As a large agriculture country, the problems of agriculture, country side, and farmers(ACF) affect the whole situation of reform and opening up and modernization construction Increasing farmers income is the core of ACF problems, while income structures and income sources of farmers (herdsmen) are the guarantee for agricultural and rural development and increase of farmers income Hence, the in depth analysis of the sampling data on income situation, sources and structure of the Tibet Autonomous Region is of great sighificance to the ACF work. The sampling survey involved 7 regional grade cities, 25 counties, 72 townships, 201 administrative villages, 763 households and 4660 people, of which 24 counties, 700 households and 4508 people are effective samples for analysis Looking from income level, the sampling involves both the absolute poor households with per capita net income less than 650 yuan, poor households with per capita net income about 650 1300 yuan, the moderate households with per capita net income about 1300 2000 yuan, and the rich households with per capita net income above 2000 yuan The number of persons surveyed in each income grade shows a spindle distribution of high representativeness Based on the sampling data this paper analyzes income structure of farmers (herdsmen) of the Tibet Autonomous Region, including sources, characteristics and wages in kind and in cash Situation of income structures and income source of the farmers in different areas (agricultural area, pastoral area and farming pastoral area, etc ) was approached The following characteristics were found through the analysis of surveyed data: ①In Tibet farmers income is mainly paid in kind with limited disposable personal income and ready money ② The variety index of income is higher in the outskirts than in the rural, the index has a direct bearing on net income ③The income sources are simplistic and outdate in the poor households, they have no ability to resist and guard against any risk, it is very difficult to increase their receipts ④ The living standard in the agricultural area is better than in the pastoral area, it is the worst in farming pastoral area. ⑤ The main elements affecting regional economic development involved the number of animals for sale, proportion of aquaculture, per capita productive investment, regional accessibility and the advantages of regional natural conditions

人类已经进入信息社会。作为获取地球资源与环境信息 ,揭示地球奥秘新手段的卫星遥感技术受到世界各国广泛重视。新的遥感卫星陆续升空 ,遥感仪器不断更新换代。然而遥感应用的发展相对滞后 ,地面站接收处理出的海量遥感数据未能快速及时转化为真正能够满足各行各业实际需要 ,可供决策依据的有用信息 ,以致遥感数据爆炸的局面 ,随着遥感技术的发展而日趋严重。为了促进遥感应用赶上遥感技术的发展步伐 ,国内外许多科学家从不同角度开展试验研究 ,陆续取得不少有意义的进展。其中戴昌达及其同事在发展遥感图像应用处理与分析技术 ,提高遥感应用水平 ,扩展遥感应用新领域方面取得的丰硕成果特别引人关注。他们在长期从事遥感应用

徐建春、张蔚文、汪晖和于伟四位博士联合撰写的专著《土地管理与国土规划新探》 ,已由北京中国大地出版社出版 ,这是一本难得的好书。该书是至今有关土地管理与国土规划方面内容丰富多彩且有许多独到和创新之处的一本专著。全书共十章 ,包括 :①城市土地经营 ;②城市化进程中的土地规划制度 ;③我国征地制度中的“公共利益”界定与征地范围划分 ;④土地资源的开发与保护 ;⑤土地退化的经济学分析 ;⑥防治土地退化的社会经济对策 ;⑦农村土地金融问题探索 ;⑧国外借鉴与历史总结 ;⑨国土规划的回顾、展望与构想 ;⑩ 2 1世纪初期国土规划编制的探索与实践等方面内容。该书的主要内容 ,反映了作者近年来主持或参加的

Ecotourism is currently a growing segment of tourism in China. The summary report of working group C on the World Ecotourism Summit in 2002 suggested it would be important to understand more about the kinds of people who were already responding to ecotourism products within destinations. As one of the largest developing countries in the world, China is also one of the most important destinations of ecotourism. However, more attention had been paid to biological and ecological issues in outdoor recreation. Previous studies whether on nature tourists or ecotourists in China were limited. This study reports results of a survey concerning behavioral characteristics of ecotourists in Beijing. A questionnaire was used to collect the data through “internet” and “face to face” interviews. The final usable sample of ecotourists was 139 responses acquired by classification of 423 tourists visited Baihuashan nature reserve during the National Day in 2003. The respondents were classified hard ecotourists, frequent ecotourists and occasional ecotourists on the basis of the times they traveled to nature-based destinations every year and their NEP (New Ecological Paradigm) grade which is used to evaluate the visitors' attitude to environment. Descriptive statistics, a series of independent t-tests and the ANOVA analysis were used to evaluate quantitative data. This study finds out that (1) the three kinds of ecotourists are different in many behavioral characteristics including demographic characteristics, motivations, environmental attitudes and management tendencies; (2) the ecotourists in Baihuashan all have a good attitude to physical environment and the hard ecotourists and occasional ecotourists have a better grade of NEP; (3) the different ecotourists may have different sources; the frequent ecotourists mainly understood the mean of ecotourism' from traveling in nature-based areas. However the occasional ecotourists firstly knew ecotourism' theory from teachers, books or newspapers. The hard ecotourists mostly grow from frequent ecotourists and occasional ecotourists; and (4) Baihuashan's ecotourists have more youngs, more males, but less have a good education compared with foreign ecotourists.

“2 1世纪是大城市、大城市群的世纪。大城市是今天中国‘世界工厂’化的支点,是支撑中国经济持续高速增长的引擎。中国需要充分认识到城市化和社会现代化的重要性和必要性,营建一个先进的市民社会,以制度的优势来确保中华民族的繁荣昌盛,托起2 1世纪中国之大鼎”。这些观点是来自于2 0 0 4年世界知识出版社出版,由长期旅居日本的周牧之博士撰写的《鼎———托起中国的大城市群》的力作。随着经济全球化的发展,资本、信息、资源、技术等逐渐形成一个相互依赖、相互作用的网络系统。大城市、大城市群是支撑这个网络系统的关键节点。一些国际性大城市不仅是本国的政治和经济中心,而且也是全球经济、金融、贸易、信息中心和跨国公

The Tibetan Plateau is a unique geomorphic unit composed of some basic geomorphic types, such as extreme high mountains,high mountains, hills, plains, and tablelands of high altitude or sub-high altitude. Different opinions for the exact scope of Tibetan Plateau exist. According to latest research achievement and the long time fieldwork, questions related to the area and boundary of the Plateau have been discussed in view of geography, and the principles taking geomorphic characters as the main rule and considering the integrity have been made to define the boundary. The 1∶1 000 000 geomorphological map was compiled based on 1∶100 000 aerial photographic map,1∶500 000 topographic map and interpretation of satellite images. By refering to the 1∶3 000 000 relief map, the boundary of the Plateau was delineated.The position of the boundary was quantitatively determined with GIS and GPS.The map of electronic version of the Tibetan Plateau was compiled. The main conclusion is that Tibetan Plateau starts from the southern edge of the Himalayan Range, abuts on India,Nepal and Bhutan,connects the northern edge of Kunlun, Altun and Qilian Mts., and joins Tarim Basin and Hexi Corridor in Central Asia.The west of it is the Pamirs and Karakorum Mts., bordering on Kirghizistan, Tajikistan, Afghanistan, Pakistan and Kashmir. The east of it is Yulongxueshan, Daxueshan, Jiajinshan and Qionglaishan Mts.as well as south or east piedmont of Minshan Mts. Tibetan Plateau joins the Qinling Mts.and Loess Plateau with its eastern and northeastern part. Tibetan Plateau in China's territory starts from the Pamirs in the west and reaches to Hengduanshan in the east. It bestrides a longitude of 31 degrees with a length of 2 945 km from east to west,and bestrides a latitude of 13 degrees with a length of 1 532 km from south to north. It ranges from 26°00′12" N to 39°46′50" N and from 73°18′52"E to 104°46′59"E, covering an area of 2 572.4×10 3 km 2. Administratively, it embraces 201 counties (cities) in 6 provinces, namely, the Tibet Autonomous Region (73 counties/cities,1 176.0×10 3 km 2, part of Cona, Mêdog and Zayü), the Qinghai Province(40 counties/cities,721.0×10 3 km 2, some counties only partially), Dêqen Tibetan Autonomous Prefecture in Northwest Yunnan Province(9 counties/cities,33.5×10 3 km 2), West Sichuan Province ( 46 counties/cities about 254.0×10 3 km 2 ,such as Garze Autonomous Prefecture, Aba Tibetan and Qiangzu Autonomous Prefecture,and Muli Autonomous County, etc.),Gansu Province(21 counties/cities, 74.9×10 3 km 2), and Southern Xinjiang Uygur Autonomous Region (about 12 counties/cities, 313.0×10 3 km 2).

In the late 1970s and early 1980s, geographical science entered a new stage, which is characterized by the shift of major attention from the nature dominated environmental changes to the human dominated ones, that is, the interactions between natural process, biological process and human activity. All this shows the changing nature of geography is at the core of dramatic changes within ecosphere, the dynamic man land relationship. Unfortunately, it is the dramatic relationship that has led to the continuing destruction of resources bases as well as ecological and environmental bases upon which human being are dependant. Given the global changes, geographers are obliged to carry out theoretical and empirical studies about sustainable development and environmental protection, from both man land relationship and regional perspectives. The central issues to be concerned are the influences of global change on China and rational approaches for China to realize sustainable development. In recent years, Chinese geographers have contributed a lot to the fields of natural environment, territorial planning and regional development, providing scientific analysis and suggestions essential to China's responses to global change and sustainable development. However, the potential advantages of geography in terms of resolution of these critical issues have not been realized so far. To change such a situation, geographers have to make great efforts to synthetic theories and methodologies, giving full recognition to the theoretical studies of man land territorial system. The issues of sustainable development should remain as major concern by China's geographers in a long time. In fact, the efforts to coordinate the man land relationship aim at the realization of sustainable development. Clearly, the theories of man land territorial system should work as important theoretical bases of sustainable development. Therefore, it is a significant task for geographers to enhance the theoretical studies of man land territorial system. The prior issues regarding man land territorial system are as follows: 1) studies on regional differences from systematic perspective; 2) a deeper understanding of the characteristics of man land territorial system; and 3) studies on the approaches for comprehensive integration. Furthermore, the development of methodologies with comprehensive and systematic perspectives, territorial and dimensional perspectives as well as model building and simulation applicable to practice deserves more efforts.

The author reviews the development process of territorial planning since the 1980s in China. According to statistical data, up to 1993,30 provinces (autonomous regions, municipalities), 223 cities and 640 counties had accomplished the compilationof territorial planning. In this process, the functions of "authority, decision making and service" were fully brought into play to serve the compilationof regional economic social developmentplanning. Meanwhile, the principle of "from top to bottom, from bottom to top" was followed in combination with that of "leaders, local operators and experts", and made a point of the study of basic theories. However, some problems were also revealed, i.e., the features of territorial planning are not distinct, having many similarities withregional economic social development planning; the planned economy still played an important role; the maneuverabilityof planning was not good; and the qualitative analysis was not so closely combined with quantitative research. Aiming at the current situations of economic globalization and informalization,China's Accession to the World Trade Organization, and the improvement of socialist market economic system, the paper puts forward basic thought to promote the new roundterritorial planning and accomplish four changes as follows: to change planned type to market and guidancetypes; to change resources exploitationand utilizationto integration of resource exploitation, utilizationand conservation; mono goal for economic development to multi goal for sustainable development which should coordinate economy,society,population,resources and environment;and to change planning focus from industrial planning to spatial locational planning that coordinates regional economic social construction.Based on the above thoughts, the improving waysare proposed, including: importanceshould be attachedtothe inter provincial territorial planning or trans urban and trans prefectural territorial planning of a province; the land use planning should be the core of basicterritorial planning; spatial policyresearch in cooperation with territorial planning should be strengthened; planning method should be evolved toward informalization and scientization; legislation of territorial planning should be formulated as soon as possible; and publicparticipation should be widely admitted in the process of planning.

By integrating quantitative with qualitative approaches, as well as GIS technology along with 12 major selected indicators which can well reflect the regional development of western China, this article makes a comprehensive assessment on the socio-economic development of the 106 cities at prefectural level. Also, the characteristics and the laws of socio-economic disparities in western China are probed. Factors that mainly influence the socio-economic territorial differentiations are identified as follows: (1) physical disparities essentially influence the socio-economic disparities; (2) regional integration of agricultural resources shapes the territorial differentiation of agriculture in western China; (3) regional combination of energy and mineral resources constitutes the key factors determining the mineral cities' formation and distribution; (4) large cities and developed regions are located along major rivers and traffic lines, taking on point-axis diffusion form; (5) the interactions of location, resources, labour forces, technology, market, and policy determine the properties and patterns of economic regions;and (6) the high correlativity between each indicator selected in this article results in the strong conflicts between socio-economic development and ecological environment, which constitutes the main constraints to the development of western China. In conclusion, the laws of the socio-economic territorial differentiation of western China reflects the immense physical restrictions to the socio-economic development, which requires reconsideration of the ecological carrying capacity and resources' restriction in the course of developing western China. Moreover, blind migration into western China and reclamation should by no means be advocated

The irrational use of land and water resources in regions around Beijing is the main cause of the environmental deterioration and the sandstorms. Huailai County is one of the six typical sand regions, which is taken as a case in the present study. Based on digital land use map of 2000 and contour map of Resources and Environment Data Center of IGSNRR, CAS, the land and water resources and their utilization status in Huailai were studied and the problems of land and water use was found: the water resource was insufficient to meet the needs for existing land use; both land use structure and land use distribution was irrational.In order to solve these problems,the Grey Linear Programme model was used to allocate the land and water resources optimally. The optimum land allocation modes were obtained under different water-saving levels and agriculturalwater supplies; theoretical base was provided about rational use of the regionalland and water.Four conclusions are drawn:1) In the optimum land allocation modes, tendenciesof each land use type under different water-saving levels are the same on the whole.2) Under three typical water use conditions (normal water use, moderate water-saving and high water-saving ), there is one land use allocation mode that the source of sand is generally controlled, one mode that the source of sand is totally controlled and one mode that the source of sand is totally controlled and the structure of crops is rational, although different amount of agricultural water supply is needed. 3)The characteristic of normal water use condition shows the investment in water-saving facilities is very little, but it needs large amount of water-supply; that of moderate water-saving condition needs certain investment to improve the efficiency of water use and the amount of water supply is lower than the first case; and that of high water-saving condition needs the lowest amount of water supply but considerable investment to improve the efficiency of water use. So the modes under moderate water-saving condition is feasible.4)Under moderate water-saving condition, there are three typical modes of optimum land allocation. When theagricultural water supply is 5.85 billion m 3,land types that are apt to form sandstormsconvert to lands moderately covered by grass, the source of sand is generally controlled and the benefit of land is 1.51 billion yuan. When the amount of agricultural water supply is 6.05 billion m 3,lands that apt to form sandstorms convert to lands highly covered by grass, the source of sand is totally controlled, and the benefit of land is 1.62 billion yuan. When the amount of agricultural water supply is increased to 6.385 billion m 3,not only the source of sand is controlled but also the structure of croplandsis rational, and the benefit of land is 1.72 billion yuan.

Land use change is a key component for global environment change, and a representation of the impact of human activities on physical environment Supported by the 1 km grid global database, IGBP, IHDP and other international organizations have implemented a series of researches including land cover dynamics, mechanism and global and regional models The 1 km grid data is an effective way of data integration, which can promote regional land use change monitoring, predication and driving forces analyses This paper, based on remote sensing,GIS and Landsat TM digital images, analyzed the structural features and spatial patterns of land use change in Beijing from 1985 to 2000 The primary findings show that conspicuous conversion, with a rate of 40 78% and 37 60% respectively, occurred for woodland and built up areas with internal conversion of woodland, conversion from woodland to grassland, internal conversion of built up areas and afforestation or grassland restoration in abandoned mining land as its main conversion categories At the same time, the net change of each kind of land use is characterized by conspicuous areal differentiation The decrease of dry land of central eastern and southern Beijing, 129,874 17 hm 2 in total, is dominant and conspicuous while that of northeastern by sparse distribution The increase of arable land, dominated by paddy field is sparsely distributed in northern and central western Beijing Forest area trends are enlarging in spatial distribution, especially in protection forest of Northeast, North and Northwest China and mountainous areas of southwestern Beijing The decreased area of grassland is almost 6 times of the increased. The former happened chiefly in mountainous areas while the latter in reused arable land or grassland areas For a long time series during 1985～2000, the trend of water body expansion obviously occurred in central western, southeastern mountainous areas and some reservoir areas of northern and eastern Beijing Above all, the most conspicuous feature of land use change in Beijing for the past 15 years is still urban expansion, undoubtedly affected by the macro social and economic conditions in China, which is densely distributed in central eastern and central southern Beijing and expanded around the downtown as well as around the towns of each county in Beijing These findings promote our understanding of land use change and contribute to the decision-making of local governments

Man-land relationship includes human dependent upon nature and human activity to nature. Contents of man-land relationship are changed with development of human society. Man-land relationship research is the basis for development of modern geography. Various schools of geography such as determinism, possibilism, cultural landscape and human ecology are focusing studies on man-land relationship. The earth system science should carry out interdisciplinary studies between natural and human sciences, to reveal interaction between man and nature as well as the corresponding countermeasures. Developments of information techniques and knowledge economy bring about new opportunities and challenges for human society. Characteristics of man-land relationship in information era differ from those in industrial era. The way and intensity of interaction between human activities and nature will be obviously different. The understanding to nature will be systematically deepened, and ideas of time and space are changing in information era. Knowledge and techniques are becoming main driving forces for social and economic development. Owing to the entirety of the earth, the complexity, protracted nature and potentiality of the interactions among various spheres of the earth, many global environmental issues, such as climate warming, ozonosphere depletion, environmental pollution, etc., are becoming the foci of the countries and public concern throughout the world. The realities impel us to learn lessons and experience accompanied with the traditional development models and to explore new development models for human society. Man-land relationship research covers extensive domains. The hotspots of both global environmental change and sustainable development are closely related to man-land relationship. Global environmental changes have been arisen from slow accumulation process of human impact, and sustainable development is a new development model, which has been obtained by self-examination to development course and model of the human society.The main frontiers of man-land relationship research include the following issues: global environmental change and its regional response, regional sustainable development and mechanism regulation of man-land relationship, studies on social ecological and environmental ethics, etc.

The database of environmental change during historical times is the foundation for the global change study. In this paper, the source data and computer standardization of environmental change database during historical times in China was expounded. Based on the technique of computer, database, the general design, main function and application prospect of the database was introduced. There are three kinds of source data including historical documents, instrumental data and natural evidence in the database, in which each kind of source data covers three main tables for keeping the original data (such as the document cards), raw data derived from the original data and the proxy data for environmental change which was reconstructed by the methodology for time series reconstruction during historical times respectively. The structure for the database includes two main parts,in which part one contains tables for saving the source data and part two serves as management ware for data table linkage and database running. There are four main functions for the database, including data browser and backup, data query and statistical analysis, data editing, appending, deletion and modification, and the user guide and help.

Air transportation is a unique and increasingly important perspective in studying spatial structure of urban system This paper illustrates the framework of urban system by analyzing structural features of air transportation network based on the data of the amount of airport passenger transportation and the number of weekly flights (1)Since open to the outside world, the nodes in China's air transportation network increased quickly accompanied with the expansion of air transportation network scale which presents positive correlation with the scale rank of urban system (2) On the whole, dispersion dominates the evolution of airport's spatial structure But in the variant periods and zones, the newly built airports and the increase of transportation capacity of the existing airports exert different influences on the expansion of air transportation network (3) Network linkage intensity differs in various provinces But the eastern coastal zone is still the core region of domestic and international airline linkage in which the international hub function of Beijing Tianjin Hebei and Jiangsu Shanghai is distinctive while Guangdong mainly acts as home hub (4) The capital city of a province is still of vital essence to this province's outward connection, but more and more developed cities of some provinces have partly substituted the capital cities (5) The spatial distribution of intensity and tightness of air network linkage separate from each other, which manifest that the spatial network structure of China's urban system is still in the process of dynamic evolution (6) The factors such as the change of airline structure, the airline linkage with foreign countries and the cooperation and competition of domestic airport cities will all influence urban system structure in future

Researches on regional physio-geographical system (RPGS) aim at studying natural complex of the earth surface, revealing rules of regional differentiations and exploring physio-geographical regionalization at different scales, from a regional point of view. Based on review of RPGS researches at home and abroad, the paper raises that the late 18th to the early 19th century is the initial period of RPGS research. Since the 1940s it has been a decision-making period for government, particularly a period serving the agriculture. And following the 1980s it is a research period of ecological regionalization. Researches of the topic will provide scientific basis for the formulation of strategic policies on regional resources exploitation and utilization, biodiversity conservation and regional sustainable development. It briefs the existing issues and debates in the study of RPGS such as various understandings on the theory of geographical zonality and principles of regionalization, the essentials of and selection of index system for ecological and geographical regionalization, demarcation of several important boundary lines of China's RPGS, consideration of human impact and mountain division and jurisdiction. It points out the future studies of RPGS will continue penetrating into methodologies of theories and construct more complete regionalization system, further perfect understandings of eco-environment and laws of other regional differentiations; and to strengthen interdisciplinary studies of natural and human sciences based on sufficient studies of physical regional differentiations. Approaching from studies of RPGS, to set up comprehensive index system consisting of both human and natural factors for the purpose of dividing different hierarchical systems so as to occupy important positions for the study of integrated framework. Future studies of RPGS should further focus on possible human impacts and feedbacks which will become a joint subject and trend of researches of RPGS. The objectivity of the results will be further enhanced. To this end, typological studies, process studies and regional studies should be closely integrated, either considering regional unit as an organic whole of resources and eco-environment or emphasizing relationships among regions. For the sake of convenient retrival and storage, database of different regional scales should be set up and perfected for conducting integrated researches of different dimensions and units along with graphic presentations by using the latest mathematic and physical statistical methods with the aid of GIS and merging results of regional surveys, remote sensing method and fixed-site experiments into one.

Globalclimate change and increasing intensity of anthropogenic activity are the main restricting factors to the development of agriculture in arid and semi-arid area. Gray relation model was applied to analyzethe main factors of wind erosion and land desertificationin Zhangbei County of Hebei Province in interlock area of farming and pasturing.Climate change and anthropogenic activities are the main factors influencing wind erosion and landdesertification. Climate change factors include monthly mean temperature and rainfall and annual mean temperature and rainfall.Factors of anthropogenic activities include population increase rate, per capital income, change of grassland and cultivated land area, the research result indicates: Wind erosion and landdesertificationare related to changing climate in interlock area of farming and pasturing of northern China, such as mean temperature and its precipitation in winter. There is no distinctiverelationship between the annual mean temperature and its precipitation. Population growth is a social factor and also a very important factor influencing agricultural production. Anthropogenic activity could intensify or mitigate wind erosion and land desertification on the background of mean temperature and precipitation changes in winter. According to changes in mean temperature and rainfall in winter, agricultural production framework and way of production can be adjusted properly by human beings in their production process. If precipitation decreased and temperature rose in winter, cultivated land area must be reduced next year. Stock raising or other ways of production should be increased. On the other hand, if the precipitation increased and temperature fell in winter, cultivated land area could be enlarged, because the soils have enough water and are suitable to be cultivated. Adjustment of agricultural production structure according to changes in mean temperature and precipitation in winter can mitigate wind erosion and land desertification and guarantee sustainable agricultural development

This paper focuses on GIScience-techniques with the involvement of two technques of data mining,the Markov Chain method and Artificial Neural Network(ANN)method.The results were used to the strategic planning and development of the city of Shanghai.In order to estimate state transtation matrix,firstly the city was divided into 5 zones based on GIS,remote sensing images and electronic maps,and then the total amount of land use in Shanghai in 2002 and 2005 was estimated by Markov Chain method. Secondly,changes in land use types in core areas of Shanghai were forecasted with ANN method which shows the ANN Model 2 (Fig.3)is better than Model 1(Fig.1).This indicates that each one has its strong point,for the ANN method can be better used to forecast directional aspect of land use,and the Markov Chain method can be better used to forecast changes of land use within the zones.Here Markov Chain method was found that is wreath to take the inside variety, ANN considered fit the land that make use in class direction is good.It is further found out that merely for the converted land use types,the standard ANN-BP method gives greater error.This can be explained as the transform process of land use types of Shanghai city is directional,a general ANN-BP arithmetic gives each land type conversion with the same weight function.Although it is self-contradictory in directionality of the transformation,the modified model can still overcome this difficulty.

The Digital City is a multi-resolution, multi-scale, multi-space and time, multi-kinds description of a city in three dimensions with techniques such as 3S, telemetry, simulation and Virtual Reality (VR) based on such techniques as computer, multimedia and large-scale storage, and taking the wide band web as vinculum. By this technique, the modern city's information can be collected, collated and generalized,and the complete spatial data model can be established on the geographical coordinate system so as to facilitate each person's acquaintance of the past, present and future of the city rapidly, entirely and visually through the web. At the present time, studies on Digital City at home and abroad make no substantive advancement, but still remain at building hardware and software conditions, or at most, at the preliminary stage of the study. The paper mainly probes into the key techniques such as Virtual Reality, Urban Spatial Data Infrastructure, integrated model study of many kinds of GIS systems, 3D-GIS, the urban planning in three dimensions, city simulation and digital society supported by VR and Digital City, etc.

It is of significance to research into nonlinear relationships between human systems and physical environment in order to explore spatial complexity, but it is of difficulty to do so in the past because of lack of effective research means and methodologies. If we develop integrated models including cellular automata(CA)which are based on geographical information system (GIS), we will be able to solve many complex problems on man land relationship. We suggest that geographers should construct a kind of metasynthetical technical systems being composed of GIS as geographical databases, GIS based CA models, integrated regional dynamic models, and other related CA based models. For the sake of making the CA models based on GIS intelligent to certain extent, artificial neural networks, which can be used to distinguish and compare between the simulation patterns and digital maps concerned, and genetic algorithms, and even genetic programming, which can be used to design and train the weights of neural nets, should be adopted into the systems. Going a step further, the multiagent systems (MAS)and the postmodern mathematics of fractal and chaos, the latter of which take the form of softwares by being compiled into some programming, should be comprised in the systems. So geographers will have an artificially intellectualized meta synthetical systems consisting of a number of integrated models based on integrated models which make it easy and convenient to expore spatial complexity on man land relationship.

There are many advantages to construct a base of energy and heavy/chemical industries in the contiguous area of Shaanxi Gansu Ningxia On one hand,the area is not only rich in resources ofoil, coal and natural gas, which form a combinative superiority ofenergy resources, but also rich in resources of bauxite and nonmetal minerals On the other hand, with the change of supply demand situation of China in recent years,a heavy task forChina'senergy industry in the future is to increase the productionand supply of the secondary energy with high quality suchas electricity,refined oil from coal,etc Therefore, there is a large market in China for the area to exploitits energy resources and to establish the processing industry ontheseresources Although the area has got a primary development in its energy and heavy/chemical industries, there are still many problems, such as the low level of technology, weak ability of competition and the lackof further machining The article holds thata general strategy shouldbe workedout, whichis "large in size, high in technology and new in mechanism to setup a conversional production system anda regional production complex", so astofoster the superiority of industrialcompetition, toextend the industrial chainas soon as possible, to cultivatethemulti industriespositively, and to step on the road ofsustainabledevelopment In order to carry out the strategy, it is necessary toformulate and implement somemeasures and policies Firstly, we should found an inter provincial management committee to get successful development of resources and harmoniousdevelopment of the region Secondly,we should build up a market of mining right actively and raise the local portion in resource division Thirdly,we should attach importance to protect environment, transformingouter negative effectof enterprises into interior Fourthly, it is significant to establish the supporting system of finance Finally, the role of the government should be changed so as to offer favorablesystem surroundingsfor the base of energy and heavy/chemical industries

Lead concentrations of surface soils taken from 30 typical parks in Beijing urban area were studied. The pollution index, which was used to assess the situation of soil pollution, was calculated according to the Soil Environment Quality Standard recommendedby European Union. The results indicated that the average concentration of Pb in soils was 66.2 mg/kg, ranging from 25 to 207 mg/kg;the pollution index was ranging from 0.51 to 4.15. It was found that soils from some parks were polluted with Pb apparently. The results of cluster analysis showed that all of theparks could be dividedinto three categories: (1) the parks with a history shorter than 100 years; (2) the parks with a history ranging between 200 and 400 years;and (3) the parks with a history longer than 400 years. Regression analysis was carried out to explore the relationship between two variables of Pb concentrations in soils and the history of parks. Using the "growth curve"to fit the datum, it could be concluded that the two variables were significantly positive correlated (p<0.001). Furthermore, geographical location of the parks was also an essential factor affecting the lead concentrations in the soils. In some parks with longer history and/or near the center of the city, the concentrations of Pb in the soilswere obviously high. However, Pb pollution was not notable in the soils of other parkswith relative short history.

Tropical forest plays an important role in global carbon cycle and carbon balance. What function the tropical forest is, carbon sink or carbon source, is still a disputed question among researchers. In this paper, we use an improved estimation method of forest biomass and forest resource inventory in Hainan Island to estimate carbon storage and its dynamic changes between 1979 and 1998. Here, the data of carbon storage includes three parts: carbon content in tree layer, carbon content in understorey, and carbon content in the litter layer. The results suggest that: 1) Carbon storage increased significantly in Hainan forest after 1979 from 30.45 Tg C to 37.74 Tg C by 1998, for the annual average accumulation amount of 0.3645 Tg C,or the annual average accumulation rate of 1.197%, is much higher than that of the national level. The function of carbon sink in Hainan forest is becoming greater and greater. 2) The mean carbon density is 32.59 tC/hm 2 between 1979 and 1993. The carbon density reduced rapidly after 1979 from 38.63 tC/hm 2 to 24.41 tC/hm 2 by 1993. The value of carbon density varies with forest types and forest ages. Generally speaking, carbon density increases with forest ages. So carbon storage potential in Hainan forest will become much greater. 3) With the measures of forest protection such as forbidding cutting, enclosing land and planting trees carrying out, forest areas will expand and the structure of forest ages will change. All these will lead to the improvement of capability of carbon storage. At the condition that the global tropical forest plays a notable role of carbon source in carbon cycle, the function and social value of Hainan forest, a representative region of tropical forest in China, will become increasingly notable in the national and even global carbon cycle. There is great difference in carbon storage among different researchers. This paper also analyses and discusses the uncertainty in calculating carbon storage and points out that it is only by strengthening the study on forest community biomass in different layers and unifying and improving the methods of calculating carbon content, can the precision of carbon storage be improved. At the same time, we should verify data first before using them.

The small watershed management information system is an integrated system of GIS and erosion model, land productivity model and cost-benefit analysis model. It can be applied in watershed planning and management in Loess Plateau.The system is developed for decision support in soil and water conservation with the functionalities of data management, data query, database updating, displaying, output and model analysis. The basic geographic unit for system integration is land-unit. The land-unit was defined as a piece of land with the homogeneous geographic characters such as elevation, soil type, land-cover, slope, aspect, etc. Based on the land-unit, three model groups were integrated with GIS. In order to realize those functions, basic integration methods were analyzed and the integration method of DLL and its extension was adopted. Then based on the method accompanied with Avenue programming language, the system was fully integrated in Arcview environment. A landunit based flow network model was developed for simulating the processes of drainage and sediment transportation among land-units, and it provides parameters for erosion model, economic model and yield model. The soil erosion model calculates soil loss for each land-unit in a watershed. Yield model and socio-economic model estimate crop productive and economic benefit in the watershed, such as river beach, check dam, agro-forest, terracing, etc. These three models are integrated with each other and fully linked to database system. Based on the result of model simulation, the soil and water loss, land productivity and economic benefits in a watershed can be estimated for different land planning and engineering strategies. The optimized management for watershed can be done through comparisons of varied planing. The arithmetic process and parameters of each model are also described in this article.

The Yellow River is the most famous heavily sediment laden river of the world, its land accretion process is sensitive to influencing factors such as the changing precipitation and human activities. Thus, the Yellow River Delta provides an ideal site to study the delta development under the land ocean interactions. The development of Yellow River Delta can be regarded as the outcome of interactions between the river and marine dynamics and of interactions between the river and tide transported material fluxes. The rate of land accretion is controlled by these interactions. When the above two aspects are in equilibrium, the land accretion process of delta may be thought under the critical conditions, and the river supplied water and sediment quantities may be considered as thresholds of runoff and sediment for land accretion. By comparison between the sea charts and remotely sensed images made in different periods, the annual area of land accretion has been obtained. To identify the water and sediment thresholds for delta development, two regression equations have been established between land accretion rate and water and sediment quantities into the river mouth, based on the data from the Yellow River Delta in the period of 1955 1989. From these relationships, the threshold of river supplied sediment quantity for land accretion has been estimated as 2.78 10 8 t, and the threshold of runoff as 76.7 10 8 m 3 ; under these sediment and water supplies, the Yellow River Delta may be in equilibrium in an average sense. In other words, if the annual sediment quantity is less than 2.78 10 8 t, and the annual runoff less than 76.7 10 8 m 3 , the delta might be eroded and the land would be lost, and thus the environmental security of the delta might be seriously affected. For a better management of the environment of the Yellow River, these thresholds should be taken as one of the constraints. The meaning of ecologically needed water use in the Yellow River should be extended, in order to include the water quantity that is required for maintaining the balance of land accretion in the delta.

Firstly, the paper predicted future food productive capacity of agricultural resources including cultivable and non cultivable land resources; secondly, the food demand was respectively forecasted in the coming three periods, based on the different nutrition supply amount according to the population forecast program; lastly, the comparison between the productive capacity and the demand was analyzed in the coming three periods The results shows that the grain productive capacity will be slightly greater than the demand because the food structure of prosperous level is as the demanding standard in 2010, however, in 2030 and 2050 the productive capacity will be smaller than the demand because the food structure of hypo affluent and affluent level is as the demanding standard So it would be difficult to satisfy the food demand during the period converting from the prosperous level to the affluent level if only depending on the limited cultivable land resources The balance analysis of supply and demand based on the comprehensive productive capacity of agricultural resources shows: the comprehensive productive capacity of agricultural resources would be higher than the food demand in the three coming periods The productive potential of non cultivable land resources should be exploited during the course of using limited cultivable land resources efficiently The food demand could be satisfied during the period converting from prosperous level to affluent level and the living standard could be improved only by depending on the comprehensive productive capacity of agricultural resources

This study was conducted to compare NO 3-N cumulation and leaching from a winter wheat/ summer maize rotation under four applied N fertilizer rates of 0,120, 240, and 360 kgN/ha.An array of 7 zero-tension lysimeters installed at 20,40,60,80,100,140, and 200cm below the soil surface in each plot was used to examine NO 3-N leaching; two disturbed soil cores were stalled, one for contrast, the other fertilized with applied N fertilizer rate of 240 kg/ha, to study leacheate and NO 3-N leacheate flux. Soil sampling performed before and after cultivation revealed that contant of soil NO 3-N in unfertilized plots decreased; and N fertilizer applied plots resulted in NO 3-N cumulation in soil of 0～100 cm; but only the fertilized rate of 360 kg/ha could maintain a constant amount of NO 3-N in soil of 100～200 cm. Average cumulative NO 3-N fluxes through the interface of 200cm below the soil surface at four N fertilizer applied rates were 0.18 , 2.41, 5.52 and 17.12 kg/ha; surface percentages of N leaching were 1.24%,1.48% and 3.14% for each fertilized treatment. The findings are beneficial to the determination of economical optimum N rate and the understanding of the potential role of N fertilizer that affects water quality.

According to a large amount of field measurements and indoor annual measuring data and research on the distribution characteristics of debris flow movement deposits in different stages since the late Cenozoic Era,we believe that the large scale debris flow movement in the east border of the Tibetan Plateau and its surrounding regions since the late Cenozoic Era started from the late Pliocene.Debris flow in the early Pleistocene was fully developed in the east border of the Tibetan Plateau and the debris flow movement was relatively weak in the east piedmont of Taihang Mountains and Beijing in North China.Debris flow movement was most active in the middle Pleistocene.There was still certain debris flow movement around Xiaojiang Valley in the east border of the Tibetan Plateau in the late Pleistocene, while the movement became weaker both in Bailongjiang Valley, south Gansu,and the north piedmont of Qinling,and stronger in Beijing area and the east piedmont of Taihang Mountains.Debris flow movement took on a characteristic of periodicity which had corresponding relationship with the periodic uplifting of the Tibetan Plateau and the establishment of Asian monsoon.Great changes in the strength and influential areas of the Southeast monsoon and the Southwest monsoon which affected China since the late Cenozoic Era had also taken place.As a product of monsoon,debris flow movement history was the same as loess and paleosol and recorded the forming and developing processes of the two monsoons since the late Cenozoic Era.Under the influence of the Tibetan Plateau movement during 3.6～1.7MaBP, typical modern monsoon was formed gradually, and precipitation in the form of torrential rain and a large scale of debris flow movement initiated in the east border of the Tibetan Plateau.The Kun(lun) and Yellow (River) movement during 1.1～0.6MaBP enlarged the rise and fall of terrain and uplifting of the Plateau got to a new critical value, meanwhile the motive power and heating power effect of the Plateau reached a new balance point. Debris flow movement was unusually active in the east border of the Tibetan Plateau. Debris character had also changed from the early Pleistocene when diluted and sub-viscous debris flow movement predominated to the period when viscous debris flow movement predominated. North China then started to enter a debris flow movement stage. Under the influence of Gonghe movement at 0.15MaBP, the influenced area by the Southwest monsoon rapidly decreased, and most parts of eastern China were mainly affected by the Southeast monsoon, and advance and retreat changes of the Southeast monsoon had an absolutely controlling impact on environmental evolution. Debris flow movement weakened in the east border of the Tibetan Plateau.During the last interglacial period, debris flow movement ceased to develop in the inland regions far away from Indian Ocean and Pacific Ocean.

Natural secondary succession, forest planting and agricultural practices after deforestation or human disturbance affect soil properties in many aspects. Characterizing soil nutrients in relation to land use/land cover types and history is important for understanding how ecosystems work and assess the effects of future land use change. A study was initiated in Wolong Nature Reserve, Sichuan province, China to elucidate the complex relationships in the humid mountainous region. Six typical ecosystems (natural forestland, grassland, shrubby land, secondary forestland, cultivated land and reforested land) were compared.Significant differences among land use were found for soil bulk density (BD), total nitrogen (TN). Cultivated land had the lowest levels for most soil nutrients compared to other ecosystems and shrubby land had a higher soil organic carbon (SOC), total nitrogen (TN) and available nitrogen (AN). There was no much difference in 0-40 cm soil carbon mass between different land use practices. Soil carbon storage (TC) of different land use indicated that land use had a greater effect on SOC greater than on BD. The comprehensive soil deterioration index (DI) showed that the cultivated land, grassland and reforested land had the lower and negative values, while the shrubby land and secondary forestland had positive values, 12% and 1% respectively. The results gave a hint that in areas where the climate is fit for secondary succession "leave the nature as it is" is a better choice for the policy of "returning farmland to forest land" in China especially for the mountainous region lack of labor and finance support. Five reforestation periods were arranged from 0-10, 11-20, 21-30, 31-40 and 41-50 years. The results showed that reforestation could greatly change soil properties. The BD, SOC and TN were significantly different between the reforested periods, but the pH, TK, AN, AP and AK showed no significant trends.Further studies on the relationship of reforestation and the soil properties gave the results that the TC and TN had a good linear relationship with the reforested years and the DI index increased since reforestation.

Based on previous research on spatial conceptual data model of GIS, the authors present an object-oriented holistic GIS data model, and discuss data organization, data storage and access mechanism of holistic GIS system. Firstly, six features of holistic data model are introduced, and a conceptual data model is presented with a key concept, Complex Object, which is introduced in detail. Secondly, data organization means of holistic GIS are introduced. Several basic concepts such as Object Set, Layer, Database, Map or Map Window, and Workspace are introduced into the data organization system. Object Set has three types: Simple Object Set, Compound Object Set and Continuous Field. A Layer is a concept related to map display in our holistic GIS software. A Database is defined as a set of stored objects, which is either a small size file or a large-scale database. Map is a frame used to load layers, and can contain multiple layers.A Workspace is a warehouse, which stores basic data info, Maps, Point, Line and Region Symbols,etc. Thirdly, data storage and access mechanism of holistic GIS are introduced. In respect of storage, database table structures of Simple Object Set, Compound Object Set and Field are analyzed, and table structure of 3D data structure and time attribute is also introduced. In order to quicken the pace of accessing to database tables,the spatial index mechanism based on quadtree data structure is built. Further data access mechanism is discussed. Fourthly, SuperMap Deskpro, a GIS software based on holistic data model, is introduced. This software is fulfilled through completely using object-oriented thinking. It can effectively store and access to geographic entities' information including location, attribute, topological relationship and semantic relationship. In respect of Layer Organization, it not only accords with users' direct apperception of geographical world,but also supports users to rationally organize data to meet actual needs. SuperMap Deskpro supports users to use files to store small amount of data, and at the same time users can also use large-scale business database such as SQL Server and Oracle to manage large amount of data.

More than 50 river basins with gauging stations were chosen for an analysis on relationships between sediment yield and basin morphological characteristics in the middle reaches of the Yellow River. They have drainage areas ranging from 500 to 2500 km 2 each and can be categorized into 6 types of basins with different physiographical backgrounds:the loess hilly basins and highly weathered mudstone & siltstone basins north to Wuding River,loess hilly basins in north Shaanxi, west Shanxi and east Gansu provinces, loess hill + bedrock mountain basins, bedrock mountain + loess hilly basins, loess yuan basins and bedrock mountain basins. A set of data on river basin morphology were obtained by using morphometric method, including drainage density, percentage of inter gully area with slope steepness less than 15°, relief ratio, basin roughness, basin circularity etc. Different relationships between sediment yield and basin morphological characteristics were obtained for different types of river basins by plotting and multi variate analyses. The results showed that the best correlation exits between sediment yield and drainage density, but the relations between sediment yield and the other morphological characteristics are not as good as expected due to heavy disturbance of surface material, vegetation coverage, morphological development from various types of river basins. If taking the basin types as parameters, different fitness, intercept and slope of correlation lines were observed between sediment yield and drainage density for different types of river basins, showing a control of other basin characteristics, such as surface material, vegetation, landform development etc., on the relationships of sediment yield and basin morphological characteristics. The intercepts and slopes of lines tend to increase from loess hilly basins through loess hill + bedrock mountain basins and bedrock mountain + loess hilly basins to bedrock mountain basins subsequently. It indicates that basin morphology is an important factor affecting sediment yield of a river basin but can exert substantial influence on sediment yield of the river basin only when the basin characteristics are more homogeneous. Therefore a classification of river basin types is necessary before a correlation between sediment yield and basin morphological characteristics is established.