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    25 May 2002, Volume 57 Issue 3 Previous Issue    Next Issue
    Effects of Qinghai-Xizang Highway on Land Use and Landscape Pattern Change: from Golmud to Tanggulashan Pass
    ZHANG Yili,YAN Jianzhong,LIU Linshan1,BAI Wanqi1,LI Shuangcheng,ZHENG Du
    2002, 57 (3):  253-266.  doi: 10.11821/xb200203001
    Abstract ( 433 )   PDF (2542KB) ( 781 )   Save

    Based on digital land use maps of 1995, 2000 and road map of Resources and Environment Data Center of IGSNRR, CAS, the land use and landscape pattern change(LULPC) of Golmud, Qumaleb, Zhidoi are studied, in macro-scale, exerting Arc/GIS 8.1 and landscape ecology methods. LULPC of road buffer zones and the bound of construction land expansion is stressed. The conclusions are given as follows: 1. Prominent changes have taken place in land use and landscape pattern from 1995 to 2000. (a) Woodland area increased 0.4%, grassland area reduced 6.26%, water area increased 7.17%, construction land area increased 323.8%, unused land area increased 6.96%, cultivated land area reduced 51.43%. Especially, land degraded seriously, grassland area reduced 22.8% and unused land area increased 43.96% in Qumaleb. (b) The comprehensive land use dynamic degree is 2.25 and the land use dynamic degree of construction land is the biggest, while cultivated land takes the second place and woodland takes the least. (c) The land use degree comprehensive index is 195.2 in 1995, and 156.4 in 2000, reduced 38.8. The fundamental reason is that a great deal of grassland had been transformed into unused land in 5 years. (d) Landscape changed dramatically. The sum of patches increased 1999 and the landscape fragmentation degree increased from 0.115 to 0.124, showing the enhancement of land fragmentation degree. The diversity index increased from 1.308 to 1.331, implying the enhancing of landscape heterogeneity. The fractal degree increased from 1.453 to 1.456 and the shape of patches got complicated. 2. Differed from the corridor effect of other traffic main lines, the corridor effect of this section of road is not obvious and its“point”radiation effect can be seen easily. (a) The land use degree comprehensive index of road buffer zones dropped except the 1 km zone, 40-45 km zone and 50-60 km zone. The land use dynamic index enhanced when the distance to the road get longer, obviously differing from other study areas due to sparse population and sluggish economic development. The landscape diversity index and fractal dimension has no relationship with the distance to the road. (b) The expanding range of Golmud City is confined in 3 km buffer, for Wudaoliang buffer, it is 1 km. No land use change happened in Nanshankou buffer. 3. The new formula ( K = (Ua +Ub - 2Uc) Ua -1T-1 ×100% ) is used to nicely define the land use dynamic degree exactly.

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    The Nature, Formation Age and Genetic Environment of the Palaeokarst on the Qinghai-Xizang Plateau
    GAO Quanzhou, CUI Zhijiu, TAO Zhen, LIU Gengnian, HONG Yun
    2002, 57 (3):  267-274.  doi: 10.11821/xb200203002
    Abstract ( 521 )   PDF (929KB) ( 692 )   Save

    The karst landforms scattering on the Qinghai-Xizang (Tibet) Plateau can be genetically classified as the Tertiary underground karst, which gradually emerged to the ground surface following later period's denudation with the uplift of the plateau during the Quaternary Period. The relative deposits of the Tertiary palaeokarst processes, such as the residuum and speleothem, were discovered recently on the plantation surface of the plateau, where both eastern and southeastern fringe has geologically been disintegrated. The results of fission track dating using the speleothem calcite revealed that the formation age of the palaeokarst and hence the plantation surface is between 19.0 and 7.0 Ma B.P. The residuum has a fine size distribution. The principal chemical components of the clay portion of the residuum consist mainly of SiO2, Al2O3 and Fe2O3. The clay minerals composition of the clay portion belongs to illite-kaolinite-type for most of the residuum samples, and kaolinite-illite-type for a few samples. It can be judged from the silicic acid index and the clay minerals composition that the formation of the residuum of the Qinghai-Xizang Plateau was in its initial phase. However, such a weak chemical weathering index only reflected the weathering degree in the bottom or lower parts of the weathering crust. The relative intensive chemical weathering processes of the surface layers of the weathering crust could be logically speculated. Also, surface textures of quartz grains in the residuum produced by chemical erosion revealed a long-term humid-tropical environment when the residuum and the palaeokarst formed.

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    Debris Flows along the China-Nepal Highway
    HE Yiping, MA Dongtao, CUI Peng, CHEN Rui
    2002, 57 (3):  275-283.  doi: 10.11821/xb200203003
    Abstract ( 478 )   PDF (1812KB) ( 630 )   Save

    The China-Nepal Highway, located in southwest Tibet, is vital not only to the economical development of Tibet, but also to national defense in China. Because of the complex of geologic structures, complicated stratigraphic and lithologic characters, intensive neotectonic movements, a great variety of hydrothermal conditions and strong glacial actions, all kinds of natural hazards occur widely on both sides of the highway, such as debris flows, landslides, avalanches, etc. The above hazards often threaten the transportation safety of the highway, and severely restrict local economic development. Among all the mountain hazards, debris flow is the major one. In this paper, based on historical data, the interpretation of aerial photos and satellite images (TM and SPOT), as well as field investigation, the environmental background of the study area, especially the geological structure, lithology, plant and soil, hydrography and climate are analyzed in detail. Some 842 debris flow gullies are identified in this area, of which 474 have clear channels and 241 develop on both sides of the highway. The mouths of debris flow gullies are located at elevations between 1810 m and 5000 m, of which more than 80% range between 3500 m and 4500 m. The drainage basins of debris flow gullies cover an area between 0.2-161 km2, especially, 75% of which with an area between 1.0-5.0 km2. According to their genesis, debris flows in this area can be divided into 3 types: glacial, glacial lake burst and rainfall. Of the 241 debris-flow gullies, 205 (85.1%) are of rainfall debris flows and 26 (10.8%) are of glacial debris flows.

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    Relations of Drainage Density to the Hidden Actve Tectonics in the Hebei Plain
    WANG Ruobai, GUO Liangqian, HAN Mukang, YE Yanlin, WU Lun
    2002, 57 (3):  284-292.  doi: 10.11821/xb200203004
    Abstract ( 581 )   PDF (1307KB) ( 532 )   Save

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    A Development Model of Red Weathering Crust on Limestones: an Example from Hunan, Guangxi, Guizhou, Yunnan and Tibet
    LI Dewen, CUI Zhijiu, LIU Gengnian
    2002, 57 (3):  293-300.  doi: 10.11821/xb200203005
    Abstract ( 651 )   PDF (584KB) ( 491 )   Save

    Based on research results of red weathering curst on limestones (WCL) in Hunan, Guangxi, Guizhou, Yunnan and Tibet, the authors analysed the relationship of red WCL and evolution of landforms using principles of geomorphology, clay mineralogy and geochemistry, and put forward a two-stage development model. Firstly, insoluble residual of carbonates have been cumulated in the later stage of geographical cycle and WCL was formed on planation surface (PS). This is called stage of lowering of landform and accumulation of residual or stage of planation and crustal formation. The gentle relief and backwater, derived from PS (in humid tropical), is available for the formation and preservation of clays (argilication), but restricts WCL to effective allitication. This accords with the characters of WCL in the study areas (including chemical composition and mineralogical assemblage of clays and granularity of 23 profiles). The second stage of the above model is incision of landform and allitication of WCL or incision-erubescence. The initial WCL located on PS is mainly gray due to reductive circumstance. WCL will have changed from gray (reductive) to red (oxidative) if only tectonic uplift and incision of rivers lower groundwater table, and geomorphologic and hydrogeological (hydrological) conditions have promoted to allitication. This is confirmed using material of field investigations. The WCL on the initial PS, such as Hunan and Guangxi, is mainly gray-color and those on the uplifted plateau, such as Yunnan-Guizhou and Tibetan plateaus, is red. In addition, red WCL is spatially located on PS.

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    On Barrier-Lagoon Development and GPR Application in BO'AO Area
    YIN Yong, ZHU Dakui, WANG Ying, GE Chendong, I. Peter Martini
    2002, 57 (3):  301-309.  doi: 10.11821/xb200203006
    Abstract ( 645 )   PDF (720KB) ( 668 )   Save

    A suite of sedimentary sequences and a three-dimensional (3D) observation of coastal bar and shoal deposits from sandy gravel coast zone in Bo'ao, eastern Hainan Island were made using cores, outcrops and ground-penetrating-radar (GPR) profiles. According to litho-facies distribution, three sedimentary sequences are distinguished in sedimentary columns, which constitutes an upward coarse-fine-coarse cycle. GPR reflectors show that water table in the area is located about 6 m below the surface and the reflective signals decrease rapidly under the water surface due to absorption of saturated sand to the electromagnetic (EM) waves. The GPR electromagnetic wave penetrates less than 5 m on modern beach because of the intrusion of salted sea water. The same phenomenon is encountered on the shoal near the lagoon where the ground water invades sediments. Several GPR facies can be identified from the profiles. As to Yudai Tan coastal bar, two types of reflector configurations of regional significance were verified up and down the water surface or unconformity in some places. Parallel to slightly wavy reflectors above water surface contrast with hummocky, chaotic, oblique and hyperbola reflectors below the water surface. The former reflectors may indicate homogeneous and fine to medium sand while the latter indicates an increase in the content of coarse sand and gravel. Discontinues, hummocky and chaotic reflectors identified on Nangang Cun shoal may indicate an alternation between sand and clay during deposition. The results show that the Nangang Cun shoal may develop in late Holocene period and before it joined the coastal bar, there was a lagoonal region separating them. It is indicated that GPR is a reliable, rapid, and economical method for high-resolution profiling of subsurface sediments in sandy gravel coastal zone. In order to increase the reliability, continuous geological logs from test holes, wells and outcrops are needed to interpret the radar data.

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    Response of Landform Development to the Tectonic Movement and the Climate Changes in Fenhe Drainage Basin
    HU Xiaomeng, FU Jianli, LI Youli
    2002, 57 (3):  310-318.  doi: 10.11821/xb200203007
    Abstract ( 649 )   PDF (2173KB) ( 795 )   Save

    Based on analysis of the characteristics of the terraces in patterns and sediment of the Fenhe drainage basin, we find it was the three tectonic uplifts that caused the formation of three-level terraces. These uplifts took place at 0.76 MaBP, 0.55 MaBP and 0.13 MaBP respectively and resulted in the three low-level stages of the paleolake in consistent with the development of S8, S5, S1 in time. Compared with the neotectonic movements in the upper reaches of the Yellow River, the three tectonic uplifts in this region are in correspondence with them, and this may imply that the neotectonic uplifts of the Qinghai-Tibet Plateau strongly controlled the tectonic movements in the Fenhe drainage basin. According to the features of laustrine sediment deposited from the time when S5 ended its formation to the time when S1 began to develop, we also find the changes in paleoclimate from dry to wet influenced the development of the paleolakes. The lake levels rose when it was wet and dropped when it was dry, but the extent of this change of the lake levels was no more than 4.5 m, and much smaller than that caused by tectonic moveme.

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    Relationship between the Formation of the First Bent of Changjiang River and the Magmatic Activity in Laojunshan District
    ZENG Pusheng
    2002, 57 (3):  319-326.  doi: 10.11821/xb200203008
    Abstract ( 533 )   PDF (1429KB) ( 678 )   Save

    Based on field observations, the author proposes a new understanding on the formation of the First Bent of the Changjiang River. It is the first time to study the relationship between the formation of the First Bent of the Changjiang River and Eocene magmatic activity, suggesting that the First Bent of the Changjiang River is the result from choking of the strong magma activity in Eocene. As a result, the upstream of the river became a natural reservoir, with channel bursting into breach between Mt. Yulong and Mt. Haba, making Jinshajiang River run eastward. At the same time, the plateau uplift and the drastic dissection of river channel led to the formation of the Tiger Leaping Gorge. Taking Mt. Yulong as a base, the magnitude of uplifting in the study area (located in the eastern of the Tibetan Plateau) is calculated, with the magnitude being 3300 m from Eocene to Pliocene, adding 700 m since Pleistocene, totaling 4000 m or so.

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    The Ecological Response of Typical Mud Flat to Sea Level Change in Jiangsu Coastal Plain
    YANG Guishan, SHI Yafeng, ZHANG Chen
    2002, 57 (3):  327-334.  doi: 10.11821/xb200203009
    Abstract ( 622 )   PDF (702KB) ( 632 )   Save

    Mud flat is the typical sensitive ecological area, while its morphological feature responds to the change of sea level, the ecological structure and function also adjust to adapting to the change of coastal environment. Based on the fixed observation, sampling and analysis of the typical profile in Jiangsu coastal plain, this paper lays emphasis on discussing the principles of ecological adverse succession of mud flat caused by sea level rise. The research results show that both sea level and the phreatic water level are related to water quality, the salt content and the nutrient of soil, as well as vegetation composition and capacity of mud flat. Through not only directly increasing the frequency of tidal inundation, but also resulting in the rise in phreatic water level and increase in salinity, sea level rise will bring a series of adverse effects on ecological succession of mud flat, such as salt accumulation and decrease in nutrient of surface soil of mud flat, poor growth or degradation of vegetation and so on, till the adverse succession of the whole ecosystem, i.e., decrease in biodiversity, decline of biological capacity and ecological type tending to be single. In the study area, the imperata cylindrica var. major marsh near sea-wall will be replaced by the artemisia schrenkiana marsh due to soil salinization. Moreover, because of limitation of sea-wall, the range of imperata cylindrica var. major marsh can not expand to inland and at last will possibly disappear. The Spartina angelica swamps near the sea will become narrow because the outer part of them will gradually be replaced by bare bank and the inner part can not extend landward quickly due to the limit of its slow speed of natural reproducing, if the rate of sea level rise exceeds its natural reproducing speed, it will disappear. The artemisia schrenkiana marsh in the middle will continually expand both inward and outward, and the distribution range will gradually enlarged. The original mud flat with various ecological types will tend to be single along with sea level rise.

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    Measurement and Analysis of Water, Heat and CO2 Flux from a Farmland in the North China Plain
    ZHANG Yongqiang, SHEN Yanjun, LIU Changming,Yu Qiang, SUN Hongyong, JIA Jinsheng, TANG Changyuan, AKIHIKO Kondoh
    2002, 57 (3):  335-344.  doi: 10.11821/xb200203010
    Abstract ( 511 )   PDF (657KB) ( 747 )   Save

    Surface energy fluxes including net radiation (Rn), latent heat flux (λE), sensible heat flux (H), soil heat flux (G) and carbon dioxide flux (FCO2) were measured by Bowen-ratio energy balance technique and eddy correlation technique from a farmland at Luancheng Agro-ecosystem Station, Chinese Academy of Sciences in the North China Plain from 1999 to 2001. Seasonal variation of a ratio of latent heat flux (λE) divided by net radiation flux (Rn) showed that Rn is mainly used to evapotranspirate by crops. λE/Rn was all higher than 70% during the four observed seasons in the two years. λE/Rn above maize canopy is slightly higher than that above winter wheat canopy. Seasonal average ratio of sensible heat flux (H) divided by Rn keeps about 15% above the field surface; seasonal average ratio of conductive heat flux (G) divided by Rn varies between 5% and 13%, and the average G/Rn from wheat canopy is evidently higher than that from maize canopy. Under given environmental conditions, when the available energy (Rn-G) is less than 200 W/m2, evaporative fraction (EF) decreases sharply; below Rn-G≈200 W/m2, EF decreases gradually until stabilizing at some specific value less than 1.0. The response process of EF to Rn-G under winter wheat field conditions is similar to that under the given conditions. With the increase of photosynthesis photo flux density (PPFD), carbon dioxide flux (FCO2) changes according to the curve of Michaelis-Mente. Water use efficiency (WUE) does not show the maximum when PPFD is the maximum at noon. On the contrary, WUE gradually decreased with PPFD equal to 1500 μmol m-2 s-1.

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    Design and Operation Channels of the Ecological Purchase in the Shaanxi-Gansu-Ningxia Border Area
    YAN Junping, YAN Yan
    2002, 57 (3):  345-355.  doi: 10.11821/xb200203011
    Abstract ( 435 )   PDF (974KB) ( 712 )   Save

    This paper aims to discuss what is the best channel for eco-environmental construction in the development of western region, taking the Shaanxi-Gansu-Ningxia Border Area for example. It is also a poverty-stricken area where soil erosion is very serious. According to investigation results, its ecological environmental construction must be economic construction, that is to say, 'Commodity Ecology' should be built and 'Ecological Commodity' could be bought and sold, in order to achieve 'ecological rich'. The paper studies the necessity, possibility and operating channel of ecological purchase project. It is suggested that the government might start 'Ecological Purchase Project'. What is called ecological purchase is that government departments pay a sum of money to owners of forest and grass for its quantity and quality each year, start special projects, set up professional organizations, carry out national marketing economic system in typical areas where ecological environmental deterioration is very serious, in order to gain Win-Win benefits for both local governments and peasants. The main part of purchase is government, that is to say, government departments pay bills for the existence of forest and grass which rights of proprietary and use belong to peasants. It is similar to crops and cotton which were government monopolistic commodities. The significance of ecological purchase is as follows: changing planned economy into market economy; changing process management into objective management; changing national wants into peasant's requirements; changing capital construction into infrastructure; changing ineffective investment into effective investment; changing static investment into dynamic investment; changing invaluable ecology into valuable ecology; changing one side participation into multi-participation; and changing national behavior into international behavior after China's WTO accession.

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    On the Development of Market Clusters of China
    SHI Yishao
    2002, 57 (3):  356-364.  doi: 10.11821/xb200203012
    Abstract ( 519 )   PDF (657KB) ( 687 )   Save

    The rising of market clusters is becoming a new landscape of market economic development of China in the early 21st century. In the present study, the features of market clusters are firstly summed up, i.e., centralized trading activities, large trading scope and remarkable scale economic benefit; complete sets of leading industries and dominant commodities; powerful inner links and derivative effects; definite marketing division of labour and notable aggregated benefit; vast areas of market convergence and divergence. Secondly, the dynamic mechanism of formation and evolution of market clusters is revealed, including the mechanism of spatial extension, differentiation and integration of specialized markets, the mechanism of coupling and joint motion of specialized markets and distinctive local industries, the mechanism of extension and aggregation between industrial chains and consumer chains. Thirdly, by means of comparison of the features of merchants' behavioral patterns, e.g. patterns of shift, sources of funds, means of transport, characteristics of management, objective choices, behavioral standards, degree of division of labour, relations between production and consumption, competition and cooperation, patterns of spatial extension and so on, it is shown that market clusters possess a series of advantages over isolated markets. Therefore, the interrelated and promoting effects of market clusters must be attached great importance to and brought into full play in the course of regional economic development. Fourthly, the network extension effects of market clusters on accelerating the integration of economic globalization with economic localization are pointed out. Finally, the sustainable development of traders should be emphasized so as to maintain the continued development of market clusters. The following suggestions should be focused on: (1) to establish "the centers of showing the solicitude and services for traders"; (2) to build up the credit network of traders; (3) to perfect the rules and regulations of levying and supervising taxes; (4) to accelerate the implementation of "the plan of traders' training"; and (5) to make great efforts to improve the level and quality of services for traders.

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    Process and Mechanism of Urbanization in Beijing Area
    HE Chunyang, SHI Peijun, CHEN Jin, XU Xiaoli
    2002, 57 (3):  365-372.  doi: 10.11821/xb200203013
    Abstract ( 762 )   PDF (1972KB) ( 923 )   Save

    Urbanization has become one of the most important methods for human to change the earth. The paper analyzes the process and mechanism of urbanization in the past two decades. Based on the analysis, three models are further explored. The first one is the polygon urbanization of the central city and the sub-central cities; the second one is the line urbanization along the major roads between the central city and the sub-central cities; the third one is the point urbanization with the non-urban land between the central city and the sub-central cities. Of them, the polygon urbanization of the central city held the leading position, while after the 1990s, the point urbanization developed very fast, causing the patch density of the urban land increase. The expansion of urban land and the formation of the regional city pattern are the result of the collective effects between the exogenous driving forces, such as population, economic policy and so on, and the internal suitable factors, such as traffic condition, locations, landforms, etc. Of them, the government behavior, such as urban planning and industrial policy, and the existing city pattern and traditional culture developed during the past 3000 years has exerted more important impacts than others on development process of this modern city.

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