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…     

The ion chemistry of surface and ground waters in the Taklimakan Desert of Tarim Basin, western China

The physio-chemical and chemical features of water in natural conditions are controlled by the weath-ering of bedrocks,local climate,landforms and other geo-environmental parameters. In order to un-derstand the characteristics of water and the origins of the dissolved loads in the rivers and in the ground waters of the Taklimakan Desert,western China,we studied the ions in the water samples col-lected from rivers and wells. We collected water samples from four rivers (Keriya River,Cele River,Tumiya River and Yulongkashi River) in the southern desert and ground water samples from many parts of the desert. Major cations and anions were measured using ion-chromatograph and titration with HCl. The total dissolved solids (TDS),pH and conductivity were examined on site by a portable multi-parameter analyzer. The data show that the water in the rivers of southern Taklimakan is still of fresh water quality and slight alkalinity,although the TDS is comparatively higher than that of many other rivers of the world. The ground water is fresh to slightly saline,with TDS a little higher than that of river water in the study area. The concentration of ions is slightly different between the four rivers in the southern Taklimakan. However,the chemistries of ground water in all samples are to a large degree controlled by sodium and chloride. The ions in the ground water are concluded to be mainly from dissolving of evaporites,consistent with the dry climate in the region,whereas the ions in the rivers are mainly from rock weathering. Low-level human imprints are recognized in the ground water samples also.     

新疆荒漠区沥青面层疲劳寿命分析

针对新疆荒漠区典型沥青路面结构,采用现场原型车辆加速加载试验手段,分析新疆荒漠区不同路面结构在实际路面荷载工况下,对沥青面层疲劳寿命的影响。结果表明:现场原型车辆加速加载作用下沥青路面层底最大拉应变随着时间的增长而增大,且与时间的数学模型关系为相关性较大的对数函数关系;当超载率从0.31%~39.84%时,沥青面层底拉应变急剧增加,从而加速了沥青路面疲劳破坏进程;同时,超载越严重沥青路面结构设计对增加路面疲劳寿命的影响就越小。     

鄂尔多斯沙漠高原白垩系地下水锶同位素的演化机理

结合地下水化学资料,应用含水介质和地下水Sr含量及87Sr/86Sr比值,对鄂尔多斯沙漠高原白垩系含水层中水-岩作用机制进行了研究.结果表明:含水介质中钾长石、斜长石和碳酸盐矿物的87Sr/86Sr比值具有差异,地下水87Sr/86Sr比值介于0.709 871～0.711 792.地下水Sr来源主要为碳酸盐矿物、硫酸...     

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.     

Spatial patterns of ephemeral plants in Gurbantünggüt Desert

In the present research, the authors measured parameters of richness, cover and importance value of ephemeral and ephemeroid plants on south-north and east-west transects in the Gurbantünggüt Desert in early spring, and investigated and analyzed the microhabitats, such as terrain, geomorphology, soil physical-chemical properties and crusts. By comparison, the regional differences in the ephemeral distribution in the desert were revealed. The species of ephemeral plants in the south and center are the richest and those in the west are the poorest in the desert. The cover of ephemeral plants in the mid-south is higher than that in the north, and that in the mid-east is higher than that in the west. The response of ephemeral plants to the spatial variation of the desert habitat forms the population-habitst gradient of ephemeral plants. The characteristics are： （1） In the habitat with higher terrain, coarser textured soil with poorer sorting and correspondingly higher organic matter and lower alkali-saline contents, Carex physoides and Eremopyrum orientale are the dominant ephemeral plants; （2） In the dry habitat with lower terrain, looser textured soil, some organic matter, alkali-saline soil, and developed crust, the ephemeral plants Alyssum linifolium and Erodium oxyrrhynchum are of characteristic of drought and alkali-saline tolerance; （3） In the habitat with lower terrain, some water and more alkali-saline soil, the ephemeral plants Neotorularia torulosa and Hypecoum parviflorum being of alkali-saline tolerance are mainly developed. However, most ephemerals are distributed in a habitat order of higher terrain, some organic, and less alkali-saline soil on the above-mentioned ephemeral population-habitst gradient. The spatial gradient of variation in desert microhabitsts is small, and as a whole, the physiological character of mesophytism is represented by the desert ephemerals.     

评析薇尔·普鲁姆德的批判性生态女性主义思想

澳大利亚生态女性主义学者薇尔·普鲁姆德的批判性生态女性主义观从剖析西方理性主义传统人手．认为理性下的主宰模式和二元对立逻辑是造成自然与女性受压迫地位的根源,并指出发展性的生态女性主义必须绕开“延续性海洋”和“差异性沙漠”等各类陷阱,重设理性的女性观和生态观。     

路堤高度和边坡对沙漠公路输沙效应的影响

长期以来,风积沙对沙漠公路一直有着特殊的影响,作为解决这一问题的基础研究--输沙效应分析也就引起了人们的足够重视.公路设计者们正逐渐把分析问题的角度从公路两边的防沙、固沙转移到对公路本身的结构设计上.结合G315线若羌-且末沙漠公路的现状调查,从路堤高度和坡度对输沙的效应进行了分析,提出了在不同的路段上,应设计合理的路堤高度和坡度.     

Holocene climatic change in Hunshandake Desert

Research on the geological data of Hunshandake Desert in China monsoon region revealed that Holocene summer monsoon had experienced six prevailing periods and seven weakening periods. The climatic humidity and the vegetation had also undergone the similar periodical variation influenced by the monsoon periodicity. The period when summer monsoon prevailed or winter monsoon weakened and climatic humidity and vegetation coverage relatively increased, corresponded to the global warming events;whereas the period when summer monsoon weakened or winter monsoon prevailed and climatic humidity and vegetation coverage relatively decreased, corresponded to the arid events in middle to low latitudes and the cold events in North Atlantic. As for the changing regularity of summer monsoon intensity there were two distinct periodicities of 1456 years and 494 years, also these two periodicities had global significance.     

Ecological and environmental explanation of microbiotic crusts on sand dune scales in the Gurbantonggut Desert, Xinjiang

Results obtained from the field investigation and the analysis in laboratory show that many species of microbiotic crusts of lichens, mosses and algae develop extensively in the Gurbantonggut Desert, Xinjiang. The formation, species and distribution are closely related to the environmental conditions at the different positions of sand dunes. The animalcule crusts develop mainly on the mobile or semi-mobile sand surface of dune tops, the alga crusts develop mainly at the upper to middle parts of dune slopes, the lichen crusts develop at middle and lower parts of dune slopes, and the moss crusts are mainly distributed at the lower part of dune slopes and the interdune lowlands. The species, thickness and developing degree of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes and the interdune lowlands, and an obvious contrast between the microbiotic crusts and the different species of plant communities forms. The development and differentiation of microbiotic crusts at the different positions of dunes are the ecological appearance and the natural selection of synthetic adaptability of the different microbiotic crust species to the local environmental conditions, and are closely related to the ecological conditions, such as the physiochemical properties of soils and stability of topsoil texture.