Study on seasonal change of terrestrial net primary productivity(NPP) and its relationship with climate as well as, its variations in different land-use types is to help understand the responses of Chinese terrestrial ecosystem to global climate change and is important to carbon cycle research. In this study, time series dataset of Chinese terrestrial NPP from GLO-PEM model and corresponding information on climate and land use were used to explore the seasonal trends of terrestrial NPP in China from 1981 to 2000. As the result, seasonal NPP in China showed a significant increase for all four seasons (spring, summer, autumn and winter) during the past 20 years. The spring NPP indicated the largest increase rate, while the summer NPP was with the largest increase in magnitude. Seasonal NPP dynamics were different in different land-use types. Croplands had the largest NPP increase and increase rate in spring, summer and autumn, and woodland had the largest NPP increase in winter, while water had the largest NPP increase rate in winter. The regions with the largest increase in summer NPP occurred in most parts of eastern China, eastern Inner-Mongolia, Sichuan Basin, eastern Guizhou, southern Xizang and western Xinjiang, while the areas with the largest decrease in summer NPP appeared mainly in Hulun Buir Plateau, Ordos Plateau, Loess Plateau, eastern Qinghai-Tibet Plateau and northwestern Xinjiang.
The grassland pasturing area is a special region for agricultural production in China, and geographical position and natural conditions endow it with unique resources advantages. However, increasingly severe desertification of the grassland in the past decades caused eco-environment deterioration in this area and held up its socio-economic development. Economy globalization and prominent population-land conflicts in the new century promote us to adjust thinking model, convert institutions and explore approaches to a harmonious society coordinating nature and economy development. Based on analysis of function, situation and problem of the area, we proposed that livestock agriculture and rural development in the area should rely on the natural, manpower and cultural resource advantages and should be grounded on governmental services and supports, such as market-fostering, laws and regulations, science and technology, education and training, and fundamental establishments. The development emphases should be laid on green and natural livestock agriculture, and grassland rural tourism, in order to drive headstream and downstream industry development as well as construction of cities and towns, and therefore to help increase the livestock farmers’ income and promote livestock agriculture and rural development.
With the research on global change deepening, hydrological effects of Land-use and Land-cover change (LUCC) are becoming the focus of attention. Based on the progress in the study on hydrological effects of watershed land use and land cover change, some issues are summarized and discussed. Spatially distributed or semi-distributed hydrological models have important applications in the interpretation and prediction of the effects of land use change. Considering the spatial variation of precipitation and land surface characteristics, the precondition of distributed hydrological model is to partition a watershed into many non-nesting units. There are four methods to delineate watershed units: partitioning watershed by precipitation gages, partitioning watershed into rectangle grids, partitioning a watershed into ‘homogeneous’ units known as hydrologic response units, HRU, by physical characteristics, and partitioning watershed into sub-watershed by divides. Sub-watersheds and hydrological response units, HRU, are preferred units in distributed hydrological model. The land use and land cover classification system based on hydrological response is established by means of adjusting and merging existing classification. There are 9 level-Ⅰcategories and 21 level-II categories in the land use and land cover classification system. Level-Ⅰcategories include arable land, grass land, forest land, orchard, shrub, water, built-up land, barren land and wetland .The methods of setting up land use and land cover change scenarios include paired contrast, historical speculation, modeling forecast, extreme land use and land use spatial allocation, etc.
The landscape ecology pattern and the land use and cover change in the center of Gansu province were investigated through land use/cover classification of two sets of TM/ETM images acquired on July 31, 1996 and May 23, 2000. Through calculating to get the indexes of landscape ecology to judge the region's ecology pattern, analyzed the region's land use/cover change in the time-spatial course, it is important to research the relation between the human and the land for the north-west region in China which the cities and towns is dense. The research results are as follows: lower and middling cover rate grasslands constitute the substrate in Lanzhou Metropolitan Coordinating Region. The valleys and transport channels constitute the region's substance and energy corridors. The research region belongs to districts of human impact intensified. The nature surroundings is the form basic in ecology pattern, the water is the most important factor to change the region's appearances. The relation between the land and the water in the region dominate the change direction in Lanzhou Metropolitan Coordinating Region. In the 19 administration regions, Lanzhou and Linxia city have changed distinctly in the process of Great Western Region Development. From 1986 to 2000, the land's expanding is the main factor in the region's land use, the agriculture structure adjustment changes the landscape patterns.
The research of land use is significant to global environmental change and sustainable development. The environmental effect of land use change is profound to water cycle, environment quality, biodiversity, productivity and response capacity of terrestrial ecosystem. The factor of nature and socity effects the spatial feature of land use. Based on the technology of GIS,the article studies several factors synthetically and unifies different units of social data and natural data. After analysis of the spatial feature under the different physical ecoregion in the middle of Inner Mongolia, it is shown that the constraint to the spatial feature of land use is different under different physical ecoregions. The pattern of quantity and space is more different under different physical ecoregions.
Urban land consolidation is an important content of land consolidation. It is the effective measures to make rational, highly effective and intensive use of urban land resources. Its substance is to re-arrange rationally urban land utilization, to make the method, structure and relationship of urban land utilization fit in with the target of economic social development, to increase utilization ratio and productivity ratio of urban land, and to improve urban ecological environment. It plays a big role in disposing rationally urban land resources and increasing profit of land. Based on the intensive analysis of urban land consolidation, theoretical basis of urban land consolidation is put forward and potentiality and benefit of it is analyzed in the article. And in view of existing situation of urban land consolidation, program and applied model of urban land consolidation are put forward. The research is of great importance to enrich urban land consolidation theory, standardize and guide urban land consolidation practice.
It is very significant of land use degree evaluation to instruct land resource use. In this paper, integrated evaluation on land use degree in county regional scale was made by using factor analysis. By taking Quzhou County as an example, the authors studied the spatial-temporal variance on land use degree in 1985, 1995 and 2000. The result of research indicated: in the period of fifteen years from 1985 to 2000, the degree of land use of ten towns in Quzhou County was greatly increased. Among them, Huaiqiao Town was the most distinct, then Liyue Town, while Henatuan Town was the least. In addition, the degree of land use during this period had distinct spatial character. For example, the degree of land use in the east-middle and west was greater than that in the south and south-east of Quzhou County. At last, considering the trait of corresponding region, the authors analyzed the driving force of degree of land use from five aspects of nature, society, economy, location and technology. It indicated that nature factor was the basic driving forces, and the society, economy and technical factors were the important external driving forces. They offered important instructions to regulate land use in Quzhou County.
Accessibility denotes the ease with which activities may be reached from a given location using a particular transportation system. Accessibility reflects the opportunities and potentialities of a particular region to exchange with other regions. There is a number of accessibility measures, some accessibility indicators are generalized and compared in this paper: time of access to city centre, mean travel costs, opportunity accessibility, economic or population potential. Also, the progress of accessibility measures is reviewed. Accessibility indicators is applied both on regional and metropolitan dimension, such as the regional development, the impact of new infrastructure, the urban land use, the providing of social facilities, the urban social problems, and so on. Relative to the overseas there is rarely research on accessibility in our country. Therefore, some problems are put up in the end and accessibility research needs to be improved.
Spatial planning is an essential tool for sustainable development, and will evolve as the social reality changes. After 1990s, rapid social and economic developments have made the world more complex and uncertain, and thus resulted in the evolvement of spatial planning. Criticism on rational planning and traditional spatial planning, advocacy of sustainable development strategy, and institutional reforms in economic, social and environmental management make people realize that spatial planning should be a strategic and holistic tool for space governance and sustainable development, rather than a departmental one for land use management; should focus on the building of consensus among different stakeholders, rather than analyzing the feasibility and seqence of space development; and should aim at development rather than economic growth. New trends of spatial planning in developed countries have been emerging since 1990s: a) redistributing powers and functions of spatial planning according to governance theory; b) inclusive participating in the whole process of spatial planning formation and implementation; c) stressing cooperation of departmental framework and integration of different scalar spatial planning resources and tools; d) emphasizing on integrating environmental concerns into spatial planning; and e) formulating more flexible spatial plans and bringing more flexibility to implementations of them. The inspirations to spatial planning practice in China are given as follows: a) harmonizing strategic frameworks and action schemes; b) formulating participation mechanisms relevant to China; c) paying great attention to flexibility of plans as well as to their binding characteristics; d) intensifying spatial planning in regional level; and e) highlighting the public management function of spatial planning, and integrating it with market instruments.
The Yellow River is the second largest river in China and the most complex and refractory river in the world, which has prominent characteristics different from other great rivers. The main sticking point of Yellow River is the bedload, where the amount of water is less than that of bedload. The grievous water and soil erosion of Loess Plateau conduces to the lower reaches of Yellow River deposit and makes the riverbed higher and higher in thousands of years. All these make the Yellow River become a famous hanging river. Virtual Geographic Environments (VGE) includes the mapping of human society environment and natural environment in the computerized three-dimension space, which is developed rapidly following the information technology advancement in recent 20 years. “Prototype Yellow River”, “Model Yellow River” and “Digital Yellow River” are propounded based on the development of geographic information system, 3D visualization technology, modern remote sensing and VGE technology. The research significance and research methods have been summarized in this paper. In the mean time, the paper has discussed the key technology problems of “Digital Yellow River” research, which includes the computer expression, the behavior depict and more factors influencing the Yellow River in natural environments and human society environments. A crucial portion, “digital channel model”, is exampled here to picture the “digital drainage basin model”, “digital reservoir model”, “digital bayou model” in VGE.
Human activity has great effect on runoff producing and conflux for basins and can not be neglected, especially for the day-scale hydrology modeling. Because of the special human activity on the Loess Plateau, the Yellow River's runoff has been decreasing from 1960’s. Because of the complex land surface condition, the relationship of rain-off and runoff is very anomaly. Runoff is hard to be modeled by uniform experience formula. And what’s more, when the land surface condition changes, the experience formula loses its validity. Based on distributed hydrologic model, a grid-based lag-and-storage method, with consideration of the effect of human activity, is in detail shown, taking Chabagou (a typical watershed on the loess plateau) as an example. The digital terrain parameters are extracted from DEM(digital elevation model) with resolution of 950m×950m. The location of dams and reservoirs et al are distributed on the grids with their real location on the watershed in mind. The model also uses the mix-runoff-producing method, which considers the variation of runoff-producing area. The modeling results show the feasibility of this method. Model using the gird-based lag-and-storage method can consider the land change on grid-scale and reflect the condition of every periods, so it would make reasonable response to rain-off. With the effect of human activity on runoff brought into the distributed hydrologic model, the nature law of watershed and the effect of human activity on runoff can be deeply understood.
Polycyclic aromatic hydrocarbons (PAHs) are some of persistent organic pollutants (POPs), which are widely existed in our environment. PAHs can result in some latent danger to our human being, such as cancer. More and more studies about PAHs are performed to discuss the chemical and physical characteristics, the spatial and temporal characteristics, the source and final of PAHs. Principal component analysis (PCA) is one method which can efficiently extract the main information from various data. In the environmental research, PCA is often used to extract character, concentrate information and reduce dimension. With one or some integrated index of PCA, the environmental samples can be classified and identified, and the source of pollution can be estimated. The method of PCA is also used in the research of PAHs pollution. The Spatial principal component analysis (SPCA), which is based on the theory of coregionalization, can enhance the understanding of the spatial characteristics of PAHs. In this study, 188 sampling sites in Taijin area were selected, and on each site, the top 10cm soil was collected for analysis. In the laboratory, the contents of 16 prior PAHs, as well as the soil properties, were determined for all the samples. Based on the multi-spatial structure analysis, the spatial PCA characteristics among 16 prior PAHs in topsoil in Tianjin area were studied. The pollution sources were also discussed. It is discovered in the result that the main polluting processes of PAHs in Tianjin area are petroleum source and combustion of fossil fuel. By the view of spatial scale, the influence range of petroleum source is less than 5km and the range of combustion source is from 5 to 10km. On the large scale, the principal origin of PAHs may be the regional deposit from atmosphere.
As the main parts of terrestrial carbon pool, soil carbon pools play an important role in global carbon balance. They are essential to understand the soil carbon cycling for the prediction of future atmospheric CO2 concentration and understanding the structure and function of soil ecosystem. Applications of remote sensing in the study of terrestrial carbon cycle open up an effective way for simulating terrestrial ecosystem process. Remote sensing of soil carbon storage is critical to understand climate change and terrestrial carbon cycle. Beginning with the Landsat-MSS data in early 1970s, spaceborne multispectral measurements from a variety of sensors have been extensively used for carrying out soil surveys. In the paper, combining many latest studies, we summarized the applications of remote sensing in soil carbon storage. First, the feasibility of using remotely sensed data to study soil carbon storage is discussed. The applications of remote sensing in estimating soil carbon storage, including remotely sensed aerial photograph, vegetation index and soil reflectance spectrum are reviewed next. Finally, the development tendency in soil carbon storage researches using remote sensing technology is specified concisely. With the link of carbon cycle model, remote sensing technique and GIS, simulating carbon cycle process in large scale will be the main research trend.
