With the intensified pressure of population increase on natural resources and the environment in China, changes in soil quality, especially in soil fertility, have become the focus of increasing world wide concern The aim of this paper is to try to precisely judge the new changing trend in soil fertility and quality in China for the sake of providing scientific basis for decision making to policy makers Data used in this article is from the second national soil census conducted in 1982 1986 and the follow up soil survey based on the sample plots of the soil census done by Nanjing Institute of Soil Science in 2000 Five soil chemical indicators-organic matter total nitrogen, effective phosphorus, effective potassium, and pH value, with close relation to the crops growth, are selected as the primary analytical variables of soil fertility In this paper, agricultural soil fertility and quality changes from the early 1980s to 2000 were described by using data from 3 regions in China-the Northeast, the North China Plain and the middle and lower reaches of the Yangtze River-covering 180 sample plots in 15 counties of 6 provincesin.The principle for sample plot and data selection in the study is that soil fertility indicators mentioned above should be recorded both in the early 1980s and 2000 on sample plot basis Meanwhile, soil sampling season and analytical methods of soil experiments in the two periods should be basically the same so as to guarantee data from each plot of the two periods one to one correspondence and comparably in agreement. This is one of the reasons accountable for the more reliable and more convincing analysis and conclusions of the present paper than other similar studies The results show that, on average, soil organic matter, total nitrogen and effective phosphorus content have been increased since rural reform in China, although soil effective potassium and pH value degraded From the perspective of spatial distribution, however, there exist significant variations in soil fertility and quality The average soil fertility rose in North China and the middle and lower Yangtze River basin, and dropped in Northeast China Additionally, with the exception of North China, which saw an improvement in soil pH value, acidification tendency was observed in the middle and lower reaches of the Yangtze River and Northeast China.

今年5月25日,中国科学院路甬祥院长以我国科学家应用地理信息技术,开发“SARS控制与预警地理信息系统”,为抗击“非典”服务为例,对地理科学创新作了重要讲话,在地理科学界引起了热烈反响。路甬祥的讲话,对地理科学加强学科交叉,实现学科布局的动态更新,促进整体优化,为国家的发展做出“基础性、战略性、前瞻性”的贡献,具有重要的指导意义。现将路甬祥等院士对地理科学创新的讨论,简要刊载于下。

The Tarim River is the longest inland river in China. There are natural species belts composed of Arbors, Shrubbery and Herbage along the River The species distribution of natural species is affected by soil water, soil salt content, human activities and so on In this paper, based on the investigation data in the middle reaches of the Tarim River, niche breadths and overlaps of the 19 main species on two environmental dimensions were calculated and analyzed The minimal spanning tree revealing ecological similarity was drawn on the basis of the niche overlaps The results showed that niche breadths of community building species were bigger than that of the others, because they could acclimatize themselves to some changed environmental conditions Niche breadths of Shrubs and Arbor were generally big except for individual species, and niche breadths of Herbage were small except for community building species The above analysis shows the ecological characters of different species in the middle reaches of the Tarim River, it also shows that the niche overlaps among different species are generally low in the middle reaches of the Tarim River, that is, different species need different nutrient which can enable different kinds of species live together for a long time The ecological character of different species in a same family is more similar, and the niche overlaps among them are also small The reason is that the ecological character among different species in a same family is more similar The needs of these species are different, which lower the degree of niche overlaps and make these species live together in a small ecological environment Based on the minimal spanning tree, the ecological similarity of 19 species was analyzed on two environmental dimensions According to different ecological needs among the 19 species, they could be divided into four categories when the niche overlap is greater than 0 278 These species could also be divided into three categories according to the soil salt content when the niche overlap is greater than 0 190 These phenomena show the importance of the ecological character in the niche evolution

水资源、人口、能源与环境已经成为当代全人类共同关注的四大问题。其中全球水资源问题尤其引起世界各国的强烈关注,水资源匮乏已经成为阻碍世界经济发展的重要因素。我国水资源总量尚属丰富,但人口众多,人均拥有水资源量居世界第88位,按照世界标准属于缺水国家。全国大部分地区缺水,多数城市又供水不足,而洪涝灾害和水污染问题还非常严重。长江是我国的第一大河,自宜昌至湖口的长江中游流域面积68万平方千米,仅占全国国土面积的7.1%,而年径流量却占全国年径流量的16.6%。丰富的水资源有利于国民经济各部门的利用,但是,降水和径流过分集中在汛期,区内和上游若发生连续性强降水,

东北森林土壤动物的研究始于20世纪70年代末,是由中国科学院地理研究所张荣祖教授倡导首次在长白山开展的。继之,东北师范大学陈鹏教授获国家自然科学基金资助(1989～1991年),对东北地区土壤动物区系、生态地理进行较系统、全面的调查研究。在此基础上继续获国家自然科学基金资助(1995～1998年),开始对土壤动物在森林生态系统中的功能作用进行研究。由东北师范大学图书出版基金资助、东北师范大学出版社出版(2001年)的《东北森林土壤动物研究》为国家自然科学基金资助项目“东北地区森林土壤动物及其功能作用研究”的主要成果,是殷秀琴教授主持、领导的多学科研究群体对基

在举世瞩目的三峡水库蓄水工程开始前夕,西南师范大学蓝勇教授主编的《长江三峡历史地理》由四川人民出版社出版,可以说是从学人角度为这项伟大的世纪工程献上了一份特殊的厚礼。《长江三峡历史地理》系国家社会科学“九五”规划项目,也是我国第一部系统研究三峡地区历史地理的大部头学术著作。通读《长江三峡历史地理》,明显地感到该书体现了以下几个特色:一、浓重的现实关怀和服务意识历史学早有经世致用的传统,历史地理学更是与社会现实、国计民生关系密切。可以说关注现实是区域历史地理学的一个重要理念和功能。当三峡蓄水高度达到175米时,不难想象千年三峡历史风貌势必大有改变,并不可避免地带来许多自然与现

由西北师范大学李并成教授完成的《河西走廊历史时期沙漠化研究》一书,已于2003年1月由科学出版社出版发行,这是中国沙漠历史地理研究领域的一项新的研究成果。我国的沙漠历史地理研究,是20世纪60年代由北京大学侯仁之院士开创和倡导的,并成为中国历史地理学研究领域的一门独具特色的学问。所谓沙漠历史地理,是关于沙漠地区历史时期环境变迁的研究,其主要研究历史时期干旱、半干旱地区由于人类不合理的开发经营活动(如滥垦、滥牧、滥樵、滥用水资源等)导致的生态平衡破坏、沙漠化扩大等环境问题的演变过程和内在机制。数十年来,经过几代学者的不懈努力,我国沙漠历史地理研究从无到有,

Wetland is a special transitional ecosystem between aquatic and terrestrial ecosystem on earth It is also an important survival environment and one of the most colorful biodiversity ecological landscapes Wetland is called the cradle of life, the kidney of the earth, the source of the civilization and the gene base of the species Wetland has indispensable functions in withstanding flood, adjusting runoff, improving climate, controlling pollution, beautifying environment and sustaining ecological balance in regional areas So according to the outline of natural protection drafted by IUCN, UNEP and WWF, wetland, forest and sea are listed as three ecological systems in the whole world, and freshwater wetland is thought as the last concentrative region for the endangered wildlife With the understanding of wetland functions, wetland science has become one of the key disciplines and frontier fields for many scholars In recent years, work has been done on soil temperature by quite a number of scholars to a certain degree but quite less work has been done in wetland soils temperature The Sanjiang Plain is the largest fresh water wetland distributed area in China, so the research on wetland soil temperature in this area is quite typical and representative The heating condition is the main characteristics of wetland soils, which has important influence on the process of wetland ecosystems The paper researches the rule of typical wetland soil changes and the influenting factors with analogy and model fitting The typical wetland soils are mire soil, peat mire soil and swampy meadow lessive First, the paper describes the basic characteristics of the different soil layers Then, it analyzes the vertical change of temperature, temperature change of different months, seasonal dynamics and main environmental factors of these typical wetland soils At the same time, it makes regression analysis of the mean temperature, air temperature and soil temperature at different layers of wetland soils Moreover, it also makes model fitting of the seasonal dynamics of these typical soils and gets satisfied results, R² >0.85 The model helps to predict the changes of these typical wetland soils and their temperatures in growing seasons of wetlands plants This study could further perfect the formation and development theory, understand the function and characteristic of wetland ecosystems and help to reasonably exploit and protect wetland soils

在20世纪的最后一个月,我国地理学界的泰山北斗,原中国地理学会名誉理事长、中国科学院地理科学与资源研究所名誉所长、《地理研究》杂志的老主编、顾问黄秉维院士,不幸因病逝世。悲痛之际,为缅怀黄先生对我国地理科学的贡献和成就,铭记黄先生多年来对《地理研究》的指导与关怀,特发表郑度、杨勤业、李秀彬三位教授的纪念文章,以表达我们对黄秉维先生深切怀念的共同心愿

Land use is one complex system, which is affected by many factors, including both socio economic elements and natural resources and environment This paper firstly established a framework for macro analysis on the driving forces of land use change in China, in which economic welfare, environmental welfare, the need for food security and the advancement of science and technology are the main forces contributing to the land use changes Then the paper analyzed the basic contradictions in the land use change in recent years on the basis of current situation of land use and economic development in China In the third section, according to the analytical framework established firstly and the basic contradictions in the land use change, and on the basis of the land use data and other related socio economic documents in recent years, this paper analyzed and computed the indexes of the driving forces of the land use change and represented their spatial distribution in China By the distribution of these driving forces, the whole China can be seen as three distinct sub areas: Tibet southwest sub area, central northwest sub area and east sub area, each of which takes on different features in respect of the driving forces of land use changes As indicated in this paper, the economic welfare is the fundamental impetus to the land use changes, and the environmental welfare and the need for food security are also important factors in China The future land use change is ultimately decided by the performance of these factors and their interactions

The advances on the research into the mechanism of hydrological cycle in Yellow River drainage basin are generalized from four aspects. Firstly, it is shown that the researches on hydrological processes have mainly focused on the single aspects such as precipitation, evaporation, infiltration, interception and runoff. Further studies should focus on the coupling between vertical water transfer and horizontal water movement, with special attention to the prominent characteristics of Yellow River such as man made dry out and high silt content. Secondly, the research results at several hydrological field experimental stations and hydrological laboratories are generalized. These stations and laboratories accumulated a large amount of hydrological data of the Yellow River over years. Unfortunately, most of these stations and laboratories ceased to run in the1960s. A new hydrological experimental laboratory, based on an old laboratory, is available soon to explore the key links in the hydrological cycle in Yellow River drainage basin. Appealing is to the government for reforming more old and/or establishing new hydrological experimental installments. They are one of the most important aspects to basic hydrological research Thirdly, the hydrological models used in operational Yellow River flood forecasting are listed. As Yellow River is mostly located in semi arid and arid climatic zone, the hydrological scenarios of the river are very complicated with high spatial variability. Sometimes the empirical method can get better results of hydrological forecasting than hill slope and or conceptual models. Because distributed model can well consider spatial variability, it is worthy to try to establish a distributed model over the Yellow River. The model will couple vertical and horizontal water transfer and movement, be parameterized by making use of remote sensing and field experimental data and interfaced with Global Circulation Model. The model is established for exploring the mechanism of hydrological cycle in Yellow River diainage basin and simulating the responses on land use/land cover change and other environmental changes. Last but not least, the scale problem, which is another key to explore the mechanism of hydrological cycle of Yellow River, is discussed. It rises because theories of many hydrological processes such as infiltration, evaporation, overland flow, sediment transport and subsurface water movement have been developed at small space-time scales. However, predictions are required at much larger space and time scales. These include the scale of large catchments where not only are the basic theories questionable but other processes or controls on spatial and temporal heterogeneity come into play. In essence, the scale problem is a search for connections between nonlinear hydrological theories developed for small scales, and the large scale hydrology of complex natural systems. Representing spatial and temporal variability in models, exploring the existence of natural time and space scales and statistical downscaling are specially needed in Yellow River drainage basin.

Huge amount of steep slope land reclamation is a key reason for soil erosion and and eco environmental degradation in China. As a fundamental countermeasure of ecological rehabilitation, the experiment of returning farmland to woodland and grassland was conducted in large areas of the upper reaches of Yangtze River and the middle and upper reaches of Yellow River in the year 2000. However, a series of problems were also resulted from the process of de farming, such as food safety, allocation of ecological emigration. An important springhead of these problems is the spatial disparity of population stress caused by spatial disparity of slope farmland distribution. The more concentrated the slope farmland is, the more complex the problem of population stress is. Four population stress index models in de farming process based on GRID is designed in this research: (1) the fundamental de farming stress model based on the ratio of slope farmland to total farmland:p i= u iv i×100%.p i stands for population stress index;u i stands for the percentage of slope farmland to the neighborhood area; v i stands for percentage of farmland to the neighborhood area. (2) the modified model concerning the disparity farmland quality. (3) the modified model concerning the spatial disparity of population distribution. (4) the modified model concerning the development of economic forest on de farmed slope farmlands. Finally, taking Fengjie County for example, simulations are conducted using these models, and available results of de farming stress indexes are obtained in different locations under various conditions.

Land cover changes are not simple processes. There are complex simultaneous patterns of land-cover change, ranging from modifications in land cover to conversions and maintenance. There is a functional complexity within types of land-cover change, and a structural complexity between types of land-cover change, both in terms of spatial arrangements and temporal patterns of change. Land-cover change needs to be measured in its complexity to fully understand it. It is important to differentiate between land cover and land use when measuring patterns of changes. Land-use/land-cover change is a kind of extremely complex phenomenon. For all researchers involving in the study to avoid the unilateralism like blind-person touching elephant, they should search a new synthesis of studies. Therefore, the traditional approach of land use study is not effective and new topics are needed to be further found. A generalized and comprehensive understanding is required for the drivers of land-use change. We need a network of case studies that represents the spatial heterogeneity of the region and a multi-level approach that allows for a linkage between regional and local scale land-cover dynamics. Case study comparison is a major tool to derive generalizations of land-use/land-cover change research. We should develop new methods in mathematical modeling, descriptive models, empirical study, systematic case study and mechanism study. Linking house-hold-level information to remote sensing data is becoming a major tool to increase our understanding of land-use dynamics. The drivers of LUCC are always present but interact differently according to the temporal and spatial dynamics of the situation. A thorough understanding and modeling of these complex interactions is a prerequisite to generate realistic projections of land-cover change. The more important hypotheses for LUCC are those that frame the integration and synthesis of the science.

Shilin in Yunnan Province of China has the most typical and integrated sword-like karst landforms across the world continental area. It has served as the special term representative of such kind of geomorphology. Shilin area is not only the national conservation area of karst landscape, but also the national scenery spot. As a scenery spot, Shilin landscape enjoys the praise of marvelous spectacle on earth and becomes the focus of aesthetics. On the basis of Chinese traditional aesthetic theory of natural landscape and the research result concerning modern geology and geomorphology, this article takes the Shilin landscape as the aesthetic object, discusses and summaries its spatial structure and visual aesthetic characteristics,identifies the component elements making up the Shilin landscape and the factors which influence the aesthetic value. Natural landscape has always been the aesthetic object of the people, there are countless descriptions of the same landscape, but however, great differences exist in the descriptions of the same landscape. Although the issue of how to assess the aesthetic value of natural landscape has been the concern of the people for a long period of time,no consensus opinion has so far been reached. We believe that the disagreement on the identification of the evaluation elements is the key to the issue. The landscape evaluation method proposed in this article, which is to combine the landscape's scientific cause of formation, scientific value and beauty of modality together, to link the experts' evaluation with the systematic investigation and analysis, will definitely promote the in-depth study of the aesthetic value of natural landscape.

Fujian Province is situated in the southeastern part of coastal zone of China with favorite geographical location, abundant and various natural resources, large population but less land. Since reform and opening to the outside world, the province's economy has developed very fast with the extroverted and non public owned economy as main body, profiting from the exertion of locality and kinship advantages. The GDP of the province experienced an average growth rate of 13 8% from 1979 to 1998, which was one of the highest growth rates in China. However, a series of problems emerged during the rapid economic growth, such as the prominent inconsistency of economic structure, the lag of urbanization to the industrial growth, the imbalance and lack of coordination in the investment environment, the deterioration of ecology and natural resources, and the broadened gap of regional development. According to the request of sustainable development strategy, in the new century, Fujian Province should coordinate the relationships of economic and social development with the ecology and resources, try for a moderate high speed and sustained economic development, promote the upgrade and optimization of industrial structure, enhance the construction of infrastructure focused on transportation, further improve the investment environment and broaden the opening, exploit the natural resources rationally, reconstruct the environment to ensure the benign circulation of ecology, and reduce the regional development gap via multiple approaches such as policy support and regional economic association and cooperation.

Sustainable land use is one of the essential objectives of exploitation, utilization and protection of the future land resources in Three Gorges Reservoir Area (TGRA) It is beneficial to revealing the structural characteristics of eco economic system of land use the situation among their subsystems to evaluate sustainable use of land resources aimed at its actual characteristics Furthermore, the scientific gist of making measures for strategic adjustment of land use and resettlement in the near future can be obtained by studying the ways and models of sustainable land use In this paper, the quantitative model for evaluation of sustainable land use is built Then based on the evaluation and analysis of sustainable land use potential and regional difference in TGRA, it is pointed out that the land use level as a whole are not only weakly sustainable, but also differs greatly in different regions Since there are a lot of impediment factors,therefore, the sticking point to make measures for land use is that the principles including adjustment measure to local conditions and guidance according to types must be complied, and the relationship among ecological rehabilitation,resettlement and economic development will be correctly disposed The main approach models inclucle four ways, namely,tree planting and of forestation, terracing slope land, optimizing structure and industrial breakthrough

Water environmental pollution, which is a complex problem, deals with the systems of ecology, society, economy, and resources Therefore, synthetic analysis of the above mentioned factors must be carried out along with the study of the coordinated development of water environment and economy.The macro economic system should be taken as a fundamental starting point to study how to control the pollution to the optimum level, and seek suitable economic structure and developing rate, so as to realize the aim of water environmental protection The regional water environment economy decision support system was designed to address water environment management issue, assisting decision makers to resolve the decision making problems of the coordinated development of water environment and economy The decision support system used modularization idea according to the characteristics of the system, for convenient model modification and expansion,each module has its particular function and independency.Meanwhile, all these modules are an integral one,taking fully into account the entire harmony. In which the macro economic module is regarded as the primary module which promotes other modules assisting decision making for decision makers, so as to achieve computerization in assisting decision making of the regional water environment and economic coordinated development The system consists of three components: database, model base and user interface Database management system, the basis of decision support system, provides the information of basic data to decision makers and the supporting data for model run so as to store calculated results The model base integrates models of macro economics, environment economy multi objective programming, water resources demand, water environmental capacity, and water environmental analysis, and the multi objective programming model includes production structure optimization model and industrial structure optimization model, the water resources demand model includes ecological, agricultural, industrial and domestic water demand model After the basic information made up and operated by the model, the optimization recommended schemes and development mode under different environmental protection aims, different economic development speeds and different macro policies were put forward, then the man machine conversation system provides this result to decision makers, thus it can help the decision makers produce correct judgement through schemes comparison The solution was achieved by using multi objective programming and regarding the constraints as optimization objectives, and the decision making information was obtained by means of input expert experience and knowledge via the step by step method The system has some functions, such as prediction, optimization, simulation and management, accordingly it provides an effective means for water resources and water environment management

Thanks to the cooperation among the scientists from many countries across the world, the year 2000saw human finished drawingthe map of his own genome. This very accomplishment bringsnot only an increasing momentumto the knowledge of life sciences and biological technology but also great impetus and enlightenment to other fields of sciences. Under such circumstances, Prof.Chen shupeng, an Academician of CAS, took the lead in puttingforward the concept of Geo informative Tupuand attached great importance to the related researchissues and possible practical uses ensued from it. And he argued that these would definitely be of great importance to the development of both geographic science and future of the country. Following him, scholars of geography and many other disciplines began their studies on this promising topic. Based onall these, this paper probes into the connotation of geo informative Tupu and the basic characteristics that it shares with transportation network, touches on the applications of Tupu that are actually found in the field of transportation, analyses the possibility that Tupu will give to the study and improvement of transportation network when it is used efficiently as the most important information source of transportation network and combined correctly with latest technology such as RS, GIS, GPS, ITS etc. And after all thesehave been done, the paper forecasts several major aspects that Tupu will benefit transportation network when its right conception is fully understood and scientifically used.

A new geographical curriculum standard will be introduced for middle school across China to replace the current general outline of geographical education and will instruct geographical education in middle school in the coming 20 years. The project, "Establishment of Geographical Curriculum Standard for Middle School", sponsored by the Ministry of Education,aims at constituting a scientific and reasonable curriculum standard for middle school. This paper discusses the importance and necessity of geographical education through analyzing the trend of geographical development,the social requirement to geographical education,the relations between psychological development of students and elementary education of geography.In addition,comparison between the elementary geographical education in China and that in other countries,such as the United States, France, Britain, Germany etc.is also made.It is different from China that the elementary geographical education in foreign countries seldom use the subject-system as the contentsystem but pay more attention to social events and students' life and consider students' in terests and development of individuality, cultivate geographical methods, abilities and thoughts and advocate explorative study. Finally,on the basis of illustrating the guidelines, goals and content-structure of the curriculum standard of geographical education in China,some important strategies are put forward.

Based on methods of geographical information system and remote sensing technology, the single element's thematic digital terrain models of the elevation, aspect, slope, temperature, precipitation, maximum potential evapotranspiration, moistureand NDVI, which areintimately related to land cover environmental background in East Asia, are studied under unifiedprojection, unifiedspatial resolution and unifiedcoordination system, respectively. Then all the single elements are integrated to generate synthetic digital terrain models containing characteristics of each element by using Principle Component Analysis method. Finally, the characteristics of environmental background of land cover in East Asia reflected by the synthetic digital terrain model are analyzed. The characteristics of environmental background of land cover in East Asia are as follows: (1)The environmental background of land cover in East Asia has regularities of extention from northeast to southwest and gradation of southeast to northwest. At the same time, the distribution range of this characteristic is consistent with the range of monsoon climate area. We also found the zonal distribution of environmental background in western edge of this region is very complex. These phenomena completely incarnate the complexityof topography and climate in this area. (2)In the monsoon climate area, there exists not only the regularities of longitudinal zonality, characterized by extention from northeast to southwestand gradation from southeast to northwest, but also the regularitiesof latitudinal zonality featured by extention from east to west and gradationfrom north to south. (3)In northwest inland area including Xinjiang, northwestern part of Qinghai-xizang Plateau, western part of Inner Mongolia and southwestern part of Mongolia, a broad sense of eastern part of central Asia dominated by mountainsand basins in topography, the southeast monsoon, temperate westerly and Arctic Ocean air currents are inaccessible to reach this area, so the quality of environmental background of land cover in this area is very low. (4)In northern part of East Asia, because of flat terrain endowed with certain amount of precipitation compared with northwest inland area,the land cover environmental background condition is relatively high and has the longitudinal zonality of extention from east to west and gradationfrom south to north.

The paper analyzes the environmental change in Bosten Lake since 1958 and points out the reasons in the context of both natural environment and human activities. In the last 40 years, the impacts of the natural factors on water level change is more than the contribution of human activities in the water level change; however, the water quality change is mainly influenced by human activities. The fact that Bosten Lake has become a salt water lake rapidly from a fresh water one is related to special geographical location of the Lake, but it mainly resulted from the reduction of Bosten Lake input amount and a great quantity of water from farmaland drained into the Lake, especially the latter. Farmland drainage is not only the direct reason leading to the increase in the mineral concentration of Bosten Lake, but also a key effect on the hydrochemical change and controls the formation of hydrochemical type of Bosten Lake water. Based on the above analyses, the paper further discusses the mechanism of the interaction between the environmental change of Bosten Lake and the environmental change of oasis in Yanqi Basin, and points out that over the last 10 years, the environmental change of oasis in Yanqi Basin has been sustainable. However, the sustainable development of the whole Basin's Yanqi environment depends largely on the reclamation scale of oasis. The appropriate scale of oasis reclamation in Yanqi Basin ensures the sustainable development of environment of both the Lake and oasis in the Basin.

To characterize the equilibrium extent of structure of urban land use, an index formula based on information entropy is advanced as follows: J=-∑NiP i log P i/ log N In the formula,P i=A i/A=A i/∑NiA i,where A is the area of urbanized area of a city, A i is the land area of a certain function type,and N is the number of land function types Correspondingly, the difference of an index is defined as I=1-J,which can be used to reflect the inequality of urban land use When information entropy is generalized to describe the spatial morphology of urban land use by means of making ‘nets’ on maps,information dimension as one of the fractal dimensions can be computed to qualify the spatial patterns of urban land use .

Soil erosion is one of the most serious environmental issues in China It is very important to investigate the mechanism of soil erosion and to develop soil erosion model, which is the useful tool to design the measures of soil and water conservation and sustainable use of soil and water resources, and is also closely related with the rehabilitating of the degenerated environment The development of soil erosion models in U S A, Europe, and Australia was reviewed briefly and then the development of soil erosion model in China was analyzed in detail Both empitical models, process based models,and the utilization condition of new techniques such as GIS, RS, REE in soil erosion were evaluated in this paper On the basis of the above evaluations, the issues existing at present research , which need to be enhanced in the future research, were identified The purpose of this paper was to learn the overseas experience and promote future soil erosion model development in China

The computational mesh should represent the geometry, physical properties and boundary conditions of the computational domain in the flood simulation model. Based on the cell shape the computational mesh can be classified into regular mesh and irregular mesh. The generation of regular mesh is easy and simple, and as for irregular computational mesh hydrologists usually generated it manually. Due to structure and shape similarity, the automatic TIN generation algorithm can be used to generate the computational mesh for flood simulation model. The detailed flood model construction process based on GIS is to (1) delineate the computational domain; (2) generate computational mesh; (3) generate the mesh topology; and (4) extract the model parameters. The model parameters include boundary conditions, initial conditions, hydrological and geomorphological parameters and as well as other parameters for controlling the model simulation process. GIS technology can provide some spatial analytical tools for extracting some of these parameters such as the manning coefficient(roughness parameter) and calculating the average ground datum of internal point of every mesh unit and the mesh nodes, improve the capacity for defining the spatial sub-units of the computational domain and provide a better method to discrete the computational domain with enough amount of computational mesh with suitable geometry. In the river reach from Huayuankou to Jiahetan in the Huanghe River these maps of topography, landuse, water conservation engineering, hydrological observation station were used to construct the flood simulation model, and the data structure of the computational mesh is described in detail.

As aging process speeds up, China is beginning to face the critical social problems of an aging population, which have already affected all aspects from the State's imperfect social security system to family traditions. After abolishing the traditional cradle-to-grave welfare system under the planned economy in the early 1980s, the retired people have gradudlly lost their links relations with their units where they once worked. Meanwhile, the size of families is growing smaller and smaller. The senior people fail to communicate with other people in society, and are more likely to feel lonely. The aged is about 20～30 % of the total population and some aged communities even emerge in urban districts of some large cities, such as Beijing, Shanghai, and so on. However, more attention has been paid to senior people's pension, medical care and living conditions. There are few studies on their need for leisure and leisure behaviors. This paper builds an empirical study on a survey, which records daily activities of 50 retired people for a whole year. With the help of time geography, the authors try to carry out a theoretical study on the need, quality and space-time pattern of senior people's leisure activities. The authors find out that (1) most senior people are living in a regular lifestyle; (2) the total daily leisure time is long, but the quality of their leisure activities is not high; (3) most of their leisure activities are carried out at their homes with their family members; (4) their leisure behaviors are different in sex, age, income, education, season and living place; and (5) the leisure facilities in communities and society are far from meeting their need nowadays. The outcome is believed to be useful to the spatial organization of leisure and urban planning in large cities.

Land use and cover change (LUCC) is an important component of global environmental change research, and terrestrial transect initiated by the international geosphere-biosphere programme (IGBP) is a suit of integrated global environmental change research, which emphasizes interpretation of global environmental change problems with grads methods. Taking transect as a series of coherent research sites, LUCC can determine how land use and corresponding land cover change under the influences of social and environmental factors. Transect of the Yangtse River (TYR), with obvious grads either in the change of physical environmental factors or in the level of socioeconomic development, was taken as a study area in this paper. Land use changes in several years or decades are mainly driven by socioeconomic factors and restricted by physical factors, and they can be mainly reflected by the changes of cultivated land and built-up land, which are tightly interrelated with human productive activities. Land use changes of TYR in future 30 years were modelled through applying revised Generalized Thunen-Ricardian model. It shows that, between 2000 and 2030, the area of cultivated land in eastern part will further decrease; however, the area of cultivated land and urban and rural settlements in overall will increase. According to the spatio-temporal characteristic of land use changes in future, corresponding countermeasures were put forward as the following to realize regional sustainable sustainable land use: (a) scientifically laying out city/town planning and strengthening reconstruction of old city zone; (b) strictly managing rural housing and carrying out aggregating scattered houses; (c) coordinating the relationship between land development and cultivated land protection; and (d) realizing regional sustainable socioeconomic development relying on resources and breaking the cycle of poverty and unsustainable land use.

Composition of modern pollen rains representing warm temperate and central Asia tropic zones has been obtained based on analysis of the year round aerial pollen samples and pollen samples in surface soils from Beijing, Yucheng and Taoyuan which are located in different climatic zones. Of them aeropollen assemblage can better reflect regional vegetation composition in contrast to surface soil pollen assemblages, and characteristics of regional pollen rain can be regarded as a mark to classify climatic zones. Analysis of pollen rain from eastern China also indicated that long distance pollen migration is closely related to East Asia mosoon, and pollen migration route reflects the trajectory of monsoon activities. Studies of pollen rain made it possible to further understand the relationships of pollen composition-vegetation-climate which will be helpful to conduct quantitative analysis on rehabilitation of vegetation and climate by means of pollen research.

Some problems in the global climate studies are discussed in this manuscript Special attention was given to the debates on global warming Although it is widely accepted that the anthropologic greenhouse effect would be responsible for the recent global warming, there are always unceasing skepticism Numerous evidences show that it is indubitable on the climate warming itself The global surface air temperature has increased by 0.4-0.8℃ since the mid 19th century Substantial changes associated with the climatic warming also occurred during the past century These related transformations have been observed in the ocean temperature, atmospheric temperature, reconstructed temperatures from the evaluation of mountain snowlines and borehole thermometry, land snow cover, sea ice cover and the mountanious glaciers It is found that 1998 is the warmest year on records during the past 150 years Global averaged annual temperature in 1998 is 0.55℃ above the mean of 1961-1990 The linear warming trend for the 20th century is 0.066℃ /10a The 1990s (with the anomaly of +0.35℃ ) is the warmest decade not only in the 20th century but also in the past 500 years and maybe even in the last millennium After all, the global warming in the 20th century is an explicit fact, whereas there are doubts on which factor should be responsible for it Anthropologic factor may be the most important reason, at least, may be one of the most important factors if there are some other crucial causes To some degree, the sciences of climate change benefit from the debates on the global warming , since there are increasing concerns and demands for a better understanding of the climate system (including their natural variability and their interaction with the human induced greenhouse effects) Unfortunately, the debates and some related conclusions are no more “pure” scientific questions, but political affairs.

Resenzweig and Parry published their paper on Nature to discuss China's Food Security in 1994 American president Clinton authorized the development report the science and technology strategy to buildup the American economic security in 1996, and the problem to buildup national economic security was presented as an important national target In 1997, President Jiang Ze min presented the problem of Chinese economic security The report of Clinton especially emphasized the problem of economic security under global change Each nation will be faced with not only the change of environment and the conflict between the economic development and the exploitation of resources, but also the problem of national economic security caused by the change of environment In fact, because of the rapid development of China, just only the use of resources probably will cause the problem of economic security The paper built models to analyse the environment and economic security of China in the future 30⁵0 years The paper is based on the food demand and production model, which was established at the Stockholm Environment Institute （SEI） At the same time, we use the model established by Ds and Shaw to calculate different global change variables' influence to the food demand and supply,then use the result to calibrate the variables In our analysis, the food demand for future people was divided into two levels, and access the quantity Then we conclude that, with the influence of global change, China's future food production can't meet the need of the increasing demand It has been estimated that there maybe 7⁸%'s insufficiency Because of the uncertainty of different global change variables, and technological progresses will enhance the increase in food production, according to the result, the risk of hunger can be avoided, if only we adopt appropriate methods to decrease the affects of global change

In the process of spatial analysis, the vector data are always rasterized into the raster data because of the convenience for spatial analysis. How the area accuracy loses during rasterizing needs to be answered when different grid sizes are adopted in order to choose a suitable grid size. The question is answered here by rasterizing the landuse vector data of Chongqing City with grid of different sizes. Firstly, the landuse vector data are rasterized with grid of different resolutions such as 30m,60m,100m,200m,300m,400m,500m,600m,700m,800m and 1000m. The value of each grid takes the landuse type code as the dominant area. Secondly, the area for each landuse type is calculated in grid. Thirdly, the area for each landuse type is also calculated in vector and used as the actual area. Both the number and average size of polygons for each landuse type are calculated. Fourthly, the relationship among the accuracy loss, grid sizes and the average block size of each landuse type is analyzed. Finally, models for describing the relationships are formulated. It is shown that: (1)The relationship between the accuracy loss(Y) of each landuse type except the high canopy grassland and grid sizes(X) which can be described by the linear regression models such as, Y = A + BX . Here, A and B are coefficients of the models. The correlation coefficients for each model of each landuse type are all above 0.82?The correlations of the absolute value of accuracy losses and grid sizes are positive. The accuracy losses denote that the area reduces compared to the true area when the area of the average block size of each landuse type is above 101 hectare, which is opposite when the area of the average block size of each landuse type is below 82.(2)The correlations between the accuracy loss and the area of the average block size (S) of each landuse type for each grid size can be described by the regression models such as, Y = A +B ln (S) . Here, A and B are coefficients of the models. The correlation coefficients for each model of each grid size are all above 0.72 except grid size of 30 M. The correlations are positive. (3) Generally, the relationship among the accuracy loss(Y), grid size(X) and the average block size(S) of each landuse type can be described by such model as, Y = 5.366 -0.179 X -0.978ln (S) + 0.0348 X ln (S) ?The correlation coefficient of the model is 0.93.