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Stochastic modelling of soil moisture dynamics in a grassland of Qilian Mountain at point scale

Science china Earth Sciences 2007年第12期50卷 1844-1856页

作者： LIU Hu,ZHAO WenZhi HE ZhiBin & ZHANG LiJie Linze Inland River Basin research Station,Chinese Ecosystem research Network Laboratory of Watershed Hydrology and Ecol-ogy,{2. and arid regions environmental and engineering research institute,Chinese Academy of Sciences,lanzhou 730000,china 1. Linze Inland River Basin research Station Chinese Ecosystem Research Network China 2. Laboratory of Watershed Hydrology and Ecology Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Stochastic modeling of soil moisture dynamics is crucial to the quantitative understanding of plant responses to water stresses,hydrological control of nutrient cycling processes,water competition among plants,and some other ecological dynamics,and thus has become a hotspot in ecohydrology at *** this paper,we based on the continuously monitored data of soil moisture during 2.02.2.05 and daily precipitation date of 1992.2.06,and tried to make a probabilistic analysis of soil moisture dynamics at point scale in a grassland of Qilian Mountain by integrating the stochastic model improved by Laio and the Monte Carlo *** results show that the inter-annual variations for the soil moisture patterns at different depths are very significant,and that the coefficient of variance(CV) of surface soil moisture(2. cm) is almost continually kept at about 0.2. whether in the rich or poor rainy ***,it has been found that the maximal CV of soil moisture has not always appeared at the surface *** of the analytically derived soil moisture probability density function(PDF) with the statistical distribution of the observed soil moisture data suggests that the stochastic model can reasonably describe and predict the soil moisture dynamics of the grassland in Qilian Mountain at point *** extracting the statistical information of the historical precipitation data in 1994―2.06,and inputting them into the stochastic model,we analytically derived the long-term soil moisture PDF without considering the inter-annual climate fluctuations,and then numerically derived the one when considering the inter-annual fluctuation effects in combination with a Monte-Carlo *** was found that,though the peak position of the probability density distribution significantly moved towards drought when considering the disturbance forces,and its width was narrowed,accordingly its peak value was increased,no significant bimodality was observed in the soil moistur

关键词： soil moisture dynamics, stochastic modelling, Monte Carlo method, probability density function, grassland ecosystem

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Magnetic characteristics of dustfall in urban area of north china and its environmental significance

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Science china Earth Sciences 2007年第11期50卷 1724-1732页

作者： XIA DunSheng1,2. YANG LiPing2. MA JianYing1, YU Ye1, WANG Guan2.& CHEN FaHu2.1 Key Laboratory of Desert and Desertification, institute of cold and {2. regions environmental and engineering, Chinese Academy of Sciences, lanzhou 730000, china 2.CAEP, Key Laboratory of West china’s environmental System (Ministry of Education), lanzhou University, lanzhou 730000, china 1. Key Laboratory of Desert and Desertification Institute of Cold and Arid Regions Environmental and Engineering Chinese Academy of Sciences Lanzhou 730000 China 2. CAEP Key Laboratory of West China’s Environmental System (Ministry of Education) Lanzhou University Lanzhou 730000 China

Urban particulate pollutants not only affect urban air quality but also directly threaten public health. lanzhou has been one of the most seriously polluted cities in the world due to its special geophysical location and weather conditions, which makes it an ideal place for urban particulate pollution study. In this study a set of environmental magnetic parameters (χ_(1f),χ_(fd)%, χ_(ARM), SIRM, HIRM, SOFT and back field IRM) were measured and analyzed for the dustfall samples collected monthly during 1997.4—2.00.5 and 2.04.11—2.05.10 at lanzhou University campus (KLD and CCS) and at a clear site of Gaolanxian (GLX). Results demonstrate that the main magnetic minerals in the dustfall are magnetite, with some maghaemite and haematite. Cross plots of M_(rs)/M_s vs. B_(cr)/B_c and χ_(fd)% vs. χ_(ARM)/SIRM indicate that the main magnetic grain sizes are pseudo-single-domain (PSD). The high concentration of magnetic minerals in the dustfall indicates that lanzhou is seriously polluted. The main pollution sources are anthropogenic activities and nature dust, with the former posing a great threat during the whole year, which is different from the general view that the natural dust is the main contributor in summer. With great efforts of the government and local authority in the past decades, the air quality in lanzhou has been improved in winter, but it is not so obvious in summer. This study also reveals that as a simple, rapid and accurate technology, environmental magnetism could be a valuable tool for urban pollution study.

关键词： environmental magnetism,dustfall,air pollution,lanzhou

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Development of a Chinese land data assimilation system:its progress and prospects

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Progress in Natural Science:Materials International 2007年第8期17卷 881-892页

作者： Li Xin~(1**) Huang Chunlin~1 Che Tao~1 Jin Rui~1 Wang Shugong~l Wang Jiemin~1 Gao Feng~1 Zhang Shuwen~2.Qiu Chongjian~2.Wang Chenghai~2.(1.cold and arid {2. environmental and engineering research institute,Chinese Academy of Sciences,lanzhou 730000,china 2.College of Atmospheric Sciences,lanzhou University,lanzhou 730000,china) [a]cold and arid {2. environmental and engineering research institute Chinese Academy of Sciences Lanzhou China [b]College of Atmospheric Sciences Lanzhou University Lanzhou China

The objective of land data assimilation is to merge multi-source observations into the dynamics of land surface model for improving the estimation of land surface *** have developed a land data assimilation system for china's land *** this sys- tem,the Common Land Model and Simple Biosphere Model 2.are used to simulate land surface *** radiative transfer models of thawed and frozen soil,snow,lake,and vegetation are used as observation operators to transfer model predictions into estimated bright- ness temperatures.A Monte-Carlo based sequential filter,the ensemble Kalman filter,is implemented as data assimilation method to inte- grate modeling and *** system is capable of assimilating passive microwave remotely sensed data such as special sensor mi- crowave/imager (SSM/I),TRMM microwave imager (TMI),and advanced microwave scanning radiometer enhanced for EOS (AMSR- E) and the conventional in situ measurements of soil and snow.A spatiotemporally consistent assimilated dataset for soil moisture,soil temperature,snow and frozen soil,with a spatial resolution of 0.2. degree and temporal resolution of one hour,has been *** paper introduces the development of Chinese land data assimilation system and the progress made on data assimilation algorithms,land sur- face modeling,microwave remote sensing of land surface hydrological variables,and the preparation of atmospheric forcing *** dis- tinct characteristics and challenges of developing land data assimilation system and the perspectives for future development are also dis- cussed.

关键词： land data assimilation land surface model passive microwave remote sensing Kalman filter

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Responses of distribution pattern of desert riparian forests to hydrologic process in Ejina oasis

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Science china Earth Sciences 2004年第z1期47卷 21-31页

作者： ZHAO Wenzhi, CHANG Xueli & HE ZhibinLinze Inland River Basin Comprehensive research Station, cold and {2. regions environmental and engineering research institute, Chinese Academy of Sciences, lanzhou 730000, china Yantai Normal University, Yantai 2.4005, china 1. Linze Inland River Basin Comprehensive research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences 730000 Lanzhou China2. Yantai Normal University 264005 Yantai China

By using the theories and methods of landscape ecology and the technology of GIS and RS, a study has been carried out on the responses of distribution pattern of desert riparian forest to hydrologic process on the basis of the hydrologic data from 1990 to 2.00 and the TM image of 2.01 year. The results showed that: (1) there appears an even distribution pattern for the relative forest area in oasis, however, the degenerated forest diaplays an increasing tendency from west to east; (2. the desert riparian forest in Ejina is in completely degenerated process at the patch scale; (3) the number of patch is influenced not only by hydrologic process,but also by agricultural activity such as cultivation. The severe deterioration of the degraded vegetation in whole oasis initiates from lower reaches, and gradually impels to upstream; the fragmentation of landscape in the terminal site is more obvious, which is influenced by river shape and decreasing flux of water. It is found that the influence of surface hydrologic process to the ground hydrologic process of desert riparian forest in Ejina oasis is little for the recent ten years. The relative area of the degenerated forest increased with increasing ground water depth in the direction of parallel to river channel. On the contrary, in the direction perpendicular to river channel, there is a decreasing tendency for the average patch area of the forest and the degenerated forest with increasing ground water depth.

关键词： Ejina oasis, desert riparian forests, vegetation pattern, hydrologic process.

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LANDSCAPE ECOLOGICAL CONSTRUCTION IN RURAL china:THEORY AND APPLICATION

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Chinese Geographical Science 2001年第2期11卷 104-114页

作者： XIAO Du-ning (cold and arid {2. environmental and engineering research institute, the Chinese Academy of Sciences, lanzhou 730000, P.R.china institute of Applied Ecology,the Chinese Academy of Sciences, Shenyang 110015,P.R.china ) cold and arid {2. environmental and engineering research institute the Chinese Academy of Sciences Lanzhou P.R. China institute of Applied Ecology the Chinese Academy of Sciences Shenyang P. R. China

In landscape with overpopulation, intensive management for economic production, and where even small natural-vegetation patches are scarce, ecological conservation generally must be developed in the course of economic development. Thus “landscape ecological construction” has evolved in china. This approach adds spatial elements and alters landscape pattern to strengthen inter-ecosystem linkages, improve functioning of damaged ecosystems, and increase productivity and stability of the whole landscape. Five examples of managed landscapes in china are presented: dike-pond systems in a river delta; multi-pond system in a rice paddy landscape; field-grass-wood grid system on unstable sand dunes; shelterbelt network in a crop field area; and field-grass-wood mosaic system on highly erodible hilly farmland. These indicate that ecological conditions can be improved along with increased economic production. Altering landscape structure and ecological flows by introducing small landscape elements in distinct spatial patterns is considered a key to the results. This reshaping of the land has focused on changing patch size, regularity of arrangement, biological and hydrological corridors, and networks, the matrix and grain size. It suggests that such changes can increase negative feedbacks and increase stability. Finally, planning and design principles are pinpointed for the landscape ecological construction process.

关键词： landscape planning ecological construction rural china

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CLIMATIC VARIATIONS IN china OVER THE LAST 2.00 YEARS

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Chinese Geographical Science 2001年第2期11卷 97-103页

作者： YANG Bao1, SHI Ya-feng2. LI Heng-peng2.(1. cold and arid {2. environmental and engineering research institute, the Chinese Academy of Sciences,lanzhou 730000, P.R. china 2. institute of Geography and Limnology, the Chinese Academy of Sciences cold and arid {2. environmental and engineering research institute the Chinese Academy of Sciences Lanzhou P. R. China institute of Geography and Limnology the Chinese Academy of Sciences Nanjing P. R. China

A compilation of paleoclimate records from ice core, tree-rings, lake sediments and historical documents provides a view of temperature change in china over the recent 2.00 years. For all-china temperature reconstruction, six sub-stages are identified for the last two millennia. Around AD 0－2.0, AD 800－1100, AD 132.－1400 and the period from AD 1880 on were warm while around AD 2.0－800, AD 1100－132., AD 1400－1880 were {2.. Also, temperature varied from region to region in each of the warm or {2. periods. The Eastern Han warm period (0－AD 2.0), the {2. period covering the span of Wei, Jin, and the Southern and Northern Dynasties, the MWP (AD 800－1100) and succeeding LIA occurred in eastern china and the Qilian Mountains. Only the first two climatic events were recorded in Guliya ice core while the so-called MWP and LIA was far weaker. Also, the warming between AD 800 and 1100 didn′t occur in the south of Xizang (Tibet) Plateau. Instead, the southern Xizang Plateau experienced warming in AD 1150－1400. The aggregated china temperature agrees well with North-hemisphere temperature in the past millennia, indicating close relationship of temperature changes between china and North-hemisphere.

关键词： climatic variations the last two millennia china

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Anomaly feature of seasonal frozen soil variationson the Qinghai-Tibet Plateau

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Journal of Geographical Sciences 2002年第1期12卷 99-107页

作者： WANG Cheng-hai1,2. DONG Wen-jie3, WEI Zhi-gang2.(1. College of Resource and environmental Science, lanzhou University,{2., china 2. cold and arid regions environmental and engineering research institute, CAS,{2., china 3. Insti College of Resource and environmental Science Lanzhou University Lanzhou 730000 cold and arid {2. environmental and engineering research institute CAS Lanzhou 730000 institute of Atmospheric Physics CAS 北京 Beijing

The seasonal frozen soil on the Qinghai-Tibet Plateau has strong response to climate change, and its freezing-thawing process also affects East Asia climate. In this paper, the freezing soil maximum depth of 46 stations covering 1961–1999 on the plateau is analyzed by rotated experience orthogonal function (REOF). The results show that there are four main frozen anomaly regions on the plateau, i.e., the northeastern, southeastern and southern parts of the plateau and Qaidam Basin. The freezing soil depths of the annual anomaly regions in the above representative stations show that there are different changing trends. The main trend, except for the Qaidam Basin, has been decreasing since the 1980s, a sign of the climate warming. Compared with the 1980s, on the average, the maximum soil depth decreased by about 0.02.m, 0.05 m and 0.14 m in the northeastern, southeastern and southern parts of the plateau, but increased by about 0.57 m in the Qaidam Basin during the 1990s. It means there are different responses to climate system in the above areas. The spectrum analysis reveals different change cycles: in higher frequency there is an about 2.year long cycle in Qaidam Basin and southern part of the plateau in the four representative areas whereas in lower frequency there is an about 14-year long cycle in all the four representative areas due to the combined influence of different soil textures and solutes in four areas.

关键词： Qinghai-Tibet Plateau seasonal frozen soil rotated empirical orthogonal function analysis anomaly areas

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Characteristics of ^(137)Cs deposition in steppe area

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Chinese Science Bulletin 2002年第10期47卷 848-853页

作者： ZHANG Chunlai, ZOU Xueyong,DONG Guangrong, ZHANG Xinbao & QIN ZhiLaboratory of Blown Sand Physics and engineering, cold and {2. regions environmental and engineering research institute, Chinese Academy of Sciences, lanzhou 730000, china china Center of D Laboratory of Blown Sand Physics and engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China china Center of Desert research at Beijing Normal University Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing China institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China institute of Modern Physics Chinese Academy of Sciences Lanzhou China

Soil wind erosion in the semiarid steppe area was studied using the 137Cs tracing technique. Comparisons of 137Cs deposition characteristics between different soil profiles indicated that slight aeolian activities occurred on sandy grasslands and semi-fixed dunes with erosion/deposition rates of less than 0.108 cm/a, whereas they were intense on semi-shifting dunes with erosion/deposition rates of higher than 1.35 cm/a.

关键词： 137Cs steppe soil wind erosion.

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Climatic and environmental changes over the last millennium recorded in the Malan ice core from the northern Tibetan Plateau

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Science china Earth Sciences 2006年第10期49卷 1079-1089页

作者： WANG Ninglian1,2. YAO Tandong2.1, PU Jianchen1, ZHANG Yongliang1 & SUN Weizhen1 1. Key Laboratory of Cryosphere and Environment, cold and arid {2. environmental and engineering research institute, Chinese Academy of Sciences, lanzhou 730000, china 2. institute of Tibetan Plateau research, Chinese Academy of Sciences, Beijing 100085, china 1. Key Laboratory of Cryosphere and Environment Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China 2. institute of Tibetan Plateau research Chinese Academy of Sciences Beijing 100085 China

In this paper, climatic and environmental changes were reconstructed since 112.A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 2.th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The “Medieval Warm Epoch” and “Little Ice Age” were also reflected by the ice core record. The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ 18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101―102.years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.

关键词： the Tibetan Plateau, the Malan ice core, climate changes, dust event frequency.

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Water environmental Degradation of the Source Area of the Yellow River on Northeast Qinghai-Tibet Plateau

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Chinese Journal of Population,Resources and Environment 2005年第3期3卷 34-36页

作者： Qi Shanzhong 1, Luo Fang 2.& Xiao Honglang 2.1 College of Population, Resources and Environment, Shandong Normal University, Jinan 2.0014, china 2.cold and {2. regions environmental and engineering research institute, Chinese Academic of Sciences, lanzhou, 730000, china College of Population Resources and Environment Shandong Normal University Jinan 250014 China cold and arid {2. environmental and engineering research institute Chinese Academic of Sciences Lanzhou 730000 China

The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.

关键词： water environmental degradation decreasing of surface water continuous lowering of groundwater table the Yellow River region Qinghai- Tibet Plateau

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