This article focuses on the analysis of the relationship between Ommastrephes bartramifishing ground and marine environmental factors. Based on daily catch data of Ommastrephes bartrami during 1995 to 2000 by China fishing boats and SST isoline chart covering 1995 to 2000 issued every 3 days by Japan Fisher Information Service Center. ArcGIS was used to store, manage and analyze the data. All the catch data were processed and spatialized to display their spatial distribution. The fishing grounds were identified interactively from the catch data maps. Matching Ommastrephes bartrami fishing ground with SST isoline map revealed that the relationship between them could be divided into 3 main patterns and 16 subclasses. The fishing ground in patternⅠis distributed on the tongue of Kuroshio and Oyashio branches, hence called as tongue type. PatternⅠcan be further classified into 5 subclasses,i.e., warm tongue type, cold tongue type, warm tongue + cold tongue type, warm tongue + cold tongue+ warm tongue type, and warm tongue + cold tongue+ warm tongue + cold tongue type. PatternⅡis located on the branch of Kuroshio or Oyashio, so called as branch type. In patternⅡ, five subclasses can be defined,i.e., warm branch type, warm branch + cold tongue type, warm branch + cold tongue+ warm branch type, cold tongue+ warm branch + cold tongue type, and warm tongue+ cold branch. Pattern Ⅲ is distributed on eddy caused by Kuroshio branch encountering Oyashio branch, also named as eddy type. Pattern Ⅲ can be ulteriorly classified as warm eddy type, warm eddy + cold tongue + warm eddy type, warm eddy + cold tongue (branch) + warm tongue type, warm eddy + cold tongue type,warm eddy + cold tongue + warm branch + cold tongue + warm branch type,and warm eddy + cold tongue + warm branch type. Statistical analyses of 239 samples indicate that pattern III has the highest occurrence frequency and highest catch, and pattern II has the lowest occurrence and lowest production. Subclass 35 has the highest occurrence frequency, and subclass 14 has the highest catch. The average CPUE of pattern Ⅲ is the highest, patternⅠthe lowest.Subclass 31 has the highest CPUE value. In 1995 and 1996, patternsⅡ and Ⅲ dominate. In 1997, pattern Ⅲ dominates. From 1998 to 2000, patternⅠis in domination. In August, patternⅡis in domination. In September, patternⅠdominates. In October, patternsⅠand Ⅲ are in domination. In November, patternⅢ dominates. The SST in patternⅠ usually falls between 15℃and 21℃,patternⅡ,17～24℃, and patternⅢ,10～18℃. The temperature grade in the patternⅠchanges slowly, while pattern Ⅲ, has a big grade change. PatternⅠis mainly located on Kurushio branches 3 and 4, patternⅡon Kurushio branches 2 and 3,and pattern Ⅲ mainly located on Kurushio branches 1 and 2.
Man-land relationship has become one of the most sensitive problems in agricultural development, and study on land productivity and population supporting capacity opens up an effective way for quantifying regional man-land relationship. In this paper, we discuss present and future environmental capacity status and variation trend in Xiangjiaba reservoir area on village basis with land potential productivity degression method and bearing capacity evaluating model, regarding cultivated land as study object. According to geographic status, land bearing capacity evaluating region is confirmed, covering 23 832.91 ha and involving 21 towns or 174 villages. Coupling analysis of land use and physiognomic characters in the study is conducted with GIS and RS, and then the integrated spatial-attribute database is established. Supported by perennial sun light and temperature data, soil physio-chemical attributes on village scale, cultivated land spatial distribution and main crops (including paddy, wheat and corn) growing period in the reservoir area, the appraising index system of land productivity is set up, synthetical crop productivity of cultivated land on village scale is evaluated with land potential productivity degression model. Taking into consideration comparatively well-off standard of living for local people,including per capita grain and farmland availability,as capacity index of grain to support population, we establish land bearing capacity model based on reservoir construction planning and spatial pattern of land productivity to forecast per village farmland resource potential carrying capacity at present and in the near future(2012), and put forward environmental capacity of the whole study area coincided with local agricultural development. The result shows that multiple-cropping practice compared with other farming methods can gain even greater population supporting capacity; it is more reasonable to study land population supporting capacity based on output of grain rather than on farmland area, however, they should be combined with each other in practice; because the impact of fully implementation of land conversion from farmland to forest and grassland on land carrying capacity is greater than changes of unit area output of grain, hence under the same farming practices, the future land population supporting capacity does not increase but is smaller than the present environmental capacity, presenting an overall decreasing trend inevitably; environmental capacity of reservoir area is inclining to saturation, man-land conflict stands out;and population supporting capacity of cultivated land should be increased to some degree by means of increasing output of grain through expanding sown area of paddy and ameliorating breed.
In the spring of 2001, several duststorm events occurred in northern China which seriously threatened production and people’s life and caused troubles to air transportations in South Korea and Japan. The duststorm weather was a strong wind erosion process in terms of duststorm source, transportation and precipitation. The mechanism of duststorm process is the cornerstone for duststorm forecast model. Estphal(1988), Joussaume(1990)and Gillette (1989) published a wind erosion based model;Shao (1997)and Lu (2001) took five different factors into account developing an integrated model including climate condition, land cover/change, wind erosion, transportation as well as precipitation factors. The duststorm also had very close relation with surface physical parameters such as soil moisture, temperature roughness and radiation which were the very important parameters for land and air energy exchange. They also played important roles in duststorm process. Brest(1987),Tian(1990) and Zu Hanwen(1993) pubilshed their retrieving models for albedo and temperature using AVHRR data. By using remote sensing data to monitor dust clouds change, transportation road and to retrieve surface temperature, soil moisture, roughness in compensation to the shortcomings of sparsely located observation stations and discontinues data collection. The data retrieved from satellite has become very important data source for duststorm monitoring. Chinese and Japanese-initiated a joint project in 2000 to set up ground observation stations along dust source areas such as transportation roads,precipitation areas for collecting TSP (dry dust precipitation) and utilizing AVHRR data to retrieve albedo(surface energy).And then data were selected from retrieved albedo temporal imageries to make curves and comparison was made between albedo curves and TSP curves. The result showed that there were good correlation betweens the two kinds of curves. It was proved that the LST/Albedo could be one of the physical parameters for predicting duststorm in future monitoring systems.
The shrinkage of China’s cultivated land is a world-wide concern, which is believed to arise from the increase of land used for construction purpose. In order to obtain a timely understanding of the land expansion for urban construction and the decrease of cultivated l and in China, remote sensing is being employed to monitor the expansion situation of land used for construction in the cities having above 500,000 non-agricultural population during various periods, and the accuracy estimation of the monitoring results constitutes an improtant aspect in this task. Up to now, many estimation indexes have been proposed which serve as a favorable base for future research. However, there still exist some drawbacks to be solved.In the article, a method of stratified random sampling is presented to obtain the accuracy analysis of remote sensing monitoring.The accuracy assessment is comprised of technological and regional assessment. It involves the assessment system of accuracy monitoring, the capacity determination of the stratified random sampling method, the procedure for sampling and evaluation, and the statistic analysis and result expression of the random survey. In addition, to verify the feasibility and suitability of this kind of method,the practice of the above system, based on data for Beijing and Chongqing in 2001 collected by remote sensing and fieldwork, is performed.Our work successfully applied the sampling theory to geoscienlific survey, which is of great theoretical and practical significance.
In North China, an unprecedented heavy sand-stormy weather with high frequency took place in the spring of 2000. Dramatically, it brought direct damage to the region around Beijing, which has aroused even more extensive concern of personages of various circles. Sand-stormy weather research has been widely carried out since then. Therefore, in this paper, based on the climate data from 1951 to 1996 and eco-environmental data, employing climate statistics methods and geographic information sciences(GIS), the author took the land around Beijing as a case to study its characters of the temporal and spatial pattern in the past fifty years. The annual sand-dust storms day was selected as the major index to divide the region into four districts, then the environmental background was analyzed based on data extracted from the remote sensing images of the 1990s. This research demonstrated the spatial distribution and temporal change of sand-dust storms in this area, leading to the following conclusions: diurnally, afternoon(from 12 p.m.to 18 p.m.)was the period of sand-dust storms;seasonally spring and late summer were the sand-dust storms most easily happening periods;interannually,the 1950s to the 1960s witnessed the high value period of the sand-dust storms while the number of the sand-dust storm days tended to reduce in the 1970s and the 1980s but increased in the 1990s again. We also found that the most easily happening period corresponded to the dry and cold climate. As for the spatial distribution, the high value regions were located in the marginal areas of Otindag Sandy Land and Hobq Sandy Land, especially in Siziwangqi-Zhurihe, Erenhot-Damaoqi, Daladqi-Junggarqi-Uradqi.
In this paper mean locations of borderline for wet and dry climate zone in northern China over the past 40 years from 1961 to 2000 and their decadal changes were studied. Over 40 years in northern China, boundary line of semiarid and subhumid zones where W (humid index) is 0.5 moved gradually toward the east.In the eastern part east of 100E, especially in the 1990s it moved toward the east and the south compared with that in the 1960s,which resulted in the enlargement of semiarid area and the shrinkege of subhumid area,and the climate tended to become dried;and in the western part west of 100E,the extremely dry area was dwindled and the climate tended to become wetted evidently.By combining the temperature with W we can call the eastern part east of 100E where the North China Plain and the Loess Plateau are located a sustaining dry and warm type; the northwestern part west of 100E can be called transitional zone from dry and-warm type into humid and warm one, of them the Hexi corridor and East Xinjiang Basin started to change in the early 1970s while the mountain region, oasis, and desert in northern Xinjiang started to change around the mid 1980s.The deterring factor for changes of borderline in the wet and dry climate zone is the variation rate of precipitation vs. potential evaporation. Over the past 40 years both precipitation and potential evaporation tended to decrease in the eastern part east of 100E,but the decreasing rate of precipitation is higher than that of potential evaporation. We think that the cause for wetting in the western part of 100E was that the potential evaporation has been decreasing with the increase of precipitation, moreover the absolute value for decreasing rate of potential evaporation is higher than that of increasing rate of precipitation.
Climate is a basic factor that controls the directions and intensities of soil-forming process, which affects the levels of weathering, the composition and decomposition of soil organic matter (SOM), the migration of soil materials and changes of their forms,and soil geographic distribution around the world and so on. Although many scholars have done a lot of work about the influence of precipitation on components and properties of regional soils, yet the main concern of their work is average precipitation or the moist indexes influencing soil individual component and properties, and the influence of rainstorm on components and properties of regional soils has not been discussed thoroughly yet. Taking the central area of rainstorm in Biyang county as an example, the influence of rainstorm on soil components and properties was discussed on the basis of field works and laboratory experiments in this paper. In comparison with the soils of other areas that are less affected by rainstorm, the soils in the central area of rainstorm in Biyang have the following characteristics: (1) Eluviation ratios of base (β) are less than 1.00, silica-sesquioxide ratios (Saf) are less than 7.00, and the soil reaction is feeble acid in the central area of rainstorm, which indicate that the processes of desilicification and allitization in soils are obvious, and that the weathering of soil is stronger. (2) Soil thickness is thinner.The amount of horizons in each soil is less, no more than two, and the patterns of soils profiles are simple. Content of gravels (>1 mm) is higher, and that of physical clay (<0.01mm) is lower. The texture of soil belongs to sandy type, most of them have some gravel. (3) Iron-manganese nodules that could be seen by unaided eye could not be found in all soils located, which indicates that soil-forming conditions are unstable in this area. (4) The content of soil organic matter (SOM) and alkali-hydrolyzable nitrogen is higher, and readily available potassium is lower in the central area of rainstorm. Because much soil organic matter (SOM) migrated from up to down, the content of soil organic matter in second soil horizon is higher too. Soils around the central area of rainstorm have different components and properties from these in the central area of rainstorm obviously, which indicates that rainstorm can influence components and properties of soils strongly.
Nonpoint sources of nitrogen (N) in agricultural soils have been identified as one of the main causes of freshwater eutrophication. Studies have showed that decades of N fertilization at rates exceeding the amount removed by crops have resulted in widespread accumulation of N in agricultural soils in Taihu Lake basin, and the accumulation of N will increase the potential of soil N loss to surface and ground waters. Therefore studying the spatial variability of soil N at large scale will be helpful to develop optimal management practices for controlling agricultural nonpoint N pollution. Geostatistics has proven to be useful for characterizing and mapping spatial variability of soil properties. In this paper, a geostatistics method, combined with Geographic Information System (GIS), was applied to analyze the spatial variability of total soil N in topsoil in the typical area of Taihu Lake basin. The results showed that the spatial variability of total soil N was apparent in isotropy within the maximum lag extent of 40km, beyond which the anisotropy of spatial variability was increasing due to the change of soil parent materials in the direction of NE34°. The isotropic semivariograms showed that the ratio of nugget to sill of the total soil N was about 0.5,indicating that the total soil N had a relatively good spatial autocorrelation in the study area, and the range of autocorrelation extended to about 16km. The map of the total soil N interpolated through Block Kriging based on the fitted exponential model depicted that the soils in Jiangyin and Yixing counties generally had much more N than that in the other counties,which was mainly contributed to the different application levels of N fertilizers;and the "hot spots" of high soil N content were apparent in low-lying polderland, which probably was the results of interaction of topography and human factors such as fertilization.
By analyzing the forming process of the cave landscape the authors think that the change of the CO 2 solubility in the water entering into the cave is vital to the formation of the cave landscape.And the temperature and partial pressure of CO 2 are the key elements to play the role on it. Calculation indicates that when the cave air CO 2 concentration is within 1800ppm the latter is the most important element to the landscape formation. The soil CO 2 is the major source of CO 2 in the cave water: Firstly it facilitates the formation of the soil water into carbonic acid water and when the water contacts with the carbonate rock above the cave the solution chemical reaction will happen. This action will provide the Ca 2+ for the cave sediments. Secondly the soil CO 2 concentration will affect the CO 2 concentration directly in the cave water. From the experts' views the soil CO 2 mainly comes from the respiration of the vegetation the amount of the microorganism and the atmosphere outside the cave. Our field work also indicates that vegetation is one of the most important elements that control the soil CO 2 concentration and its distribution. We do the research in the Yaolin cave by comparing the effect of different CO 2 concentrations to simulate the different CO 2 concentrations under different types of vegetation dealing with the cave landscape. The conclusion is that when the soil CO 2 concentration is higher it will be good to the cave landscape protection and development.That is to say the cave landscape covered by the vegetation is much better than the one covered poorly. But if the CO 2 concentration is too high the soil CO 2 can filter into the cave through rock slot and make the cave water keep the acid character to dissolve the old landscape sediments and the dissolved views are formed.
The evolution of Lake Dongting is determined by three main factors, which are tectonic subsidence, siltation and human impacts. "The Dongting Basin" and "the basin of Lake Dongting" are two different spatial concepts. "The basin of Lake Dongting" is only one of the components of "the Dongting Basin". The basin of Lake Dongting, the levees and the farmlands synchronously keep subsiding and relatively actionless due to the tectonic subsidence of the whole Dongting Basin. At present, the mean sedimentation rate of Lake East Dongting,Lake South Dongting and Lake Muping is 9.43, 19.11, 12.46mm/a, respectively. The rate of tectonic subsidence of the lake is low (3～10mm/a), but the capacity of tectonic subsidence still counteract a certain capacity of siltation, which restrains the shrinkage of Lake Dongting. The sedimentation rate is bigger than the rate of tectonic subsidence in Lake Dongting. Sandbars will continue to grow and expand, and Lake Dongting will still keep the trend of siltation and shrinkage. At present, the whole Dongting Basin is subsiding and expanding due to tectonic subsidence, which has no influence on the change of the capacity of storing flood of Lake Dongting, and siltation is playing a main role. The capacity of storing flood of Lake Dongting will continue to decrease as siltation goes on. During the 80 years after the Three Gorge Dam is completed with the completion of "the 4350 Project", the sedimentation rate of Lake Dongting will reduce to 1.79 mm/a. Then, the trend of siltation of Lake Dongting will be restrained.
Under economic globalization, the free flow of capital, goods, technology and information will have impact on the spatial location of product elements. However, the local force based on local economic development is important. So, the behavior of regional economic main body-enterprise under economic globalization is the result of co-action of global force and local force. In this paper, we will probe into the mechanism and type of actions between global force and local force, and analyses the evolution of local production network in the view of the game play between global corporation and local enterprise. Firstly, on the assumption that two kinds of enterprise are economic reasonable bodies, their strategic behavior under globalization all aimed to make their benefits maximized. In order to realize their aims, the global corporation and the local force all only have two choices: the global corporation could select entering or not entering into local production network, while the local enterprise could select connecting or not connecting with global production network. So, this will lead to four results of combinations and results of these two enterprises. Secondly, with regard to four game results of the global corporation and the local enterprise, which will lead to four types of evolution of local production network, which are connecting and expending, breaking and solving, growing and stringing, and resisting and waning. Finally, we conduct analysis by taking three field examples of Chinese current three types of regional spatial structure’s evolution.
Taking advantage of a GIS data set of county-level administrative regions and the National Population Census data in 1982 and 1990, this research analyzes the regional growth patterns in China through the change of regional density functions. To minimize the influence of physical environments on population densities, the study areas are limited to four major plains of China: the Northeast China, North China,Hubei-Hunan Plains and the Sichuan Basin. These plain areas are defined approximately according to cultivation ratios at the county level. A gravity-based model is used to delineate the influential regions of 17 cities. In other words, the influence of a city on a county is positively proportional to the city's population size but negatively proportional to the distance between them. A county is included in the influencial region of a city if this city exerts the largest influence on the county among all surrounding cities. The model is implemented in a GIS environment. In China, regional densities decline with distance from a city, similar to western countries. Four simple bivariate functions are tested: (1) linear, (2) exponential, (3) reverse exponential and (4) power functions. Among the four functions, function (3) or D r =a+blnr fits the regional density patterns in China the best. This is different from urban density patterns, which are best captured by the (negative) exponential function. Based on the change of fitted density curves over time, regional growth patterns can be identified. The results show that in all 17 regions, areas close to central cities grew faster than remote areas, described as a trend of centralization. However, regions with strong core growth are generally associated with stagnant hinterlands; and regions with moderate core growth are usually matched by similar growth rates in the hinterlands. This indicates that most regions in China are still on the process of centralization, i.e., fast growth in core areas (urban and suburban) at the expense of peripheral areas. This trend is strongest in regions where the central cities have gained the fastest growth.
Using social investigation and segmentation approach, the authors conduct in site investigation upon the attitudes and behaviors of residents to the tourist attractions in Xidi, Zhouzhuang and Jiuhua Mountain. Residents in these places are classified into four types by using hierachically clustering and are named ambivalent supporters, indifferent supporters, enthusiastic supporters and rational supporters respectively based on the analysis of the attitudes and behaviors of these residents toward the development of tourism. There exist distinctive differences between these four types of residents in their demographic characteristics and social background. Mainly and in general, those who are aged, long time resided and relatively higher educated become ambivalent or rational supporters, those who are less related to and dependent on tourism become indifferent supporters, while those, who are young, or engaged in tourism, or whose family members or relatives are engaged in tourism or whose main income depends on tourism, taking up the greater proportion among the enthusiastic supporters. Economic interest, educational background, the knowledge about tourism development and the age remain the main affects on their attitudes to and behavior in tourism. Comparison shows that Chinese residents in tourist attractions are more active and supportive in attitude and behavior than their foreign counterparts, and until now there are no opponents against tourism in China.
Tourist flows are the results of the interaction between tourist destination between tourist destination and tourist origin.The spatial characteristic of tourist flows is one of the most important research fields of tourism geograpy.Domestic scholars of tourism geography have achieved some related research fruits,but there are few researches on the mathematic models of the spatial distribution of tourist markets and the spatial flows of tourist.Based on lots of on-the-spot investigations and surveys,this paper studies the spatial characteristics of tourist flow in Sanya City,which is a typical coast resorts.Firstly,the authors analyse the distribution of its domestic tourist origins and study its spatial use curve of tourist flows.It is found out that its tourist origins are widely distributed,and its spatial use curve of tourist flows is very complex,which is difficult to be explained by the curves of Basic Model,U Model,and Maxwell-Boltzman Model.There are huge fluctuations in the curve,and the trend of distance decay is not obvious.This question needs further discussion.Secondly,based on gravity model,they choose the factors of the urban population of tourist origin,the per disposable income of urban residents in tourist origins,and the price of plane tickets from the origin to Sanya City to construct a spatial potentiality model indicate that the disposable income of urban residents in tourist origins and the price of plane ticket have greater tourist market positioning and marketing of Sanya City,and the model has some value of reference to other destinations.Thirdly,the authors analyse the traveling spatial behavior of tourist in Sanya City,and they find that the Fly/Drive model is the main type,the airway corridor is of great significance to the expansion of the tourism markest of Sanya City.Finally,in order to increase the tourist flows in Sanya City,on the basis of the above conclusions,the authors suggest that an aviation fund should be established to cut down the price of plane ticket and make the threshold of tourist transportation lower.
By reviewing the two research frames appearing in the textbooks of Human Geography The Human Mosaic by Terry G. Jordan and Human Geography: Culture, Society, and Space(6 th edition ) by de Blij et al., the author indicates that although the Chinese textbooks of Human Geography have drawn on and accepted the Jordan's frame, this frame still belongs to the traditional human geography which stresses too much on cultural ecology and the Saurian cultural landscape school. However, the frame cited in de Blij's above-mentioned book, which is originally from the National Research Council in US,shows some fresh issues and perspectives in current Human Geography. The development of New Cultural Geography has made it necessary and emergent to construct a new research agenda which can be integrated with both the old and the new human geographies. This article tries to use and redefine five concepts:attributes',spaces',times',approaches' and worlds' to build a research frame, namely ASTAW frame. With this ASTAW frame, the author expects that Human Geography as a discipline will be more systematic and more easily understood by non-geographers. This frame can be also expected to be used in active academic researches esp. on issues in a changing reality. ASTAW frame is essentially based on new cultural geographies' epistemology, approaches and world views. In this frame, the boundary of subjects esp. the boundary between Geography and Human Geography has been understated intentionally. Cultural and social factors influencing the order of nature are emphasized in the frame. The idea of regarding scientific positivism as just one of all human being's wisdom is highlighted in the paper. Therefore, the new research issues in Human Geography as well as Geography will also focus on the representational world rather than just on the real world or physical world which is usually thought of independent on human being and which is traditionally the research core of scientific geography. Spatial study and representational study in new Geography and Human Geography will emphasize the approaches of cultural studies rather than just study the cultural items in traditional and scientific spatial research perspective. The author expects this paper on the new construction of research frame of human geography will attract more attention on the cultural turn of geography and the new cultural geography in China's academic field.
The dynamic simulation and scenario analyses on the spatio-temporal patterns of land use change, as a hotspot in the research field of land use and land cover change(LUCC), is involved with many driving factors. This paper reclassified the driving factors into three categories (stable controlling factors, seasonal changing factors and socio-economic factors) and revealed the influencing direction and intensity of different factors on land use change by logistic analyses between land use change and its driving factors. Furthermore, regarding CLUE-S model as the modeling framework, this paper designed a dynamic simulation model on the spatio-temporal patterns of land use change in Taibus County. In terms of the running results of the System Dynamic Model of Land Use Change and the change of social and economic factors, this paper realized the dynamic simulation of land use change as well as the scenario analyses of baseline, ecologically-oriented and economically-oriented models in Taibus County. The comparisons of the simulated results of baseline, ecologically-oriented and economically-oriented scenarios disclose the competitions and successions in spatial and temporal scales affected by the integrated effects from all kinds of driving factors. the findings show that the northeastern and northwestern sections covered by unused land at present will become the most sensitive belts for land use change, which further reveal the necessity of macro planning for land use in those areas. In this sense, the research results will serve the decision making on land use planning, the rational exploitation of land resources and the implementation of sustainable development strategy of Taibus County.
Based on detailed survey data of land use from early 1991 to late 2001, using models such as synthetic dynamic degree model,conversion rate model, new increase rate model, synthetic index model and synthetic index change model of land use, this paper analyzed great changes in land use in Shaanxi Province during this period of time.Figures indicated that 119.40×10 4hm 2 of farmland, 2.21×10 4hm 2of garden land,7.64×10 4hm 2 of forest land,21.02×10 4hm 2 of grassland,1.52×10 4hm 2 of rural residential land and city and town land,0.13×10 4hm 2 of traffic land,1.07×10 4hm 2 of waters and 14.85×10 4hm 2 of unused land changed to other types of land. Meanwhile, 10.44×10 4hm 2 of farmland, 45.47×10 4hm 2 of garden land, 59.79×10 4hm 2 of forest land, 29.28×10 4hm 2 of grassland, 9.65×10 4hm 2 of rural residential land and city and town land, 2.66×10 4hm 2 of traffic land, 2.36×10 4hm 2 of waters,and 8.19×10 4hm 2 of unused land were converted from other types of land. The synthetic dynamic degree of land use in Shaanxi is 0.726%·a -1. The covertsion rate of farmland is 1.885%·a -1, the biggest number among conversion rates of other land use types.Synthetic index of land use degree in Shaanxi is 2.301 in 1991, and 2.282 in 2001. The conclusions are drawn as follows: (1)Land use changed greatly in Shaanxi Province from 1991 through to 2001. Garden land changed most greatly, with cultivated land, traffic land, residential and urban land, and grassland also witnessing greater changes. (2)Land use in Yangling was most active and in Hanzhong was least active. The overall relative change rate of land use in Yan'an was high, because Yan'an emphasized the adjustment of industrial structure, put the policy of returning cultivated land to forest and grass into effect, and improved the infrastructure construction such as traffic conditions during the last 11 years. (3)Urban, rural residential and traffic land uses increased quickly, which indicates that under the situation of the West China development, the traffic conditions were improved and the urbanization steps quickened constantly in Shaanxi. (4)The land use degree in Yangling was the biggest. The one in Shangluo was the least. The land use degree in Weinan, Xi'an and Yangling increased during the last 11 years, and the land use degree in other regions decreased. (5) The cultivated land returning to forest and grass mainly happened in south and north of Shaanxi and agricultural structure adjustment mainly in the middle of Shaanxi.(6) The driving factors of land use change in Shaanxi are natural factor, policy factor, economic adjustment and population factors.
Research of runoff generation and routing mechanism is the foundation of hydrological simulations. Further analysis based on hydrological data is an effective means. Lushi basin (4623km 2) located above Luohe in the middle Yellow River is a typical tor-forest area. Its runoff generation and routing characteristics are different from the others’. To further research the asymmetry of precipitation spatial distribution, the following three indexes can be used: dispersion coefficient of basin precipitation (C V), asymmetry coefficient of basin precipitation (η),and ratio of the maximum and the minimum precipitation in basin area (α).To separate runoff components and show changes of air temperature, evaporation, precipitation,runoff and rainfall-runoff coefficient, a hydrograph recession curve displacement method and mass departure method were respectively used. The analysis of the selected 43 rainfall-runoff data from 1971 to 2000 revealed that the region's rainfall spatial distribution is very asymmetric with the existence of a distinctive a storm center; its mean dispersion coefficient of basin precipitation (C V) is 0.51, mean asymmetry coefficient of basin precipitation (η) 0.53 and mean ratio of the maximum and the minimum precipitation in basin area (α) 16.06. Its routing mechanism and modes are very complicated, including over-infiltration and over-fall patterns.The annual direct flow accounts for 74.7% of the total, routing time is 18.0h and lag time 13.7h. An in-depth analysis of routing characteristics on the variational conditions resulted in important conclusions : changes of annual runoff yield and rainfall-runoff coefficient were resulted from rainfall characteristics; changes of underlying surface and human activities did not cause prominent effect on the relation of rainfall-runoff; while to flood, biological protection and water and soil conservation measures increased the cover degree of vegetation and forest, improved interception and soil fixation abiligy, reduced runoff generation capacity and improved the correlation of flood-runoff in the study area, to a certain extent.
Flow routing model (FRM) plays important roles in the distributed hydrological modeling. Whether a simple or complex FRM is chosen depends on the relative relationship between the time resolution and the lagging time of routing. Generally, the FRM of a distributed hydrological model(DHM) consists of three components: the first is subdivision method of the basin; the second is the routing path; and the last is the routing method based on the routing path. In order to decrease the runtime of model, an efficient routing method, the so-called Ranked-Grid-based Kinematic Wave Routing model (RGKWR), is developed in this paper. This model applies the kinematic wave method to successive routing on ranked raster grids. Raster grids can be divided into different ranks due to each grid's flow direction computed by the single direction algorithm. We define the basin's outlet grids as the first rank, and the grids from which water flows into the first ranked grids as the second rank, the rest can be deduced by analogy, so the most upstream grids are defined as the highest rank. Flow routing is undertaken from those grids having higher rank onto the grids having lower rank.This paper puts forward the classifying method for raster grids, discusses the kinematic wave model and its numerical solutions, and carries out a case study on Chaobaihe River Basin in North China. The basin, with a drainage area of 13,846 km 2, has two outlets to Miyun Reservoir: one is Xiahui hydrologic station on Chaohe River, the other is Zhangjiafen station on Baihe River. The whole basin is divided into 55,444 grid elements at a 500-m resolution, with the Chaohe River basin partitioned into 298 ranks, and Baihe River basin 398 ranks. The application shows RGKWR based on GIS/DEM is reasonable and efficient.
A relationship between mean annual temperature, mean annual precipitation and mean annual runoff was derived with the contemporary data for 30 small catchments in northern China. With the relationship between magnetic susceptibility and climatological variables and between oxygen isotopic compositions and climatological variables established by other investigators, the past annual-temperature and annual-precipitation of the early and middle Holocene were inferred for Quzhou area situated in the southern Hebei Plain from the previously measured magnetic susceptibility and carbonate oxygen isotopic composition of sediments sampled in an inter-channel depression in this area. With the derived relationship between mean annual temperature, mean annual precipitation and mean annual runoff, the corresponding past annual-runoff of the early and middle Holocene was inferred for this area from the so inferred annual-temperature and annual-precipitation. During >10,210-10,000 yr BP, the annual runoff was abundant and apparently more than nowadays. It was relatively spare, being probably less than, roughly the same to or still more than during the contemporary time in 10,000-8,500 yr BP. In 8,500-8,000 yr BP, the annual runoff was again remarkably more than that in the modern time. It was relatively rare again during 8,000-7,200 yr BP. From 7,200 yr BP onwards, the annual runoff tended to increase and was extremely abundant at ～6,700 or 6,500 yr BP when it might be 2.4, 3.4, 4.1 or even 5.0 times more than today. After ～6,000 yr BP, it began to gradually decrease. The general trend of variations in annual runoff inferred for Quzhou area is generally similar to those inferred by other investigators for other parts of the Hebei Plain. However, the comparison of our estimates with those of other investigators indicates that the surface water was much more abundant in Quzhou area than in other parts of the Hebei Plain during the mid-Holocene (7500-5500 yr BP).
With rapid development of tourism, the environmental degradation in Wulingyuan Scenic Spot, especially the degradation of the air and water quality, has attracted some scholarly and governmental attention. To quantitatively evaluate the environmental quality, this paper developed an evaluation model based on the field work and a Delphi methodology. The main findings show that although there exist advantageous ecological environment and tourism resources, the rapid development of tourism has laid more pressure on the environment capacity which further leads to a series of environmental problems. In this sense, this paper brought about some suggestions on the tourism resources exploitation, optimum determination of the tourism planning and tourism environmental management and suggested that the local government should strength the monitoring of environmental quality, promote the assessment programs of environmental impacts, strengthen the systematic reforms to internalize the external effects of environment and develop the industries of environmental resources to guarantee the rational exploitation of environmental resources.
The features of pollen assemblages are dealt with in this paper using the methods of DCA and correlation analysis. Altogether 23 samples taken from topsoils at 8 sites in the east of Qaidam Basin are studied. In this study area, pollen taxa are mainly shrubs and herbs, whose total percentage is 92.77%～100%. Pteridophyta pollen is found in 5 samples, but the percentage is quite low, only less than 0.38%. This pollen assemblage clearly shows the characteristics of obvious desert and steppe desert area without trees. In the pollens of shrubs and herbs, Artemisia and Chenopodiaceae dominate in desert area, being respectively about 40% and 70% in general and 66.38% and 74.54% at maximum. Comparatively, Ephedra is also commonly seen, whose percentage is usually less than 5%, but in 6 samples the percentage is more than 10% and 49.27% at maximum. Gramineae and Compositae also occupy a certain percentage, the maximum may reach 10.6% and 6.82%. Results of DCA and correlation analysis appear that the features of topsoil pollens in different vegetations are not the same. Different assemblages of pollens can be distinguished and are in accordance with corresponding vegetations and environments. According to the aridity, the vegetation communities are divided into four groups: severe drought group, moderate drought group, slight drought group and slight-drought-and-slight-wetness group and it is found that A/C (Artemisia/ Chenopodiaceae) in the desert can indicate the aridity. A/C value is less 0.2 in the severe drought group, 0.2～0.5 in the moderate drought group, 1.63 in the slight drought group and 5.72 in the slight-drought-and-slight-wetness group with aridities being 8.96, 3.00, 2.98 and 2.82 respectively.
Soil organic carbon is the main part of terrestrial carbon pool. It plays an important role in terrestrial carbon cycle and is one of the important components in the research of global change, so it is important for soil carbon cycle to ascertain soil organic carbon reserves and spatial distribution in soil carbon cycle research. This paper adopted the soil distribution areas, sampling data and soil organic contents from 84 samples and 50 profiles to estimate soil carbon pool in Xingguo county of Jiangxi province. The calculation results show that parent material has influence on contents of soil organic carbon, soil derived from lime rock has higher levels of organic carbon (17.92 g/kg) in surface layer(0-20 cm),soil derived from red sandstone has lower levels of organic carbon (6.11 g/kg); and contents of soil organic carbon increased in turn from red clay,red sandstone, granitic, phyllite to lime rock. The contents of soil organic carbon vary greatly under different vegetation types.Soil under pin (Pinus massonniana) has lower levels of organic carbon, but soil under fir(Cunninghamia lanceolata) or broad-leaved forest has higher levels of organic carbon. The total amount of soil organic carbon is about 559.38×10 4t and organic carbon density is about 2.47 kgC/m 2 in depth of 20cm, the total amount of soil organic carbon is about 1437.19 10 4t and organic carbon density is about 6.36 kgC/m2 in depth of 100cm. The distribution of soil organic carbon density is high in the northwest and northeast but low in the middle and southwest in Xingguo county. Soil organic carbon and topographic variables have correlations. In topsoil(0-20cm), the correlations of aspect and the content of soil organic carbon is positively significant while that of elevation and the content of soil organic carbon is highly significant. In profile(0-100cm), the correlation of elevation and the content of soil organic carbon is significant while the content of soil organic carbon and aspect and slope grade have no obvious correlations.
Based on an analysis of fieldwork data collected by the authors from 80 households in the Shapo Village of Shuicheng County in Guizhou Province, the phenomenon of differentiation between behaviors of households who own different resources has been found. The differentiation is adaptable to resources, environment and structure of society and economy up against households. The paper has revealed the main characteristics of employment structure, employment behaviors in both agricultural and nonagricultural sectors and has explained the causes. The results show that factors such as household registration system, low economic accumulation, limited knowledge and simple technology restrict the farmers to be employed by nonagricultural sectors; and household registration constitutes the greatest institutional barrier constraining the migration of rural workers. Because of the low input and output agricultural production mode, households have few accumulation generally, helping the households break out the greatest institutional barrier of registration system to migrate. But owing to the limited knowledge and simple technology, the farmers can not get stable job and incomes, which pull them back home, most of the farmers cannot but choose part time work in nonagricultural sectors. Part time work in nonagricultural sectors can improve the farmers' living standard to a certain degree, which however can contribute little to the optimization of the rural resources, as well as the rural social and economic development. Finally some feasible suggestions are put forwards, i.e.,control the amount of population and increase investment of education; to establish uniform system of social security; and to strengthen rural infrastructure construcion.
Using the data of 1,000 questionnaires, the authors try to analyze the behavior of intra-urban migration and residential suburbanization, the second house and seasonal suburbanization, and other correlative spatial behaviors including commuting, traveling and shopping of urban residents in the process of suburbanization in Beijing. The main findings include the following: To begin with, the moving ratio is higher in Beijing, comparing with that in other Chinese cities, and the moving ratio in the inner suburb of Beijing is the highest, comparing with that in the core and the outer suburb, showing the typical characteristics of inner suburbanization in Beijing. The fact that the temporal characteristics of intra-urban migration accord well with the process of development of real estate and renewal of the old city in Beijing reflects the development of residential suburbanization. In Beijing, investigation of intra-urban migration also shows that local urbanization and inner suburbanization are obvious, that the most important reasons of intra-urban migration include the allocation of housing by danwei (place of work), and housing rehabilitation, and that the separation between habitation and place of work has broken the traditional pattern of unity of habitation and job, causing the changes of urban residential spatial structure. Secondly, the authors think that there are 900 thousand second houses in Beijing. Then, why do urban residents have their second houses? Investigation shows that the most important reason is the allocation of housing by danwei, and the second one is that they need them when work. Most of the second houses are put out to lease,for other purpose and inhabitancy by parents or some relatives coming from hometown. In Beijing, second house has not reached the extent of centralization in large scale, although it manifested some characteristics of seasonal suburbanization. Thirdly, the behavior of commuting, traveling and shopping of Beijing's residents changed in the process of residential suburbanization. Migration improves the commuting of long period in Beijing. On weekdays, migration improves the traffic conditions of urban residents, with the decreasing of ratio of changing buses in the core and the increasing of ratio of private cars in the core and inner suburb, while on weekends, migration also changes the traffic ways of urban residents with the increasing of ratios of non-changing buses and private cars, inflecting the characteristics of change and renewal of urban traffic ways. The changes of choice of shopping place of Beijing's residents and the changes of frequency of going to shopping place of residents now and ten years ago are investigated and analyzed, indicating that urban residents in Beijing are decreasing their dependence on commercial facilities in the core, and that residential suburbanization is quickening its step.
China has a long history of urban development and has numerous cities.Macroscopically the congnition of development law of China’s urban system provides an ideal source for enrichment of urban system theoretical research.Furthermore,China,as a developing country on the fast track,is experiencing rapid urban growth.A better understanding of China’s urban system development will be helpful for predicting the city scale(such as,urban land scale,urban population scale)and macro-planning of China’s urban growth. The urban rank-size and the fractal theories are the important bases for studying the urban system.The former can perfectly depict the distribution of urban size,and the latter can be employed to explain the characteristics of distribution of urban size.At the same time,the fractal dimension and the Zipf dimension are the basic parameters of the two theories.But when studying the urban rank-size rule and the fractal,some scholars theoretically believe there is the relationship between Zipf dimension and the fractal dimension of distribution of urban size,that is,their product equals 1.But,we think,if D and q are the results of OLS(Ordinary Least Square)estimation,then their product should be R2(R2,the coefficient of determination).Then,this paper deduces and proves this result. To study the relationship between Zipf dimension and the fractal dimension of distribution of urban size is helpful to understanding the rule of urban rank-size.Moreover,this study is also necessary for grasping urban development in the future characteristics of urban system evolution in the past and predicting in the urban development future because China is experiencing rapid urbanization process.
The sandy land of western Jilin Province is located in the ecotone of semi-humid and semi-arid area in the temperate zone of China, which is a sensitive region to eco-environmental changes.Sandy desertification is widely distributed in this area because of the vulnerable natural conditions and the unreasonable human activities.As a result, the precious land resources and the economic development in the area have been seriously threatened. In this paper, the spatial distribution change of the sandy desertification and its causes in western Jilin is analyzed in detail. The sandy land eco-environment geographical information system is established based on the multi-spectral, multi-temporal Landsat TM images and field investigation. The comprehensive indexes of sandy desertification extent assessment which include vegetation degradation, windy erosion extent and soil depth are presented to classify the sandy land in western Jilin into three levels-slight, moderate and severe sandy desertification with the support of GIS platform. The results demonstrate that the sandy desertification has been effectively controlled in the past twenty years, except some small sites. The sandy desertified area has reduced 86.4×10 3hm 2, especially in Tongyu and Fuyu counties where sandy desertification has been generally controlled, too. It is partially because that there is relatively ample rainfall and thermal conditions. Most of the rainfall turn into soil water and seldom passes by in the formation of running water, thus the sandy land in this area is more easily to rehabilitate comparing with the same latitude zone of China. On the other hand, the successful ecological engineering and landscape ecological engineering projects in typical sites have effectively facilitated the amelioration of sandy land. However, this doesn't necessarily mean that there is nothing for more concern. The two main causes of sandy desertification still exist, one is its natural factors, especially the physical and chemical characters of the Quarternary deposit and the dry climate; another is the immoderate economic activity of human being that has highly accelerated the sandy desertification process. The sandy desertified area has increased in several sites comparing with the 1980s, in particular in Taonan, Zhenlai and Changling counties. The three sandy belts are spreading to the southeast tardily under the influence of the prevailing wind, and their width tends to be larger.
The new-born wetland in the Yellow River Delta (YRD) is located in the active river mouth in the east of the YRD, which is one of the separate parts of the Nature Reserve in YRD. From 1976 to 2000, as Yellow River water with high sediment content flowed over the flood plains, a progressing coastline and conspicuously changing land cover in this new-born wetland have occurred. Spatial and temporal landscape patterns resulting from interactions between natural conditions (e.g. vegetation, soil properties, and hydrology) and anthropogenic land use activities (e.g. agriculture, road construction and oil exploration) changed greatly during the last 20 years. Landscape is classified into 9 zones according to its different land covers in this region, i.e., sea in the study Bohai area, tidal flat, Seablite-Chinese tamarisk, Chinese aeluropus-Lalang grass, Common weed, Hankon willow and artificial forest, water bodies, agriculture area, and residence, road and oil field zone. They respectively stand for saline habitat, swamp habitat, neutral habitat and artificial habitat for different ecosystems. The archive of satellite data allows us to quantify land cover changes in the region over the past 20 years. Based on supervised classification by ERDAS with field survey and statistical data, fourtemporal land cover classifications were achieved by LandsatTM432,CBERS-1 CCD432 imager and vector data from atlas of the Yellow River Delta covering 1984, 1991, 1996 and 2000. Two ecological evolving series are concluded in those maps and intertwined with each other in the region, i.e., the wetland ecological evolvement and the saline ecological evolvement. Three evolving patterns of the zonal centroid of these 9 types of landscapes are summarized according to their different spatial distributions and temporal evolvement directions. One is the Land-evolving pattern, which is followed by tidal flats, common weed, water bodies, forested land, and Seablite. Another one is the Sea-backward pattern, which is followed by sea in the study area and Chinese aeluropus-Lalang grass. The third pattern is Human-resulting pattern, i.e., cultivated land and residence and industrial zone, which is mostly controlled by human beings in suitable living environment for productivities.
Starting from the three dimensions and virtual reality, the hot spots of ”digital Earth” and ”digital city” of GIS,this paper analyses the development status of 3D visualization GIS at home and abroad, and discourse upon the key technologies of 3D-GIS. In view of the specialty of surveying and mapping, the 3D cyber-landscape GIS in Tangcheng of Wuxi was realized based on 4D surveying and mapping data(DEM,DOM,DLG,DRG). In addition, some modifications on traditional 3D spatial data model of GIS were made.The authors think that the division of point object in 3D modeling of object-oriented is different from that of 2D GIS.The single tree of the generally defined point object is usually composed of bulk data storage and one of the difficult technologies of GIS modeling. At the same time, the authors think that the way of using oriented curves for modeling complicated geometric objects is simple and direct. Based on oriented curves the paper makes several descriptions for common geometric objects, and puts forward the mathematical way which constructs simple surface object and complex 3D objects. As a basic data stream, 4D of surveying and mapping data was modeled by automatic and manual ways through digital technology for editing textures of buildings and linking their attribute data, then the 3D landscape reappearance and virtual reality of Tangcheng scenic spot were completed.
This paper discusses about the extraction of urban green space from an IKONOS image using a hierarchical classification technique. Green space information was obtained based on the spectral characteristics of different objects with the help of available corresponding methods after the combination of IKONOS multi-spectral data. Due to high resolution of IKONOS imagery, large amount of data and heterogeneous nature of spectrum, the extraction of urban green space was carried out on segments after image segmentation. This would help much improving the accuracy of extraction of urban green space from the whole image. In test area of the image, the spectral characteristics of different features in all 4 bands are analyzed. The spectral characteristics of old urban area and asphalt road are similar to those of part of green space. Moreover, it is difficult to extract green space under the shadow. In order to extract information from the mixed green space with non-green space, through enhancing NDVI values of a green space under the shadow, parts of green space are extracted (NDVI > 0.18), then parts of non-green space are eliminated. The next step is to extract green space from mixed green space and non-green space based on spectral knowledge and unsupervised ISODATA clustering. Finally, green space information of test area is obtained by aggregating different levels of green space. The methodology is basically concerned with the object spectral features and noise due to the mixture of different land-use/land-cover categories is significantly avoided. To demonstrate the efficiency of proposed method, unsupervised ISODATA clustering method was used to extract green space from the test area,then both results were compared to show accuracy. The visual interpretation and ground truth checks of the test area have proved that the classification accuracy and productivity accuracy of the first method are higher than that of the latter.
Kaifeng City, one of China ’s "seven ancient capital cities"and an important member of "Zhongyuan city croup", plays an important role as the regional central city of East Henan province in Henan's urban system City open space is a huge container regulating and controlling urban ecosystem In order to bring Kaifeng City into the situation of sustainable development, it is necessary to improve the construction of Kaifeng ecological city by means of optimizing open space system On the basis of the discussions of the significance and requirement of the construction of ecological city and the necessity of the optimization of city open space system, this paper analyses Kaifeng City ’s salient features and new developing ways, and raises theoretical basis and principles for the optimization of Kaifeng City ’s open space system The overall optimization of Kaifeng City ’s open space system should proceed from two sides The first side is the readjustment of the spatial distribution structure of the city The new spatial distribution structure in Kaifeng City should expand effective area of open space system, strengthen supporting of open space system to ecological capacity of Kaifeng City,and build a base for the integration of the three circles in open space system The second side is the integration of the three circles in Kaifeng City ’s open space system The integration in each circle, and between the three circles, should make Kaifeng City ’s open space turning into an integrated and organic system, from which the construction of Kaifeng ecological city should obtain powerful spatial support The element optimization of Kaifeng City ’s open space system has two contents The first one is the optimization of green open space in the city The municipal government should adhere to the urban ecological norm, create high quality ecological, living and landscape environments, make wooded area, garden area and water area into a natural integration, make point, line and flat green land into an unitary system, thereby, establishing a green basis for the construction of Kaifeng ecological city The second one is the optimization of gray open space in the city The municipal government should adhere to the urban ecological norm, create high quality ecological, operational and building environments, make urbantraffic, outside traffic, square and parking area into a situation of coordinated development,makeroads from east to west, from south to north and loop roads into an unitary system, thereby, establishing a gray basis for the construction of Kaifeng ecological city
Based on progress reviews the of eco city study at home and abroad,the rules of optimization and reorganization of spatial structure of eco city and "the green center with around groups network spatial structure model" was put forward taking Xiangfan as a case First, the present eco city's research status and successful practices abroad, and the concept of eco city, the urban eco areas dividing, planning and design, the evaluation index system and other theories and methods of eco city in China since the 1980s were reviewed Second, the authors put forward the rules based on those reviews, which guide the optimization of spatial structure of eco city They are: ① to perform natural harmoniousness fundamental to human; ② to develop at an appropriate scale and suit measures to local conditions; ③ to practise landscaping and achieve perfection and high efficiency;and ④ to pursue overall coordination and benign circulation And with these rules, the authors commend a new model of spatial structure named "the green center with around groups network spatial structure model". Third, based on the analysis of the evolution and problems of its spatial structure, four development forms of urban land use were compared and urban land use for construction were comprehensively evaluated Combining population prediction, the authors suggest that the regional function collaboration of the peripheral area with Xiangcheng and Fancheng should be strengthened, and the planning idea of "a continent, three mountains, three rivers"should be stressed to guide the city change to the green centre with around groups network spatial structure in the process of optimization and reorganization of spatial structure for creating a modern ruralizing eco city Finally, a authors think that the eco city is an inevitable trend of city development; the establishment of the city development leading mechanism makes the city turning gradually to an eco city that is more suited to human settlement;and green centre with around groups network spatial structure model is one of the ideal urban spatial structures
This paper discusses the property and marks of urbanization as a self organizing process, which can be thought of as a kind of phase transition from a rural to an urban settlement system. Several empirical observations including fractal structure and rank size distribution can be used to identify the self organized criticality (SOC) of urbanization dynamics. Fractal structure such as central place landscapes in spatial field and the rank size distribution associated with Zipf ’s law in hierarchical field always ‘emerge ’ while urban systems in a region approach to the self organized critical state of urbanism. The central place hierarchy can be characterized with a set of scaling laws as follows: N m=N 1r m-1 n,P m=P 1r 1-m m,A m=A 1r 1-m a . From these exponential scaling laws, we can derive the power laws such as the three parameter Zipf law, P(r)=C(r-ζ) -d , and the law of allometric growth, A m=ηP b m .The exponential distribution indicates random process, while the power law implies some order in complex systems, but we find the unity of opposites between order and chaos of urban systems through the derivation of power laws from the exponential type scaling laws. Moreover, this means that the spatial network of central places and the hierarchical structure of city size distribution reach the same goal by different routes. This in fact corroborates the viewpoint that both the urban hierarchy and spatial network represent the different sides of the same coin. The self organized networks of cities usually become scale free because of the dynamics of urbanization. The map of the urban network patterns in hierarchical field is just the rank size distribution, which appears in the larger picture, not at the level of an individual city. Once the distribution forms, it will become very stable over a long period of time. The formation of the scale free network of cities associated with the rank size distribution is an information rich evolution, which can be simulated using cellular automata (CA) models, cellular space (CS) model, multi agent system (MAS), and so on. Simulation as an experimental tool may be very useful for us to research spatial complication proceeding from urbanization dynamics. However, the simulation based on computer graphics doesn't help us conceptually in understanding the rules of behavior of urban systems at the higher level. As a complement, post modern mathematical theory esp. fractal geometry, chaos mathematics, renormalization group, etc., will play a significant role in the studies of self organizing urbanization.
This paper deals with the physical and chemical properties characteristic and its affected factors of latored soils in southern subtropical hills Results showed that compared with the soil under zonal natural vegetation it suffered more physical and chemical properties degradation under secondary or man made vegetation It was found that the physical properties degradation in latored soils was characterized by the lowering of aggregates stability with decreasing water stable aggregates, the deteriorating of soil porosity with increasing bulk density and decreasing bigger pore content and the deteriorating of water properties with lowering water permeability and available water retention capacity For natural latored soils, the increasing bulk density and lowering bigger pore content were more obvious, but for cultivated one, the lowering structural stability was more serious It was showed that the chemical properties degradation was characterized by nutrients improvement and nutrients supplying ability with lowering organic matter, nitrogen, phosphate, potassium and cation exchange capacity Statistic analysis indicated that the 10～0 25mm water stable aggregate and its mean geometric diameter value were obviously positively correlated with the organic matter content and total nitrogen content in the soils, that the total porosity and >0 05mm porosity were also positively correlated with the organic matter content in the soils; that the soil structure coefficient and <0 005mm porosity were positively correlated with soil clay content This means that nutrients improvement, especially the organic matter deficient might be the main factor which caused the latored soils physical properties degradation Natural vegetation destroyed by human disturbance might induce soil nutrients improvement, in order to prevent soil degradation, more attention should be paid to protecting vegetation and increasing soil organic matter content
Limestone dolines are much developed in Lunan Stone Forest National Park with soil mantle We choose 9 sites in the bottom or slope of 4 dolines in Lunan Stone Forest in order to study the soil particle size distribution, water content(%), chemical composition of soil developed in the doline bottom or on the slope and their relationship with doline development Study shows that soil water content, chemical composition and particle size distribution are all controlled by karst topography The soil in the bottom of the depression has a lower water content, total Al 2 O 3 and Fe 2 O 3 content than that of the soil in the slope of the depression, However, total SiO 2 of soil in the doline bottom is higher than that of the slope We mainly study the clay and silt content of the soil mantle soil in doline bottom has higher silt content and less clay content than that of the soil on the slope Research results show that with the increase of soil fine grain size, the SiO 2 content decreases while both of Al 2 O 3 and Fe 2 O 3 content increase The water content of soil is highly positive related with content of fine grain size and strongly negative related with content of coarse silt content In order to determine the limestone erosion rate at different depths, 27 limestone tablets were buried at different depths(20 to 60 or 120 cm, one layer every 20 cm) of soil, which were developed in the bottom and slope of a doline in November 1999 Two years later(November, 2001), 25 tablets were exhumed and sent to lab to measure their weight loss then calculate dissolution rate Result of dissolution experiment shows that limestone dissolution rate in the soil of doline bottom is much higher than that in soil on the slope At the same time, result of correlation analysis shows that limestone dissolution rate is highly positive related with content of coarse silt content(R 2 =0 85) and strongly negative related with content of fine grain size(R 2 =0 84) To some extent, even though limestone dissolution rate was decided by soil CO 2 concentration and soil chemical composition, it is still affected by the soil particle size distribution
Previous studies on relationships between hillslope and gully erosion are mainly concentrated on exploration of water and silt relations, few on quantitative studies of evolution relationships between hillslope and gully landform erosion in small catchments of original scales Quantitative studies on synthetic impact and interactions of hillslope and gully geomorphologic characteristics on catchment dissected extent are still a blank in particular This paper, supported by 3S techniques, based on 1∶5000 digital orthophotomap (DOM), digital elevation model (DEM) and topographic map of the same period and of the same scale, quantitatively analysed the impact and interactions of hillslope and gully geomorphologic characteristics on catchment dissected extent by using orthogonal polynomial regression analysis Research results indicated that gullies play a leading role in the catchment morphologic evolution and ground surface dissected extent When inter gully areas are the same, the 0 1 km 2 gully area is the maximum area affecting erosive evolution intensity of the catchment dissected extent The smaller the catchment area is, the greater the affecting extent of catchment surface fragmentation would be The geomorphologic evolution mechanism of channel slopes and gullies can be explained with synthetic impact of geomorphologic indicator of slope and gully fluvial energy Gullied land plays the leading role in affecting catchment dissected extent indicators of D r and L e , when inter gullied land area ( A p ) is constant, there exists maximum value of the dissected extent indicator L e and critical gully catchment area, the catchment dissected extent is the greatest when gully catchment area is about 0 1 km 2. The smaller the gully catchment area is, the greater the gully density would be. When inter gullied land area increases, the dissected extent indicators D r and L e decrease. When gullied land area ( A g ) keeps constant, the catchment dissected extent indicators D r and L e decrease with the increase of inter gullied land area.Catchment dissected extent is synthetically affected by fluvial erodibility under conditions of varying gradients of inter gullies and gullies and their interactions. The evolution mechanism of slope and gully landforms of gully catchment can be explained via synthetic effect of slope and gully fluvial energy landform indicators and their interactions.According to erosional characteristics of slope and gully landforms, to elevate erosional basement level is the key link for controlling modern gully head advancement and hillslope expansion rate of the catchment basins. Priorities should be given to soil and water conservation management of gully catchment area of 0 1 km 2.
It is well known that the Yellow River is the river with the highest sediment contents of all rivers in the world Several hundred million tons of sediments are transported to the coast and to the sea nearby annually, so the Yellow River Estuary area has witnessed the fastest coastline changes in the world This paper describes the spatio temporal features of the coastline dynamics in the estuary area using remote sensing images since the course of the Yellow River was changed to Qingshuigou channel artificially in 1976 Trying to anatomize the spatio temporal features of coastline evolution, 20 sheets of Landsat images were used as the data source The multi temporal satellite images were rectificated precisely and registered each other, and all the images have the same coordinate system After supervised classification the coastlines were extracted automatically from remote sensing images The result shows that a new land of 330 km 2 was formed during 1976 to 2000 by GIS overlay analysis Finally, combined with the hydrologic data from Lijin station, the relation between coastline change and the runoff and sand transportation was analyzed, and the evolution trend was forecasted The results are as follows: (1) The method in the paper is viable to monitor the coastline change (2) Generally, the land forming speed is faster at the initial stage after course change, and the range of the spit shows a strong linear positive correlation with the net epirogenetic area But the coastline begins to erode after the sediment source is broken off absolutely (3) The evolution process during 1976 to 2000 is divided into four stages based on the spatio temporal features of the coastline (4)There is a consanguineous correlation between the ranges of the spit and the runoff and sand transportation, and the speed of the coastline change will become slow in the future according to the present condition of the runoff and sand transportation
Global warming will lead to changes in many environmental factors and disturbance regimes (e g fire, drought, insect outbreak etc ) As a consequence, changes in characteristics of existing ecosystems, such as species composition and competition, stability and productivity, ecosystem health, ecological safety and ecosystem services, are to be expected Palaeoecological evidence and palaeoclimatic records pointed out plant pole ward migration in latitude and upward shift in elevation with increased temperature after the last glaciation Ecological observations also showed that the elevation of the alpine timberline moved upward worldwide with increasing global temperatures during the last 100 years Current global warming could mean that the plants currently growing at lower elevations or at lower latitudes might progressively migrate to higher elevations and latitudes However, it does not mean that all plants of an ecosystem move upward or pole ward with the same velocity Many species may re adapt to the changed and changing environmental conditions and survive for generations at their present location Many species will shift their ranges to track climate change As climate may change faster than plants are able to migrate from one region to another, species will become extinct An extinction of a plant species will also harm the animals depending on this specific species On the other hand, global warming and new disturbance regimes could favour the invasion of non native species due to the reduced stability and resistance of ecosystems Biological invasions will lead to massive losses of biological diversity on local, regional and global scales Global warming during the past 20 30 years has already had a severe impact on sensitive biological systems As a continued warming has to be expected, the global warming issue should be addressed by conservation planners and policy makers, as one of the most serious and immediate threats to biodiversity
