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  • 1999 Volume 54 Issue 3
    Published: 15 May 1999
      
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  • THE CHANGE OF NATURAL ZONES AND THE EVOLUTION OF RED EARTH IN CHINA
    Huang Zhenguo, Zhang Weiqiang, Chen Junhong
    1999, 54(3): 193-203. https://doi.org/10.11821/xb199903001
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    According to the spatial and temporal distribution of the brown reddish soil, red earth and relicular mottled red clay, the locations change of subtropical and tropical zones since late Pliocene in China are discussed in this paper. From the change of the limit of natural zone, the climatic variation and its amplitude in southern China can be deduced respectively. The north limits of the northern part of subtropical zone in N2, Q12, Q21 and Q 3 were 41°～42°N, 46°N, 42°～45°N and 35°～40°N, 30°～33°N for the southern part of subtropical zone and 25°～32°N, 30°～32°N, 25°～30°N and 24°～26°N for tropical zone. Comparing with the present limit of the northern part of subtropical zone was of the largest amplitude moving northward, but the other two zones were of a similar moving amplitude during the four periods. The limits of the three kinds of red earth during Q12 period are latitude of 12°～13°, 8°～12° and 5°, that showing the most warm period of Quaternary in China. Comparing with the climatic condition at present, a rising amplitude of annual temperature in 1℃～4℃ during the four warm periods in general is predicted. North China and the area of the middle lower reach of Changjiang River occured obvious environmental change especially during the period of Q12 with a variation of two natural zones, and was a confrontation state each other between the southern part of subtropical and tropical zone in central China during the four periods, but as tropical zone always in south China. The north limit of tropical zone had moved to 30°N during three periods, so there was tropical for a long term in south east China causing extensive development of the relicular mottled red clay especially during the period of Q21. Until late Pleistocene central and east China is of a stable zone of the southern part of subtropical, thus a corresponding scope of the present tropical and red earth distribution is formed finally.
  • A STUDY ON THE PATTERNS OF MIGRATION IN CHINESE LARGE AND MEDIUM CITIES
    Gu Chaolin, Cai Jianming, Zhang Wei, Ma Qingyu, Roger CK CHAN, Li Wangming, Shen Daoqi
    1999, 54(3): 204-212. https://doi.org/10.11821/xb199903002
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    This paper reveals the mechanism of population migration along the coastal urban regions in China. This is the first large scale survey on floating population ever conducted in large and medium cities including Beijing, Tianjin, Tangshan, Langfang, Nanjing and Kunshan. The paper first reviews the intellectual foundation of demographic studies on migration. With the survey data and further analysis, it examines the characteristics of population migration in Chinese cities. China is now undergoing a large scale of rural migration into the urban domain with mechanistic increases in the number of floating population. The motive for migration is predominately economic. Family type migration is getting more popular than individual migration. From an economic perspective, low value added, semi skilled jobs are taken up by the first time migrants, and there is also the corresponding shift to service and managerial type of work for the local residents. Chain type migration with upward movement on the job ladder is observed for the second time migrants. From a social viewpoint, jobs for migrants are mostly untenured and without welfare provision as compared with those available for the urban dwellers. Migrations in cities coalesced together to form cliques and syndicates. This has resulted in a more segregated urban morphology.
  • THE EVOLUTION AND SOURCES OF NORTH CHINA’S FLORA
    Wang Hesheng
    1999, 54(3): 213-223. https://doi.org/10.11821/xb199903003
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    The flora of North China (excluding Qingling Mts.) includes about 151 families, 914 genera, and 3 925 species of seed plants. A comparison of paleobotanical material and present day flora provided information on their evolution and sources. The evolution of North China’s flora and vegetation since the Cretaceous may be divided into the following five periods: 1. In the Early Cretaceous, floras were dominated by ferns and gymnosperms comprised mainly of Lygodiaceae, Ephedraceae, Cycadaceae, Ginkgoaceae and the genus Brachyphyllum of coniferae, etc. A few of the angiosperms that appeared initially are Tricolpollenites, Quercoitites type of family Fagaceae and Salixpollenites of family Saliaceae, etc. The vegetation was arid tropical subtropical in aspect. 2. During the Late Cretaceous, angiosperms increased greatly, becoming about equal in number to ferns and gymnosperms. They are mainly composed of Exesipollenites, Gothanipollis, Plicapollis , etc. and formed a subtropical mixed forest and scrub vegetation. 3. In the Paleogene, floras were dominated by angiosperms and hydroherbs such as Potamogeton . The earlier ferns and gymnosperms were greatly depleted or became extinct. However, the coniferae developed including the families Pinaceae, Taxodiaceae, and the genus Podocarpus . The vegetation was a subtropical forest landscape. 4. In the Neogene, angiosperms increasingly flourished with a great number of Amentiferae, temperate elements, and herbs. The differentiation between the northern and southern parts of North China became obvious. The vegetation is a warm temperate mixed needle and broad leaved forest and deciduous broad leaved forest in the north, and a warm temperate subtropical evergreen broad leaved forest in the south. The xerophilous deciduous broad leaved forest and steppe appeared in the late Neogene. By then, the present flora and vegetation were basically formed. 5. In the Quaternary, climatic fluctuations induced plants to migrate and reassemble resulting in warm temperate forest and open forest steppe alternating during glacial and interglacial periods and in the increase in herbs and the expansion of steppe. After the late glacial, the flora and vegetation were similar to that of the present because of a warming climate. The sources of the present flora of north China may be recognized as taking four paths. It is mainly of autochthonous origin with evolution from the Paleogene to the present like various ancient woodplants, temperate and subtropical or tropical elements. Herbs occurred mostly since the Neogene. Besides, many species are from subtropical tropical regions of southwest and south China, especially from Henduan Mts. Some are from the Central Asia Mediterranean and Europe Asia steppe as well as northeast Asia and the Siberian temperate cold area due to the expansion of steppe as the climate became cold during the Neogene and the Pleistocene.
  • THE SEABED SEDIMENT OF THE SHENZHEN BAY, CHINA
    Zhu Dakui, Li Haiyu, Pan Shaoming, You Kunyuan
    1999, 54(3): 224-232. https://doi.org/10.11821/xb199903004
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    In collaboration with a coastal engineering project, an investigation into the structures and spatial distribution of the seabed sedimentary stratification of the Shenzhen Bay has been undertaken. Shenzhen Bay is located between Shenzhen City and Hong Kong and in the east coast of the Pear R. Estuary, with an area of 112 km 2. The seabed topography of the bay is rather flat, with most water depth less than 5 m. The bay is developed along a tectonic fault depression, therefore, the configuration of the coast is controlled mainly by fault tectonics. The bedrock of the Shenzhen Bay is composed of granite of Yanshan Period. The surface of the bedrock had undergone intensive weathering with a weathering layer thickness of about 5 m～10 m; some of them have become laterite. The climate of the region is tropical monsoon. East wind is dominant throughout a year. Typhoon affects the area often, with a frequency of 2 times each year, normally in September and October. The tides here are irregular and semi diurnal, with tidal ranges of 3 4 m and 1 36 m for maximum and mean tides, respectively. Flood tidal current velocity is almost equal to that of ebb, at about 70 cm/s. The sediments in the Shenzhen Bay are mainly from the offshore, with marine material taking about 95%; this implies that the region is an estuarine embossment with low sedimentation rates. The fieldwork undertaken includes two parts. First part is geomorphologic and Quaternary survey in the bay and along the coastline, with the objectives of investigating the initial geomorphologic characteristics and the outlines of environmental evolution. The second part if the survey of the seabed stratification using GPS(model 1008-586), Geopulse(5210A) and chartered steel hull ship which has a load capacity of 200 tons and light draght of 0.5 m, along the grid lines in NS and WE. The seismic profile records were interpreted, on the bases of comprehensive analysis of seabed geomorphology and Quaternary Geology, and core data. Five sedimentary units were found in the seabed sedimentary stratification in the Shenzhen Bay. (1) Marine muddy layer: it is the fine materials deposited in the quiet water environment, with well developed horizontal bedding structures; (2) Fluvial sub clay layer: it is a kind of rather solid sediments, with milky white and grayish green strips, and originated from flood plain sediments. It has been deposited in water for quite a long time, and then emerged out of water to be in the oxidizing and leaching environment; (3) Fluvial sand layer: it is composed mainly of pure coarse sand, with a mean grain diameter of 0 5 mm～1 0 mm. The sands are mostly white, with clean surface and many fresh, sharp edges; (4) Layer of mixed sand and clay: it is the alluvial/diluvial sediments on the surface of the weathering crust; (5) Layer of weathered rock: it is the transit layer between the deposited sediments and fresh granite. All the data were input into computer, and processed using GIS software ARC/INFO. The outputs are various data sets and images about the spatial distribution of seabed sedimentary stratification. The study gives an good example to show that the application of geophysical survey and GIS in coastal water has the characteristics of high speed, high resolution, and illustrative displaying effects, and is promised to have bright future in the studies on regional geomorphology and Quaternary Geology.
  • ON THE SPATIAL STRUCTURE OF CHANGJIANG RIVER PORT SYSTEM
    Cao Youhui
    1999, 54(3): 233-240. https://doi.org/10.11821/xb199903005
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    It has great significance, both theorefically and practically, to study the change of the spatial structure of port system. In the West, Geographers interested in this problem have focused on two aspects the competition of hinterlands or forelands among ports and the degree of traffic concentration in port system. But scholars at domestic have not study this problem from view of change of cargo flow up to now. The main purpose of this paper is to study the dynamic features, formation causes and change tendencies of the spatial structure of the Changjiang River port system. Based on annual cargo throughout of 24 principal ports on the Changjing River from 1952 to 1995, author calculates Gini coefficients of the port system in eight base years. Gini coeffient in 1952 as only 0.209 5 that was rather low, then there appeared an steady tendency to rise. In 1980, Gini coefficient reached its maximum which was 0.528 0. But an evident drop took place at the early of 1980’s. According to above calculating results, author holds that there are four dynamic features of spatial structure of the port system, (1) The spatial structure of the port system has become more concentration from 1952 to 1995 by and large; (2) It is based on much deconcentrated port distributions that the spatial structure tends concentration; (3) There is obvious difference for the change of spatial stracture in 4 phases; (4) An evident deconcentration process took place at the early of 1980’s. A systematic analysis has been carried out on the formation causes of the change of the spatial structure of Changjiang River port system. The paper holds that the following factors have profound implications on its evolution: economies of scale, uneven economic development along the Changjiang River, the change of the prot system’s technological conditions, the development of transport network, and the transformation of the nation’s economic policies. Compared with some port systems in the West, the Changjiang River port system is still in the primary fromation stage. The present spatial state of the port system is unfavourable to elaboration of the whole benefit itself. In the author’s opinion, from now on the basic trend will be continued toward the concentration in the spatial structure but the developing velocity will be slowed down. Nanjing, Wuhan and Chongqing will grow faster than the other ports.
  • THE EFFECT OF LAND USE CHANG ON THE REGIONAL ENVIRONMENT IN THE YANGJUANGOU CATCHMENT IN THE LOESS PLATEAU OF CHINA
    Fu Bojie, Chen Liding, Ma Keming
    1999, 54(3): 241-246. https://doi.org/10.11821/xb199903006
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    Land use changes may influence a variety of natural phenomena and ecological processes, including soil conditions, water runoff, soil erosion and biodiversity. Irrational land use is one of the main reasons for the soil erosion and nutrient lose in the loess hilly area. The Yangjuangou catchment in the Loess Plateau of China, with typical loess hill and gully topography, was selected as the study area. The study focus on the affects of land use changes on soil erosion, the distribution of soil nutrient and soil moisture from catchment, and land use type at three spatial scales. Aerial photography interpretation and field survey mapping were used to produce land use maps in 1984 and 1996. GIS was used for data storage, analysis and display from a comparison of land use areal changes in 1984 and 1996. It was determined that the area of forest and grassland increased 42% and 5% respectively and slope farmland decreased 43%. Land use changes result in a decrease of soil erosion by 24%. Three types of typical land use structure during 15 years in the loess hill slope were selected in order to study the effect of land use structure on the distribution of soil nutrients and soil moisture. From the bottom to top of hills, the patterns of land use types are: grassland slope farmland forest, slope farmland grassland forest and slope farmland forest grassland. By measuring the contents of the total N, total P, available N, available P, organic matter of soil and soil moisture in 0 cm～70 cm depth, the results show that the land use structure type of slope farmland grassland forest has high contents of soil nutrients and low antecedent soil moisture. This indicates that this land use structure has a better capacity for retaining soil nutrient and a high efficiency for soil conservation. The analysis of soil nutrient and soil moisture in different land use types showed that the content of soil nutrient are: forest>grassland>slope farmland, while the content of soil water are: forest
  • BIO ENVIRONMENTAL MECHANISM OF HERBACEOUS PEAT FORMING
    Bai Guangrun, Wang Shengzhong, Leng Xuetian, Bai Yan
    1999, 54(3): 247-254. https://doi.org/10.11821/xb199903007
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    Peat forming and accumulation is one of main approaches of natural ecosystems on surface of the Earth to store the solar energy. A series of simultaneous field spot fixed experimental study were conducted at 4 wetlands respectively in different environment in Northeast China and North China from 1993 to 1996. Based on the experiments, it is researched that the relation of decomposition of herbaceous wetland plants and peat accumulation to the physiological properties of plants and environmental condition. Aquantitative model for relation of peat forming to the climate is established. Two species of mire plant, i.e. reed (Phragmites communis) and sedge (Carex schmidtii) were selected for the nelon bag test to determine the decomposition rate in 5 different kinds of microenvironment in the wetlands. The experiments show that the substantial composition and the anaerobic environment of roots are both not favorable to decay. The sequence of the micro environments on decomposition of plants is water surface>underground>groundsurface>underwater>abovewater. The dynamic change of decomposition is very obvious. In the first year, there are two decomposition rate peaks occured respectively during 0～10℃ period in spring and 20℃～20℃ period in summer. The changing curve of decomposition in the second year presented a monopeak form. When the temperature is much high for the humidity, the decomposition is fast; when the humidity is much high for the temperature, the restrained decomposition is advantageous for peat to form. Finally, a model for the global peat forming climate was established, that is V=(S-56 % )/T=0 009 28 in whichV : the humidity thermal ratio of peat forming climate; S: multiyear average of relative humidity during the >0℃ period; T: multiyear average of air temperature during the >0℃ period. When S >56%, and ( S -56%)/ T >0 009 28, the climate environment is favorable to peat forming; when S <56% or S >56% while ( S -56%)/ T <0 009 28, the climate is not favorable to peat forming.
  • A STUDY OF LANDSCAPE HETEROGENEITY FOR THE CHANGPING AREA IN THE EASTERN PART OF ZHUJIANG DELTA
    Zeng Hui, Shao Nan, Guo Qinghua
    1999, 54(3): 255-262. https://doi.org/10.11821/xb199903008
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    Heterogeneity is the most essential landscape characteristic and one of the most important objects of landscape research. In this paper, we use six types of landscape remote sensing maps along with a new procedure that combines average information levels and a lacunarity index, to the analysis of the landscape heterogeneity of the eastern part of the Zhujiang delta. Heterogeneity types and spatial distributions of landscape elements in working areas are very significant. Arable land and orchards are microheterogeneous elements with a homogeneous distribution and a low heterogeneity level. Developing areas are macroheterogeneous elements with luster distributions and high heterogeneity levels. A woodland looks like a microheterogeneous element, but its distribution is more uneven. Natural environmental changes and human disturbances are the main causes of the significant differences in heterogeneity and spatial distribution among the landscape elements. Homogeneous management of agricultural production converts arable land and orchards into nonheterogeneous elements, but as areas decrease there is a gradual increase in their heterogeneity. Vigorous human disturbances in a local area, like non-agricultural land exploitation, causes the difference in the spatial distribution of towns and other developing areas. Since geomorphology is a medi-scale impact factor, the woodland has more of a cluster distribution pattern because of its effect. Water’s high heterogeneity level is produced by a river’s linear characteristics after most of its surface area is changed by construction. Its results can be used for classifying the microheterogeneity of landscape elements. The lacunarity index method, although losing some detailed structural information, provides results that are not impacted by any local special element distribution. We also gain important structural information such as area change and autocorrelation. Using the two methods simultaneously in heterogeneity studies compensates for the weaknesses of each other and improves the results.
  • DERIVING GLACIER CHANGE INFORMATION ON THE XIZANG (TIBETAN) PLATEAU BY INTEGRATING RS AND GIS TECHNIQUES
    Li Zhen, Sun Wenxin, Zeng Qunzhu
    1999, 54(3): 263-268. https://doi.org/10.11821/xb199903009
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    Glaciers on the Xizang (Tibetan) plateau play an important role in the earth’s climatic system. Regular surveys of glacier change is almost impossible in some areas of the region, and the use of remote sensing techniques is at present the primary, and in may places the only, means of measurement. GIS provides an efficient tool to analyze the status and the changes of glaciers. In this study, we use 1973～1974 serial RBV, MSS and TM Landsat data and GIS to construct glacier maps and to measure glacier changes for the Bukatage Peak located in the middle section of the Kunlun Mountains. Between 15 and 20 ground control points were selected from topographic maps and identified on each image. The root mean square error (rms) of an independent set of points was selected and used to assess the accuracy of coregistration. The maximum verification error from coregistration of all images was 53 m in the X and 67 m in the Y direction. The details of glacier change such as the velocities of glacier movement at different times were obtained by using GIS tools, based on the results of the serial images’ coregistration, classification, vector analysis and calculation. The result shows that there was no significant change in the study area as a whole, but the northern glaciers advanced while the southern glasiers retreated at the velocity of between 50～105 ma-1. Climatic record for the area shows that both temperature and precipitation had a rising trend from the mid 1950s to the late 1980s. This study suggests that the southern cirque/valley glaciers, especially the bukatage Glacier, responded more rapidly to temperature than precipitation change because of their small areal extent and volume and their south slope positions where more powerful solar radiation occurs. Because of emission from surrounding slopes, the valley bottoms receive more thermal radiation than the unobstructed areas. On the other hand, the northern glaciers, especially the West Bukatage Glacier, are larger in size and receive less solar radiation and thus are less affected by temperature than by precipitation. The northern glaciers show an advancing trend because precipitation, mainly snowfall, increased. The deficiencies of this method and the problem areas for future research are presented in the final section of the paper.
  • A CRITICAL EXAMINATION OF THE HYPOTHESIS OF DESERT ENVIRONMENT ON THE CHINESE CONTINENTAL SHELF
    Li Zhizhong, Zhu Daqui, Wang Ying
    1999, 54(3): 269-276. https://doi.org/10.11821/xb199903010
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    Since 1991, some scholars have proposed the hypothesis that at the end of the late Pleistocene when the sea level was low and glaciation reached its maximum, the environment of China’s continental shelf was once a desert. The idea has been used to interpret the formation of the remnant deposits in the shelf region. The main evidence includes the presence of uniform disintegration of marine strata, extensive mixed deposits, long erosional basal plane, repose angle type of structure, buried dune groups and ventifacts. We contend that whereas the idea has some merit when the environment at that time is seen at the macro scale, the evidence submitted thus far is not convincing. Moreover, the idea does not take into consideration the possible impact of aeolian sand on the environment during marine transgression in the post glacial period. On this issue, we offer three views. (1) In the absence of biological evidence, to distinguish aeolian sand facies (ancient sand dunes) from the desert environment (ancient desert) should follow the principle of using multiple indices, and the indices selected should be able to diagnose landform processes and environmental features. But thus far much of the evidence proposed to support the hypothesis such as the “buried sand dune groups” is not unique to desert environment. (2) Although ventifacts (aeolian gravel) do indicate strong aeolian activities, they are not the only indicator of an arid desert environment. A comparative analysis of the grave forms and surface texture of the gravel from the seabed of the South Sea with the ventifacts of a modern desert environment shows that they differ markedly. They should not be regarded as the same thing. (3) Under the dry and cold glacial climate, aeolian sand (sand dunes) does not speedily cemment and diagenize into rocks. In addition, aeolian san (sand dunes) was highly susceptible to damage and change by marine trnasgression during the post glacial period. Thus it is not likely that sediment structure such as repose angle type of structure and sand dune morphology such as buried sand groups could be preserved in large areas. In short, the remnant deposits on China’s continental shelf should not be seen as ancient desert deposits.
  • GEOGRAPHY RESOURCES AND THEIR EXPLOITATION IN THE INTERNET
    Chen Youfei, Xu Shiyuan
    1999, 54(3): 277-283. https://doi.org/10.11821/xb199903011
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    Internet is becoming more and more important in geography research. This makes it possible for geographers to do their research by international cooperation and thus to probe deeply into the essence of geography. Geography resources in the Internet include the following aspects: 1 Virtual geography libraries. This section gives many useful web addresses of virtual libraries, geography links and resource guide. 2 Remote sensing images and maps. They are important means to express geographical information. Some of those resources in Internet are introduced here such as space and aerial photographs, digital images, atlas and cartography. 3 Academic organizations web site. Many academic organizations in geography have established their services in the Internet. 4 Electronic publications. There are some electronic publications known as E Periodical in geography are available for subscription. 5 Electronic forums. The usenet and the mailing lists in various professional geographic fields provide the place for geographers to share their ideas and discuss common interests. Some of them are completely user driven. 6 Software resources. GIS and other geographic analysis software web sites are the main topic here. 7 Educational resources. Online universities and geography courses will bring about great changes in geography instruction, especially by means of multimedia and distance education. Some non profit organizations have set up their web sites to encourage and help teachers to use the Internet in their classrooms. In this paper the authors not only enclose many classified geography resource addresses but also point out some ways to access the Internet efficiently.