Table of Content

    15 March 1995, Volume 50 Issue 2 Previous Issue    Next Issue
    Cai Yunlong, Barry Smit
    1995, 50 (2):  97-106.  doi: 10.11821/xb199502001
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    Agriculture is a complex of the processes that take place within a threefold environmental framework, which consists of biophysical. socio-political and economic-technological dimensions.Sustainability of agriculture, therefore, can be generalized as a threefold definition. Ecological definition of sustainability focuses on the biophysical processes and the continued productivity and functioning of ecosystems. Longterm ecological sustainability requires the maintenance of the resource base quality, and eventually its productivity, especially the sustained yield of the land. Social definition of sustainability addresses the continued satisfaction of basic humanneeds─food and shelter─as well as higher level social and cultual necessities. It commonly includes the notion of equity, including intra-generational equity and inter-generational equity. The former refers to the fair and equitable distribution of benefits from resource use and agricultural activity among and between countries, regions or social groups. The latter refers to the protection of the rights and opportunities of future generations to derive benefits from resources whichare in use today. The economic definition of sustainability is concerned primarily with the long term benefits to agricultural producers, including sustained yield and the economic performance and viability of farming.Sustainable agriculture may also be viewed as a series of interacting systems at various spatial scales. At field and farm levels, the focuses are on the technologies and management of ecological farming. At regional, national and global levels, key problems are the food supply and the equitable distribution of agricultural resources and products.Based upon the three dimensions′framework of sustainability in agriculture, this paper discusses the current situation of Chinese agriculture in relation to sustainability. The main challenges are population pressure, land degradation, environmenntal pollution, global climate change, non-agricultural activities, market uncertainty, low level of capital investment, and some policy and behavioral conditions. On the other hand, there are opportunities related to natural resources, labor, education, science and technology and some models of sustainable farming which already exist.Can Chinese agriculture be sustainable in the changing environment?The answer depends on how Chinese people will think and act. As Brundtland pointed out∶‘A new environmental ethics must enter our consciousness’. New patterns of living together with new structures of economy and society also need to be established. No single blueprint of sustainability will be found, as economic and social systems and ecological conditions differ widely among countries. Each nation will have to work out its own concrete policy implications’. How do we design Chinese sustainable agriculture?In many respects, China’s long history with intensive but ecologically-adapted production systems provides a strong basis at the farm management level. The big question is at the macro-scale∶how will the production capacity─food needs equation work out?
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    Zhao Huanting, Wen Xiaosheng, Sun Zongxun, Zheng Deyan, Yuan Jiayi
    1995, 50 (2):  107-117.  doi: 10.11821/xb199502002
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    The sea bottom landforms of Nansha Islands (Fig. 1) have three steps, descending from south to north. The first one is southern continental shelf(Sunda)of South China Sea and its depth is less than 150m, the second one is Nansha step(sea plateau) and its depth is 1 500─2 500m, the third step is central abyssal plain of South China Sea and its depth is about 4 000m (Fig. 2). There are upper and lower continental slopes among these three steps. Drowned valleys exist on continental shelf. Nansha step develops a crisscross network of troughs, the coral reefs which tower over sea plateau and the sea bottom reliefs contrast greatly. The bottom deposits are terrigenous silt and sand, organic detritus, coral reef, organic hemi-deep sea to deep sea calcareous mud, organic abyssal siliceous mud, and organic-terrigenous abyssal clay.Abundant coral reefs are distributed in Nansha Islands, and about 200 of them have been named. There are 23 lime-sand islets based on coral reefs. According to preliminary statistics, the reef-building corals have 100 species belonging to 11 families. The main reef-building organism to construct reefs are Porites, Faviidae, Acropora, Corallinaceae and other species. There are hundreds of species of reef-liking mollusks. The general growing rate of Porites and Faviidae is 5─10 mm/yr. . Nansha Islands began to develop organic reefs when the deep sea basin of South China Sea was formed 27 000 000aBP. The organic limestone in Lile Bank is 2 164m thick. Thesection of Nanyong─1 core(152. 07m)in the Yongshu Reef has revealed the strata of organic bone carbonate sediments since 900 000aBP. and the history of geological evolution and environmental change.The coral reef types in Nansha Islands are mainly atolls, secondary table reefs and reef hillocks, and perhaps a few tower reefs. The atolls can been divided into 5 types∶open, half-open,quasi-closed, closed, and tablized (Tab. 1). Atoll geomorphy and modern sedimentary facies can also be divided into 4 zones∶reef front slope facies, reef flat facies, lagoon facies (Fig. 3),and tidal channel facies. Table reefs can be regarded as tablized atolls. Reef hillocks prostrating on continental shelf and upper continental slopes were developed during the transgression of postglacial period. The lime-sand islet on reef top was accumulated by storm surge, wave and wind on reef flat when the sea level rose to the highest point during the middle period of Holocene epoch.The 10─20m high tropical arbor forest which includes cordia subcordata, Pisonia grandis and Guettarda speciosa, and the 2─3m high bush and grass which includes mainly scaevola sericea,constitute the vegetation of tropical ever-green coral islets. In forest, lots of sea birds live there and form guano layer accumulations. There is phosphocalcic soil only. Many types and great quantity of marine organisms live in the coral reef waters. Nansha Islands presents a typical tropical coral reef landscape.Since Tertiary period, Nansha Islands belongs to tropical sea, with tropical organisms and laterite on its peripheral lands. The climate of this area is warm to hot during the global palaeoclimate change(Fig. 4). The surface water temperature is about 3℃ lower in glacial period than in interglacial period, but the reef-building corals can still live. The palaeo-sea level changes in Quaternary period were synchronous with the global palaeo-sea level changes. Coral reefs and southern continental shelf of South China Sea emerged and became land when sea level was low during glacial periods, and South China Sea became a halfclosed gulf due to the closure of westsouth mouths. The surface current field was clockwise in winter and counter-clockwise in summer, circling the Nansha Islands. The sedimentary rate in the Nansha Islands water was fast. In interglacial period, the configuration of South China Sea and the surface current field was the same as the present.
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    Wang Ying, Wu Xiaogen
    1995, 50 (2):  118-127.  doi: 10.11821/xb199502003
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    It has prevailed that the sea level rise amounted to 10-20cm over the past 100 years. The recent predictions of greenhouse-related sea level rise in the next century vary considerable, but all agree that an acceleration is possible. This process has gradually reduced wave winnowing on submerged coastal sediments. At the same time, erosion on the upper beach by break waves has been enhanced. On the other hand, following the rise of sea level, the slopes of the river beds have been reduced, decreasing the fluvial sediment discharges. The lack of coastal sediment supply is a world-wide phenomenon. Combined with the increasing frequency of ELNino and Storm surge, beach erosion and land ward migration of sand barrier islands are the comprehansive results of adjusting the coastal dynamic balance responsing the century trend of sea level rising.By using the Bruun’s model, it is estimated that the major tourist beaches along the China coast zone will lose about 13-66% of their present area while sea level is continully rising to 50cm higher by the year of 2100. Beach protection by building up groin and artificial barrier and beach nourishment are the major methods used under such circumstances.
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    Xu Xueqiang, Li Shengxue
    1995, 50 (2):  128-137.  doi: 10.11821/xb199502004
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    The main purpose of this research is to study the evolution process and spatial disparities of foreign investment in Guangdong province since China’s reform and open-door. Wrth the changes of international situation and national economic policy. five stages of foreign investment in guangdong were divided according to the quantity. the source and the industrial sectororiented of the foreign investment. These five stages are the starial sectororiented of the foreign investment. These five stages are the starting stage(1979-1984) . the expanding stage(1984-1986) .the adjusting stage (1986-1989) . the dropping stage(1989-1990) and the rising stage(after 1991) sequently. The spatial disparity of foreign investment distribution in Guangdong and its causes were analysised with the aid of Factor and Regression analysis in which 95 counties and cities in Guangdong were chosen as the cases. The five factors abstracted from 22 varibles were the driving force of economic development, scale of the region, location, agriculture status and the assembling degree of nonagriculture industry. The general interrelation coefficient between the regional geographic situation (or investment condition) represented by the five factors and the quantity of foreign investment is 0. 9054. The result revealed that the foreign investment in guangdong had been increasin unsteadyly from 1979 to 1992. The regional disparities of foreign investment existing in this period were mainly resulted from the difference in geographic and human situations between the sub-regions of Guangdong. Study results suggest that the regional policies to attract foreign invesment should focus on improving the investment conditions and keeping the continuity of national economic policy.
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    Hou Jianjun, Han Mukang, Zhang Baozeng,Chai Baolong, Han Hengyue,
    1995, 50 (2):  138-146.  doi: 10.11821/xb199502005
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    The geomorphic features. especially the changeable structure of alluvial-pluvial fan and the offset difference of river terraces along the North Qinling Piedmont fault zone, show that there are three characteristics of the fault zone activity between Baoji and Lantian: (1)The main moving type is vertical along the fault since Quaternary Period. its active nature and level are different in space and time. The western and eastern segments in the northern-wall(basin side) of the fault slightly subside and the middle segment greatly goes down relative to the southern-wall (mountain side) in the early Pleistocene. the western and eastern parts inversely rise. but the middle part continues to sink violently in the middle Pleistocene. the western and eastern segments intensely uplift, and the middle segment rises slightly in the late Pleistocene. The characteristics of vertical displacement and average moving rate of North Qinling Piedmont fault zone agree with the active feature of fault segmentation based on the analysis of the first and second terraces which are well preserved and dated by the method of thermoluminescence. (2) The river terraces across the Piedmont fault in the uplift-wall is higher at the exits of the mountain than the parts at the upper reaches of rivers, which reflect that the block of Qinling mountain continues to tilt from north to south since Quaternary Period. (3) The characteristics of alluvial-pluvial fan structure and altitude of deposit bed crossed by fault on both walls of the fault zone show there are a lot of listric faults along the Piedmont.The characterisctics above provide a very important scientific basis for further understanding the forming mechanism of the Weihe fault basin and the Qinling fault block rnountain.
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    Zeng Zhaomei, Zhang Mingli, Ji Jinjun
    1995, 50 (2):  147-159.  doi: 10.11821/xb199502006
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    In order to predicl the future climate tendency. it is necessary to investigate the history of climate evolution. especially for the last hundred years. This paper studies the patterns of global temperature. sea level pressure during two special warm periods (1936-1945 and 1979-1988)and two special cold periods(1906-1915 and 1966-1975) . The main conclusions are as follow :(1) The global climate has been warming up in the last hundred years. The period of 1906-1915 was the coldest decade and the period of 1979-1988 was the most warm in this century.The global temperature had experienced two abrupt warming events during 1920s’ and by the end of 1970s’. However there was an abrupt cooling by 1960s’. The changes of temperature over the land areas are generally earlier than those over the ocean areas the temperature patterns show that the signs of temperature were opposited between land and ocean and between northern and southern hemispheres during the warm period of 1936-1945 and the cold period of 1966-1975 after the abruupt changes. The abrupt changes of Asian and African monsoon accompanied with the transformation of precipitation pattern during the mid 1960s’ were responsiable to the temperature contrast between land and sea. as the temperature over the northern continents began to decrease. while the oceans continued warming up.(2) The temperature patterns were different between these two warm periods and also between the two cold periods. However, they had a similar feature. the temperature variability centers located over continent in the northern high latitudes. especially at Alaska and Northern Asia.(3) The sea level pressure fields display quite a different characters related with the temperature variation. In the cold period. the winter Mongolia high in Eurasian continent is intensified, and the North American ridge shifted westward. Over the northern oceans. the Iceland Low is weakened together with the deepened Aleution Low. The patterns were on the contrary during the warm periods.(4) The results of harmonic analysis on zonal temperature field show that. during the warm periods, the ultra-long wave were more active than the long wave, while during the cold period the situation were opposite.(5)We should not overlook the synthetical role of natural factors when we predict the future climate tendency in response to the increase of the concentration of greenhouse gas.
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    Fang Jingyun
    1995, 50 (2):  160-167.  doi: 10.11821/xb199502007
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    Basic structure of forest vegetation zones in east Asia can be characterized by four zones:tropical-subtropical rain forest(or monsoon forest) zone. warm-temperate evergreen broadleaf forest zone, cool-temperate deciduous forest zone and subarctic coniferous forest zone. Distribution altitudes of these zones change with latitude(thermal gradient) and longitude(humidity/aridity gradient) . In the present paper, the tendency of the change was studied and simulated from a view-point of eco-climatology, using a large number of geobatanical data. As results, the distribution altitude of the forest zones dropped from lower latitudes to higher latitudes in a humid climate region, and from the inland to the coast(from the west to the east) . Empirical equations of the three-dimension distribution for every forest zone were given based on the relationships mentioned-above, and their eco-climatological significance was described. The result of analyzing characteristics of these equations and applying these equations to actual data of vegetation distribution showed that these equations could described well the tendency of three-dimension distribution of the forest zones in east Asia. Accordingly, the equations provided a powerful method for predicting vegetation/climate zone, and had an important theoretical and applying value.
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    Qi Pu, Sun Zanying
    1995, 50 (2):  168-177.  doi: 10.11821/xb199502008
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    Beiluohe River, a tributary of the Huanghe River(Yellow River), is located in the middle region of the Yellow River basin. This branch is characterized by its high sediment yield. Its annual mean discharge is 25 m3/s and its sediment concentration is measured at 128 kg/m3. The river has a bed slope of 2. The mean diameter of the suspended sediment is 0.036mm. Both of the bed slope and the sediment composition are similar to those at the lower reaches of the Yellow River.Since most of the sediment (72% of the sediments are produced annually in long term average) are transported by floods with a concentration of higher than 300 kg/m3(sometime it can be as high as 800-900kg/m3) . bank slumping associated with lower sediment concentration flow occurs rarely. In contrary, the sediment concentration is very low during non-flood season. However, if the sediment transport is described by the empirical equation Qs=kQm for all situations,the value of m for this river can be as high as 5. 0. which is the condition for meander river to form. Since he hyper-concentrated flow occurs during flood season. sediments are mainly deposited on the flood plain and the channel is usually deepened in this period. This character is in favor of not only the sediment transport during flood season but also the formation of a meander river.In summary, having narrow and deep channel is a necessary boundary condition for a river to become a meander one.
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    Qin Dahe, Ren Jiawen, Xiao Cunde
    1995, 50 (2):  178-184.  doi: 10.11821/xb199502009
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    The Antarctic ice sheet is the largest grounded ice in the world, which occupies more than three fourths of the Earth’s fresh water and contains sufficient ice to raise world-wide sea level by more than 60m if melted completely. Since major interactions between the ice sheet, atmosphere and oceans affect the entire global system, the ice sheet plays a critical role in global change. The ice sheet not only respond to climatic change but also influence climate greatly through feedback. Any changes in mass balance of the ice sheet may be of importance to global sea-level change. The special geographic location, ice thickness, snow accumulation rate and surface temperature combine to make the Antarctic ice sheet the storehousee of the longest and potentially most diverse ice records on earth. The global changee information preserved in the ice sheet is unique because of its wide range of direct and proxy measures, long time-scale. and high resolution and fidelity. During the past decades, research on the Antarctic ice sheet has made great progress both in investigation of the ice sheet and recovery of climatic and environmental record preserved in it, primarily due to modern technological advances. To date the form and extent of the surface features of the ice sheet have been defined much clear, and a lot of data on the ice thickness and the sub-ice bedrock topography (and hence estimation of the ice volum) has been acquired. Studies of ice cores taken from the ice sheet have already provided climatic and environmental records over the last ice age cycle. Some achivements in monitoring of the greenhouse gases and the anthropogenic pollutants have also been made. Since the global change is becoming increasingly important to the human race. to further understand the ice sheet and investigate the ralationships between the ice. atmosphere and oceans and to monitor and detect the global change in the ice sheet will be the front of Antarctic research in future. More widespread international and multiple disciplinees cooperation is certainly emphasized in the coming programs .
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    Chen Cei
    1995, 50 (2):  185-191.  doi: 10.11821/xb199502010
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    The shift from central planning system to the socialist market economy in China creates many new study topics for the development of Chinese economic geography. Starting with the summarization of the discipline’s development in China. this paper analyzed the present situation and existing problems of the subject, discussed the ways to strengthen the researchs, and proposed the ways to promote the development of the subject with Chinese characteristics in the framework of socialist market economy.The development of Chinese economic geography in the past was mostly promoted by the requirements of social and economic growth of the stage, so many related theories concerning man-land relationship. location and regional development were characterized by the central planning economic system. The subject is now under the requirements of socialist market economy.There are mainly four problems. Firstly, the old theories belong to a sort of isolated or semi-isolated ones with little attention to outside world and international markets. Secondly, with the limitation of central planning system, the past studies did scarcely in analyzing the dynamic powers of spatial economy and the fundamental roles of markets for resource allocation. Thirdly, the previous research of economic geography was lack of enough notice to the dynamic function of economic activities and resulted in the fact that economic geographers could not take part in the policy-making and management actions in many regional development programs. And lastly, the previous studies often laid too much stress on the theoretical rationalization of development programs but less on their operational possibility for the lack of the analysis of the practical situations of China as well as the real regional development demands.Based on the above understanding of the problems limiting the development of the discipline, under new situation, some efforts should be made to improve the subject. Firstly, economic geographers should widen their eye views by making further understanding of the basic theory and dynamics of socialist market economy. Their study should not only cover the traditional material-processing activities but also the tertiary industries. Markets should be the focus of their concerns. especially the situation of world economy and international markets. At the same time, regional investment environment and the ways to absorb investment should also be placed on an important position in the studies of production allocation. In addition, subjects related to micro-economic activities such as business actions and village industries are becoming new tasks for economic geographers. In general. economic geography should be a discipline not only for the planning of regional development but also for the policy-making and management of the development programs. Secondly, some theories. formed under central planning system, such as those on man-land relationship, production allocation, economic regionalization, territorial production complexes, location and regional development are needed to be examined and edited with new views under the requirements of socialist market economy in order to make them work well for the better application of the subject. Thirdly, to advance the subject to be the one with Chinese characteristics, Chinese economic geographers should make more efforts in some respects. That means to make better understanding of the real situations of China and the provincial regions which is the base of developing the discipline, to take part in more practical economic activities, to try to join in policy-making and management actions actively and to develop and modify the theories of the discipline.
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