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
This paper investigates the dry climatology of Sahara and Northwest China deserts from the viewpoint of local meridional circulation with Xie and Arkin rainfall dada and NCAR/NCEP reanalysis data. Results show that th...This paper investigates the dry climatology of Sahara and Northwest China deserts from the viewpoint of local meridional circulation with Xie and Arkin rainfall dada and NCAR/NCEP reanalysis data. Results show that there are very dry centers with annual rainfall less than 50 mm over these two deserts while the rainy seasons are very different. In the south part of Sahara desert center and Northwest China desert, over 70% rainfall takes place in June, July and August (JJA). While in the north part of Sahara, rainfall mainly concentrates in December, January and February (DJF). The local biosphere-radiation mechanism proposed by Charney cannot explain the climatology of such very dry centers. Neither can the monsoon-desert mechanism proposed by Rodwell and Hoskins do for the strongest descent center is much more northward than the driest center over Sahara in JJA. From the viewpoint of local meridional circulation, the dryness climatology of Sahara and Northwest China deserts is investigated and compared. It is shown that in DJF, descent of local meridional circulation dominates the two deserts and very dry climate is unavoidable although the relative wet season is weak over the northern part of Sahara due to Mediterranean climate. While in JJA, there is ascent over the two deserts especially over Northwest China. Such ascent can explain the rainy season in south part of Sahara and Northwest China deserts. However, it is the local meridional circulation that takes strong and dry northerly from higher latitudes. The northerly either takes little moisture to the centers or prevents deep and strong convection over the centers. Such local meridional circulation leads to the dry climatology over the two deserts.展开更多
The special issue deals with the Cretaceous-Tertiary deserts in southwestern China and relevant sedimentological problems about deserts. The study area is located between 101°10＇- 107°00＇E and 28°00＇...The special issue deals with the Cretaceous-Tertiary deserts in southwestern China and relevant sedimentological problems about deserts. The study area is located between 101°10＇- 107°00＇E and 28°00＇-30°40′ N. The ancient desert study is so little in China that there has not been a systematic report about it up to now. Based on the study in many ways on Cretaceous-Tertiary deserts in southwestern China, plentiful data have been obtained. Though it is still a bit rough, the study is a good beginning of the ancient desert study in China. The main ideas and conclusions are summarized as follows.展开更多
Jordan is blessed with shallow geothermal resources in NE and SE deserts. Jordanian deserts compose more than 70% of the country area. Furthermore, it’s the second vital area in fauna and flora variation after Jordan...Jordan is blessed with shallow geothermal resources in NE and SE deserts. Jordanian deserts compose more than 70% of the country area. Furthermore, it’s the second vital area in fauna and flora variation after Jordan valley. Geothermal gradient in this area shows high promising future potential. New renewable energy systems installation in Jordan will have a positive environmental and economic contribution to the national bill. Currently, limited geothermal utilizations were evaluated in the Jordanian deserts. Thermal waters in the deserts were used for irrigation only. Six different applications for direct and indirect geothermal applications in Jordanian deserts were suggested and evaluated. Ground source heat pumps for heating and cooling purposes and crops drying were expected to be the most appropriate applications of geothermal energy in the deserts. Geothermal utilizations were investigated regarding their probable impact on local and national economic scale. Therefore, an integrated plan for geothermal applications in Jordan is becoming very essential in the future. It has been found that geothermal energy in Jordanian deserts could be utilized for different applications. Despite of the potential political, technical and financial barriers, exploiting new geothermal utilization in the deserts will contribute to solving socio-economic and environmental problems challenging poor deserts areas.展开更多
Desertification is a global phenomenon that affects about two billion people. It occurs in arid zones where the annual precipitation is below 400 mm, partic- ularly in the marginal areas of the world＇s largest desert...Desertification is a global phenomenon that affects about two billion people. It occurs in arid zones where the annual precipitation is below 400 mm, partic- ularly in the marginal areas of the world＇s largest deserts. It is a result of water and wind erosion, over- grazing, global warm-ing, improper soil cultivation, and increased pressure ot population growth, and it causes degradation of soil and natural and agricultural vegetation. The direct result is less food for people and livestock, which influences pop- ulation and animal husbandry fluctuations. Despite ef- forts to combat and reduce desertification, the affected areas are annually increasing.展开更多
The Iraqi Western and Southern deserts are part of the Iraqi Stable Shelf (Inner Platform) that belongs to the Arabian Plate. Therefore, both deserts lack tectonic forms like folds and faults;however, very rarely faul...The Iraqi Western and Southern deserts are part of the Iraqi Stable Shelf (Inner Platform) that belongs to the Arabian Plate. Therefore, both deserts lack tectonic forms like folds and faults;however, very rarely faults and regional lineaments can be seen in both deserts. Although both deserts are tectonically stable, tens of Neotectonic indications can be seen everywhere in both deserts. Among those indications are: Straight valleys, perpendicular valley bendings, sinkholes aligned along straight lines, dislocated valleys, knickpoints within valleys aligned along straight lines, regional lineaments, anomalous valley shapes, trends, and types, dissected alluvial fans. We have used existing geological maps of different scales and Esri World Imagery to recognize those Neotectonic indications. All those recognized features are excellent indications that both the Iraqi Western and Southern deserts are tectonically not stable. Accordingly, new terminology is suggested instead of the Stable Shelf (Inner Platform) which is the “Less Disturbed Shelf”.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
Sediment transport of sand particles by wind is one of the main processes leading todesertification in arid regions, which severely impairs the ability of mankind to produce and live by driftingsand into settlements. ...Sediment transport of sand particles by wind is one of the main processes leading todesertification in arid regions, which severely impairs the ability of mankind to produce and live by driftingsand into settlements. Optimization designs of artificial facilities have lately attracted extensive interest forhuman settlement systems in deserts because of their acceptable protection effect, convenience ofimplementation, and low material cost. However, the complexity of a settlement system poses challengesconcerning finding suitable materials, artificial facilities, and optimization designs for sand depositionprotection. In an effort to overcome these challenges, we propose a settlement system built with brick, solarpanel, and building arrays to meet the basic needs of human settlements in arid regions while preventingwind-sand disasters. The wind flow and movement characteristics of sand particles in the brick, panel, andbuilding arrays were calculated using computational fluid dynamics and discrete phase model. Theperformance of three types of arrays in wind-sand flow in terms of decreasing the wind velocity and sandparticleinvasion distance was evaluated. The results show that the wind velocity near the surface and thesand invasion distance were significantly decreased in the space between the brick arrays through properlyselected vertical size and interspaces, indicating that the brick arrays have an impressive sand fixing andblocking performance;their effective protection distance was 3–4 m. The building arrays increased the nearsurfacewind velocity among buildings, resulting in less deposition of sand particles. The solar panel arrayswere similar to the building arrays in most cases, but the deposition of sand particles on solar panels exerteda negative effect on energy utilization efficiency. Therefore, taking the optimal configuration of thesettlement system into consideration, this study concludes that (1) brick arrays, which were proven effectivein preventing sand particles, must be arranged in an upwind area;(2) solar panel arrays could accelerate thewind flow, so they are best to be arranged at the place where sand particles deposited easily;and (3) buildingarrays present a better arrangement in downwind areas.展开更多
Sandy desert landscape is a geological product of arid climate and abundant sand materials supply in natural conditions, therefore the formation of sandy desert is an ideal studying object for understanding the intera...Sandy desert landscape is a geological product of arid climate and abundant sand materials supply in natural conditions, therefore the formation of sandy desert is an ideal studying object for understanding the interaction between various stratigraphic/epigenetic spheres of the earth system. However, until now, the knowledge about the provenance and formation of these deserts in Xinjiang, Central Asia is diverse and inconsistent, a systematic review is necessary. Ancient aeolian sand sediments in the internal areas of these deserts and their twin dust deposits in the Cenozoic strata surrounding the Xinjiang deserts are direct and indirect clues reflecting the provenance of sand materials and the formation and evolution of deserts. Based on the geochemical, mineralogical and isotopic evidences of desert sands and relevant deposits in the peripheral regions, this paper reviews the research progress on the development of the sandy deserts in Xinjiang, Northwest China. Many proofs proposed that desert sands in Xinjiang were mainly sourced from the ancient pluvial, alluvial and fluvial sediments and were eventually achieved because of the local sand supply. It pointed out that the settings of tectonic structure in Xinjiang had made sediments both in the Tarim Basin and the Junggar Basin being influenced greatly by regional hydrological system and aeolian processes originated from the planetary wind system of westerly, the East Asian winter monsoon and the topographical mountain-valley winds. However, the directions of transpor- tation paths are different between the hydrological dynamics and the aeolian dynamics, which are decided by the slantwise structures of the basins tectonics and the regional atmospheric circulation routes, respectively, and have determined anisotropies of the transport pathway of these sediments delivered by different agents. This results in a geological cycle of detrital sediment transportation in the two large sediment mixing, alternation and recycle basins and thus largely increases the degree of between younger and older sediment sources, as well as the complexity and diversity of sand provenances.展开更多
Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the r...Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the relationship between sandy desertification and surface characteristics in these regions are lacking. We monitored the surface characteristics and their changes in time using information about soil, vegetation, and landforms in the Badain Jaran Desert(BJD), Tengger Desert(TD), and Ulan Buh Desert(UBD) in the northern China. The monitoring was done using tasseled cap angle(TCA), disturbance index(DI), and topsoil grain size index(TGSI) from Moderate Resolution Imaging Spectroradiometer(MODIS) images combined with a decision tree classification. Results showed that the TD had higher topsoil fine sand content, and the ratio of non-vegetated to vegetated areas was similar with that in the UBD. Northeast-southwest coarse sand dunes with thin interdune(NECTI) dominated the BD, fine sand dunes(FSD) dominated the TD, and a combination of northeast-southwest coarse sand dunes with wide interdune(NECWI) and northwest-southeast coarse sand dunes with wide interdune(NWCWI) dominated the UBD. From 2000 to 2015, in the BJD the area of the NECTI, non-sand dune(Non) and potential sand sources(PSS) increased, whereas the area of the NECWI, FSD and NWCWI decreased, indicating a improve process in the BJD. In the TD, the area covered by Non increased, whereas the area covered by PSS, NECWI, NECTI, FSD, and NWCWI decreased from 2000 to 2015. The area covered by the various surface characteristic types fluctuated annually in the UBD from 2000 to 2015. Changes in surface characteristics reflect the combined effects of natural conditions and human activity. The findings of our study will assist scientists and policy makers in proposing different management techniques to combat sandy desertification for the different surface characteristics of these regions.展开更多
The present paper reconstructs the biogeographic diversification for Nolana L.f. （Solanaceae）, a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Pre...The present paper reconstructs the biogeographic diversification for Nolana L.f. （Solanaceae）, a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate for Nolana using a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns. Nolana occupies habitats within a continuous coastal desert and forms a terrestrial archipelago of discrete ＂islands＂ unique in size, topography, and species composition. Each locality contains at least one Nolana species and many contain multiple species in sympatry. The genus has a Chilean origin, with the basal clades confined to Chile with wide geographic and ecological distributions. Peru contains two strongly supported clades, suggesting two introductions with subsequent radiation. A Chilean clade of shrubby, small-flowered species appears to have had its origins from the same ancestors of the second line that radiated in Peru and northern Chile. Nolana galapagensis is endemic to the Islas Galapagos, with origins traced to Peruvian taxa with a divergence time of 0.35 mya. Rates of diversification over the past 4.02 mya in Nolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success in Nolana may be attributed to characters that confer a competitive advantage in unpredictable and water-dependent environments, such as succulent leaf anatomy and ecophysiology, and the reproductive mericarp unique to Nolana. The processes affecting or shaping the biota of western South America are discussed.展开更多
Based on the palaeoclimatic and palaeoenvironmental evidences of geological history and human history periods, this paper reviews the researches and progresses on the development of the sandy deserts in Xinjiang. It p...Based on the palaeoclimatic and palaeoenvironmental evidences of geological history and human history periods, this paper reviews the researches and progresses on the development of the sandy deserts in Xinjiang. It pointed out that the features of tectonic structure in Xinjiang had made both the Tarim Basin and the Junggar Basin being influenced greatly by the foehn effects originated from the planetary wind system of westerly, the East Asian ocean-continental monsoon and the topographical mountain-valley winds. The regional patterns of climate and environment since the Quaternary were characterized by the overall persistent drought accompanied by fluctuations in the secondary scale. Formations of aeolian sediments in the basins and at the margins are a potential response to global climate change, particularly the aridification of the Asian hinterland deduced by the uprising of the Tibetan Plateau and its surrounding highlands. For the question about the formation time of the Tak- lamakan Desert, because the research methods, objects and information carriers used in previous studies are different, there are many disputes in the academic circles at present. Evidences from aeolian deposits/rocks at the edge and in the hinterland of these sandy de- serts and their chronological data indicate that an arid climate and land surface aeolian processes have occurred at the edge of the Tarim Basin and its hinterland areas since the Tertiary period. However, the duration time of these processes at mass scale should have begun after the middle Pleistocene and lasted to the Holocene. Occurrence of dune fields in recent 2000 years in the oasis areas should be greatly influenced by human factors.展开更多
Two new species of the genus Anatolica Eschscholtz,1831,A.badainica Ba,Ren&Liu sp.nov.and A.gurbantunggutica Ba&Ren sp.nov.,are reported from the deserts of northwest China.Both are described and illustrated.T...Two new species of the genus Anatolica Eschscholtz,1831,A.badainica Ba,Ren&Liu sp.nov.and A.gurbantunggutica Ba&Ren sp.nov.,are reported from the deserts of northwest China.Both are described and illustrated.The circadian rhythms of these two new species are briefly discussed.展开更多
Rivers in deserts present unique geographical features owing to aeolian-fluvial interactions.In this study,510 surface sediment samples were gathered from eight watersheds to systematically examine the major element c...Rivers in deserts present unique geographical features owing to aeolian-fluvial interactions.In this study,510 surface sediment samples were gathered from eight watersheds to systematically examine the major element characteristics of riparian sand dunes in northern China deserts.The findings revealed that these dunes could be categorized into three primary zones:Type I,comprising Keriya,Tora,Heihe,and Langqu rivers in the west;TypeⅡ,featuring the Maquan River in the Tibetan Plateau;and TypeⅢ,including Mu Bulag,Kuye,and Xar Moron rivers in the east.Specifically,the TypeⅢregion is characterized by a limited fresh material supply,a relatively high Chemical Index of Alteration(CIA),and the influence of nearby rivers on the provenance of riparian dunes,leading to a higher degree of chemical weathering than that of TypeⅠin the west.Notably,TypeⅡis marked by weak-moderate chemical weathering degree and a comparatively higher CIA value.These classifications and their difference of degree of chemical weathering are possibly governed by the type of parent rock and the availability of material.This research offers new insights into the classification of riparian dunes impacted by aeolian-fluvial interactions in arid regions of the northern China deserts.Furthermore,it provides valuable implications for studies focusing on the provenance of sediments.展开更多
The method was developed for a Range Management Handbook of Kenya and the pre-liminary results published 1991. Now it is improved to a stage ready for international discus-sion.1. Main moisture Zones are defined by a ...The method was developed for a Range Management Handbook of Kenya and the pre-liminary results published 1991. Now it is improved to a stage ready for international discus-sion.1. Main moisture Zones are defined by a specified sum of monthly moistureindices:展开更多
Heteroptera is an important group among the insect orders,not only for its number of species,but also for its distribution and food preference.A total of 405 species of Heteroptera were identified in the desert areas ...Heteroptera is an important group among the insect orders,not only for its number of species,but also for its distribution and food preference.A total of 405 species of Heteroptera were identified in the desert areas of Kazakhstan,in which 158 species are distributed in the sandy deserts,105 species in the Solonchak deserts,75 species in the clay deserts,and 67 species in the rocky-rubbly deserts.展开更多
Hot arid zones represent vital reservoirs of unique species and ecosystems,holding significant importance for biodiversity.This study aimed to explore the plant diversity associated with tree plantations in urban ecos...Hot arid zones represent vital reservoirs of unique species and ecosystems,holding significant importance for biodiversity.This study aimed to explore the plant diversity associated with tree plantations in urban ecosystems under hyper-arid climatic conditions in the Sahara Desert of Algeria.In May 2022,30 quadrats measuring 1 m^(2) each were established at the base of Phoenix dactylifera,Leucaena leucocephala,and Tamarix aphylla,corresponding to the dominant tree species in each of three plantations.In each quadrat,the plant quantitative inventory was conducted to measure plant diversity and similarity among the studied plantations.Based on this,we assessed the plant functional traits and rarity/abundance status of the flora.The findings revealed a diverse flora associated with the studied plantations,comprising 29 plant species grouped into 27 genera and 12 families.Notably,Poaceae(accounting for 30.8% of the flora),Asteraceae(25.0%),and Zygophyllaceae(21.6%)were well-represented.With an overall density of approximately 555 individuals/m^(2),Zygophyllum album(120 individuals/m^(2))and Polypogon monspeliensis(87 individuals/m^(2))emerged as the most abundant species.Functional trait analysis underscored the pivotal role of therophytes(constituting over 50.0% of the flora)and anemochorous species(33.0%-62.5%).Phytogeographic analysis emphasized the prevalence of the Saharo-Arabic element(constituting over 31.0% of the flora)and the Mediterranean Saharo-Arabic element(9.5%-21.5%).The Cosmopolitan element thrived under disturbance factors,recording percentages from 13.0% to 20.0% of the plant community.The rarity/abundance status of the flora emphasized the significance of rare,common,and very common species in the studied plantations.These findings could provide fundamental data for the effective control and management of biodiversity in hot hyper-arid urban ecosystems.展开更多
The study of seed dispersal,biotic seed dispersal,and even less,the role of birds in it,have been almost neglected in deserts.Virtually absent from the literature on seed dispersal are the ground-jays,genus Podoces,fo...The study of seed dispersal,biotic seed dispersal,and even less,the role of birds in it,have been almost neglected in deserts.Virtually absent from the literature on seed dispersal are the ground-jays,genus Podoces,four species of the crow family that inhabit arid environments,even true deserts,from Iran to Mongolia.Although they are omnivorous,they seem to mainly depend on the seeds of desert plants during the cold season.There are suggestions in sparse literature that they may contribute to seed dispersal similarly to several corvid species of other climates,by caching seeds in useful microsites to save them for later consumption and thus actually favoring the germination of the seeds they fail to recover.Future research might benefit from comparison with the vast literature on their better-known seed-caching relatives.This paper is aimed at providing basic information on each ground-jay species and some sug-gestions for investigating their likely symbiosis with desert plants,with possible applications to the maintenance and restoration of vegetation in a very extended arid zone.展开更多
According to the bioclimatic zones, dune mobility and the fabric characteristics of stratigraphic sedimentary facies, the deserts in China are divided into Eastern, Western, Central and Northwestern deserts. Based on ...According to the bioclimatic zones, dune mobility and the fabric characteristics of stratigraphic sedimentary facies, the deserts in China are divided into Eastern, Western, Central and Northwestern deserts. Based on the records of stratigraphical facies, climatic proxies, historical data, etc. in each desert region, the evolution of deserts with climatic changes in time and space since 150 ka B. P. in China are dealt with; then the evolution of deserts in relation to the glacial climatic fluctuations caused by solar radiation changes, underlying surface variation and their feedback mechanism is discussed through comparison with global records; finally, in consideration of global wanning due to increasing of greenhouse gases such as CO2, the possible tendency of the evolution of deserts and the climatic changes is discussed.展开更多
Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the pe...Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the performance of composite shelterbelts that integrate C.esculentus.This study systematically evaluated five shelterbelt models—Populus euphratica(P.euphratica),P.euphratica–C.esculentus composite,P.euphratica–nylon net–C.esculentus composite,Tamarix chinensis(T.chinensis),and T.chinensis–C.esculentus composite—using wind tunnel experiments and field observations.Sediment flux was measured at a normalized downwind distance(x/h)of 5,where x refers to the distance from the front edge(upwind side)of the shelterbelt for upwind measurements,and the distance from the rear edge(downwind side)for downwind measurements,and h represents the canopy height.Wind velocity was measured at x/h of–2,–1,1,2,3,5,and 7,and sand flux was measured at x/h=5,under initial wind velocities of 8.0 and 12.0 m/s.The results indicated that the P.euphratica–nylon net–C.esculentus composite was the most effective in reducing wind velocity,followed by the P.euphratica–C.esculentus composite.In contrast,the P.euphratica and T.chinensis exhibited relatively weaker wind reduction capabilities.Regarding sand flux,under moderate wind velocity(8.0 m/s),both the P.euphratica–C.esculentus composite and P.euphratica–nylon net–C.esculentus composite demonstrated the lowest sand flux values.However,under high wind velocity(12.0 m/s),the P.euphratica–nylon net–C.esculentus composite significantly outperformed the other shelterbelt models in sand retention,highlighting its superior windbreak and sand fixation efficacy.Field observations further validated the windbreak and sand fixation effects of C.esculentus.Comparisons between the bare sand plot and C.esculentus plot within protective forests demonstrated that planting C.esculentus can provide substantial ecological benefits in windbreak and sand-fixation.These findings,reinforced by field observations,strengthen the wind tunnel experiment results and highlight the critical role of C.esculentus in enhancing the performance of composite shelterbelts for desert ecological restoration.展开更多
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This study was supported by the National Key Programme for Developing Basic Sciences underGrant No. G1998040900-Part 1, and NS
文摘This paper investigates the dry climatology of Sahara and Northwest China deserts from the viewpoint of local meridional circulation with Xie and Arkin rainfall dada and NCAR/NCEP reanalysis data. Results show that there are very dry centers with annual rainfall less than 50 mm over these two deserts while the rainy seasons are very different. In the south part of Sahara desert center and Northwest China desert, over 70% rainfall takes place in June, July and August (JJA). While in the north part of Sahara, rainfall mainly concentrates in December, January and February (DJF). The local biosphere-radiation mechanism proposed by Charney cannot explain the climatology of such very dry centers. Neither can the monsoon-desert mechanism proposed by Rodwell and Hoskins do for the strongest descent center is much more northward than the driest center over Sahara in JJA. From the viewpoint of local meridional circulation, the dryness climatology of Sahara and Northwest China deserts is investigated and compared. It is shown that in DJF, descent of local meridional circulation dominates the two deserts and very dry climate is unavoidable although the relative wet season is weak over the northern part of Sahara due to Mediterranean climate. While in JJA, there is ascent over the two deserts especially over Northwest China. Such ascent can explain the rainy season in south part of Sahara and Northwest China deserts. However, it is the local meridional circulation that takes strong and dry northerly from higher latitudes. The northerly either takes little moisture to the centers or prevents deep and strong convection over the centers. Such local meridional circulation leads to the dry climatology over the two deserts.
文摘The special issue deals with the Cretaceous-Tertiary deserts in southwestern China and relevant sedimentological problems about deserts. The study area is located between 101°10＇- 107°00＇E and 28°00＇-30°40′ N. The ancient desert study is so little in China that there has not been a systematic report about it up to now. Based on the study in many ways on Cretaceous-Tertiary deserts in southwestern China, plentiful data have been obtained. Though it is still a bit rough, the study is a good beginning of the ancient desert study in China. The main ideas and conclusions are summarized as follows.
文摘Jordan is blessed with shallow geothermal resources in NE and SE deserts. Jordanian deserts compose more than 70% of the country area. Furthermore, it’s the second vital area in fauna and flora variation after Jordan valley. Geothermal gradient in this area shows high promising future potential. New renewable energy systems installation in Jordan will have a positive environmental and economic contribution to the national bill. Currently, limited geothermal utilizations were evaluated in the Jordanian deserts. Thermal waters in the deserts were used for irrigation only. Six different applications for direct and indirect geothermal applications in Jordanian deserts were suggested and evaluated. Ground source heat pumps for heating and cooling purposes and crops drying were expected to be the most appropriate applications of geothermal energy in the deserts. Geothermal utilizations were investigated regarding their probable impact on local and national economic scale. Therefore, an integrated plan for geothermal applications in Jordan is becoming very essential in the future. It has been found that geothermal energy in Jordanian deserts could be utilized for different applications. Despite of the potential political, technical and financial barriers, exploiting new geothermal utilization in the deserts will contribute to solving socio-economic and environmental problems challenging poor deserts areas.
文摘Desertification is a global phenomenon that affects about two billion people. It occurs in arid zones where the annual precipitation is below 400 mm, partic- ularly in the marginal areas of the world＇s largest deserts. It is a result of water and wind erosion, over- grazing, global warm-ing, improper soil cultivation, and increased pressure ot population growth, and it causes degradation of soil and natural and agricultural vegetation. The direct result is less food for people and livestock, which influences pop- ulation and animal husbandry fluctuations. Despite ef- forts to combat and reduce desertification, the affected areas are annually increasing.
文摘The Iraqi Western and Southern deserts are part of the Iraqi Stable Shelf (Inner Platform) that belongs to the Arabian Plate. Therefore, both deserts lack tectonic forms like folds and faults;however, very rarely faults and regional lineaments can be seen in both deserts. Although both deserts are tectonically stable, tens of Neotectonic indications can be seen everywhere in both deserts. Among those indications are: Straight valleys, perpendicular valley bendings, sinkholes aligned along straight lines, dislocated valleys, knickpoints within valleys aligned along straight lines, regional lineaments, anomalous valley shapes, trends, and types, dissected alluvial fans. We have used existing geological maps of different scales and Esri World Imagery to recognize those Neotectonic indications. All those recognized features are excellent indications that both the Iraqi Western and Southern deserts are tectonically not stable. Accordingly, new terminology is suggested instead of the Stable Shelf (Inner Platform) which is the “Less Disturbed Shelf”.
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This research was supported by the National Natural Science Foundation of China(11772143,11702163,41730644)the National Key Research and Development Program of China(2016YFC0500901).
文摘Sediment transport of sand particles by wind is one of the main processes leading todesertification in arid regions, which severely impairs the ability of mankind to produce and live by driftingsand into settlements. Optimization designs of artificial facilities have lately attracted extensive interest forhuman settlement systems in deserts because of their acceptable protection effect, convenience ofimplementation, and low material cost. However, the complexity of a settlement system poses challengesconcerning finding suitable materials, artificial facilities, and optimization designs for sand depositionprotection. In an effort to overcome these challenges, we propose a settlement system built with brick, solarpanel, and building arrays to meet the basic needs of human settlements in arid regions while preventingwind-sand disasters. The wind flow and movement characteristics of sand particles in the brick, panel, andbuilding arrays were calculated using computational fluid dynamics and discrete phase model. Theperformance of three types of arrays in wind-sand flow in terms of decreasing the wind velocity and sandparticleinvasion distance was evaluated. The results show that the wind velocity near the surface and thesand invasion distance were significantly decreased in the space between the brick arrays through properlyselected vertical size and interspaces, indicating that the brick arrays have an impressive sand fixing andblocking performance;their effective protection distance was 3–4 m. The building arrays increased the nearsurfacewind velocity among buildings, resulting in less deposition of sand particles. The solar panel arrayswere similar to the building arrays in most cases, but the deposition of sand particles on solar panels exerteda negative effect on energy utilization efficiency. Therefore, taking the optimal configuration of thesettlement system into consideration, this study concludes that (1) brick arrays, which were proven effectivein preventing sand particles, must be arranged in an upwind area;(2) solar panel arrays could accelerate thewind flow, so they are best to be arranged at the place where sand particles deposited easily;and (3) buildingarrays present a better arrangement in downwind areas.
基金National Basic Research Program of China （973 Program）, No.2009CB421305 National Natural Science Foundation of China, No.91025023+1 种基金 No.41371060 No.41271049
文摘Sandy desert landscape is a geological product of arid climate and abundant sand materials supply in natural conditions, therefore the formation of sandy desert is an ideal studying object for understanding the interaction between various stratigraphic/epigenetic spheres of the earth system. However, until now, the knowledge about the provenance and formation of these deserts in Xinjiang, Central Asia is diverse and inconsistent, a systematic review is necessary. Ancient aeolian sand sediments in the internal areas of these deserts and their twin dust deposits in the Cenozoic strata surrounding the Xinjiang deserts are direct and indirect clues reflecting the provenance of sand materials and the formation and evolution of deserts. Based on the geochemical, mineralogical and isotopic evidences of desert sands and relevant deposits in the peripheral regions, this paper reviews the research progress on the development of the sandy deserts in Xinjiang, Northwest China. Many proofs proposed that desert sands in Xinjiang were mainly sourced from the ancient pluvial, alluvial and fluvial sediments and were eventually achieved because of the local sand supply. It pointed out that the settings of tectonic structure in Xinjiang had made sediments both in the Tarim Basin and the Junggar Basin being influenced greatly by regional hydrological system and aeolian processes originated from the planetary wind system of westerly, the East Asian winter monsoon and the topographical mountain-valley winds. However, the directions of transpor- tation paths are different between the hydrological dynamics and the aeolian dynamics, which are decided by the slantwise structures of the basins tectonics and the regional atmospheric circulation routes, respectively, and have determined anisotropies of the transport pathway of these sediments delivered by different agents. This results in a geological cycle of detrital sediment transportation in the two large sediment mixing, alternation and recycle basins and thus largely increases the degree of between younger and older sediment sources, as well as the complexity and diversity of sand provenances.
基金Innovation Project of LREIS(No.O88RA20CYA,08R8A010YA)National Natural Science Foundation of China(No.41671422)International Cooperation in Science and Technology Special Project(No.2013DFA91700)
文摘Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the relationship between sandy desertification and surface characteristics in these regions are lacking. We monitored the surface characteristics and their changes in time using information about soil, vegetation, and landforms in the Badain Jaran Desert(BJD), Tengger Desert(TD), and Ulan Buh Desert(UBD) in the northern China. The monitoring was done using tasseled cap angle(TCA), disturbance index(DI), and topsoil grain size index(TGSI) from Moderate Resolution Imaging Spectroradiometer(MODIS) images combined with a decision tree classification. Results showed that the TD had higher topsoil fine sand content, and the ratio of non-vegetated to vegetated areas was similar with that in the UBD. Northeast-southwest coarse sand dunes with thin interdune(NECTI) dominated the BD, fine sand dunes(FSD) dominated the TD, and a combination of northeast-southwest coarse sand dunes with wide interdune(NECWI) and northwest-southeast coarse sand dunes with wide interdune(NWCWI) dominated the UBD. From 2000 to 2015, in the BJD the area of the NECTI, non-sand dune(Non) and potential sand sources(PSS) increased, whereas the area of the NECWI, FSD and NWCWI decreased, indicating a improve process in the BJD. In the TD, the area covered by Non increased, whereas the area covered by PSS, NECWI, NECTI, FSD, and NWCWI decreased from 2000 to 2015. The area covered by the various surface characteristic types fluctuated annually in the UBD from 2000 to 2015. Changes in surface characteristics reflect the combined effects of natural conditions and human activity. The findings of our study will assist scientists and policy makers in proposing different management techniques to combat sandy desertification for the different surface characteristics of these regions.
基金supported,in part,by grants to MOD from the National Science Foundation (DEB 0415573,DEB 9801297,DEB 8513205)
文摘The present paper reconstructs the biogeographic diversification for Nolana L.f. （Solanaceae）, a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate for Nolana using a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns. Nolana occupies habitats within a continuous coastal desert and forms a terrestrial archipelago of discrete ＂islands＂ unique in size, topography, and species composition. Each locality contains at least one Nolana species and many contain multiple species in sympatry. The genus has a Chilean origin, with the basal clades confined to Chile with wide geographic and ecological distributions. Peru contains two strongly supported clades, suggesting two introductions with subsequent radiation. A Chilean clade of shrubby, small-flowered species appears to have had its origins from the same ancestors of the second line that radiated in Peru and northern Chile. Nolana galapagensis is endemic to the Islas Galapagos, with origins traced to Peruvian taxa with a divergence time of 0.35 mya. Rates of diversification over the past 4.02 mya in Nolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success in Nolana may be attributed to characters that confer a competitive advantage in unpredictable and water-dependent environments, such as succulent leaf anatomy and ecophysiology, and the reproductive mericarp unique to Nolana. The processes affecting or shaping the biota of western South America are discussed.
基金National Basic Research Program of China(973 Program),No.2009CB421305National Natural Science Foundation of China,No.41371060,No.41271049
文摘Based on the palaeoclimatic and palaeoenvironmental evidences of geological history and human history periods, this paper reviews the researches and progresses on the development of the sandy deserts in Xinjiang. It pointed out that the features of tectonic structure in Xinjiang had made both the Tarim Basin and the Junggar Basin being influenced greatly by the foehn effects originated from the planetary wind system of westerly, the East Asian ocean-continental monsoon and the topographical mountain-valley winds. The regional patterns of climate and environment since the Quaternary were characterized by the overall persistent drought accompanied by fluctuations in the secondary scale. Formations of aeolian sediments in the basins and at the margins are a potential response to global climate change, particularly the aridification of the Asian hinterland deduced by the uprising of the Tibetan Plateau and its surrounding highlands. For the question about the formation time of the Tak- lamakan Desert, because the research methods, objects and information carriers used in previous studies are different, there are many disputes in the academic circles at present. Evidences from aeolian deposits/rocks at the edge and in the hinterland of these sandy de- serts and their chronological data indicate that an arid climate and land surface aeolian processes have occurred at the edge of the Tarim Basin and its hinterland areas since the Tertiary period. However, the duration time of these processes at mass scale should have begun after the middle Pleistocene and lasted to the Holocene. Occurrence of dune fields in recent 2000 years in the oasis areas should be greatly influenced by human factors.
基金supported by the National Natural Science Foundation of China(31750002,41771290)。
文摘Two new species of the genus Anatolica Eschscholtz,1831,A.badainica Ba,Ren&Liu sp.nov.and A.gurbantunggutica Ba&Ren sp.nov.,are reported from the deserts of northwest China.Both are described and illustrated.The circadian rhythms of these two new species are briefly discussed.
基金National Natural Science Foundation of China,No.41871010,No.41901094,No.41801004The Second Comprehensive Scientific Expedition to the Qinghai-Tibet Plateau,No.2019QZKK0906。
文摘Rivers in deserts present unique geographical features owing to aeolian-fluvial interactions.In this study,510 surface sediment samples were gathered from eight watersheds to systematically examine the major element characteristics of riparian sand dunes in northern China deserts.The findings revealed that these dunes could be categorized into three primary zones:Type I,comprising Keriya,Tora,Heihe,and Langqu rivers in the west;TypeⅡ,featuring the Maquan River in the Tibetan Plateau;and TypeⅢ,including Mu Bulag,Kuye,and Xar Moron rivers in the east.Specifically,the TypeⅢregion is characterized by a limited fresh material supply,a relatively high Chemical Index of Alteration(CIA),and the influence of nearby rivers on the provenance of riparian dunes,leading to a higher degree of chemical weathering than that of TypeⅠin the west.Notably,TypeⅡis marked by weak-moderate chemical weathering degree and a comparatively higher CIA value.These classifications and their difference of degree of chemical weathering are possibly governed by the type of parent rock and the availability of material.This research offers new insights into the classification of riparian dunes impacted by aeolian-fluvial interactions in arid regions of the northern China deserts.Furthermore,it provides valuable implications for studies focusing on the provenance of sediments.
文摘The method was developed for a Range Management Handbook of Kenya and the pre-liminary results published 1991. Now it is improved to a stage ready for international discus-sion.1. Main moisture Zones are defined by a specified sum of monthly moistureindices:
文摘Heteroptera is an important group among the insect orders,not only for its number of species,but also for its distribution and food preference.A total of 405 species of Heteroptera were identified in the desert areas of Kazakhstan,in which 158 species are distributed in the sandy deserts,105 species in the Solonchak deserts,75 species in the clay deserts,and 67 species in the rocky-rubbly deserts.
文摘Hot arid zones represent vital reservoirs of unique species and ecosystems,holding significant importance for biodiversity.This study aimed to explore the plant diversity associated with tree plantations in urban ecosystems under hyper-arid climatic conditions in the Sahara Desert of Algeria.In May 2022,30 quadrats measuring 1 m^(2) each were established at the base of Phoenix dactylifera,Leucaena leucocephala,and Tamarix aphylla,corresponding to the dominant tree species in each of three plantations.In each quadrat,the plant quantitative inventory was conducted to measure plant diversity and similarity among the studied plantations.Based on this,we assessed the plant functional traits and rarity/abundance status of the flora.The findings revealed a diverse flora associated with the studied plantations,comprising 29 plant species grouped into 27 genera and 12 families.Notably,Poaceae(accounting for 30.8% of the flora),Asteraceae(25.0%),and Zygophyllaceae(21.6%)were well-represented.With an overall density of approximately 555 individuals/m^(2),Zygophyllum album(120 individuals/m^(2))and Polypogon monspeliensis(87 individuals/m^(2))emerged as the most abundant species.Functional trait analysis underscored the pivotal role of therophytes(constituting over 50.0% of the flora)and anemochorous species(33.0%-62.5%).Phytogeographic analysis emphasized the prevalence of the Saharo-Arabic element(constituting over 31.0% of the flora)and the Mediterranean Saharo-Arabic element(9.5%-21.5%).The Cosmopolitan element thrived under disturbance factors,recording percentages from 13.0% to 20.0% of the plant community.The rarity/abundance status of the flora emphasized the significance of rare,common,and very common species in the studied plantations.These findings could provide fundamental data for the effective control and management of biodiversity in hot hyper-arid urban ecosystems.
文摘The study of seed dispersal,biotic seed dispersal,and even less,the role of birds in it,have been almost neglected in deserts.Virtually absent from the literature on seed dispersal are the ground-jays,genus Podoces,four species of the crow family that inhabit arid environments,even true deserts,from Iran to Mongolia.Although they are omnivorous,they seem to mainly depend on the seeds of desert plants during the cold season.There are suggestions in sparse literature that they may contribute to seed dispersal similarly to several corvid species of other climates,by caching seeds in useful microsites to save them for later consumption and thus actually favoring the germination of the seeds they fail to recover.Future research might benefit from comparison with the vast literature on their better-known seed-caching relatives.This paper is aimed at providing basic information on each ground-jay species and some sug-gestions for investigating their likely symbiosis with desert plants,with possible applications to the maintenance and restoration of vegetation in a very extended arid zone.
文摘According to the bioclimatic zones, dune mobility and the fabric characteristics of stratigraphic sedimentary facies, the deserts in China are divided into Eastern, Western, Central and Northwestern deserts. Based on the records of stratigraphical facies, climatic proxies, historical data, etc. in each desert region, the evolution of deserts with climatic changes in time and space since 150 ka B. P. in China are dealt with; then the evolution of deserts in relation to the glacial climatic fluctuations caused by solar radiation changes, underlying surface variation and their feedback mechanism is discussed through comparison with global records; finally, in consideration of global wanning due to increasing of greenhouse gases such as CO2, the possible tendency of the evolution of deserts and the climatic changes is discussed.
基金supported by the Xinjiang Key Research and Development Programme Project(2022B02040-2)the Tianshan Yingcai Program of Xinjiang Uygur Autonomous Region(2024TSYCLJ0028).
文摘Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the performance of composite shelterbelts that integrate C.esculentus.This study systematically evaluated five shelterbelt models—Populus euphratica(P.euphratica),P.euphratica–C.esculentus composite,P.euphratica–nylon net–C.esculentus composite,Tamarix chinensis(T.chinensis),and T.chinensis–C.esculentus composite—using wind tunnel experiments and field observations.Sediment flux was measured at a normalized downwind distance(x/h)of 5,where x refers to the distance from the front edge(upwind side)of the shelterbelt for upwind measurements,and the distance from the rear edge(downwind side)for downwind measurements,and h represents the canopy height.Wind velocity was measured at x/h of–2,–1,1,2,3,5,and 7,and sand flux was measured at x/h=5,under initial wind velocities of 8.0 and 12.0 m/s.The results indicated that the P.euphratica–nylon net–C.esculentus composite was the most effective in reducing wind velocity,followed by the P.euphratica–C.esculentus composite.In contrast,the P.euphratica and T.chinensis exhibited relatively weaker wind reduction capabilities.Regarding sand flux,under moderate wind velocity(8.0 m/s),both the P.euphratica–C.esculentus composite and P.euphratica–nylon net–C.esculentus composite demonstrated the lowest sand flux values.However,under high wind velocity(12.0 m/s),the P.euphratica–nylon net–C.esculentus composite significantly outperformed the other shelterbelt models in sand retention,highlighting its superior windbreak and sand fixation efficacy.Field observations further validated the windbreak and sand fixation effects of C.esculentus.Comparisons between the bare sand plot and C.esculentus plot within protective forests demonstrated that planting C.esculentus can provide substantial ecological benefits in windbreak and sand-fixation.These findings,reinforced by field observations,strengthen the wind tunnel experiment results and highlight the critical role of C.esculentus in enhancing the performance of composite shelterbelts for desert ecological restoration.
