There exists about 1.4～1.7GtC missing sink in the global carbon budgets. The missing sink might happen in terrestrial biosphere and coastal continental shelf. However, this guess is lack of support from scientific observation data and research methods. Progress in geo-information science is paving way for studying carbon cycle and its mechanisms of terrestrial ecosystems. To address the scientific issues such as temporal and spatial pattern of terrestrial ecosystem carbon sink, and driving mechanism and scenarios of carbon cycle, this paper proposes a method of geo-information science for studying carbon cycle of terrestrial ecosystems.Bottom-up approach and top-down approach are combined by means of scaling models. The bottom-up approach is based on observations of comprehensive network of carbon storage and carbon cycle process of terrestrial ecosystems, adaptive experiments of biological processes, and researches on carbon transportation processes of rivers. the top-down approach is based on detecting land cover change and retrieving ecological parameters by using satellite data. Retrieval models of carbon budgets are developed by means of the capacity of satellite remote sensing that can frequently supply surface information of geographical processes and ecological processes. On the basis of analyzing data-at-points collected by stations of Chinese Ecosystem Research Network, stations of Chinese Forest Ecosystem Research Network, and observation stations of HINAFLUX, combined with the retrieval models, a numerical simulation model of terrestrial ecosystem carbon cycle is constructed by means of surface theorem, grid generation method and grid computing technique. Pattern and process of carbon cycle are to be simulated; natural and human impacts on carbon cycle of terrestrial ecosystems are to be analyzed; and evolution trends of carbon cycle process of terrestrial ecosystems are to be discussed under the condition of global climate change.
Based upon the review of the developed achievements and the facing problems, this paper deals with the difficulties and challenges met by geographic sciences in modern China. Some aspects related to the geography development in the 21st century's China are discussed and probed. Within more than 50 years since the foundation of P. R. China, China's geography has been greatly achieved in the fields of theoretical and application research, the utilization of technology, subject construction and education, basic research abilities and international cooperation. Accompanied with the development of China's geography, it is also meeting the unprecedented challenges due to the changing natural-social-economic environments, such as the rapid growing of global change sciences, the appearance and deepening of plenty of inter-sciences and branch sciences, the geographical specialty adjustment driven by market economic. At the same time, these challenges also give a great of opportunities for China's geographical development. By the analyses, the authors suggest that the present and future development and financial devotion should be put on these key aspects, such as regional studies and sustainable development, the inter-actions among the factors of earth surface system, man-land relations and the terrain system, regional response and adaptation under global changes, Syntheses of multi-disciplines, new techniques utilization and quantitation, in-situ observation and scale conversion, specialty adjusting and education reforming, research abilities etc. These efforts will greatly promote the China's geography development and realize the jumping from a big country to a powerful country on geographical sciences in China.
Science and technology innovations have played an important role in our society in the new century. In this paper, after a discussion of the concept of land science and technology innovation, the key tasks and principles of land science and technology innovation facing some significant problems in land use and land management in China are analyzed. The primary conclusion and suggestion are as follows:(1) The land science and technology innovative system is both an important portion of national science and technology innovative system in land resources exploitation and utilization and an essential precondition to deepen the research of land science, innovation of land management and advancement of land technology in China. (2) Based on the analysis of the connotation and essential theory of land science and technology innovative system, the framework of land science and technology innovative system including four aspects such as land science system, land institution system, land management system and institutional system of land science and technology and the concept of land science and technology innovative spatial domain, which was composed of four aspects such as knowledge, technology, management and institution, were put forward. (3) The operative model of land science and technology innovative system in China, which was selected, is the ones of science and technology marketification controlled by State and government, so it will be very important to construct the effective conduction mechanism of land science and technology innovative system among government, enterprises and institutions of scientific research. At the same time, to optimize land science system construction, promote innovation of land system, exert the main role of government and strengthen innovation of management of land use and enhance the auspice of information technology are important tasks to do in the future in order to construct land science and technology innovative system in China.
The study on the land use/cover change is one of the frontiers and the hot spots in the global change research. By using the Landsat TM and ETM data which were acquired in 1989～1990,1995～1996 and 1999～2000 respectively, we analyzed the spatial-temporal characteristics of land use/cover changes in the Jianghan Plain at time scales of 10 years and 5 years. The result shows that the spatial-temporal characteristics of land-use change varied with the change of scales during this period of time. During this period of time,the cultivated land area decreased by nearly 5×104ha2, of which 67.83% occurred in the previous 5 years between 1989-1990 and 1995-1996. The built-up land and water area expanded with an increase of 1.56×104ha2 and 3.54×104ha2 respectively, and the expansion at the latter 5 years between 1995-1996 and 1999-2000 was only about 1/2 of the increase amount during the previous 5 years. Large-scale reclamation that was a popular method to get arable land before the 1980s has been limited. There are significant shifts among cultivated land, water bodies and built-up land. From 1990-2000, 76.47% of the lost arable land was converted to water bodies and 22.36% to built-up land. 78.93% of the increased built-up land was gotten at the expense of cultivated land, while 12.93% and 7.04% at the expense of woodland and water bodies respectively. The rate of land-use change in every county and city is different. Wuhan and Xiantao have gotten the greatest value of the dynamic degree of land-use change in all the administrative districts due to the relatively developed industry and economies and fast urbanization, which means that the land-use in these cities changed quickly. The slowest changed areas were Jianli,Songzi and Tianmen. On the whole, the land use changes from 1990-2000 in the study area have been driven by urbanization and industrialization, infrastructure and agricultural intensification. The rapid growth of population and economies play an important role in the land use changes, and the advances in techniques also give rise to the changes obviously. To a great extent, the policy on land use has a definitively influence on the land use changes of different scales. In view of the results mentioned above, some strategies and policies should be reoriented to attenuate the conflicts among the protection of cultivated land and ecosystems and social-economic needs for expansion of built-up land.
As one of the most important study fields of global change, land use and land cover change has significant impacts on regional and global climate, soil characteristics, and function of terrestrial ecosystem. Most researchers, both in China and abroad, have given much more attentions to the study on land use types and the laws of regional land cover change with synthetic analysis of the factors that influence land use and land cover change. In recent years, some Chinese researchers have carried on studies in this field by stationary inspection methodology, e.g., Professor Fu Buojie and others studied the impacts of land use and land cover change on soil nutrients, regional hydrological condition in loess hilly areas and Zunhua low mountainous areas in Hebei province, Professor Shi Peijun and others studied the impacts of land use and land cover change on natural agricultural disasters in Inner Mongolia Autonomous Region on the basis of long period investigations and statistical materials. But few researchers studied the impact of land use and land cover change on soil erosion by stationary methodology, and few papers have been published in this area. This paper studied the impacts of land use and land cover change on soil erosion in Fujian mountainous areas on the basis of analysis on long period observational and experimental materials at Jianou Niukenglong Experimental Station and the Provincial Soil and Water Conservation Station, researched soil erosion mechanisms of mountain grassland ecosystem, and different soil erosion modulus under different land use and land cover types. The analytical results indicate that the coefficient of runoff has minus linear relation with grassland coverage, and the modulus of soil erosion has index relation with grassland coverage. This paper also studied the mechanisms and processes of land cover impacting runoff and soil erosion, i.e., land cover influences runoff and soil erosion through the following processes: 1) The grassland cover reduces the forces of rainfall that beats on earth surface, which will impact soil erosion on the surface of the earth, grassland cover has minus index relation with soil erosion modulus, and minus linear relation with coefficient of runoff. 2)The roots of vegetation strengthens the erosion resisting capacity of soils through interluding, twinning and fixing forces on soil particles, and increases the absorbing water capacity of soils . 3) The increase of soil organic material concentration makes the soil particles and structure more and more stable. This paper also points out that there are other mechanisms and processes that need to be further studied, e.g., the relation between land use/land cover and runoff coefficient, the variations of different vegetation's impacts on soil erosion,etc.
Vegetation and bare soil are the main land cover types in Karst and non-Karst area.Bare rock another land cover type only appearing in Karst area,is distributed extensively. There are a variety of methods to detect land cover in Karst area with remotely sensed imageries. But most ordinary remotely sensed approaches can't get the three attributes at the same time. In fact,they almost can do nothing in detecting the quantitative result of rock desertification. The linear spectral unmixing approach,based on the linear mixture model can estimate vegetation cover, bare soil and bare rock abundance at the sub-pixel scale. It's fit for studying land cover in Karst area because of the obtained quantitative unmixing results of vegetation cover, bare soil, bare rock and other types. In the case study of this paper, four endmembers were identified from two TM images of six bands taken on 17th February 1987 and 27th November 1999 respectively. They represent four land cover types: vegetation, bare soil, rock and shadow. The abundant distribution and RMS (Root Mean Square) distribution of the four land types were derived by linear spectral unmixing. The land cover changes could be learned from the multi-time comparison. During the period from 1987 to 1999, the proportion of bare soil reduced evidently due to the increase of vegetation cover and the improved cultivation management. While, the proportion of rocky desertification enhanced owing to the little amount of soil in some place. Bare soil reduced and rock increased mostly in rainfed cropland, grassland and economic woodland. Over-cultivating and overgrazing are still the main driving forces of rocky desertification in Karst area. So people still need to pay attention to water and water soil conservation in economic woodland because economic woodland mainly came from "dry land reforest". The linear spectral unmixing approach still needs to be improved, though it has been proved fitting for dealing with mixture pixel and detecting quantitative results of land cover by the case study and many other literature. If endmembers need to be identified from image, it's hard to detect those elements without extraordinary characters presenting in images of different bands. For example, urban region is just such an element difficult to detect. So the approach is not the most suitable method for urban region or rapid urbanized area. And the impact of shadow is still a problem, just as in other methods.
Studies are preliminarily made on spatial structure of point-axis systems in the paper, which reveal that a point-axis system as a unique giant component (UGC) is in fact a fractal system. The theoretical starting point of the point-axis model in the aspect of spatial patterns is the triangular lattice that is the same as that of central place theory, but the configuration of developed point-axis systems is of irregularity based on random process to a certain extent. On the other hand, the point-axis model is as advanced as a new optimization design which signifies that an ideal point-axis system must have some kinds of optimum structure, especially the spatial structure with some kinds of ‘order’, the order may be what is called self-similarity that is always emerging ‘at the edge of chaos’ which is mathematically related to the concept of ‘self-organized criticality’. In reality a point-axis system usually appears concretely as an urban system depending on one or two ‘axes’such as seaboard, great rivers, railways and so on, and systems of cities and towns proved to be fractal systems. This implies that point-axis systems may have fractal structure. From the viewpoint of a general dynamic system that can be used to describe point-axis systems, an allometric growth equation is deduced out as x i ∝ x jα , from which, the relationship between measures and yardsticks of point-axis systems, M ( r )∝ r D , can be derived by means of the theorem of ergodicity. According to the measure-scale relationship, two kinds of fractal dimensions can be given to characterize point-axis systems. One is the point-distribution dimension that is defined by the formula N ( r )∝ r D , where r is a yardstick, N ( r ) is corresponding number of points in a point-axis system and D is fractal dimension. The other is the line-distribution dimension that can be defined by the formula L ( r )∝ r D , where L ( r ) is length of communication lines joining points together corresponding the yardstick r . In addition, the line-distribution dimension can also be defined by number of branches of the network of communication lines linking one point with another. The four growth stages of point-axis systems are reinterpreted using ideas from fractals, and theoretical results are applied to the system of cities and towns in North Henan including three urban subsystems. It is demonstrated and illustrated that the urban system as a UGC has fractal dimensionality, which only goes to prove that the hypothesis of self-similar point-axis system is correct empirically. A least squares computation of the quantities gives the values of the fractal dimension D =2.387 with a determination coefficient of 0.996 for Zhengzhou subsystem, D =1.747 with a determination coefficient of 0.997 for Kaifeng subsystem, and D =1.659 with a determination coefficient of 0.997 for Luoyang subsystem. As for the system on the whole, D =1.715 with a goodness of fit of 0.999. The results bring to light a great deal of temporal-spatial information on the development and evolution patterns of the point-axis system in Central Plains.
The Western Long Hai-Lan Xin Economic Zone is an important part of the "two zones and one district" in the great strategic development of western China. The authors analyze the overall characteristics of the node cities along the Western Long Hai-Lan Xin Economic Zone, and considers that though the cities are distributed concentratively and the urbanization level is higher than that of the western region and the whole country, yet the metropolises are far away from each other and no big cities lying between them. So three weak zones come into being along the Western Long Hai-Lan Xin Economic Zone and the cities' spatial distribution of "point-axis" type will still exist. According to multi-hierarchical and multi-target comprehensive measurement model, all the cities' comprehensive competitiveness along the zone is evaluated. Xi'an,Lanzhou and Urumqi are considered as the first class node cities along the zone and Xianyang,Jiayuguan,Baoji,Jiuquan,Karamay,Hami,Shihezi,Korla,Tianshui and Kuytun are considered as the second class node cities along the zone. Based on this, the development orientation and the industrial division of the node cities along the Western Long Hai-Lan Xin Economic Zone are put forward. Xi'an-Xianyang metropolitan district is considered as the first class key node city in western China and the east of the Western Long Hai-Lan Xin Economic Zone, which should be constructed as the core of the Guanzhong Economic District and Guanzhong New High-tech Industrial Development Zone. Lanzhou-Baiyin metropolitan district is considered as the first class subordinate node city in western China and the first class key node city in the middle section of the Western Long Hai-Lan Xin Economic Zone, which should be constructed as the core of the multi-nationality economic zone in the upper reaches of the Yellow River. Urumqi-Changji-Miquan-Fukang metropolitan district is considered as the second class key node city in western China and the first class key node city in the western section of the Western Long Hai-Lan Xin Economic Zone, which should be constructed as the core of the northern Tianshan Mountain economic zone. Baoji,Tianshui,Jiuquan-Jiayuguan-Yumen,Hami,Kuytun-Dushanzi-Usu are considered as the second class subordinate node cities in western China and the first class subordinate node cities in the Western Long Hai-Lan Xin Economic Zone, which should be constructed as the five “piers” in the weak zones of the continental bridge to support the whole economic zone.
Based on data of the fifth census of Beijing in 2000 and of the second census in 1982, methods of Factor Analysis and Cluster Analysis are used to analyze the social spatial structure of Beijing Metropolitan Area and its evolution. In 1982, the main components of social space in Beijing Metropolitan Area include: population of workers and cadres, agricultural population, population of intellectuals, and population of the mining workers; and four types of social areas are identified: (1) high population density, worker areas, (2) intellectual areas, (3) government cadre areas, and (4) mining worker areas. The authors also find that, in 2000, the main components of social space in Beijing Metropolitan Area include the following: population of ordinary workers, agricultural population, temporary population, population of intellectuals and national minorities, and housing condition; and six types of social areas are identified: (1) high density and crowded areas, (2) intellectual and national minority areas, (3) areas of low population density and large living space, (4) temporary population areas, (5) areas of urban population in the outer suburb, and (6) agricultural areas. The authors also extract the model of the social spatial structure of Beijing Metropolitan Area in 1982 and 2000, respectively. In a word, the main components, types and models of social areas, and the forming mechanisms of the social spatial structure of Beijing Metropolitan Area in 2000 changed much, comparing with those in 1982. The model of the social spatial structure of Beijing Metropolitan Area in 1982 is very simple, which shows typical homogeneity as a whole, while the social spatial structure in 2000, which mainly exhibits a zonal pattern, accompanying with a multi-nuclear and a sectoral one, tends to be complex, and shows typical heterogeneity. Finally, the authors put forward a model of interlaced mechanism of the evolution of social spatial structure at the macroscopical, medium and microcosmic levels, and think that it is this kind of mechanism that propelled the social spatial structure of Beijing Metropolitan Area to change from one in the planned economy to one in the market transition.
This paper explores the community sustainable development indicator system which is established by means of group-based public participation under the guidence of professional personnel but conforms to the situation in China.Chongming County in Shanghai was taken as a case.An initial "long list" of 86 indicators was identified based on previous indicator systems developed in China. This "long list" was reduced via consultations with local scientists and government official from Shanghai City and Chongming County.This "shortened list" of 17 indicators waiting for further community consultation involves 149 local authority officers, teachers, students (aged 12-14), farmers and workers.The outcomes showed obvious difference in the understanding of sustainable development among various sectors. By integrating data from these sectors it was possible to identify a system involving 4 cores and 7 additional indicators as the criteria to steer local sustainability. Compared with other local indicator systems in Europe and the UK, local people in Chongming showed the same interest concerning on environment but with a stronger desire for economic development. By using the sustainable indicators, the sustainability of community development in Chongming County was appraised during 1991-2000. And the results showed that in community level, Chongming had a general sustainable trend in that period. This study, involving the residents of Chongming County, has special significance in discussing development issues because it is a region with good environmental quality and weak economy and as such is typical in many rural areas of China.
Urban-rural development has always been illustrated as the interaction relationship, represented by the free flow of population, commodities, capital and information between urban and rural areas, which, in some sense, guarantee the effective and efficient uses of resources in urban and rural areas. The urban-rural interaction should not be understood as a process of urbanization for rural areas or that of counter-urbanization for metropolis, rather, it is as a process of joint development, represented by the exchange of materials and energy, for the urban and rural areas. The joint development of urban and rural areas depends on the increase of capital investment for infrastructures mainly covering transportation, telecommunication, education, medical facilities and welfare. Since the industrial reformation, convenient telecommunication, transportation has directly accelerated the intercommunications; indirectly boosted the flow of commodities between urban and rural areas, which has significantly affected the urban-rural interaction. Improved education, medical facilities and society welfare infrastructure serving as the foundation for the joint development of urban and rural areas, together with the equal rights and change for villagers or citizens in education and society welfares, guarantees the urban-rural interaction and integration. This paper gives out a comparatively precise definition of urban-rural interaction. Based on the anterior models,the authors construct a new urban-rural interaction model. To be validated, the model is applied in Shandong province, and its result is acceptable. It was made clear that the concerted development of urban and rural areas is a process of regional social-economic development and it's the re-organization of regional urban and rural factors. Essentially speaking, urban-rural interaction is the degree of urban-rural inter-relationship. The construction of urban-rural interaction model will be helpful for the spatial description of urban and rural relationship, the formulation of regional plan and the development of regional urbanization.
Development of small towns is the key to China’s urbanization and the increase of farmers’ income. During the past several years the developments of small towns have made great progress in China and lots of researches have quickened their pace of research on the development of small towns.But we should acknowledge that in the process of small town development lots of problems have appeared and needed to be solved successfully for sustainable development, such as how to get harmonious economic and environmental development, how to balance the disparity between rich and poor, etc. So the researchers should pay more attention to the development of small towns and put forward more feasible suggestions to facilitate the development. This paper tries to analyze the development of small towns by using theories and measures different from conventional by taking Huaiyuan County, Anhui Province as an example. Firstly it acknowledges the Huaiyuan County has made rapid progress in small town development in the past several years. Then it points out the problems related to the development, including the unreasonable planning and allocation, insufficiency of construction fund, the lag of basic infrastructure and lack of talented personnel and so on. In order to get more legible judgment the authors analyze the developing level of Huaiyuan County by using quantitative method. The author takes the density of roads in towns, the level of labor forces’ income and other factors as the evaluating index. The result indicates that Huaiyuan County is undergoing the transition period from the prophase to the metaphase of the small town development. Considering the situation and problems in Huaiyuan's development, the author identifies several strategies to ameliorate its development. Firstly, to pay more attention to the construction of epicenter towns. Taking the quantity of exporting commodities, the increase of investment from outside and other ten factors as index, the authors filtrate out Chenji, Zhutuan, Dongmiao, Xiaoyi, Boji and Gucheng towns as the centric towns. All the towns have great potential and influence to the surrounding towns. The local government should pay more attention and provide funds to these towns to make them develop more efficiently and speedy in the future. Furthermore, the authors put forward some suggestions to accelerate the development of Huaiyuan County. They are: to collect funds from multiple channels; to protect the environment and pay more attention to the sustainable development; and to consummate the market system.
A series of advanced instruments were applied to get the field data of bed sediments, riverbed shapes and relevant dynamic factors of the 150-km-long reach from Jiangyin to the Hengsha Island in March 2002. The fine sand predominates the bed sediments in terms of granularity of bed sediment on the surface from Jiangyin to the Hengsha Island, the granularity becomes finer and finer from land to ocean. From the cumulated distribution of the bed sediments in the Changjiang estuary, we found that the rolling grains were absent in dry season and the saltation grains jumped twice.The first group was in majority and well-sorted because of the ebb tide, and the second group was in minority and bad-sorted because of the flood tide. The suspended sediment was also in minority and bad-sorted. There was stronger flow and the longer duration during the ebb tide in dry season and the grains could saltate fully and continuously. The form of sandwave was related to the interaction of tidal current and sediment, the sandwaves grew well in the reach from Jiangyin to north of Zhangjiagang port, the lower reach of Nantong and south channel of the Changjiang estuary and so on in dry season, and which became the major type of bed sediment transporting in estuary. In the Hengsha Island, the bed sediments were composed of fine sands and the sandwaves mostly dispersed to the upper reach, but the bed sediments were composed of clayey silt and sandwaves couldn't form in the following north and south passages, which was accordant with the theory of dune formation on the bed. The direction of sandwave was normally vertical to the flow direction, the longitudinal form of sandwave might be symmetry or asymmetry, and the latter had the sharp slope in the lower reach and the slow slope in the upper reach. Near the tidal interface, the tidal current was greater during the ebb tide than that during the flood tide and the forms of sandwaves of the estuary were similar to those of rivers. But in the lower reach of the estuary, the quantities of transportation to the upper and lower reaches were both large, the sandwaves had symmetry forms and round crests. In conclusion, the sandwaves had more complicated influencing factors in the Changjiang estuary than those in the river, and which became the major form of bedload transportion in the Changjiang estuary.
Spartina alterniflora Loisel is introduced from the USA to China and it is a new adventitious species of plant to Chinese environment, which can occupy vast areas between mean sea level and mean high level with many special biological characteristics, such as high plant, great community coverage and robust root. By the influence of the interaction between the tidal current and Spartina alterniflora Loisel, the particular landform configuration is forming. There has formed many Spartina alterniflora salt marsh on Jiangsu coast since the planting of Spartina alterniflora Loisel in 1982, especially in the tidal flat outside of Badou Reclaim region, Dongtai County, which has developed a mature salt marsh with the mature and integrated channel system. By field investigations and interpretation of remote sensing imageries of Badou Reclaimed region, many particular channel characters in the salt marsh of Spartina alterniflora Loisel are identified: (1) high density channels, which can reach 50km/km 2; (2) small width-depth ratio, which is often smaller than 8; (3) remarkable creek bank; and (4) obvious gulch outside edge of the salt marsh. Combining the survey result of tidal current in Spartina alterniflora Loisel salt marsh, reasons accountable for the formation of the particular channel characters mentioned above in the salt marsh of Spartina alterniflora Loisel are analysed.One of the important reasons is attributed to the substantial soil and ebb-dominance current resulting from the special biological characteristics, such as high plant, great community coverage, robust root in the salt marsh of Spartina alterniflora Loisel.etc.
