover and P bioavailability.These findings will inform better water management strategies for desertification restoration in hyper-arid desert ecosystems.
基金funded by the Guangxi Science and Technology Plan Project(Guike AD22080050)the Basic Research Ability Improvement Project of Young and Middle-aged Teachers of Universities in Guangxi(2022KY0386)+1 种基金the Opening Foundation of Key Laboratory of Environment Change and Resources Use in Beibu Gulf,Ministry of Education,Nanning Normal University(NNNU-KLOP-K2202)the National Natural Science Foundation of China(42471055).
文摘Root system architecture has often been overlooked in plant research despite its critical role in plant adaptation to environmental conditions.This study focused on the root system architecture of the desert shrub Reaumuria soongorica in the Alxa steppe desert,Northwest China.Plant samples were collected during May-September 2019.Using excavation methods,in situ measurements,and root scanning techniques,we analyzed the root distribution,topology,and branching patterns of R.soongorica across an age sequence of 7-51 a.Additionally,we investigated the allometric relationships of root collar diameter with total coarse root length,biomass,and topological parameters.The results showed that the roots of R.soongorica were predominantly concentrated in shallow soil layers(10-50 cm),with lateral root branching and biomass allocation increasing with shrub age.The root topology exhibited a herringbone-like structure,with average topological and modified topological indices of 0.89 and 0.96,respectively,both of which adjusted with shrub age.The root system displayed a self-similar branching pattern,maintaining a constant cross-sectional area ratio of 1.13 before and after branching,deviating from the area-preserving rule.These adaptive traits allow R.soongorica to efficiently expand its nutrient acquisition zone,minimize internal competition,and optimize resource uptake from the upper soil layers.Furthermore,significant linear relationships were observed between log10-transformed root collar diameter and log10-transformed total coarse root length,biomass,and topological parameters.These findings advance non-destructive approaches for studying root characteristics and contribute to the development of root-related models.Besides,this study provides new insights into the adaptive strategies of R.soongorica under extreme drought conditions,offering valuable guidance for species selection and cultivation in desert restoration efforts.
基金supported by the Major Science and Technology Project of Inner Mongolia Autonomous Region (2024JBGS0011-02)Foundation for Innovative Research Groups in Basic Research of Gansu Province (25JRRA490)+1 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences (2022437)National Natural Science Foundation of China (42207538)。
文摘Amid global climate change, rising levels of nitrogen(N) deposition have attracted considerable attention for their potential effects on the carbon cycle of terrestrial ecosystems. The desert steppes are a crucial yet vulnerable ecosystem in arid areas, but their response to the combination of N addition and precipitation(a crucial factor in arid areas) remains underexplored. This study systematically explored the impact of N addition and precipitation on net ecosystem exchange(NEE) in a desert steppe in northern China. Specifically, we conducted a 2-a experiment from 2022 to 2023 with eight N addition treatments in the Urat desert steppe of Inner Mongolia Autonomous Region, China, to examine changes in NEE and explore its driving factors. The structural equation model(SEM) and multiple regression model were applied to determine the relationship of NEE with plant community characteristics and soil physical-chemical properties. Statistical results showed that N addition has no significant effect on NEE.However, it has a significant impact on the functional traits of desert steppe plant communities. SEM results further revealed that N addition has no significant effect on NEE in the desert steppe, whereas annual precipitation can influence NEE variations. The multiple regression model analysis indicated that plant functional traits play an important role in explaining the changes in NEE, accounting for 62.15% of the variation in NEE. In addition, plant height, as an important plant functional trait indicator, shows stronger reliability in predicting the changes in NEE and becomes a more promising predictor. These findings provide valuable insights into the complex ecological mechanisms governing plant community responses to precipitation and nutrient availability in the arid desert steppes, contributing to the improved monitoring and prediction of desert steppe ecosystem responses to global climate change.
基金supported by the National Public Welfare Forest Desert Shrubbery Monitoring Project。
文摘Desert shrubs are indispensable in maintaining ecological stability by reducing soil erosion,enhancing water retention,and boosting soil fertility,which are critical factors in mitigating desertification processes.Due to the complex topography,variable climate,and challenges in field surveys in desert regions,this paper proposes YOLO-Desert-Shrub(YOLO-DS),a detection method for identifying desert shrubs in UAV remote sensing images based on an enhanced YOLOv8n framework.This method accurately identifying shrub species,locations,and coverage.To address the issue of small individual plants dominating the dataset,the SPDconv convolution module is introduced in the Backbone and Neck layers of the YOLOv8n model,replacing conventional convolutions.This structural optimization mitigates information degradation in fine-grained data while strengthening discriminative feature capture across spatial scales within desert shrub datasets.Furthermore,a structured state-space model is integrated into the main network,and the MambaLayer is designed to dynamically extract and refine shrub-specific features from remote sensing images,effectively filtering out background noise and irrelevant interference to enhance feature representation.Benchmark evaluations reveal the YOLO-DS framework attains 79.56%mAP40weight,demonstrating 2.2%absolute gain versus the baseline YOLOv8n architecture,with statistically significant advantages over contemporary detectors in cross-validation trials.The predicted plant coverage exhibits strong consistency with manually measured coverage,with a coefficient of determination(R^(2))of 0.9148 and a Root Mean Square Error(RMSE)of1.8266%.The proposed UAV-based remote sensing method utilizing the YOLO-DS effectively identify and locate desert shrubs,monitor canopy sizes and distribution,and provide technical support for automated desert shrub monitoring.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
基金funded by the National Natural Science Foundation of China(42207539,42377470)the Key Research and Development Project of Science and Technology Plan of Gansu Province in China International Science and Technology Cooperation Project(25YFWA009).
文摘Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the size and composition of belowground bud banks and their response to environmental factors in the desert steppe zone remain poorly understood,challenging desertification control efforts in arid desert areas.This study examined the density and vertical distribution of horizontal and vertical rhizome buds of a rhizomatous legume herb Sophora alopecuroides L.,its population characteristics,and soil physical-chemical properties in three habitats(interdune lowland(IL),flat sandy land(FSL),and desert steppe(DS))in a desert steppe zone,northern China.Our findings revealed that:(1)total and horizontal rhizome bud densities of S.alopecuroides differed significantly among the three habitats(P<0.05),with the largest total rhizome bud density(177 buds/m2)in IL and the smallest(63 buds/m2)in DS;(2)horizontal rhizome buds distributed in the deep soil layer were dominant in IL,while vertical rhizome buds in the top soil layer were predominant in DS;and(3)soil coarse sand,nutrient content,and population density were the primary factors affecting bud bank density of S.alopecuroides.Specifically,horizontal rhizome buds were dependent largely on soil coarse sand content,and vertical rhizome buds tended to be more related to soil organic matter content and population density.Our results indicated that horizontal rhizome buds were more important in IL with frequent aeolian disturbance,whereas vertical rhizome buds were more important in DS with abundant water and nutrient resources.The plastic responses and survival strategies of S.alopecuroides bud bank to different habitats provide valuable information for the effective implementation of desertification control measures and the management of desert steppe ecosystems.
基金financially supported by Youth Science“Research on Failure Mechanism and Evaluation Method of Sand Control Measures for Railway Machinery in Sandy Area”(12302511)Ningxia Transportation Department Science and Technology Project(20200173)The Central Guidance on Local Science and Technology Development Funds(22ZY1QA005)。
文摘Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section of the Wuhai-Maqin Expressway as a case study,employing CFD numerical simulation methods to calculate and analyze the wind-sand flow field distribution characteristics in different longitudinal slope sections.The results show that:(1)Along with the direction of the incoming flow,the windward and leeward slope toes of the embankment are low-wind-speed zones,with the wind speed at the leeward slope toe being even lower.The higher the embankment,the larger the low-wind-speed zone at the windward and leeward slope toes.As the longitudinal slope increases,the extent of the lowwind-speed zone at the same location along the route also increases.(2)Along the route direction,the wind speed at the windward and leeward slope toes decreases as embankment height increases.At the embankment toe,sand particles are transported from the top to the bottom of the longitudinal slope,and the greater the longitudinal slope,the stronger the transport effect.(3)Along the route direction,the sand accumulation around the embankment gradually gathers toward the bottom of the longitudinal slope as the slope increases.When the longitudinal slope is 3%and 4%,the trend of sand accumulation moving from the windward side at the end of the route to the leeward side at the start of the route is more significant.When the longitudinal slope is less than or equal to 3%,severe sand accumulation within the embankment range is reduced by 86.4%or more compared to when the slope is 4%.(4)Under the same longitudinal slope,the higher the embankment height,the smaller its transport rate.When the embankment height is the same,the greater the longitudinal slope,the greater the embankment transport rate.
基金supported by the National Natural Science Foundation of China (41271020, 41330746)CERS-China Equipment and Education Resources System (CERS-1-109)
文摘Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field ob- servation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows： 1） The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were ap- proximately 33%-100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0-31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 q）, were finer than those （2.15 q）） outside the system. In addition, wind velocities basically followed a loga- rithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2） There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90-22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51-15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.
基金the National Natural Science Foundation of China(grant no.:41430532)the Alexander von Humboldt Stiftung/Foundation,Germany for support
文摘Due to large deserts on Earth surface a thorough understanding of climate change, landscape evolution and geomorphological processes having occurred in deserts is crucial for Earth System Science. The landscapes in deserts are, however, diverse and different over the globe with regard to their geomorphological nature, human activities and geological histories. In the last decades a great number of efforts have been put to the investigation of the initial timing of the occurrence of arid climate, e. g. in northwestern China. Silty sediments in the downwind directions have been used to deduce the histories of deserts. In general, there is a lack of knowledge about processes and landscapes in Chinese drylands between the initial Miocene silt sedimentation at desert margins and the late Quaternary multiple occurrences of wetter climate with assumed large lakes in many of the deserts in northern China. The geomorphological concept of three primary triggering factors, i.e., the sediment supply, sediment availability and transport capacity of wind, and additionally the underground geology need to be fully considered for a better understanding of the environmental histories of sand seas which should not be viewed as equivalent for deserts because sand seas cover between 〈 1% and ca. 45% of the desert areas in various continents dependent on a complex interaction between various processes of both exogenous and endogenous origins.
基金supported by the National Natural Science Foundation of China (41571256, 41471251, 31670007)the Youth Innovation Promotion Association CAS (2015356)
文摘Desert mosses, which are important stabilizers in desert ecosystems, are distributed patchily under and between shrubs. Mosses differ from vascular plants in the ways they take up nutrients. Clarifying their distribution with ecological stoichiometry may be useful in explaining their mechanisms of living in different microhabitats. In this study, Syntrichia caninervis, the dominant moss species of moss crusts in the Gurbantunggut Desert, China, was selected to examine the study of stoichiometric characteristics in three microhabitats(under living shrubs, under dead shrubs and in exposed ground). The stoichiometry and enzyme activity of rhizosphere soil were analyzed. The plant function in the above-ground and below-ground parts of S. caninervis is significantly different, so the stoichiometry of the above-ground and below-ground parts might also be different. Results showed that carbon(C), nitrogen(N) and phosphorus(P) contents in the below-ground parts of S. caninervis were significantly lower than those in the above-ground parts. The highest N and P contents of the two parts were found under living shrubs and the lowest under dead shrubs. The C contents of the two parts did not differ significantly among the three microhabitats. In contrast, the ratios of C:N and C:P in the below-ground parts were higher than those in the above-ground parts in all microhabitats, with significant differences in the microhabitats of exposed ground and under living shrubs. There was an increasing trend in soil organic carbon(SOC), soil total nitrogen(STN), soil available phosphorous(SAP), and C:P and N:P ratios from exposed ground to under living shrubs and to under dead shrubs. No significant differences were found in soil total phosphorous(STP) and soil available nitrogen(SAN), or in ratios of C:N and SAN:SAP. Higher soil urease(SUE) and soil nitrate reductase(SNR) activities were found in soil under dead shrubs, while higher soil sucrase(STC) and soil β-glucosidase(SBG) activities were respectively found in exposed ground and under living shrubs. Soil alkaline phosphatase(AKP) activity reached its lowest value under dead shrubs, and there was no significant difference between the microhabitats of exposed ground and under living shrubs. Results indicated that the photosynthesis-related C of S. caninervis remained stable under the three microhabitats while N and P were mediated by the microhabitats. The growth strategy of S. caninervis varied in different microhabitats because of the different energy cycles and nutrient balances. The changes of stoichiometry in soil were not mirrored in the moss. We conclude that microhabitat could change the growth strategy of moss and nutrients cycling of moss patches.
文摘Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatiotemporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversity, providing diverse microhabitats tightly interweaving with resource partitioning. Determination of a ＂scale unit＂ to help understand ecological processes has become one of the important and most debatable problems in recent years. A fieldwork was carried out in the northern Negev Desert highland, Israel to determine the influence of fine-scale landscape patch moisture heterogeneity on biogeochemical variables and microbial activity linkage in a desert ecosystem. The results showed that the spatio-temporal patchiness of soil moisture to which we attribute influential properties, was found to become more heterogenic with the decrease in soil moisture availability （from 8.2 to 0.4 g kg^-1） toward the hot, dry seasons, with coefficient of variation （CV） change amounting to 66.9%. Spatio-temporal distribution of organic matter （OM） and total soluble nitrogen （TSN） was found to be relatively uniformly distributed throughout the wet seasons （winter and spring）, with increase of relatively high heterogeneity toward the dry seasons （from 0.25% to 2.17% for OM, and from 0 to 10.2 mg kg^-1 for TSN） with CV of 47.4% and 99.7% for OM and TSN, respectively. Different spatio-temporal landscape patterns were obtained for Ca （CV = 44.6%）, K （CV = 34.4%）, and Na （CV = 92%） ions throughout the study period. CO2 evolution （CV = 48.6%） was found to be of lower heterogeneity （varying between 2 and 39 g CO2-C g^-1 dry soil h^-1） in the moist seasons, e.g., winter and spring, with lower values of respiration coupled with high heterogeneity of Na^＋ and low levels of TSN and organic matter content, and with more homogeneity in the dry seasons （varying between 1 and 50 g CO2-C g^-1 dry soil h^-1）. Our results elucidate the heterogeneity and complexity of desert system habitats affecting soil biota activity.
基金program introducting distinguished personnel from abroad/wind-blown sand physics project Chinese Academy of Sciences
文摘As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway enables the Highway itself to operate properly and creates enormous socio-economic benefits. However, due to delivery time pressure, the sand-controlling system was built in a haste. Lack of studies on sand-controlling system brought deficiencies on design and construction of the sand-controlling system. And with the lapse of time, troubles such as sand deposition on the roadbeds and erosion on roadsides came to surface and caused more serious problems for the traffic routes[1.2]. This paper discusses two forms of the sand-controlling system-the upright fence and the send-covered sand barrier, then analyzes the general benefits of the sandcontrolling system along the Desert Highway.
基金National Project for Basic Research, No.2002CB412507 National key project of fundamental research, No.G1999043500 National Natural Science Foundation of China, No.90202002
文摘Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.
基金sponsored as a sub-project of the National Key Research and Development Program of China-Desertification Land Management and Sand Industry Technology Research and Development and Demonstration in Inner Mongolia Desertification Area,named Key Techniques and Demonstration of Sand Damage Control in Oasis and Saline-alkali Lake(2016YFC0501003)Central Government’s Special Fund for Guiding Local Science and Technology Development:Inner Mongolia Desertification Control and Innovation Research Center
文摘Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to date.This research describes an oasis protective system in the southeastern border of the Tengger Desert.The system consists of a sand barrier belt,a shrub and herbaceous plant belt,and a farmland shelter belt.The system was compared to a bare dunes area as the control zone.The study investigated windproof effect,sediment transport,and erosion through field observations.Results showed that the roughness of the shrub and herbaceous plant belt,farmland shelter belt,and sand barrier belt were increased compared with bare dunes.The shrub and herbaceous plant belt provided the highest windproof effect values for the same wind velocity measurement height,and the windproof effect values for different protective belts were as follows:shrub and herbaceous plant belt>farmland shelter belt>sand barrier belt.The sand barrier belt provided effective wind and sand control at heights from 0 to 50 cm above the ground.The total sediment transport for each protective belt is as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.The sediment transport decreased exponentially as the height increased.In the bare dunes and protective systems,the sediment transport is mainly within 30 cm of the ground surface.The wind erosion intensity for this protective system was as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.This research offers quantitative evidence for how oasis protective systems can effectively intercept sand and prevent erosion in oases.The results of this study can be applied in similar regions.
基金funded by one of National Basic Research Program of China (No. 2013CB429903)National Natural Science Foundation of China (Grant Nos. 41201248 and 31170496)
文摘Shrub is an important factor on structuring ground arthropod communities in desert ecosystems. In this study, in order to determine how shrubs and their species influence ground arthropod distribution patterns in a sandy desert scrubland dominated by two different shrub species, Calligonum mongolicum and Nitraria sphaerocarpa, the ground arthropods were sampled with pitfall traps during spring, summer and autumn. At the community level, total arthropod abundance was shown to be significantly higher under shrubs than in intershrub bare areas in spring; similar patterns occurred in terms of the richness of arthropod groups in the spring and over three seasons, suggesting season-specific shrub presence effects on arthropod activity. In addition, more arthropods were found under N. sphaerocarpa shrubs than under C. rnongolicum shrubs in autumn, suggesting season-specific effects of shrub species of arthropod activity, whereas more arthropods taxa were captured under C. mongoIicum than N. sphaerocarpa. At the trophic group level, the abundances of predator and herbivore arthropods were significantly greater under shrubs than in intershrub bare habitats, whereas herbivore arthropods were more abundant under N. sphaerocarpa than C. rnongolicum, and an opposite rule was detected for predator arthropods At the family level, the mean abundances of Carabidae, Curculionidae, Gnaphosidae and Lycosidae were significantly higher in the shrub microhabitats than in the intershrub bare habitat, there was no significant difference between habitats on the mean abundances of Formicidae and Tenebrionidae. The study results suggested that shrub presence and shrub species variation are important determinants of ground arthropod assemblages in this desert ecosystem, but the responses of ar- thropods differed among trophic and taxonomic groups.
基金supported by the Joint Funds of National Natural Science Foundation of China (U1203201)the National Natural Science Foundation of China (41371516, 31100144)
文摘Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.
基金supported by Project in the National Science & Technology Pillar Program (2600BAD26B02-1)
文摘Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.
基金Sponsored by Scientific Research Program of National Forestry Public Welfare Trade(201504710)
文摘[Objective] To establish drought resistance evaluation index system of desert shrubs,and provide scientific support for selecting quality tree species.[Method] Taking 2-year-old seedlings of 12 desert shrubs in Ulan Buh Desert ecosystem as the test materials,7 water physiological indexes were tested,principal component analysis and cluster analysis were applied to explore drought resistance of the shrubs.[Results](a) Water potential of Ephedra distachya Linn.,Nitraia tangutorum Bobr.,Caragana korshinski Kom.was lower than that of the other 9 species;bound water content(V_a) and bound water/free water ratio(V_a/V_s) of Zygophyl um xanthoxylon Maxim.was 64.20% and 3.3,higher than the others';transpiration rate of Atraphaxis bracteata A.Los.,Nitraia tangutorum Bobr.and Tamarix elongata Ldb.was significantly lower than the others';constant weight time of Haloxylon ammodendron(C.A.Mey.) Bunge and Ephedra distachya Linn.was the longest(144 h);residual moisture content of Ammopiptanthus mongolicus Maxim.was the highest(44.80%).(b) Water potential,bound water/free water(V_a/V_s),residual moisture content,bound water,constant weight time,and transpiration rate had great impact on drought resistance of plant,and the accumulative variance contribution rate achieved 87.59%.[Conclusion] According to the drought resistance,the 12 species were classified into 3 categories,namely shrubs with strong drought resistance(Ephedra distachya Linn.),shrubs with moderate drought resistance(Haloxylon ammodendron(C.A.Mey.) Bunge,Nitraia tangutorum Bobr.,and Zygophyllum xanthoxylon Maxim.);shrubs with poor drought resistance(Hedysarunn scoparium Fisch,Hedysarum mongolicum Turcz.,Tamarix elongata Ldb.,Caragana korshinskii Kom.,Ammopiptanthus mongolicus Maxim.,Atraphaxis bracteata A.Los.,Cal igonum mongolicum Mattei.,and Caragana microphylla Lam.).
