Based on a series of1∶1000000maps of natural resources of China,6categories of ecological assets were divided,which included forest,grassland,farmland,wetland,water body and desert.By means of GIS,the1∶4000000Ecological Assets Map of Tibetan Plateau was compiled and the relative data were calculated.According to partial global ecosystem services value evaluation results obtained by Costanza et al.(1997)along with responses of ecological questionnaire s from specialists of China,this paper established the ecosystem services value unit area of Chinese terrestrial ecosystems.We used the ecological assets value table as a basis and also adjusted price value by biomass and then,the ecological assets value of the Tibetan Plateau was estimated.The results indicated that ecosystem services value of Tibetan Plateau is some 9363.9×10⁸ yuan annually,accounting for17.68%of annual ecosystem services value of China and0.61%of the world.The value of soil formation and disposition provided by ecosys-tem s is the highest,which occupies19.3%of the total ecosystem services value and then,the value of waste treatment takes up16.8%,water conservation value,16.5%and biodiversity,16%.The forest and the grassland ecosystem s offered the main ecosystem services value,being31.3%and48.3%of the total value provided by different ecosystem types,respectively.

Valuation of global ecosystem services by R Costanza(1997)has attracted attention of the Chinese ecological researchers over the years. And many Chinese scientists have been using the methods to valuate the ecosystem services for forest, grassland and farmland ecosystems. However, it has been turned out that there are several shortcomings in direct adaptation of the methods, for instance, some ecosystem services have been insufficiently valuated or even ignored via using Costanza’s method. To fill this gap, we have, on the basis of Costanza’s method, developed a new method or 'unit value’ based method for assessment of ecosystem services. Expert interviews with structured questionnaire were contacted in 2002 and 2007 respectively, and altogether 700 Chinese ecologists were involved in the interviews for testing the method. It has been found that the values of ecosystem services from expert knowledge based unit value method and biomass based method are comparative. Therefore, expert knowledge based assessment of ecosystem services could be used as a method for assessing ecosystem services with known land use areas, and a good result could be generated within a short period of time. However, for scientifically sound and concrete results, the spatial disparity of ecosystem services should be taken into account.

Forest ecosystem plays a special role in maintaining the structure,function and ecologi-cal process of natural ecosystems.At present,a series of ecological problems are becoming more and more serious because of forest damage in some regions.The accurate valuation of forest ecosystem services is very important to the reserve and rational development of forest resources in China.Forest ecosystem services are divided into four groups:provisioning services,regulating services,cultural services,and supporting services in this paper.On the basis of the service mechanism analyses,an index system for the assessment of forest ecosystem services has been established,which consists of 13 service indexes such as timber and other products,weather regulation,C fixation,water storage,erosion control,air quality purifying,nutrients cycle,windbreaks,cultural diversity,recreation and ecotourism,O2 release,and provisioning of habitat.Then,10 services of China forest have been assessed and evaluated by taking the year of 2000 as the base year.Including timber and other products provision,C fixation,water storage,erosion control,air quality purifying,nutrients cycle,recreation and ecotourism,O2 release,and provisioning of habitat.As a result,the economic values of these services are 2 325.14×108,1 626.76×108,2 134.7×108,136.46×108,41.85×108,372.37×108,194.31×108,6732.48×108,and 495.94×108 yuan,respectively.The total value is estimated as 14 060.05×108 yuan with indirect values being 11 540.60×108 yuan,4.6 times that of the direct values.The results show that forest ecosystems provide huge indirect values to human being besides the direct value of goods,and that the indirect values are egually important as the direct values.The focuses of forest ecosystem services and their valuation in the future should be the service mechanism and the coupling and the application of different scales data.

This paper focuses on the description of phenomena and analysis of mecha nism of land use/cover change in Beijing based on three typical stages:1970s,1980s and 1990s.There are some main spatial patterns about expansion of the urban built up area in Beijing:(a)urban spread;(b)extending along growth axle;and (c)urbanization in urban fringe.In recent years,Beijings land cover changes very fast because urban land has become a kind of productive factor and the market system is used gradually.Three main phenomena are found,i.e.,decline of downtown area,urban renewal of inner city and peasant enclaves of urban fringe.Moreover,suburbanization is becoming a new urban spatial growth process.

The Yangtze River Delta is one of the regions with most densely population,fastest economic growth and most intensive land use,the contradiction of land shortage sharpened by high speed economic development has become the problem not to be ignored which restricts regional sustainable development This paper has revealed the characteristics of high intensity land exploitation and the basic process and driving forces of change in arable land area according to the data of long series statistics of arable land area during the past 50 years and detailed investigation of land use during the recent five years The research results show that there is a trend of obvious fluctuant decrease in arable land area during the past 50 years.The changes of arable land area undergo the process from increase to steep decrease to gently decrease to rapid decrease,in which,there are three height periods of decrease in arable land,they are 1958 to 1963,round about 1985 and round about 1993 respectively The mechanism of decrease in arable land are mainly the driving forces of policy,economic development and population growth

It is of great significance to estimate ecosystem services value By using method proposed by Constaza et al (1997) and others,this paper calculated the unit area value of rangeland ecosystem services in terms of its biomass in China The results showed that the total value of annual rangeland ecosystem services in China was about US＄149.79 billion,among which,the percentage of gas regulation took up 2 66%,that of disturbance regulation accounted for 16 07%,water regulation and water supply 14 44%,erosion control and sediment retention 9 08%,soil formation 0 31%,waste treatment 42 03%,pollination 7 83%,biological control 7 2%,refugia 1 08%,food production and raw material 22 26%,and recreation and culture 5 78% Owing to the integrated effects of biological communities distribution and ecosystem function of unit area,the contribution ratio of ecosystem services of various rangeland types different greatly The contribution ratio of marsh type made up 52 34%,the total contribution ratio of temperate steppe type,tropical herbosa type,tropical shrub herbosa type,lowland meadow type and alpine meadow type varied in the range from 5 03% to 7 74%,that of others types below 5%

This paper applies Canonical Correlation Analysis to identify the driving forces of land use structure in 1992 in Yulin Prefecture.Through operations of the Statistical Package for Social Science (SPSS) and specific analysis of the results,the contribution of each driving force to land use structure can be identified quantitatively.At the same time,tests were carried out through the canonical correlation coefficient and redundancy analysis.

Water resources carrying capacity(WRCC)is a basic measurement of water resources security that plays a very important role in recognizing and building water resources security system.This paper focuses on the WRCC's measurement and quantifying method,which include the usable water resources evaluation,water demand calculation from eco-system and socio-eco-nomic development and the indicator of WRCC and its vector index.As a representative of water conflict in the Northwestern part of China,this paper addresses several key issues related to quantifying WRCC in this region,such as water cycle modeling in the changing environment,water demand problem for eco-system etc.It holds that the hydrological basis related to WRCC,integrated study of natural change and social economics,present practical models and RS/GIS technology,as well as regional variability should be emphasized.

With the use of MSS and TM data of Shenzhen in 1980,1988 and 1994,land use/cover map was compiled.The paper analyzes the temporal spatial regulation of land use/cover change during the last 20 years followed by the analysis of the correspondence relationship between the land use change and the urban environmental security. The results show that the land use/cover change is the key factor accountable for the rapid urbanization process;urbanization aggravated the urban flooding and the soil erosion;the spatial difference of the environmental pollution of the research area presents the obvious positive correlation with the proportion of the corresponding urban land,whose significant coefficient can reach 0 001.Hence,rehabilitation of the vegetation has the unsubstituted function on reducing the citys eco environmental problem in the urbanization process.

National food security is based upon grain self sufficiency in general.Cultivated land resource is an important base influencing the available grain self sufficient capability.In China,the pressure of grain demand becomes greater and greater in the 21st century owing to the continuous population growth and income increase.Conflict between population and land will become more acute because scarce cultivated land will be partly transformed irreversibly into non agricultural uses in the process of the speedy industrialization and urbanization and economic development.Through analyzing the impacts of quantity change and quality status of cultivated land on grain production,the authors identify the relationship between cultivated land change and food security in China.This research tends to offer a basis for China to set down food security strategy in the 21st century.

and sustainable use has become one of important environment issues in the world. It is necessary to have the proper land use technology and an appropriate method for land use evaluation. This paper deals with the development of a new method for land sustainable use evaluation. We attempt to combine the classical land evaluation method with the landscape ecology method. The classical land evaluation method emphasizes the abiotic factors, such as soil, landform,climate and so on, while the landscape ecology method pays more attention to the spatial relation and processes.In the newly proposed evalution system, we select a series of factors as the evalution indices. Some of the factors reflect the quality, attributes and the use process of the land; others are ecologic, economic and social factors that restrain the land sustainable use. At last, a model of land sustainable use evaluation is given.

Through subdividing the spatial changes of each land use type into three categories of components,i.e.,the unchanged part,the converted part and the newly-increased part,this paper finds out that the two existing models for measuring the rate of land use changes have serious limitations.The traditional quantity analysis model only considers the quantitative change of land use but completely neglects the spatial changes of land use.The GIS-based dynamic degree model would seriously underestimate the change rate of those land use with rapid growth,in par-ticular urban land use because it only takes the conversion process into account but neglects the spatial expansion process of land use change.Therefore,a new spatial analysis model is then pro-posed to modify those limitations and to improve the measuring precision.Secondly,the proposed spatial analysis model is applied in a detailed case study on land use change in urban fringe of Beijing and the measuring results from the3models are compared which substantially demon-strate that the proposed spatial analysis model can more precisely measure the dynamic change rate of land use.

Ecological footprint which was put forward in recent years by ecological-economists is a useful indicator for measuring the pressure imposed by human on natural capital and also a powerful indicator for regional sustainability.Base on the analyses about EF theory's back-ground,the concept ,theory and method is concisely introduced in this paper.Particularly,the pa-per analyses the advantages and disadvantages of the ecological footprint model systematically and reviews the past decade researches that have been reported.Finally,this theses analyses the trends of EF to the full.

Dynamics of arable land and its driving forces in China during the past 20 years are discussed in this paper based on statistical and survey data at national,provincial and county levels.It was found that (a)the general trend of net arable land loss started in the late 1950s which got continued and accelerated in the study period;(b)peaks of arable land loss were usually correspondent to the booming up periods of the economy;(c)the lost arable land was mostly those high quality land in the eastern part while the acclaimed land was mostly marginal land in the western part of the country;(d)area of arable land occupied by non agricultural sectors was sensitive to investment in fixed assets,indicating a low efficiency of land utilization in non agricultural sectors;and (e)urbanization rate had a positive influence on the efficiency of land utilization.The author claims that the following points should be emphasized in land management in order to protect the valuable arable land resources in the country:(a)importance should be placed on both the quantity and quality of arable land.In this connection,the present policy of “keeping quantity balance" within an administration territory is no good to the very land required protection,namely,the high quality arable land;(b)policies on rural urban migration and the development of rural industry should be reviewed,since land utilization of the non agricultural sectors in rural areas is far more inefficient than those in urban areas; and (c)land market construction in both urban and rural areas should be strengthened,since the poor circulation of land resources is a major factor of the low land utilization efficiency in China.

Developing indicator system of sustainability for land resources is one of the superiority fields of study of science and technology put forward in Agenda 21st for each country.The Ministry of Land and Resources has started to deal with this project.The paper probes into the theory and methodology for developing the indicator system of sustainable land use in China.It firstly reviews the domestic and overseas evolvement in the study on sustainable land use,then analyzes and summarizes the current conditions and experience about indicator system for sustainable land use in foreign countries.It points out that three aspects must be taken into consideration to researches of the indicator system for sustainable land use.They are:1)to divide land use regions and establish territorial indicator system for sustainable land use;2)to classify main land use systems and set up their indicators and threshold for sustainable land use;3)to select indicator system and threshold of sustainable land use in typical areas for case study.Only to integrate the three aspects organically can the scientific meaning,systemalization and practicability be assured.

In recent years,many fruitful semi quantitative and quantitative approaches have been used to assess sustainability of economic system,but most of them fail to evaluate the effects of environment and resources on economic processes due to imperfect market and externality.Emergy analysis (EMA),which was developed by H.T.Odum,is a broad reaching attempt to quantify the environment and resources in supporting economic activity.In this paper,indices and ratios based on emergy flows are calculated and employed to evaluate the behavior of economic system.The trends of these indices provide useful information about the dynamics of economic systems within the carrying capacity of the environment in which they develop.A new index,emergy based sustainability index (ESI),of measuring regional sustainability is defined and applied to assess Chinese economy.The result of declining ESI values through the investigation period(1978～1998) indicates that the sustainability of economic system in China has been lowered.

This paper presents an index system and a method for calculating the comprehensive index of land use degree. The latest data from two projects titled “Remote Sensing Macro Investigation and Dynamic Study of National Resources and Environment” and “Resources and Environment Database of China”have been fully applied. In addition, this paper analyzes the regularity of the regional differentiation of land use degree in China and the socioeconomic and physical factors which affect the change of land use degree in China.The“polar” model and the “Longitude Distance” model of land use degree of China are also developed.

Ecological conservation or protection is a kind of socioeconomic activity with positive externality.To internalize the externality,the concept of Ecological Compensation (EC) is put forward.It adopts economic and market-based instruments to encourage people participate in ecological conservation.Participant Gets Principle (PGP) and Beneficiary Pays Principle (BPP) are the two basic principles of it.EC has been widely applied to afforestation,watershed management,agro-environmental protection,biodiversity conservation,carbon sequestration,and so on.While its theories and practices are still in infancy,the compensation system is imperfect with respect to who should be compensated,who should pay,how much to be compensated,and how to finance and allocate compensation payments.By reviewing EC approaches and some efforts that have been made in developed countries (e.g. America and some European countries) and developing countries (e.g. China and Latin American countries),we find out there was very little use of the BPP,ecology and economics have not been well integrated into EC studies,most programs just focus on payments,ignoring the influence of socioeconomic factors on ecological conservation,and so on.After the review and comments,we summarize a functioning mechanism of ecological compensation,which can guide us to improve ecological compensation system.The improvement methods concern:(a)identifying providers and beneficiaries of ecosystem services; (b)on the basis of opportunity cost approach,integrating ecological conservation with regional socioeconomic development,settling proper compensation standards to services providers;(c)calculating payment levels from the side of beneficiaries by integrating the quantity of services they receive,their willingness to pay and their bearing capacity;(d)seeking financing sources and allocating payments cost-effectively;and(e)building up the framework of EC.We consider an effective EC system should take “hematogenesis” rather than “blood transfusion” as its object,and EC research should integrate ecological theories and methods with those of economics.

Based on collections and reviews of the land evaluation papers published on Chinese journals in recent 10years the major progress in this research field is presented in this paper.During this period the research on land evaluation in China has witnessed much progress in its theory,methodology and application.Firstly,much attention has been paid to the integrated considerations of social and economic factors as well as natural elements which are used in land evaluation,and to those methods which make a close combination of qualitative approach with quantitative one.Secondly,land suitability evaluation has received more rapid development although other activities such as land capability assessment were still conducted.Thirdly,the evaluation for cultivated land including the grading and valuation was popularly carried out almost in whole country and,however,the land evaluations for forestry and livestock still are less developed research fields.In the same time,very active activities have been found in the evaluation on urban land following the rapid development of land market in urban areas in China since the early1990s,and a number of new ideas have emerged and some new method-ologies have achieved in the land evaluation for tourism resources development.Fourthly,some new fields of application of land evaluation have appeared,such as the land evaluation for land degradation control in ecologically fragile regions and for land consolidation in urban and rural areas.Besides,the land evaluation for sustainable land use,particularly the development of indicator systems used in the evaluation has become one of the enthusiastic activities in the research of land evaluation.Finally,several advanced approaches such as Artificial Neural Networks(ANN)and Genetic Algorithms have been attempted in use for land evaluation even if the conventional methods such as the Analytical Hierarchy Process(AHP)were still used.In add-ition,Geographical Information System(GIS)has been popularly used in land evaluation,espec-ially in land suitability assessment.

Based on Synergistic Theory and the coupling rule of urbanization & ecological envi-ronment,the coupling degree model (CDM) of urbanization & ecological environment has been put forward,which is divided into coupling degree function and coupling coordination degree fun-ction.The temporal & spatial distribution of the coupling degrees and the coupling coordinationdegrees in China has been analyzed with CDM.The results show that:firstly,the coupling coordination degrees of urbanization & ecological environment are lower and the time sequence of their coupling degrees is basically at resisting stage from 1985 to 2002.Secondly,there obviously exists regional disparity of the coupling degrees and coupling coordination degrees,i.e., the coupling degrees in the eastern regions are higher than those in the middle & western regions;meanwhile,there exists spatial corresponding relationship between the coupling coordination degrees and the levels of economic development,which the coupling coordination degrees are higher in the provinces (regions) where the levels of economic development are higher,otherwise,the coordination degrees are lower.Thirdly,the spatial distribution of coupling degrees and coupling coordination degrees is inconsistent because of differences in economic development,historical evolution,natural environment and policies.Hence,people should adjust its relationship to avoid adverse effect of urbanization development on resources & environment.

With the development of society and economy,the main aim of land readjustment in our country will be changed from merely adding arable land to multipurpose development direc-tion of promoting agricultural comprehensive productive ability,protecting eco-environment and consummating rural infrastructure.So how to reasonably analyze land readjustment potentiality becomes an essential item,and also is necessary for the land readjustment planning and land readjustment project.In fact land readjustment potentiality is a kind of potentiality that relatives to land readjustment criterion and restricts to economic and eco-environmental status.The essence is land use potentiality.Arable land readjustment potentiality is to add arable land area,promote agricultural comprehensive productive ability,reduce production cost and protect eco-environment.It could be achieved by renovation of country road and irrigation and drainage canals,combination and regularization of farmland,elimination of limiting factors and construc-tion of shelter belts.Rural residential land readjustment potentiality is to add arable land and to improve survival environment.It could be achieved by reduction of residential area,promotion of construction rate,use of idle land,combination of small village to central village and consumma-tion of infrastructure.Comparing to overseas land readjustment,China still belongs to the ele-mentary phase of land readjustment that the aim is to add arable land simply and does not be-long to the advanced phase that the aim is to improve comprehensive productivity and consum-mate eco-environment.Once land readjustment in our country comes into advanced phase,the potentiality would come great.

It is very important to establish a suit of eco-compensation system for natural reserve residents,and which is the key to acquire sustainable development for nature reserve.The paper puts forward the concept of touristic ecological footprint and its calculation model by taking Jiuzhaigou natural reserve as an example,calculates and analyses the tourists and residents ecological footprints.Based on the touristic ecological footprint,it constructs an eco-compensation estimate model for residents of the nature reserve.Four conclusions have been summarized:(1)The touristic ecological footprint of Jiuzhaigou is 0.061hm² per capita in 2002.In comparison, extrapolating the footprint of a tourist to Jiuzhaigou (1.8 days) to 1 year,results in an area of 8.8817hm² per capita in 2002, 9.27 times that of the average footprints 0.961 6hm² of citizens of Jiuzhaigou. (2) Plus the tourist ecological footprint,the total ecological footprint of Jiuzhaigou in 2002 is 1.005 3hm² per capita,ecological capacity is 1.202 6hm² per capita,ecological remainder is 0.197 3hm² per capita.(3)In Jiuzhaigou,the average tourist output of 1 hm² ecological footprint is 8 643 yuan,3.31 times the average output 2 613 yuan of the Jiuzhaigou citizens ecological footprint.(4) Takes the direct lost benefits of De-farming and Reafforestation as the lowest eco-compensation level,Jiuzhaigou residents should be paid 2 159 yuan per family or 472 yuan per person.Takes the adding recreational benefits of De-farming and Reafforestation as the highest eco-compensation level,Jiuzhaigou residents should be paid 7 142 yuan per family or 1 561 yuan per person.Takes the difference of economic efficiency of ecological footprint between tourists and residents as a reasonable level,Jiuzhaigou residents should be paid 4 983 yuan per family or 1 088 yuan per person.

Based on analysis on land use change and driving forces in Shenzhen,this paper divided urban land into industrial land,residential land and service land,and put them in the same framework with arable land and major driving forces,namely industrial investment,population growth,income level and water availability.And then the method of system dynamics was used to quantitatively describe their dynamic relationships.The basic result of system dynamics simulation shows that the long term trend of urban land change is a“S shaped" curve,and the fastest period is between 1980 and 2030.After a relatively long time fluctuation,the proportions of industrial land,residential land and service land in urban land use will become stable from 2020.Arable land has been decreasing continuously and will finally disappear.

Soil erodibility serves as a major parameter for soil erosion prediction and land use planning.Olson and Wischmeier gave it a very clear definition which has been used in many soil erosion models.However,it is not suitable for China.Based on the review of the 70 years research achievements on soil erodibility,and in light with China's actual conditions on land use as well as the available erosion data,the definition on soil erodibility index and its measurement in China was developed The soil erodibility for China might be defined as the average soil loss per unit of the erosion index from the clear tilled fallow on a plot 20 meters long on a slope of 15° This defi nition may help us for field measurement and Chinese soil erosion prediction model deve lopment.

Evaporation(evapotranspiration),on the one hand,is an important component in the heat and water balance of the Earth's surface,and is the component of the hydrologic cycle most directly influenced by land-use and climate change.On the other hand,evaporation(evapotran-spiration)consumes much of the water and energy that are available on the surface of the earth and therefore influence all hydrological and most meteorological processes.Basic knowledge for evaporation change over global or regional scale redounds to understand the law and causations of climate change.Up to now,studies on global climate change are,more and often,concerned with temperature and precipitation.Researches on the influence of climate change on evapora-tion(evapotranspirtation)are in small numbers.Based on observational data from1960～2000of123meteorological stations,near and in the Yellow River Basin,the spatial and temporal distri-butions of trends for pan evaporation are studied.The results show that,although the annual mean air temperature over the Yellow River Basin has,on average,increased0.6℃over the past40years,the rate of pan evaporation over the Yellow River Basin has,on average,steadily de-creased,especially in summer and spring.Compared with the1960s～1970s,the rate of annual pan evaporation of the1980s～1990s has decreased136mm or7.5%.Spatial distribution of the change rate shows that this trend is general but not universal,pan evaporation has significantly decreased over the upper and lower reaches of the Yellow River Basin,and increased in a small degree over the middle reaches of it.

Harmonizing the contradiction between economic growth and cultivated land conser-vation has important effect on the realization of sustainable development in China,and land conversion is the focus of that contradiction.In order to control land conversion rationally,we must understand the driving factors.In this paper we construct a theoretical framework of land conversion economic driving mechanism,and make an empirical analysis using the data of provincial level between 1995 and 2001.Results indicate that population increase and fixed assets investments are the major driving factors,land use comparative benefit and cultivated land endowment are the basic driving factors,land conversion income and the anti-governance behavior of local government has a positive relationship with the quantity of land conversion,but the development of land market and the comparative benefit of farmland has a negative relation-ship with the quantity of land conversion.As a result,some valuable propositions are presented.

Papers on studies of tourism resources evaluation published abroad from the late1960s to the late1990s are reviewed,especifically those related to issues of evaluation research into the visual qualities of tourism resources,evaluation research into the social cultural and heritage values of tourism resources,and evaluation research into the monetary value of tourism re-sources.The paper aims at promoting theoretical research and practical application of tourism resources evaluation in China.

Land use system is a complicated and macro system with dissipative structure.It has orderly characteristics of function and structure.The order degree of land use system is applied to express information entropy values and the applications in the regulation of the land use struc-ture in a region are discussed in this paper.The information entropy values of land use structure in different periods of time and regions sare calculated,and the laws and causes are analysed.Firstly,the information entropy values of land use structure of Lishui city in Zhejiang Province and the province itself covering the peri-od of1990to1999are calculated.The results show that the information entropy values in1990are the lowest and then rise.They fall after they arrive at the highest values.This indicates that the land use systems go through a course from order to disorder and returning to order.Secondly,the information entropy values of land use structure of the whole country and the East region,the Central region,the West region,Zhejiang Province and the cities of the province,Hangzhou city and the five counties under the jurisdiction of the city are calculated.The information en-tropy values decrease progressively from the coastal area to inland.This indicates that the order of land use system increases progressively from the coastal area to inland.The applications of the information entropy values of the land use structure are discussed in the paper.The information entropy values are of guiding significance to the regulation of the land use structure in a region as they can reflect the dynamic change and transformation degree of land use types in a region in a certain period of time.However,the point is how to set remains to be researched with the optimum information entropy value of the land use structure in differ-ent region s.

Ecosystem health is a multidisciplinary integrative field exploring the interrelations between human activity,social organization,natural systems,and human health.An ecological sys-tem is healthy and free from"distress syndrome "if it is stable and sustainable,i.e.,if it is active and maintains its organization,and autonomy over time and is resilient to stress.The basic ecolog-ical axioms of evolution ecosystem health include the axiom of dynamism,the axiom of hierarchy,the axiom of creativity,the axiom of relatedness and the axiom of differential fragility.The evolu-tion components of ecosystem health include eight criteria,e.g.,vigor,organization,resilience,etc.E-cosystem health is at the early stage of development,and there are some problems to solve.As we further develop the theory of ecosystem health,the quantitative methods,particularly those from the development of remote sensing applications and GIS technique will contribute to the capacity to analyse and evaluate ecosystem health over large areas.The advanced technique will promote its further development.

The agricultural ecosystem in Beijing rural areas plays a special role in maintaining the environmental function of the city.At present,because area of farmland in the area is decrea-sing,a series of ecological problems are becoming more and more serious.The accurate valuation of farmland ecosystem services is very important to reserve rational development of agricultural resources.In this paper,the agricultural ecosystem (farmland and orchard) service values are evaluated by various methods such as market value,substitution engineering,shadow price,pportunity cost for various crop types.Some index systems are selected for assessment of agricultural ecosystem services,which consist of 11 service indexes such as agricultural products,CO² fixation and O² release,environment purifying such as air quality purifying,sewage treatment,dung decomposition,OM accumulation in soil,nutrients cycle,soil conservation,water storage,and agriculture tourism.The results showed that the total service value of agricultural ecosystem decreased from 45133.84 million yuan in 1996 to 34 269.90 million yuan in 2002 a decrease of 10 863.93 million yuan,of which various values of food crops decreased and others increased to some extent.The total average value of agriculture services during six years was eight times of the production value.The total average value of agricultural ecosystem services during this period of time added up to 91 567.61 million yuan with indirect values being 34 616.05 million yuan,i.e.,six times of the direct values.In terms of composition,under present cultivation system,the value of farm products is 12.41%;the total value,including carbon fixation,oxygen production and environment purification,are very great,making up 77%(carbon fixation and oxygen production 39.48% and environment purification 37.51%);the value of soil OM accumulation 4.4%;nutrients cycle maintenance 1.27%;water-holding and agricultural tourism 2.21% and 3.8% respectively; and soil conservation 0.01%.Therefore,agricultural ecosystem has provided huge indirect values to human beings besides direct values.