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

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

10Be in quartz gravel from the Gobi Desert and evolutionary history of alluvial sedimentation in the Ejina Basin,Inner Mongolia,China

Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate. However, such work is limited by a lack of suitable dating material preserved in the Gobi Desert, but cosmogenic ¹⁰Be has great potential to date the Gobi deserts. In the present study, ¹⁰Be in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages. Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago, whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka. The latter developed gradually northward and eastward to modern terminal lakes of the river. These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin. Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin. Intense floods and large water volumes would mainly occur during the short deglacial periods.     

Landscape evolution and palaeoclimate in the deserts of northwestern China, with a special reference to Badain Jaran and Taklamakan

A comparative study of geomorphologic landscapes in the Badain Jaran Desert and Taklamakan Desert was made on the basis of field investigations, thermolumi-niscence and radiocarbon dating as well as analysis of sand grain texture. The sand seas of the Badain Jaran Desert differ greatly from that of the Taklamakan Desert in terms of dune morphology, interdune relief, dune stratigraphy and sand sources. The thermoluminiscence ages of the dunes suggest that the basic configuration of the megadunes in the Badain Jaran Desert has not changed at least since Middle Holocene. There were periods of more humid environment during the last glaciation and Holocene in both deserts, but events of higher precipitation in the Badain Jaran Desert were more frequent than in the Taklamakan. In both desert areas, aeolian processes have been intensified during the last 2000 a.     

远源地下水入侵阿拉善高原沙漠:酸溶物Sr同位素证据

选取北方西－东向气候剖面上物质组成相似的四个沙漠（塔克拉玛干、巴丹吉林、腾格里和毛乌素）,测定其地表沙酸溶物87Sr/86Sr比值、Ca2+和Sr2+浓度。Ca2+和Sr2+浓度相关性极好,在降雨量低的塔克拉玛干沙漠中最高,向东逐渐降低,在降雨量多的毛乌素沙漠中最低。降雨量是控制阳离子浓度变化的主导因素。酸溶物87Sr/86Sr比值在四个沙漠中有不同于阳离子变化的区域特征。塔克拉玛干沙漠酸溶物87Sr/86Sr比值在0.71以下,巴丹吉林和腾格里沙漠的大于0.7112,而毛乌素沙漠的在0.71-0.7112之间变化。塔克拉玛干和毛乌素沙漠地表沙酸溶物87Sr/86Sr比值仅受气候变化的制约。巴丹吉林和腾格里沙漠除了受气候因素影响外还受其它因素的制约,最可能的就是远源地下水。经计算,远源地下水对巴丹吉林沙漠的影响份额为47%,对腾格里沙漠为44%,接近气候因素的影响。     

巴丹吉林沙漠沉积物的地球化学特征

在第四纪沉积物研究中,特别是现代沉积环境的研究中,沉积物的地球化学特征在分析物源和重建古环境等方面发挥积极的作用.通过采集了巴丹吉林沙漠不同区域、不同类型沙丘、不同地貌部位的沙样,分析了巴丹吉林沙漠沉积物的地球化学特征,得出巴丹吉林沙漠沉积物在矿物学上和沉积学上的成熟度较低,但是具有很好的均质性的结论.这一结论对于推断巴丹吉林沙漠沉积物的物源有很好的指示意义,同时对于研究巴丹吉林沙漠高大沙山的成因也有一定的线索意义.     

The microstructure and formation of biological soil crusts in their early developmental stage

Biological soil crust is a complex organic integrity ofcyanobacteria, green algae, lichens and mosses, fungi, andother bacteria. This is a common phenomenon in desertareas all over the world. Biologically, this kind of crustdiffers a lot from physical soi…     

从晚更新世以来我国沙漠的变迁看干旱区沙漠化问题

通过野外调查研究,作者提出我国东部干旱地区的沙漠早在有史记载以前的第四纪地质时期就已存在.晚更新世以来沙漠几经流沙(?)半固定、固定沙丘一系列正、逆变迁过程.人类历史时期以来出现的沙漠化,只是沙漠长期演变过程最近经历的一个发展阶段;沙漠化是自然因素和人为因素共同作用的结果,且总的看来,自然因素是第一位的.在全国干旱—半干旱区范围内沙漠的变迁和沙漠化的形成,在时间上是可以对比的,基本上是同步的.     

古尔班通古特沙漠南缘绿洲净辐射及其热量通量的变化研究

对古尔班通古特沙漠及其南缘绿洲间各观测点的热通量、波恩比和净辐射进行了分析。结果表明，从沙漠到绿洲，下垫面获得的净辐射热量中，感热通量和土壤热通量所的占比例逐渐减少，而潜热通量的比例逐渐递增，离沙漠越远潜热通量越大；在12：00-18：00，绿洲裸地上波恩比在2．0—8．9变化，而在沙漠边缘为10-11；早上和晚上沙漠的净辐射高于绿洲，白天近地面净辐射绿洲大于沙漠。     

植被-气候关系遥感分析研究进展

对当前植被-气候关系遥感分析研究进行了总结.过去几十年内,全球不同尺度、区域和时间序列的植被变化对气候变化表现出了明显响应.植被的生长变化与气温和降水的变化密切相关.而大尺度上土地覆被类型的变化及植被覆盖的变化对局地及区域的气候产生重要的反馈作用.当前植被-气候关系研究的常用的遥感数据源较多,但也存在单一遥感数据源时间...     

利用沙漠砂合成硅酸盐材料——硅酸盐工业和沙漠治理可持续发展的新方向

 为揭示利用沙漠砂合成硅酸盐材料的优势和重要性，以内蒙古西部库布齐、乌兰布和、腾格里和巴丹吉林4大沙漠为例，通过实地考察并在沙漠边缘取样，研究了该沙漠砂的理化性质。总结了国内外沙漠砂材料的研究和应用现状，分析了利用沙漠砂合成硅酸盐材料的社会效益和经济效益，指出了其发展前景和面临的主要问题。     

Elevated CO2 increases productivity and invasive species success in an arid ecosystem

Arid ecosystems, which occupy about 20% of the earth's terrestrial surface area, have been predicted to be one of the most responsive ecosystem types to elevated atmospheric CO2 and associated global climate change. Here we show, using free-air CO2 enrichment (FACE) technology in an intact Mojave Desert ecosystem, that new shoot production of a dominant perennial shrub is doubled by a 50% increase in atmospheric CO2 concentration in a high rainfall year. However, elevated CO2 does not enhance production in a drought year. We also found that above-ground production and seed rain of an invasive annual grass increases more at elevated CO2 than in several species of native annuals. Consequently, elevated CO2 might enhance the long-term success and dominance of exotic annual grasses in the region. This shift in species composition in favour of exotic annual grasses, driven by global change, has the potential to accelerate the fire cycle, reduce biodiversity and alter ecosystem function in the deserts of western North America.     

古尔班通古特沙漠种子大小对物种分布格局的影响

为了从种子层面了解种子大小对物种生存繁衍具有的适应意义，在古尔班通古特沙漠70个固定样地中采集了87种植物种子，通过测量种子大小，结合野外调查数据，分析了不同种子大小物种的丰富度与多度的空间格局。结果发现：1）古尔班通古特沙漠植物种子大小可分为：A（0．1mg％SM％1rag）、B（1mg％SM％10rag）、C（10mg〈SM％100mg）、D（100mg〈SM〈1000mg）、E（1000mg〈SM〈5000mg）5种类型；2）C型、D型、E型种子物种丰富度与总物种丰富度变化格局相同，随经度、海拔和年均降水的增加物种数目极显著增加，但随纬度增加物种数目极显著降低；3）C型、D型2类种子物种多度与总物种多度的变化格局相同，随经度、海拔和年均降水的增加物种多度极显著增加，但随纬度增加物种多度极显著降低，E型种子植物则相反。本研究证明不同种子大小对物种分布会产生不同的影响，其中大种子物种随降雨的增加优势度将降低，所以在未来的沙漠植物保护中要加大对梭梭、白梭梭、沙拐枣等大种子植物的保护力度。     

Response of forest distribution to past climate change: An insight into future predictions

Vegetation dynamics could lead to changes in the global carbon and hydrology cycle, as well as feedbacks to climate change. This paper reviews the response of forest dynamics to climate change. Based on palaeoecological studies, we summarized the features and modes of vegetation response to climate change and categorized the impacts of climate change on vegetation dynamics as three types： climate stress on vegetation, buffer effects by non-climatic factors, and perturbation of the vegetation distribution by stochastic events. Due to the openness of the vegetation system and the integrated effects of both climatic and non-climatic factors the vegetation-climate relationship deviates far from its equilibrium. The vegetation distribution shows a non-linear response to climate change, which also makes it difficult to quantify the modern vegetation distribution in terms of specific climatic factors. Past analog, space-for-time-substitution and Dynamic Global Vegetation Models （DGVMs） are three approaches to predicting the future vegetation distribution, but they have all been established on the assumption of vegetation-climate equilibrium. We propose that improving DGVMs is a future task for studies of vegetation dynamics because these are process-based models incorporating both disturbance （e.g. fire） and the variability in Plant Functional Types （PFTs）. However, palaeoecological results should be used to test the models, and issues like spatial and temporal scale, complexity of climate change, effects of non-climatic factors, vege- tation-climate feedback, and human regulation on vegetation dynamics are suggested as topics for future studies.     

塔克拉玛干沙漠简单横向沙丘形态学示量特征

通过对塔克拉玛干沙漠不同区域发育的简单横向沙丘的形态学示量特征分析，表明简单横向沙丘的形态特征与沙源的供应有十分密切的关系，沙源的不同丰度导致简单横向沙丘的形态学参数之间有明显的不同，简单横向沙丘在发育过程中并不存在稳定的平衡状态，可能随沙源供应的改变其形态有所改变，而次生的横向沙丘由于主体沙丘对其有足够的沙源供应，因而形态可以得到充分发展，沙丘形态参数的统计数据表明，在简单形新月形沙丘-简单形横向沙丘-沙丘复合体的发展模式中，随沙源供应的增加，沙丘发育时间系列的延长以及其他因素如：风环境、植被等因素的作用，沙丘形态参数之间很难有确切的关系表达式。     

沙生类短命植物粗柄独尾草(Eremurus inderiensis)的种子扩散及种子库分布格局

古尔班通古特沙漠南缘典型荒漠地区沙生类短命植物粗柄独尾草对干旱荒漠环境有极强的适应性,是早春季节荒漠区沙面固定、植被恢复的主要物种。为了认识粗柄独尾草群落更新的特征和能力,及进一步揭示其生态适应机制提供科学依据,采用模拟风速试验与样地调查法探究了其种子散布方式、种子库分布格局等种群生态学特征。结果表明:粗柄独尾草种子散布采取高种子数、近母株密集分布的r对策,种子库主要呈现为种群内聚集分布,种子产量和不同时期种子库密度均随季节和环境的变化而动态变化;粗柄独尾草种子雨持续时间短、强度大、单株产生完好种子在200~400之间,种子千粒重平均为8.895g;种子库输出途径主要有死亡后腐烂、发芽、动物当场取食和搬运,其中动物搬运和风力作用是影响种子库动态分布的最主要因子。     

Distribution of sand dunes and sand shifts along the southern fringe of the Mu Us Desert since the Ming Dynasty

This article takes the two segments of the Ming Great Walls, Dabian and Erbian, and their associated barracks and forts as geographical references. Based on a detailed scrutiny of historical records of the Ming and Qing dynasties, and on field surveys, the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in the Ming and Qing dynasties are carefully reconstructed. A comparison of the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in Ming and Qing with the modern boundary revealed in remote sensing imagery clearly shows that the southern boundary of dunes and shifts in the Mu us Desert has expanded only in a few areas and on a small scale. In the area to the south of Changle Fort, along the direction of annually prevailing winds, sand drifts have penetrated through the Jialu River valley into the loess region and have formed a sand strip of 32 km long and 3 km wide. To the east of Qingping Fort, sand drifts penetrated toward the eastern loess region through the Luhe River valley and have formed another sand strip of 8 km long and 2 km wide. Generally speaking, though the intensity of human activity has been increasing in this area since the Ming Dynasty, the Mu Us Desert has not significantly expanded toward the southeast or southwest. The sand-loess boundary in the southern fringe of the Mu Us Desert has been almost unchanged since the Ming Dynasty.     

羽毛状沙丘辨析

近年来,随着库姆塔格沙漠研究的深入,中国学者对羽毛状沙丘的争论愈来愈多。本文综合分析了国内外沙丘分类学中关于羽毛状沙丘的论述,确认羽毛状沙丘是复合线形沙垄的变型,其中沙垄主脊构成"羽柄",而叠加其上的次级沙丘脊歧出主沙丘脊,构成"羽毛"。对比分析世界其他沙漠与中国库姆塔格沙漠所谓羽毛状沙丘的形态学特征发现,库姆塔格沙漠所谓的羽毛状沙丘实际上是典型的赛夫沙丘,不应视为羽毛状沙丘。以往根据遥感影像确定的羽毛状沙丘的"羽毛"部分是由地表沉积物反照率对比形成的羽毛状图案,与垄间地的沙埂没有很好的对应关系。羽毛状沙丘是在比较复杂的风况和沙源供应不够充分的条件下形成的。因此本文认为以往关于库姆塔格沙漠羽毛状沙丘的不确切认识概念应予以纠正。     

水平井稠油携砂变质量流动模拟装置设计

疏松砂岩稠油油藏适度出砂开采过程中,在水平段储层产出砂粒随稠油进入水平井筒后容易沉积形成砂床,造成油层砂埋、油管砂堵等危害。针对稠油携砂理论及实验研究较多,但研究内容与实际工况差别较大,针对稠油携砂变质量流动规律研究仍缺乏行之有效的研究手段。目前针对适度出砂开采完井参数设计理论及试验研究仅针对井筒内稠油携砂流动,稠油携砂变质量流动理论及试验研究较少。建立全尺寸的水平井稠油携砂变质量流动规律模拟装置,可用于实验研究水平井段至垂直井段的稠油携砂变质量流动规律,为今后针对稠油携砂变质量流动规律实验研究奠定了基础。     

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

Eolian loess is widely distributed on the various geomorphic surfaces between 700–2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuyama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be ∼0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at ∼0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous enhancement led to the environment presently observed. This tremendous environmental effect, caused by large-scale expansion of the desert and arid region of inner Asia, might be an important driving force for the global temperature drop that occurred in the mid-Pleistocene.     

Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

Inordertoquantitivelyevaluateeffectsofdustaerosolonradiativeforcing[1],andtounderstandtheprocessofatmosphericchemistryandbiogeochemistry[2,3],modelingthedustemissionfluxisakindoffundamentalwork.TheDPMmodel[4—6]isidealforpredictingdustemission[7—10]becauseitconsiderseffectsofsurfacefea-tures(MASDofsurfacesoil,roughnesslengthandsoilmoisture,etc)andsandblastingprocess.Italsoprovidesanexplicitphysicalmechanismthatisvalidatedbywindtunnelandfieldexperiments[7—10].Themeandiameterofsurfacesoilsi…