Earth system science aims at earth system and particularly focuses on its different spheres, key factors and the interactions between nature and human activities. It is the emerging fields promoted by scientific development and social demand. The concept of Earth system science was proposed for solving the problems of global resources and environment, which was an important stage for earth science changing into the direction of integration study. At present, a number of important international joint research programs have been organized on global scale under the guidance of earth system science that attempts to unite global scientists to boost the development of earth science. The development of earth system science relies on the integrated observation of the physical, chemical and biological processes in key elements and spheres of earth system. Since 1980s, many observation, monitoring and information sharing networks have been established on regional, national and international scales by some countries, international organizations and projects. International Long Term Ecological Research Network (ILTER) was established in 1980s. The scientific objectives of ILTER are to carry out long- term observation on ecological processes, study the interaction among various ecological factors, investigate the long - term changes of ecosystem and environment and offer scientific support for ecosystem assessment and management. Chinese Ecosystem Research Network (CERN) was initially established in 1988. It has played important roles in the dynamic observations, scientific research and production demonstrations of ecosystem and environment in China. Based on CERN, Chinese National Ecosystem Network (CNEN) was established by the Ministry of Science and Technology in 2005. Fiftythree stations have been enrolled to CNEN for dynamic observations and research in cropland, forest, lake, gulfs and grasslands as well as deserts. CNEN will become a necessary part of the GEOSS and take important roles in the development of earth system science in China. This study will discuses the potential roles of ecosystem observation and research network in earth system science and future directions of CERN.
Ecosystem integrity has recently been proposed to facilitate enhanced protection of biological and ecological resources. It is valued as a basis for environment ethnics and public environment policy. In many aspects it has been assumed that to maintain ecosystem integrity or system integrity is the general purpose for ecosystem management. Yet ecosystem integrity is a relatively new concept with multi- aspect definition. Briefly to say, it focuses on the system components from structure point of view, while it prefers the integrity and dynamic characteristics from function point of view. Further more, it focuses on whether human value plays a great role in defining and measuring ecosystem integrity. There are merits and limitations in different definitions of ecosystem integrity, for each acknowledges of different aspects of ecosystem structure and function reflect the subjective perspectives of humans on the value, importance, and role of biological diversity. From the point of self- organization, a system with health and the ability of self- evolution or of long- term adaptation to changing environmental conditions and human uses is of integrity. It is pointed out that ecosystem integrity and ecosystem health are different. The paper also gives explanations on methodology of ecosystem integrity measuring and assessing. It suggests that the indices for measuring ecosystem integrity comprise index of components, index of structure, index of services and index of human disturbances. The concept of ecosystem integrity has been applied in biodiversity conservation, ecosystem management and searching for proper human- nature relationship. It also makes up the ecological understanding and values of the sustainable development.
As the continuation and development of NOAA/AVHRR NDVI, the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) of MODIS have been comprehensively used in many fields. In order to investigate the difference between NDVI and EVI derived from MODIS, comparative study of these two vegetation indices was conducted by statistics and geo- statistic methods (semi- variance function). By the comparison of the two kinds of vegetation index distribution maps in different period, it is demonstrated that EVI improve the sensitivity for well- vegetated areas where NDVI is saturated when plants grow well, which will be helpful in monitoring plants growth status. At same resolution, i.e. 250m, 500m and 1000m, by means of the geo- statistics, the results show that range, variance and variation coefficient of EVI is higher than that of NDVI, the value of NDVI is even, and its spatial relativity is higher than that of EVI, which all show that EVI is more sensitive to the spatial heterogeneity of plants in research area.
Wetland is one of the most important ecosystems, and it has high social benefit, economic benefit and scientific research value. Global wetland degraded and its amount decreased in the past several decades. Wetland resources are taking on a heavy pressure, and romote sensing technique plays an important role in real- time monitoring of dynamic changes of wetlands. In this paper, wetland monitoring mainly means classification and recognition of wetland based on remote sensing technique. Current status of researches on wetland monitoring based on remote sensing technique in China and abroad was systematically discussed from multiple aspects, including classification systems of wetland, pre - processing of images, remote sensing data sources of multi - resolution (multi - spatial resolution, multi - spectral resolution,multi - temporal resolution), methods of information extraction for wetlands(visual interpretation and computer auto- interpretation) and so on. Finally, three current shortcomings and six future keys of wetland monitoring based on remote sensing were presented.
The Alpine Treeline Ecotone (ATE) indicates the characteristics of the complicated ecosystems in the mountainous environment. It can also reflect the transition of the lower vegetations to the alpine vegetations. The location of the treeline is the result of a combination of a great number of unfavorable conditions for tree regeneration, seedling establishment and tree growth. For the sensitivity of the ATE to the climate change, ATE has become a hot topic in the alpine environmental and global change research. Recently, the landscape patterns and ecological processes of the ATE are mainly two aspects of the researches in the ATE. The researches majored in the landscape patterns of the ATE focus mainly on the landscape pattern of the ATE. And the researches majored in ecological processes of the ATE focus mainly on the formation mechanisms of the treeline. The development of GIS enhances the integration of the pattern and process of the ATE, and provides a useful tool to evaluate the relative importance of the biotic and abiotic factors in the research of the ATE.
Heavy metal pollution in aqueous system is a significant world- wide problem. Heavy metal ions which are present as ions in wastewater are toxic and can be readily absorbed into the human body through the food chain in aquatic ecosystem. The prevention of heavy metal contamination in aquatic environments is often performed by conventional methods. However, these methods have many disadvantages, such as incomplete metal removal, toxic sludge generation and cost inefficiency. Metal uptake by microorganisms has been studied for some years. Researches indicate that algae have the abilities to accumulate trace metals. Based on findings, technologies of bioremediation of heavy metal contaminated water by algae in living and nonliving form have been developed and got more and more attention around worldwide for its costeffective and environmental friendly characteristics. Some of the technologies in heavy metal removal, such as High Rate Algal Ponds and Algal Turf Scrubber, have been justified for some practical application in China and abroad and limitations of these methods in large scale still exist. As an innovative clean- up technology, it mainly depends on the biosorption and bioaccumulation abilities of algae, and the former is dominated in the whole process of bioremediation. Studies suggest that the constituents of algae cell wall such as alginate and fucoidan which have key functional groups are chiefly responsible for biosorption of heavy metal ions. Cell storage and extracellular polysaccharides play important role in heavy metal detoxification of algae. In order to quantification of metal - biomass interactions, several adsorption models are also discussed for algae so that we can evaluate their potential for metal uptake. Although a number of studies using different types of algae have proved that bioremediation is a more effective method for heavy metal removal than the conventional methods. However, there still exist some deficiencies in mechanism and application of bioremediation. So, further investigation is still needed to elucidate the process of bioremediation and optimize the maximum efficiency of removal, which is expected to lead to its large scale exploitation in our country.
Large - scale distributed hydrological model plays an important role in the coupling atmospheric and hydrological models research at present. In this paper, ZB algorithm is proposed to obtain base on 1 km grid scale DEM data, because it can maintain data information about drainage basin boundaries and river networks very well at coarser resolutions. We apply ZB algorithm and grid- averaged algorithm at 5km, 10km, 15km, and 20km scales in the upper Yellow river (above Tangnaihai station, drainage area 121, 972 km2). Elevation, slope, wetness index, drainage density, length of main channel, watershed area and other parameters are extracted and compared with the parameters that are obtained based on 1 km DEM. Results show that DEM data obtained by ZB algorithm can hold stream network continuity and real watershed boundaries very well, and meanwhile it can decrease the amount of other geographical information falling off, compared to other algorithms. The method can supply satisfied digital watersheds for constructing large- scale distributed hydrological model.
Management System of Resource and Environmental Model base (MSREM) is one of the essential issues in resource and environmental field. There are usually two ways to develop MSREM, of which one is the model management techniques including database approach, structured modeling approach, object - oriented approach and knowledge - based approach, and another one is model management in GIS software such as Model Builder in ArcGIS. The first way can efficiently manage the models, but requires creating lots of codes to handle spatial data. The second way can utilize GIS to manipulate spatial data, but it doesn't support building complex mathematical models. This paper proposes an object- oriented framework for MSREM, in which models are abstracted to model class and model instance. Model class and model instance are represented as an object. Spatial data and mathematical equation are parsed by Model Engine that is composed of mathematical library and GIS component. Model management and model reuse can be efficiently realized by combination of model base and database.
In geography study, wirelike geo- objects often have basic influence on regional characteristics, such as fault affecting regional crustal stability, traffic line affecting regional social and economic activity,and etc. But in the process of regional comprehensive assessment, the study of influences of wirelike geo- object currently uses approximate assessment methods, such as setting fixed affecting width or simply making off high, middle and low affecting areas, and etc. And the produce of assessment is inefficient. By analysis, the regional influence of wirelike geo- objects has common characteristics such as: distance attenuation, class effect, congregate effect and direction effect, etc. And the basic feature of field includes spatial construction and feature domain, continuity and differentiability, istropic and anisotropic, self- mutuality, and etc. In contrast to wirelike geo- object influence and field model, the result shows that the distribution of wirelike geo- object influence belongs to 2- D field model and using the feature of field can adequately reflect the characteristic of wirelike geo- object to region. Therefore, we suggest taking the model of regional influence field to imitate wirelike geo- object influence for region. And by using of GIS to form regional influence field of wirelike geo- object, the results show that regional influence field can preferable reflect the degree of wirelike geo- object affected field and is applicable to express the regional influence of wirelike geo- object.
The population distribution reflects the mode of the urban internal population and social spatial structure. Because the population data is very easy to obtain and can be compared in temporal and spatial series. A lot of researchers use population data to reflect the urban internal spatial structure. GIS technologies have been used in spatial structure research in the social sciences frequently recently. In this paper, Shenzhen city is taken as an example in this paper to show how to research urban internal population spatial structure based on GIS. The data of Fifth (in 2000) and Fourth (in 1990) censuses of Shenzhen is used in our research in two aspects. Between 1990 and 2000 every street's population density changed a lot, but the highest value street did not changed. The population center of gravity moved to north west about 4km from year 1990 to 2000. Several population density models were simulated for the population distribution. The method of curve estimation is used in finding the population density mode. The optimal population density mode was the Inverse distribution functions, which means that the further from the center and the spars the city would be. And the exponential model (Clark model) is not the best. The results of spatial auto correlation means that the population in the suburban was growing fast but centripetence in the city center still exists.
The process of urbanization in China has been in a sustainable and rapid development period, and every city begins to pay more attention to the integration of urban and rural development. In some economically developed area, in order to push the process of urban and rural integration, harmonious development strategy of urban and rural integration should be made in time. On the base of discussing the new viewpoint of harmonious development strategy of urban and rural integration, this paper puts up some suggestions to make harmonious development strategy of urban and rural integration, such as analyzing systematically and harmonizing wholly; making use of the advantage and make up disadvantage; considering the urban and rural development at the same time; and paying more attention to industry, space and ecology strategy. The development situation and main problems should be mastered, which can put up related development strategy. As for Shuangliu county, it has an advantageous location and economic base, so it can take advantage of its excellent condition and outer development environment and carry out the following strategies: actualizing step by step and sustainable development; northern promotion and circular development; using resources appropriately and breaking through on key sides, which can promote concerted development of urban and rural integration.
It is very important to research driving factors and ecological effects of agriculture landscape pattern change. Studies at the present time focus on dynamic changes of agriculture landscape pattern and its components, while rarely on induction and mechanism of driving factors and ecological effects. The new development of researches on agriculture landscape pattern change, driving factors, and ecological effects was summarized briefly in this paper, and the study emphasis aftertime was also put forward as follows: developing landscape pattern indexes which can reflect ecological processes (inducing driving mechanism of agricultural landscape pattern change), researching on ecological effects mechanism of agricultural landscape pattern change, developing methods in combination with holistic landscape index and long located observation data, researching on restoration methods in ecological degradation brought by agricultural landscape changes, agricultural landscape planning and actualizing, and designing high efficient farmland landscape structure.
Externality of agriculture includes both external economy and external diseconomy. The external economy implies multiple roles of agriculture in food security, economic, ecological, social and cultural aspects besides providing food and fiber for human beings, while the external diseconomy is mainly focused on negative environmental impacts of agriculture, such as soil erosion, depleting water resources, non- point source pollution and greenhouse gas emission, etc. Externalities of agriculture in China in aspects of soil, water, air, biodiversity and landscape are identified and explained in detail. Many researches have been carried out on valuing the ecosystem services and external cost of agriculture, including a few about environmental cost in China. Yet the results can not be compared with each other simply because of numbers of reasons: strong regional characteristics of externalities, shortage of standard evaluating methods and different stands of evaluators. As both external economy and diseconomy are low efficient in resource allocation, the source of externality, whether from market failure or policy failure, or both, is being internalized by policy reform or technology amelioration. Objectives of both domestic agricultural policy and international trade one are to optimize multi- values of agriculture and to control the diseconomy of agriculture. Therefore, sustainable development of agriculture becomes one of preconditions. Policies and regulations that can protect rural environment, ensure food security and promote rural development have been attempted by Japan, USA and EU, etc., which have taken effects in different degrees. And sustainable agriculture technology has been proved to be one of feasible measures for internalizing external cost of agriculture, including: diversifying landscape, Integrated Pesticide Management, soil and water conservation, no tillage, and Best Management Practice, etc.
Fractal world is constructed by the invisible hands of nature. Coastline, mountain ridges, faults, river basins, and etc. are fractal objects. Human beings select to stay in the beautiful places, so the natural and man- made integrated objects are formed gradually. Then the network space of tourism system is formed accordingly. Mandelbrot stated the uncertainty of the coastline length in his paper "How long is the coast of Britain? Statistical self- similarity and fractional dimension”published in "Science"in 1967. The concepts of fractal and fractal dimension were presented for the first time in that paper and have been applied to quantitatively describe the difference of crooked coastlines of British and South Africa. Based on extensive and thorough observation of a large amount of geographical, geological and economic phenomena, Mandelbrot discovered an inherent character in nature that he called fractal, and he also considered the fractal dimension as a quantitative parameter to describe numerous irregular phenomena in nature. As a new tool to picture the complexity of nature, the fractal theory has been widely used in many fields. Compared with the Euclidean geometry of more than two thousand years of history, fractal and fractal dimension are fitter for describing various complicated objects in nature. The fractal theory has been applied to many fields, which has actually constituted a scientific field with a broad frontier called Fractal. At present, it becomes a field with vast potential for use and application in many disciplines. And no doubt it also provides new analytical capability and scope to the innovation of tourism study. As to the study of tourism, researches on the fractal characteristics and fractal dimensions of the network space of tourism system have not been attempted till now. In this paper , the scientific significance and research aspects are prospected. As a case study of Beijing, the fractal proof is provided in terms of the network space of tourism system. It is useful to advance the theory level of China tourism science.
