Study of ecological security involves multiple scales of species, ecosystem, watershed, region, and country. Regional ecological security（RES） serves as the basis of sustainable regional and national development, as the prerequisite for establishing harmonious and environment-friendly society, and as the essence of human ecological security. RES should thus be the focus of ecological security. The hitherto study of RES has been concentrated on comprehensive assessment of multiple indexes, species or ecosystem security, and the effect of land use and land cover changes. A scientific basis for determining the degree of RES is still lacking. This paper argues that geographical zonation should be considered the first principle for studying RES; the virginal value of landscape (or land type) may act as the objective criterion of RES; and the degree of deterioration of landscape as the major index of RES. Geographical zonation, the virginal value of landscape, and the degree of deterioration of landscape together constitute the scientific foundation for studying RES. The working frame for studying RES may include (1) quantifying the virginal value of landscape; (2) determining the degree of deterioration of landscape; (3) analyzing regional deteriorated landscape pattern; (4) considering the ecological effect of neighboring areas; (5)creating the diagnosing model for RES; and (6)selecting indexes of RES according to the RES diagnosing model.
Ecological security is critical to sustainable development of human society in the 21st century, which has been paid great attention to by Chinese government since 2003. Firstly, introducing many different understandings on the concept of ecological security, this paper summarizes ecological security concept as follows: Ecological Security is an interdiscipline of natural sciences and social sciences. The concept of ecological security connotes (1) the health, integrity and sustainability of ecosystems and (2) the ecosystems services contributed to human welfare. Ecological security has the characteristics of globality， nonreversibility of ecological damage and chronicity of ecological recovery. Secondly, this paper reviews the research progress on ecological security and puts up a frame of ecological security that is the health, integrity and sustainability of ecosystems, the ecosystems services, and the analysis and assessment of ecological security. The main researches focus on the regional construction and management of ecological security. But the weak researches are on ecological security with globalization and climate change; especially, there is no generally recognized concept of ecological security now, and little new methods of analysis and assessment on ecological security are developed recently. Thirdly, 3 basic theories are concluded on ecological security developing in over 10 years: (1) Assessment of ecosystems health and environmental risk; (2) National interests in environmental /ecological security; and (3) Ecological right theory and legal practice. And several main research methods on ecological security are sum up too. Finally, the research proposal outline in the future is offered: a. to make and bound the concept of ecological security; b. to build the theory for ecological security subject; c. to develop the research methods; d. to build the assessment systems; and e. to make the decision-support model for the regional sustainable development.
Federal Republic of Germany experienced a way of Pollution-Treatment-Prevention in the field of ecological and environmental protection， namely a policy transformation from a technological and emergency policy to a political and preventive environmental protection policy. The ecological and environmental protection policyes are formulated together by environmental activists， big enterprises， and academics as well as the local and federal governmental departments concerned， and will be supervised and carried out by a comprehensive monitoring system on a national level. The public has the right to not only learn the results， but also participate in the drawing up and supervision of this policy. Spatial planning， especially ecological and environmental planning have become an important part in preventing ecological and environmental pollution. The German spatial planning system includes 6 levels from the higher level to the grass roots， i.g., EU， Federal Republic of Germany， state， region， city and construction bureau. The implementation of ecological and environmental planning， however， has to face the challenges of the pollution caused by private traffic and small enterprisers as well as the challenges of the location disadvantage caused by the increasing of environmental protection cost on the enterprises. These experiences and lessons of Germany could be used as a point of reference for improving of objectives， policy and measure of ecological and environmental protection as well as formulating， implementing and supervising spatial， ecological and environmental planning in China， including: 1) transformation of ecological and environmental policy from improving technological measures to preventing environmental pollution; 2) assuring the implementation of ecological and environmental protection; 3) regarding spatial planning as a tool to protect the environment and realize regional economic and social sustainable development; and 4) paying more attention to land use for residence， traffic， vocation and nature preservation zone at the technological level of planning.
In 21 century, the restrictions of water resources shortage and eco-environmental crisis in the urbanization process in arid area are even more evident. However, what are the real roles of water resources and eco-environment in the urbanization process? What kind of urbanization modes should be adopted under the dual restraints of water resources and eco-environment? This paper reviewed the domestic and international research progress about the theories, ideas, methods and practices of the research of urbanization and eco-environment in arid area. Then the viewpoint that the relation between urbanization and eco-environment is mutual promotion while inter-coercing was put forward. Finally, the author pointed out the weak side of studying in this field at present, and prospected the main research directions in the future. Studies showed that international scholars generally paid close attention to the research of urbanization and eco-environment reciprocation relation, and thought much of the research of urbanization and eco-environment reciprocation mechanism in arid area. They generally adopted “3S” technology and quantitative analytical method to appraise the response course of urbanization and eco-environment respectively, and strengthened to research the sustainable developmental modes of urbanization and eco-environment in arid area progressively. Domestic scholars mainly studied on the phenomena of water deficiency and ecological degradation, the interactional mechanism between urbanization and eco-environment, the quantitative analysis models and the urbanization development modes in arid area. Although a series of theories to study the relation of urbanization and environment have emerged recently, there are a lot of weak points which should bring our attention in. For example the researches of urbanization or eco-environment solely were more, but the researches combining them together were less; the empirical researches were more, but the law summarization researches were less; and the researches of coercing effects were more, but the researches of restraint effects were less. So, an independent and integrated theoretical system of urbanization and eco-environment research in arid area has not formed yet. In the future, the multi-disciplinary merges, the close integration with practice and the application of new technical method and the dynamic simulation will be the main research directions.
A wetland is a structural and functional unit of a landscape consisting of various environments and sustaining a certain biodiversity. Conservation of wetlands is important at both the regional and the national level. The paper elucidated the changes in marsh spatial pattern during a period of about 16 years after 1986 in the Zhalong wetland. Three Landsat TM remote sensing images in 1986, 1999 and 2002 were used to analyze the evolution of Zhalong marsh pattern assisted by GIS and RS technology. The landscape indices such as fragment index, fractal dimension, distribution centroid points, etc were calculated and analyzed. At the same time the paper studied the changes of marsh area in each district relative to the changes of the whole marsh area. The results show that the fragmentation of wetland patches is increasing, the shape of marsh patches changes little, the distribution centroid points of marsh wetland has moved towards northwest and that marsh in Zhalong northwest is less stable and affected more by human actions than that in Zhalong southeast.
Nitrous oxide is one of the most important greenhouse gases, which is 200 times more potent than carbon dioxide. Apart from being a greenhouse gas, it can also deplete the stratospheric ozone, exposing humanity to the harmful effects of solar ultra-violet radiation. Nitrous oxide in atmosphere has been increasing continuously due to human activity and it will influence the environment severely, so study on the emission of nitrous oxide is more and more important. Soil is the main source of nitrous oxide. In this paper, the authors give an overview on the mechanism and the key influencing factors of production and emission of nitrous oxide. The temporal and spatial characteristics of the emission of nitrous oxide and its modeling simulation are also studied. Nitrous oxide is mainly produced by the action of nitrification and de-nitrification in soil. The processes of nitrous oxide production and emission is very complex, and the key influencing factors include soil temperature, soil water content, soil pH, soil texture and agriculture management. Finally, some suggestions are put forward for further investigation in the near future. It is recommended that further study be focused on quantitative description between nitrous oxide and these factors, on the estimation of emission amount at global level, and on development of methods of reducing nitrous oxide emission in the future.
This paper studies the effects of alpine meadow cultivated on soil organic carbon (SOC) using soil physical fraction to understand the stability of SOC at Haibei research station zone, CAS. The SOC contents and its fraction in soil physical fraction (light fraction organic carbon (LFOC) and Heavy fraction organic carbon (HFOC)) in 0~40cm soil depth were investigated. The law of soil organic carbon changed with the cultivation year is studied synchronously. The artificial grassland was selected by different cultivation year(0, 1, 11, 16, 20 yr) after alpine meadow had been cultivated. The results showed that SOC, LFOC and HFOC only decreased in 0~10cm, and respectively, lost 10.97 %, 7.75 % and 7.4 % with 20 years of cultivation，which was mainly caused by wind erosion, tillage erosion and soil organic matter decomposition in 0~10cm after cultivation. The gross organic matter in 0~10cm leached with the rainwater to deposit in deeper horizon of soils. SOC, LFOC and HFOC increased in 0~40 cm soil depth, respectively, with the rate of 0.08 tC·hm-2·yr-1, 0.07 tC·hm-2·yr-1 and 0.14 tC·hm-2·yr-1 after conversion of alpine meadow to artificial grassland for 20 years. Furthermore, the results indicated that conversion of alpine meadow to artificial grassland did not affect the carbon sink function of alpine meadow, but the storage of carbon-fixed in the soil-plant systems decreased obviously compared to the alpine meadows: the rate ranged from 7.38 tC·hm-2·yr-1 to 6.89 tC·hm-2·yr-1。
Geography of transportation is the important research field of human geography, and it is necessary to review its developing history integrally in China , appraise its research progress and discuss its future developing trend. In this paper, based on expounding about appraising system, the author narrated the research history and newest studying progress of transportation geography in detailed in China from different studying field since 1927, including: ①theory system of transportation geography; ②regional integrative transportation and its regional plan; ③different department transportation geographical research; ④urban transportation geographical research; ⑤the research of traffic spatial influence, and the author reviewed the macroscopical skeleton of transportation geographical development and research in China. Furthermore the author concluded and evaluated its development and research progress in China simply. Then the author referenced the authoritative journals of international transportation geography, and expounded simply its international research progress and main theory viewpoints, including: ①spatial influence of air transportation networks; ②container transportation systems; ③geographical research of modern logistics; ④spatial influence about release of transportation control; ⑤environment appraising of large transportation construction. In the final, based on current research and social-economical environment of China, referenced the international studying focus, the author discussed the important research fields and developing trend of transportation geography in China, including: ①spatial optimising of transportation networks resources; ②social and economical mechanism of spatial flows; ③social-economical and environment influence of transportation construction; ④geographical research of modern logistics; ⑤effect of corporation operation.
As one of the largest energy consumers and producers in the world, China has faced great challenges of energy security on the way of modernizing itself. Energy security mainly concludes reliable energy provision and safe energy use. The paper reviews the progress in China’s energy security, energy strategy and law related energy problem. Though great progress has been made in energy security, there are many shortcomings, such as false energy prediction in some years, mainly because of the short industrialization history of China and weak researching on the complex energy system. It is the time to rethink energy security when China is turning from reliable energy provision to safe energy use. Based on researching, the paper points out that China should attach greater importance to energy security researching, including the phase of energy security, changing of energy consumption, energy management, energy price, law related energy problem and the development of renewable and new energy. The government should adapt its management to the market economy. Resource-price reform must be accelerated and prices should be decided by the market as much as possible. China must also develop its reproducible energy resources. In conclusion, solving energy security problem requires the participation of the entire nation.
SRTM90m digital elevation data contains no-data voids. Based on the analysis after retrieving the voids in the region of China, several processing methods are used to fill in them. Those methods are: (1) patching the void area with DEM data interpolated from contour line from paper map at scale of 1:1 000 000; (2) adding contour line from paper map at scale of 1: 1 000 000 to the void at SRTM90m data and then interpolating the patched data,; (3) patching the void by directly interpolating SRTM90m, and (4) retrieving and interpolating contour line from SRTM90m data. It is verified that the most operable method to fill in no data area is to interpolate the contour line which is retrieved directly from the original SRTM90m, but this method is effect to patch the small no data area; when no data area is big, it is better to use contour line from paper map with large scale, however, the quality of current paper map with large scale is not high enough, furthermore, the acquisition and publishing contour line from paper map with large scale (e.g. large than 1:1 000 000) is limited by related state security regulations. Further processing steps such as to add water body region are provided for better application of the data.
The earth system is composed of lithosphere, hydrosphere, biosphere, atmosphere and outer space. Earth system science probes into interaction between these spheres, rules of earth system changes and mechanism leading the changes. It will lay foundation for predicting global environmental changes and provide scientific basis for managing earth system. Data is the key to earth system science's existence and development. The theoretic study on earth system science has to rely on plentiful data. Data construction and information system development have been regarded an infrastructure of geosciences. Data classification is a fundamental work for data organizing, data management and data sharing. On the basis of spheres of the earth, main disciplines for each sphere and data contents of each discipline, with the principles of scientism, systematism, hierarchy, expansibility, practicality and compatibility obeyed, data of earth system science is classified into 14 categories and 88 subcategories. This classification system is actually applied to a national Scientific Data Sharing Program, named China Sharing Network for Earth System Science Data. Data classification is a very work. Earth system science is in form-taking stage and it has not complete theoretical and methodological systems. With development of earth system science, data classification system put forward in this paper will be updated and perfected unceasingly.
Digital elevation model(DEM) is a digital model-building process of terrain relief. DEM is an important data set in sustaining geographical process model research. The DEM precision of acquiring, operation and compression would influence the simulation effect and research quality of relative Geo-models directly. In this paper, several DEM datasets had been analyzed and compared, which are used abroad in the international geographical society. 3D profile and check-point methods were applied in the research to complete the precision verifying and appraising of the three main DEM datasets, which are GTOPO30 DEM data with 30 arc resolution, SRTM DEM with 90m resolution and the DEM with 25m resolution produced by national foundational geographical information center. Based on the comparison, the main factors effecting the precision and the quality of SRTM_DEM are discussed. The results indicate that, in the indexes of extremum, mean and std. variance, SRTM_DEM is two times as well as GTOPO30_DEM. SRTM_DEM has better data quality control in the difference value as compared to NFGIS_DEM, and SRTM_DEM also has the mean absolute value about 0.3m (ie. SRTM_DEM has a higher confidence level in the general quality). The precision of SRTM_DEM has a great predominance in the geographical process model research, especially for the relative research ability sensitive to the spatial resolution of DEM.
Distributed hydrological models have been shown high light on because of the spatial variability of hydrological processes. On the other hand, the complexity of the hydrological processes, the multi-purposes of hydrological modeling and the availability of observed data have made it difficult to bring forward a hydrological model system for general use. It is always confused and time consumed to find a model of most fit to practical application because of the variety types of hydrological models. In this paper, the framework of a modular based distributed hydrological modeling system has been discussed. The system was so called Hydroinformatic Modeling System (HIMS), include hydroinformatic management system, data pre- and post-processing system, and hydrological model & function library. For the management and processing of spatial information, basic GIS functions have been integrated into system on the basis of SUPERMAP, which is component based GIS software. The hydrological function library (HFL), which represents different processes of hydrological cycle, was the core of the entire system. Distributed hydrological models of different scale were all established on the HFL. The HIMS has been applied to hydrological research in the Yellow River Basin and has reached to some success. However, since it is still in its trial version, much more work need to be done to improve it.
Topographic wetness index, which takes into account the integrated effects of topography and soil hydraulic characters on soil moisture, plays important theoretical and applied potentials in the studies of spatial distribution of soil moisture. Considering the spatial-temporal variation in upslope contributing area, topographic wetness indexes were divided into three types, e.g. static, quasi-dynamic and full dynamic. The effects of computing methods of topographic wetness index and resolution of DEMs as well as the universality of the index should be analyzed discreetly in application of topographic wetness index. At the same time, for the apparent differences between the current assumptions of topographic wetness index and actual water cycling process and runoff mechanism in arid/semi-arid region, the research approaches and the conceive of the application of topographic wetness index are proposed for the Losses Plateau to provide theoretical and practical foundation for the vegetation restoration and the conservation of soil and water in the region.
