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185篇 您的检索式:作者名="DONG Zhibao"
    题名 作者 年代 出处 被引量
1Chinese deserts and sand fields in Last Glacial Maximum and Holocene Optimum显示文摘The Last Glacial Maximum (LGM, c. 26-16 ka) and the Holocene Optimum (HO, c. 9-5 ka) were characterized by cold-dry and warm-wet climates respectively in the recently geological Earth. How Chinese deserts and sand fields responded to these distinctive climatic changes is still not clear, however. To reconstruct environments of the deserts and sand fields during the LGM and HO is helpful to understand the forcing mechanisms of environment change in this arid region, and to test paleoclimatic modeling results. Through our long-term field and laboratory investigations, 400 optically stimulated luminescence (OSL) ages and more than 100 depositional records in the Chinese deserts and sand fields were obtained; on the basis of these data, we reconstruct spatial distributions of the deserts and sand fields during the LGM and HO. Our results show that the sand fields of Mu Us, Hunshandake, Horqin and Hulun Buir in northern and northeastern China had expanded 25%, 37%, 38% and 270%, respectively, during the LGM; the sand fields of Gonghe in the northeastern Qinghai-Tibetan Plateau had expanded 20%, and the deserts of Badain Jaran, Tengger in central northern China had expanded 39% and 29% separately during the LGM; the deserts of Taklimakan, Gurbantünggüt and Kumtag in northwestern China had expanded 10%-20% respectively, compared to their modern areas. On the other hand, all of the sand fields were nearly completely covered by vegetation during the HO; the deserts in northwestern and central northern China were reduced by around 5%-20% in area during this time. Lakes in this arid region were probably expanded during the HO but this conclusion needs more investigation. Compared with the geological distributions of deserts and sand fields, human activity has clearly changed (expanded) the area of active sand dunes at the present time. Our observations show that environmental conditions of Chinese deserts and sand fields are controlled by regional climate together with human activity.LU HuaYu YI ShuangWen XU ZhiWei ZHOU YaLi ZENG Lin ZHU FangYing FENG Han DONG LiNa ZHUO HaiXin YU KaiFeng MASON Joseph WANG XiaoYong CHEN YingYong LU Qi WU Bo DONG ZhiBao QU JianJun WANG XunMing GUO ZhengTang 2013Chinese Science Bulletin2013,58,23:40
2Bacterial diversity and distribution in the southeast edge of the Tengger Desert and their correlation with soil enzyme activities显示文摘The nature of microbial communities and their relation to enzyme activities in desert soils is a neglected area of investigation. To address this, the bacterial diversity and distribution and soil physico-chemical factors were investigated in the soil crust, the soil beneath the crust and rhizosphere soil at the southeast edge of the Tengger Desert, using the denaturing gradient gel electrophoresis of 16S rRNA genes amplified by the polymerase chain reaction. Phylogenetic analysis of the sequenced DGGE bands revealed a great diversity of bacteria. The Proteobacteria, consisting of the α, β, and γ subdivisions, were clearly the dominant group at all depths and in rhizosphere soil. Analysis of the enzyme activities indicated that the rhizosphere soil of Caragana korshinskii exhibited the highest protease and polyphenol oxidase activities, and in the soil crust there were increased activities of catalase, urease, dehydrogenase and sucrase. The bacterial community abundance closely correlated with soil enzyme activities in different soils. The presence of Cyanobacteria correlated with significant increases in protease, catalase and sucrase in the soil crust, and increased urease in the rhizosphere soil of Artemisia ordosica. The occurrence of Acidobacteria was associated with significant increases in urease, dehydrogenase, and sucrase in the rhizosphere soil of C. korshinski. The presence of γ-Proteobacteria correlated with a significant increase in polyphenol oxidase in the rhizosphere soil of A. ordosica. The study indicated a close relationship between the soil bacterial community and soil enzymes, suggesting the necessity of further investigations into bacterial function in this desert ecosystem.Wei Zhang Gaosen Zhang Guangxiu Liu Zhibao Dong Tuo Chen Manxiao Zhang Paul J.Dyson Lizhe An 2012Journal of Environmental Sciences2012,24,11:14
3Grain-size characteristics of linear dunes on the northern margin of Qarhan Salt Lake, northwestern China显示文摘In order to clarify the formation mechanism of linear dunes on the northern margin of Qarhan Salt Lake, northwestern China, we analyzed the grain-size and sorting parameters of the dune and interdune sands. The surface sands(0–30 mm) from the dune base to the crest of both flanks and interdune corridors were sampled along transects from upwind to downwind through the dune field. The results indicated that the grain-size distribution differed at different positions between and within the dunes. The frequency curve for dune sands mainly showed a bimodal distribution, while the interdune sediments showed a trimodal distribution. The grain size distribution of the linear dunes showed a finer crest pattern, i.e. the crests were composed of sands that were generally finer, better sorted than those of base sands. In addition, at the dune field scale, the dune crest sands were tending to become much finer but sorting became worse along the downwind transects. However, the grain-size parameters of sediments in the interdune corridors showed no clear pattern. The results demonstrated that the grain size and sorting parameters exhibited a systematic change not only at the individual scale but also at the dune field scale. Our results quantitatively estimate the limited role of cohesive sediments on the formation of linear dune under unidirectional wind regime. More attention should be paid to a long-term wind regime observation, internal sedimentary structures and their formation ages.LI Jiyan DONG Zhibao ZHANG Zhengcai QIAN Guangqiang LUO Wanyin LU Junfeng 2015Journal of Arid Land2015,7,4:13
4Sand harm in Taklimakan Desert highway and sand control显示文摘Re puted as a wonderful achievement of the world’s highway construction h istory, the Taklimakan Desert highway is now facing serious sand drift encroachment problems due to its 447-km-long passage of sand sea consist ing of crescent dunes, barchan chains, compound transverse dune ridges and co mplex megadunes. To solve some technical problems in the protection of the highway from sand drift encroachment, desert experts have been conductin g the theoretical and applied studies on sand movement laws; causes, severities and time-space differentiation of sand drift damages; and control ways in cluding mechanical, chemical and biological measures. In this paper the authors give an overall summary on the research contents and recent progress i n the control of sand drift damages in China and hold that the theoretica l research results and practices in the prevention of sand drift encr oachment on the cross-desert highway represent a breakthrough and has an epoch-making significance. Since the construction of protective forest along the cross-desert highway requires large amount of ground water, what will be its environmental consequence and whether it can effectiv ely halt sand drift encroachment on the highway forever are the questions to be studied urgently.HAN Zhiwen,WANG Tao,SUN Qingwei,DONG Zhibao,WANG Xunming(Laboratory of Blo wn Sand Physics and Desert Environment, Cold and Arid Regions Environm ental and Engineering Research Institute, CAS, Lanzhou 730000, China) 2003Journal of Geographical Sciences2003,13,1:13
5Major advances in studies of the physical geography and living environment of China during the past 70 years and future prospects显示文摘The natural environment provides material essentials for human survival and development. The characteristics,processes, regional differentiation and forcing mechanisms of the elements of the natural environment(e.g. geomorphology,climate, hydrology, soil, etc.) are the main objects of research in physical geography. China has a complex natural environment and huge regional differentiation and therefore it provides outstanding reserach opportunities in physical geography. This review summarizes the most important developments and the main contributions of research in the physical geography and human living environment in China during the past 70 years. The major topics addressed are the uplift of the Tibetan Plateau and the evolution of its cryosphere, the development of fluvial systems, the acidification of the vast arid region of the Asian interior, variations in the monsoon and westerly climate systems on multiple timescales, the development of lakes and wetlands, the watershed system model, soil erosion, past human-environment interactions, biogeography, and physical geographic zonality. After briefly introducing international research developments, we review the history of research in physical geography in China, focusing on the major achievements and major academic debates, and finally we summarize the status of current research and the future prospects. We propose that in the context of the national demand for the construction of an ecological civilization, we should make full use of the research findings of physical geography, and determine the patterns and mechanisms of natural environmental processes in order to continue to promote the continued contribution of physical geography to national development strategies, and to further contribute to the theory of physical geography from a global perspective.Fahu CHEN Bojie FU Jun XIA Duo WU Shaohong WU Yili ZHANG Hang SUN Yu LIU Xiaomin FANG Boqiang QIN Xin LI Tingjun ZHANG Baoyuan LIU Zhibao DONG Shugui HOU Lide TIAN Baiqing XU Guanghui DONG Jingyun ZHENG Wei YANG Xin WANG Zaijun LI Fei Wang Zhenbo HU Jie WANG Jianbao LIU Jianhui CHEN Wei HUANG Juzhi HOU Qiufang CAI Hao LONG Ming JIANG Yaxian HU Xiaoming FENG Xingguo MO Xiaoyan YANG Dongju ZHANG Xiuhong WANG Yunhe YIN Xiaochen LIU 2019Science China Earth Sciences2019,62,11:11
6Experimental analysis of sand particles' lift-off and incident velocities in wind-blown sand flux显示文摘The probability distributions of sand particles' lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry (PDA) in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the χ2-test for these probability distributions, that the probability density functions (pdf's) of the sand particles' lift-off and incident velocities as well as their vertical components are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions. These pdf's depend on not only the sand particle diameter but also the wind speed.Li Xie Zhibao Dong Xiaojing Zheng 2005Acta Mechanica Sinica2005,21,6:9
7Recharge sources and chemical composition types of groundwater and lake in the Badain Jaran Desert, northwestern China显示文摘在 Badain Jaran 沙漠基于湖水和浅地下水的离子化学药品作文的分析,这份报纸在荒芜的区域讨论了离子化学药品作文,湖水的空间变化,和湖水和地下水的可能的供应来源的特征。结果证明 pH,咸度, TDS 和湖水的电的电导率比地下水的那些大。水样品的离子内容被 Na+ 和 Cl 统治。大多数更高的咸度湖是 Na (K)-Cl-(SO4) 类型,并且低咸度湖的一些属于 Na-(Mg )-(Ca)-Cl-(SO4)-(HCO3) 类型。大多数地下水是 Na-(Ca )-(Mg)-Cl-(SO4)-(HCO3) 类型,把湖,和仅仅在场的一些归因于 subsaline Na-Cl-SO4 类型,流动在盐的湖下面。在东南的湖的 pH,咸度, TDS 和电的电导率是相对低的,并且有稍微碱的湖。在北湖的 pH,咸度, TDS 和电的电导率比东南的湖的那些大得多,并且北湖是中等碱、盐的。在 Badain Jaran 沙漠的东南的部分,到北方表演的来自南方的湖水的离子化学药品特征 subsaline salinehypersaline 的一个变化趋势。离子在的化学作文的变化趋势最近 9 年显示大多数离子内容在 Boritaolegai, Badain, Nuoertu 和 Huhejilin 湖有一点儿减小,它清楚地声明新鲜的水供应的数量在 9 年的时期正在增加。湖水的离子化学药品作文表明湖水的流动方向从东南到在 Badain Jaran 沙漠的西北。离子化学药品作文,沙层水水平高度的潮湿内容和湖水和地下水的层次簇分析证明湖水被降水的本地降雨和渗入主要在 Yabulai 山和 Heishantou 山供应,并且从 Qilian 山的供应是几乎不可能的。SHAO Tianje ZHAO Jingbo ZHOU Qi DONG Zhibao MA Yandong 2012Journal of Geographical Sciences2012,22,3:7
8Aeolian transport over a developing transverse dune显示文摘The spatial and temporal changes in aeolian transport over a dune are fundamental factors that control the morphology of the dune.In the present study,we obtained direct field observations of aeolian transport over a developing transverse dune at the Shapotou Aeolian Experiment Site in the southeastern part of China’s Tengger Desert.The transport rate versus wind speed relationship is complicated over a developing dune compared with the relationships over flat surfaces and over dunes that are in equilibrium with the wind.We obtained trend lines for transport rate over the transverse dune versus distance.The transport rate generally increased from the toe to the crest above the stoss slope,but the difference in transport rate between the crest and the toe was smaller than those that have been proposed for taller dunes.The crest/toe ratio for transport rates therefore seems to depend greatly on dune height.Flux density profiles for different points above the dune at different wind speeds were well described by the exponential decay law,as has been proposed for saltation flux density profiles.Coefficients in the flux density profile function can be defined in terms of the transport rate and wind speed.However,the dependence of relative decay rate with height and average saltation height on wind speed was weaker than that observed in a wind tunnel and above a flat surface.The preliminary results obtained in this study require more evidence from field observations to fully describe aeolian transport above developing dunes.ZhiBao DONG Ping LV ZhengCai ZHANG JunFeng LU 2014Journal of Arid Land2014,6,3:7
9Driving forces of land use and land cover change (LUCC) in the Zoige Wetland, Qinghai-Tibetan Plateau显示文摘The Zoige Wetland is located in the northeastern Qinghai-Tibetan Plateau, which is highly sensitive to global environment change and human disturbance because of its high elevation and cold environment, thus, it's a hotspot for land use and land cover change (LUCC) research. We used Landsat MSS images from 1975, Landsat ETM images from 2000, and Landsat TM images from 1990 and 2005 to assess the LUCC in the study area, using GIS techniques, as well as topographic, vegetation, and soil maps combined with field investigations. The monitoring result shows that the study area's environment degraded rapidly between 1975 and 2005, including wetland shrinkage from 5,308 km 2 to 4,980 km 2 , sandy land expansion from 112 km 2 to 137 km 2 , forest land decreasing from 5,686 km 2 to 5,443 km 2 , and grassland degradation from 12,309 km 2 to 10,672 km 2 . According to the analysis of meteorological data and social-economic statistical data, we concluded that the LUCC in the Zoige Wetland was caused by both natural and anthropogenic factors, but human activities were primarily responsible for the observed LUCC, thereby, we suggest human behaviors must be adjusted to control environmental degradation.GuangYin Hu ZhiBao Dong JunFeng Lu ChangZhen Yan 2012Research in Cold and Arid Regions2012,4,5:7
10Observations of several characteristics of aeolian sand movement in the Taklimakan Desert显示文摘With both sides of the Taklimakan Desert highway line as the study area, three typical aeolian sand landforms, i.e. complex dune ridge, barchan dune and flat sand land, were selected as sand beds for the observation, analysis and research of the characteristics of aeolian sand movement such as aeolian sand stream structure, sand transport intensity, etc. in the Taklimakan Desert. The results show that there is a linear relation between the height and the log of sand transport rate over transverse dune chain, longitudinal dune ridge and flat sand land, i.e. the sand transport percentage decreases exponentially with increasing height. Sand transport rate within the 10 cm height above the bed surface accounts for 80%-95% of the total sand transport rate of the observed height (40 cm), while the sand transport rate in 20 cm occupies 98% of the total amount. Sand transport rate (g·cm-1·min-1) differs greatly with respect to different landform types and different topographic positions. Based on the investigation and analysis on aeolian sand landform origin, morphological type and distribution feature, the two typical landform assemblages, complex transverse dune chain-alluvial plain and huge longitudinal dune ridge-interridge lowland in the Taklimakan Desert were divided into several characteristic zones of aeolian sand movement states. From this one can qualitatively judge the types and severities of sand disasters at various topographic positions in the engineering installation region and further put forward concrete schemes and measures to control sand damages.HAN Zhiwen DONG Zhibao WANG Tao CHEN Guangting YAN Changzhen YAO Zhengyi 2004Science China Earth Sciences2004,47,1:7
11Optically stimulated luminescence dating of sandy deposits from Gulang county at the southern margin of the Tengger Desert, China显示文摘Aeolian deposits from the deserts in northern China have been used for palaeoenvironmental research to understand aeolian sedimentology and its dynamic connection to past climate conditions. The Tengger Desert in China is sensitive to the waxing and waning of the monsoonal system. In response to past climate change, the southern margin of the Tengger Desert has evolved significantly since the last glacial period. However, previous attempts to date aeolian deposits in this region were mainly based on radiocarbon dating, which has problems when applied to aeolian deposits. Moreover, sedimentary records are limited. Accordingly, past aeolian activity in this desert remains poorly understood. In the present study, we dated sand samples from Gulang county at the southern margin of the Tengger Desert using optically stimulated luminescence(OSL) to understand the history of aeolian activity in this region. Our samples represented well-sorted aeolian sands and sandy loess. Aeolian sands are evidence of dune field buildup and sparse vegetation cover whereas sandy loess is evidence of improved stabilization of sand dunes resulting from ameliorated vegetation cover. Certain samples showed a decline in the equivalent dose(De) values when successive integration intervals were applied, which resulted from unstable OSL signals from non-fast components in the initial part of the decay curve. In order to obtain reliable De estimates, we investigated component-resolved and different background subtraction approaches, and compared the resultant De estimates. We adopted the early background subtraction method to derive De values. Luminescence chronologies and sedimentary records indicated that sand dunes accumulation occurred before 10 ka, and sandy loess developed between 9.5 and 7.6 ka when sand dunes were stabilized as a result of increased effective moisture levels. The transition between sand dune mobilization and stabilization emphasizes the significance of an effective moisture threshold in controlling aeolian activity. Mobilization of sand dunes at ~2.3 ka might be related to an increased aridity during the Late Holocene.PENG Jun DONG Zhibao HAN Fengqing 2016Journal of Arid Land2016,8,1:7
12Pattern analysis of a linear dune field on the northern margin of Qarhan Salt Lake,northwestern China显示文摘In terms of formation mechanisms of linear dunes,there are open arguments for their widespread distribution and multi-morphological diversities.In order to clarify the formation mechanism of linear dunes of Qarhan Salt Lake,we used pattern analysis method to analyze the statistical characteristics and spatial variation of their pattern parameters.Except at the west-northwest margin,the pattern parameters showed regular spatial variation from the up-middle part towards the downwind end of the dune field.Based on the cumulative probability plots for inter-crest spacing and crest length,we divided the linear dunes into three groups,which corresponding to the three evolution stages of these dunes.The first group comprises erosional relics,with shorter crests,smaller inter-crest spacing and more random dune orientation.The second group comprises dunes whose sand supply is just sufficient to maintain stability and these dunes are approaching the net erosion stage.The crest length and inter-crest spacing of these dunes are much larger than those of the first group,and dune orientation is closer to the resultant drift direction (RDD) .The last group comprises linear dunes that are still undergoing vertical accretion and longitudinal elongation,which follows the RDD of the modern wind regime.The presence of regular spatial variation of pattern parameters and a similar geometry with the vegetated linear dunes suggest that deposition and erosion coexist in the development and evolution of linear dunes of Qarhan Salt Lake,i.e.deposition predominates at the downwind end of linear dunes in the vertical accretion and longitudinal elongation stage,whereas erosion mainly occurs at the upwind end of linear dunes in the degradation stage.Therefore,the formation mechanism of linear dunes in Qarhan Salt Lake can be reasonably explained by the combination of depositional and erosional theories.LI Jiyan DONG Zhibao QIAN Guangqiang ZHANG Zhengcai LUO Wanyin LU Junfeng WANG Meng 2016Journal of Arid Land2016,8,5:6
13Evaluating the optimal porosity of fences for reducing wind erosion显示文摘Porosity is the most important parameter determining the shelter efficiency of fences.Wind measurements were made around fence models with different porosities in a wind tunnel.The optimal fence porosity is evaluated by means of Gandemer's method that com-bines the effects of wind reduction and turbulence fields on the shelter efficiency for abating wind erosion.Defining the optimal po-rosity must take into account of its own purposes,required shelter degree and area to be sheltered.Turbulence has profound impacts on the shelter efficiency of high degree.Two concepts:absolute optimal porosity and practical optimal porosity concerning optimal porosity are proposed.Choosing the practical optimal porosity means reducing cost without significant expense of shelter efficiency.According to the evaluation in present study,the absolute optimal porosity for providing high degree of shelter to abate wind erosion is 0.20 while the practical optimal porosity is around 0.40.If a less shelter degree but over wider area is required,the absolute optimal porosity ranges from 0.05 to 0.10 and the practical optimal porosity is 0.10.For any degree of shelter for abating wind erosion effec-tively,the fence porosity must be less than or equal 0.40.ZhiBao Dong WanYin Luo GuangQiang Qian HongTao Wang 2011Research in Cold and Arid Regions2011,3,1:5
14An investigation of the effects of dust storms on rat lung using HRCT and blood gas analysis显示文摘The increasing intensity and frequency of sand-dust storms in China has led to greater prominence of associated environmental and health issues. Many studies have focused on the health effects of air particulate contaminants, but few formal investigations have studied the effects of sand-dust storms on human and animal health. The aim of this study was to investigate the effects of dust storms on rat lung by using high resolution computed tomography(HRCT) and blood gas analysis through a wind tunnel simulating. We found that the rat lung damage effects can be detected by the HRCT imaging after exposure to sand-dust storm environments, but had no obvious result through blood gas analysis. Exposure durations positively correlated with the damage degree to lung tissue. These will provide some evidence for clinical diagnosis of non-occupational pneumoconiosis.FengFeng Lei WanYin Luo ZhiBao Dong YingZhu Sang LiZhu Luo Gang Huang Hua Liu QiZhang Chen 2016Research in Cold and Arid Regions2016,8,4:5
15Near-surface wind environment in the Yarlung Zangbo River basin,southern Tibetan Plateau显示文摘Aeolian processes have been studied extensively at low elevations,but have been relatively little studied at high elevations.Aeolian sediments are widely distributed in the Yarlung Zangbo River basin,southern Tibetan Plateau,which is characterized by low pressure and low temperature.Here,we comprehensively analyzed the wind regime using data since 1980 from 11 meteorological stations in the study area,and examined the interaction between the near-surface wind and aeolian environment.The wind environment exhibited significant spatial and temporal variation,and mean wind speed has generally decreased on both annual and seasonal bases since 1980,at an average of 0.181 m/(s•10a).This decrease resulted from the reduced contribution of maximum wind speed,and depended strongly on variations of the frequency of sand-driving winds.The drift potential and related parameters also showed obvious spatial and temporal variation,with similar driving forces for the wind environment.The strength of the wind regime affected the formation and development of the aeolian geomorphological pattern,but with variation caused by local topography and sediment sources.The drift potential and resultant drift direction were two key parameters,as they quantify the dynamic conditions and depositional orientation of the aeolian sediments.Wind affected the spatial variation in sediment grain size,but the source material and complex topographic effects on the near-surface wind were the underlying causes for the grain size distribution of aeolian sands.These results will support efforts to control aeolian desertification in the basin and improve our understanding of aeolian processes in high-elevation environments.YANG Junhuai XIA Dunsheng WANG Shuyuan TIAN Weidong MA Xingyue CHEN Zixuan GAO Fuyuan LING Zhiyong DONG Zhibao 2020Journal of Arid Land2020,12,6:5
16Effects of geomorphic conditions, wind speed, and precipitation on dustfall over northern China显示文摘We investigated how dustfall flux (DF) and dust particle size (DPS) were affected by geomorphic conditions, wind speed, and precipitation using data from 27 sites in northern China. The sites with the greatest DF and greatest median diameter of dustfall (MDD) were primarily in desert regions and had extensive mobile sands. DF and MDD were lowest in agricultural regions, which had low levels of coarse particles because of human land use and high vegetation coverage that restrained blowing sand. DF values were higher and MDD values were lower in the western agricultural region than in the eastern agricultural region because the former is closer to desert regions and contains more fine dust that has traveled far. In regions with extensive desertified lands, DF values were lower than those in desert regions, and MDD values were greater than in agricultural regions, possibly due to coarsening of soil texture by desertification processes combined with higher vegetation coverage and soil moisture than in desert regions, thereby restraining blowing sand. Although high DF and MDD always coincided spatially with strong winds and low precipitation, the strong winds and low precipitation did not always mean high DF and MDD. High DF also coincided temporally with periods of low precipitation, but low precipitation did not always mean high DF. Thus, although the spatial trends in DF and DPS were controlled mostly by geomorphic conditions, and monthly trends in DF were controlled mainly by wind speed, weak wind and high precipitation can restrain the blowing sand at certain times and locations. Seasonal changes in DPS may be controlled simultaneously by geomorphic conditions, meteorological factors, and distance from source areas, not solely by the winter monsoon.JinChang Li ZhiBao Dong GuangQiang Qian WanYin Luo 2010Research in Cold and Arid Regions2010,2,4:4
17Different Responses of Vegetation to Frozen Ground Degradation in the Source Region of the Yellow River from 1980 to 2018显示文摘Frozen ground degradation under a warming climate profoundly influences the growth of alpine vegetation in the source region of the Qinghai-Tibet Plateau.This study investigated spatiotemporal variations in the frozen ground distribution,the active layer thickness(ALT)of permafrost(PF)soil and the soil freeze depth(SFD)in seasonally frozen soil from 1980 to 2018 using the temperature at the top of permafrost(TTOP)model and Stefan equation.We compared the effects of these variations on vegetation growth among different frozen ground types and vegetation types in the source region of the Yellow River(SRYR).The results showed that approximately half of the PF area(20.37%of the SRYR)was projected to degrade into seasonally frozen ground(SFG)during the past four decades;furthermore,the areal average ALT increased by 3.47 cm/yr,and the areal average SFD decreased by 0.93 cm/yr from 1980 to 2018.Accordingly,the growing season Normalized Difference Vegetation Index(NDVI)presented an increasing trend of 0.002/10 yr,and the increase rate and proportion of areas with NDVI increase were largest in the transition zone where PF degraded to SFG(the PF to SFG zone).A correlation analysis indicated that variations in ALT and SFD in the SRYR were significantly correlated with increases of NDVI in the growing season.However,a rapid decrease in SFD(<-1.4 cm/10 yr)could have reduced the soil moisture and,thus,decreased the NDVI.The NDVI for most vegetation types exhibited a significant positive correlation with ALT and a negative correlation with SFD.However,the steppe NDVI exhibited a significant negative correlation with the SFD in the PF to SFG zone but a positive correlation in the SFG zone,which was mainly limited by water condition because of different change rates of the SFD.WANG Rui DONG Zhibao ZHOU Zhengchao 2020Chinese Geographical Science2020,30,4:4
18Land use and land cover change and its driving forces in Maqu County, China in the past 25 years显示文摘LUCC;;driving forces;;Maqu County;;source region of the YellowJunFeng Lu ZhiBao Dong GuangYin Hu WenJin Li WanYin Luo MingLiang Tan 2016Research in Cold and Arid Regions2016,8,5:4
19Change of lake area in the southeastern part of China's Badain Jaran Sand Sea and its implications for recharge sources显示文摘Understanding the relationship between the changes in lake water volume and climate change can provide valuable information to the recharge sources of lake water. This is particularly true in arid areas such as the Badain Jaran Sand Sea, an ecologically sensitive area, where the recharge sources of lakes are heatedly debated. In this study, we determined the areas of 50 lakes(representing 70% of the total permanent lakes in this sand sea) in 1967, 1975, 1990, 2000 and 2010 by analyzing remote-sensing images using image processing and Ar GIS software. In general, the total lake area decreased from 1967 to 1990, remained almost unchanged from 1990 to 2000, and increased from 2000 to 2010. Analysis of the relationship between these changes and the contemporaneous changes in annual mean temperature and annual precipitation in the surrounding areas suggests that temperature has significantly affected the lake area, but that the influence of precipitation was minor. These results tend to support the palaeo-water recharge hypothesis for lakes of the Badain Jaran Sand Sea, considering the fact that the distribution and area of lakes are closely related to precipitation and the size of mega-dunes, but the contemporaneous precipitation can hardly balance the lake water.Zhi ZHANG ZhiBao DONG ChangZhen YAN GuangYin HU 2015Journal of Arid Land2015,7,1:4
20Geomorphologic patterns of dune networks in the Tengger Desert,China显示文摘Dune networks are widely distributed in the world's deserts,which include primary ridges and secondary ridges.However,they have not been sufficiently studied in a systematic manner and their origins and spatial and morphological characteristics remain unclear.To provide information on the geomorphology of dune networks,we analyze the software geomorphologic patterns of the dune networks in China's Tengger Desert using matrix and laboratory to process remote-sensing images.Based on analysis of image features and their layout in a topographic map,we identify two types of dune networks (square and rectangular dune networks) with different size and morphological structures in the Tengger Desert.Four important geomorphic pattern parameters,ridge length,spacing,orientation and defect density,are analyzed.The length of primary ridges of dune networks decreases from northwest of the desert to the southeast,resulting an increasing spacing and a transition from rectangular dune networks to square dune networks.Wind regime and sediment supply are responsible for the variation in pattern parameters.We use the spacing and defect density data to estimate the construction time of dune networks and found that the dune networks in the Tengger Desert formed since about 1.3 ka BP.WEN Qing DONG Zhibao 2016Journal of Arid Land2016,8,5:3
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