Table of Content

    25 December 2006, Volume 21 Issue 6 Previous Issue    Next Issue
    Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS
    Evolutional Analysis of Coupling between Population and Resource-environment in China
    WU Wen-heng, NIU Shu-wen, GUO Xiao-dong, CHANG Hui-li, LI Gang
    2006, 21 (6):  853-861.  doi: 10.11849/zrzyxb.2006.06.001
    Abstract ( )   PDF (252KB) ( )   Save
    Due to rapid population growth and economic developing since reform and opening to the outside world,resource-environment has been influenced intensively in China,so the man-land contradiction is becoming more and more obvious.Based on the panel and serial statistical data,status of population and resource-environment coupling has been researched by the principal component analysis and the coordinated development degree model in China during 1985-2004.The results are:①On one hand,the comprehensive development capability of population has increased continuously.The maximum integrated population development index reached 0.809 4 in 1998.On the other hand,the comprehensive status of resource-environment has declined with a fluctuant falling trend since 1985,and its integrated index has decreased from 0.551 1 to-0.147 9.Population development is at the cost of unsustainable utilization of resource-environment.②The relationship of population and resource-environment coupling varies gradually from awful maladjustment to elementary harmony,and then to secondary maladjustment.The maximum coordinated development degree came up to 0.637 9 in 1994.The direct cause of variation of coupling relationship is that population system and resource-environment system didn't continuously cooperate with each other from 1985 to 2004.③The carrying capability of resource-environment is limited while demands of human being are increasingly expanding,so sustainable development faces huge pressure in China.It is difficult to achieve the goal of ensuring our people a relative comfortable life since China's per capita GDP was only 3 923 yuan in 1994.④Suggestions that would make for sustainable development were put forward in this paper,such as controlling population quantity,improving population quality,making progress in technology,strengthening protection to resource-environment,and moderation consumption.The coordinated development mode that makes population and resource-environment interact well should be chosen.
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    Analysis on Temporal Variation of Environmental Impact Based on STIRPAT Model——A Case Study of Energy Consumption of China
    WANG Li-meng, HE Kang-lin
    2006, 21 (6):  862-869.  doi: 10.11849/zrzyxb.2006.06.002
    Abstract ( )   PDF (393KB) ( )   Save
    Human activities have dramatically altered the global environment,quantitative analysis on the impacts of human activities on environment is one of the highlights in the research field of sustainable development.The total energy consumption and the pollutions from energy consumption processes were taken as the indexes of two different kinds of environmental impacts.Utilizing the STIRPAT model,taking total energy consumption time-series data of China from 1952 to 2003 as an example,this paper analyzed the effect by the anthropogenic driving forces on environmental impacts,including total population,affluence,energy intensity and chosen behavior of energy consumption.The result showed that a 1% change in total population or energy intensity results in a 1.992% or 0.777% change,respectively.With the growth of affluence,the coefficient of affluence elasticity of impact will increase.So,in this empirical study,the overall findings do not support the environment Kuznets curve hypothesis.In different decades,the effects of the anthropogenic driving forces vary dramatically.The growth of total population and affluence has positive effect on environmental impacts;however,the fluctuation of energy intensity has positive or negative effect on environmental impacts in different decades.The behavior of clean energy consumption is helpful to control the environmental impacts which takes the pollution from energy consumption processes as an index.The change of environmental impacts was determined by the net effect of all kinds of anthropogenic driving forces.
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    Estimation of Cropland Residue Bioenergy Using Remote Sensing:A Case Study of Guangdong Province
    WANG Fang, LI Xia, SHI Xun
    2006, 21 (6):  870-878.  doi: 10.11849/zrzyxb.2006.06.003
    Abstract ( )   PDF (735KB) ( )   Save
    Energy shortage and greenhouse gas emissions are two serious problems in China because the growing economy has consumed a large amount of energy in the world.Energy issues have become one of the top agenda in making its national policies.Reduction of greenhouse gas emissions and seeking for alternative energy sources are important for alleviating the environmental problems in China.Centralized using of agricultural residue as a possible source of feedstock for bio-energy production can offer interesting options of producing energy for China.At the same time biomass residues are relatively abundant in China.The estimation of the amount of available biofuel is the first step to utilize this kind of energy.However,the quantities of biomass energy are often calculated based on the statistical data and traditional measurement.There is a general lack of spatial details in using this kind of information because of the aggregated measurement.Detailed information about the distribution of biofuel is important for decision making in using this kind of energy,such as finding the suitable sites for plant building.This can guarantee that the use of biofuel is economical and operational.This paper provides a method to estimate the amounts and spatial distribution of biomass residues using remote sensing imagery,such as the modified MOD17A2/A3 data by light utilization efficiency in Guangdong Province based on BIOME-BGC model and TM data.A decision-support model is developed for measuring the usable biomass for generating bio-fuel by analyzing a number of factors.This model has been tested in Guangdong,which is one of the largest amount of energy consumption in China.The study demonstrates that this method has advantages in biofuel estimation with plausible results.The total available amount of biomass for paddy rice and dry crops in Guangdong is about 20,756.61×1010kJ according to this model.
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    Application and Modification of CVM in China——An Empirical Research Coming from Wuhan
    WANG Rui-xue, YAN Ting-wu
    2006, 21 (6):  879-887.  doi: 10.11849/zrzyxb.2006.06.004
    Abstract ( )   PDF (426KB) ( )   Save
    During recent years,non-market valuation has become the hot topic of research in developed countries.Contingent valuation is the most appropriate method frequently used for placing monetary values on public goods,such as environmental goods and services.In the Western countries,the results of CVM play an increasing important role in government policy decision-making.Since the 1990's,some empirical researches of CVM have emerged in China,but most of them were concentrated in application aspects.As a typical method of stated preferences valuation methods,CVM works on the basis of the West economic theory.So,special attention should be paid to the application of CVM in China.In this paper,many significant issues of CVM are decided according to Wuhan and domestic situation.Key design and implementation issues involved in undertaking a CV survey are discussed in details.Under the guide provided by NOAA Blue Ribbon panel and those famous environmental economists,we conduct the research as follows:First,organize focus groups and assure what is the valuation objective by means of deep interviews.Second,design the whole survey and choose appropriate techniques according to actual situation in Wuhan,which include the choice between WTP and WTA,partition of value-affected area and selection of payment vehicles.Considering the reaction of rural residents to different payment vehicles,we modify the classical theory of CVM and put forward a new model.The external benefits of farmland are calculated according to choices made by survey respondents by single-bounded dichotomy model.In this research the sum of questionnaires amounts to 400,and effective questionnaires reach to 322,which are far beyond the demand put forward by NOAA panel.Under the definition of farmland function,the WTP of Wuhan rural residents is 22-day,which is equal to 1 523.83 yuan per ha.At the end of this paper,we discuss the results of the research and point out issues,which are worthy for further research.
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    The Arable Land Potential Calculation in the Land Consolidation Project of Rural Habitat under Natural and Economic Limits in Tianjin
    SONG Wei, ZHANG Feng-rong, KONG Xiang-bin, JIANG Guang-hui, CHEN Xi-wei
    2006, 21 (6):  888-899.  doi: 10.11849/zrzyxb.2006.06.005
    Abstract ( )   PDF (662KB) ( )   Save
    Because of the cultivated land loss due to rapid urbanization process and arable land deficiency,the Chinese government has paid much more attention to the recultivation of rural habitat.According to the calculating results from the Ministry of Land and Resources,there would be 2.87 million ha of cultivated land that can be increased through land consolidation of rural habitat in 2010.But it is not necessary to transform all the rural habitat into cultivated land in land consolidation process,because there are many natural factors that limit the cultivation properties of rural habitat.And also the re-cultivation of rural habitat must consider the economic benefit,i.e.,consolidation of rural habitat must be economically viable.This paper develops a specific mathematical model to calculate the arable land potential in the land consolidation of rural habitat in China.Tianjin was taken as a case for the study of the arable land potential calculation in the land consolidation of rural habitat.The data came from the land use map,soil map and water resources map of Tianjin in 2004.Firstly the naturally suitable evaluation indexes were selected as the calculation basis of arable land potentiality in the land consolidation of rural habitat.The natural limiting correction coefficient of potential arable land in the rural habitat consolidation in Tianjin was 0.393-0.954.Then the naturally arable land potentialities in the rural habitat consolidation in Tianjin are 143.198-9117.865 ha in 2010 and 188.125-9397.091 ha in 2020 by multiplying the naturally limiting correction coefficient of potential arable land and total area of the rural habitat.The naturally arable land in the rural habitat consolidation is mainly distributed in Jixian,Wuqing and Baodi counties.Secondly the economically viable evaluation indexes were selected as the calculation basis of arable land potentiality in the land consolidation of rural habitat.The economically limiting correction coefficient of arable land potentiality in the rural habitat consolidation in Tianjin was 0.242-0.813.Then the economically arable land potentialities for the rural habitat consolidation in Tianjin are 64.893-2206.523 ha in 2010 and 68.289-2274.096 ha in 2020 by multiplying the economically limiting correction coefficient of potential arable land and the natural arable area of the rural habitat.The economically arable land in the rural habitat consolidation is mainly distributed in Ninghe,Xiqing and Dongli counties.Not only the natural suitability but also the economic viability should be considered when calculating the potential arable land for the rural habitat consolidation.
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    Strategic Thoughts and Patterns on the Sustainable Exploitation and Utilization of Natural Resources for Mining Cities in China——Learning from the Experience of Cities of Dongying,Jiaozuo and Karamy
    BAO Chao, FANG Chuang-lin
    2006, 21 (6):  900-909.  doi: 10.11849/zrzyxb.2006.06.006
    Abstract ( )   PDF (429KB) ( )   Save
    Sustainable exploitation and utilization of natural resources is the key to the sustainable development of mining cities.It is also a general problem for all kinds of mining cities to resolve.Three typical mining cities in the eastern,central and western parts of China are taken as a case,including Dongying,Jiaozuo and Karamy.From their experience on exploiting and utilizing natural resources(mining resources and other natural resources),five problems during the exploitation and utilization of natural resources in all mining cities are summarized:(1)mining cities are all threatened by the exhausted mining resources;(2)eco-environmental problems are more serious and need more attention;(3)mining resources and other natural resources requires effective combination;(4)mining resources and other natural resources need competing in exploitation and utilization according to the game theory;and(5)all kinds of natural resources should be exploited and utilized synthetically and the relationship between natural resources and social resources should be harmonized.According to these problems,the strategic thoughts on the sustainable exploitation and utilization of natural resources for mining cities in China are presented,and seven kinds of rational patterns are introduced:(1)economize to avoid running short;(2)black to green;(3)combining preponderant resources;(4)extending preponderant industrial chains;(5)amalgamation of local and state-owned enterprises;(6)two main driving forces from state-owned and private enterprises and(7)two important parts of public-owned and private economic system.
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    A Tentative Discussion on the Impact of Human Activities on the Variability of Runoff Series of the Beijiang River Basin
    LI Yan, CHEN Xiao-hong, WANG Zhao-li
    2006, 21 (6):  910-915.  doi: 10.11849/zrzyxb.2006.06.007
    Abstract ( )   PDF (352KB) ( )   Save
    With the development of society and more intensive human activities,especially after the large-scale economic construction in recent decades,some new characteristics appeared beyond the intrinsic laws in water resource.Recognizing the new laws of runoff evolvement under the changing environment seemed very necessary.This paper analyzed the characteristics of precipitation and runoff of Beijiang River basin in the past 45 years(1956-2000)based on the measured data of precipitation and the hydrological data at Shijiao station which is the main controlling station on the river.The research found that the runoff series shows a rising tendency while the precipitation is even,indicating that the rising trend of runoff is caused by human activities.Analysis of the runoff coefficient series.Result showed the coefficient had changed around 1973.So we assumed that the runoff is under the natural conditions before 1973.We obtained a regression equation based on the data of precipitation and runoff in 1956-1972.Using this equation the impact of human activities on runoff can be quantified.The calculated results showed that human induced runoff increase are 3.81×108,2.54×108 and 4.13×108m3 at the three periods of 1973-1980,1981-1990 and 1991-2000 respectively.Finally,we analyzed the water and soil erosion and vegetation change of the basin in recent two decades,and the results further proved that it is the human induced change of the underlying surface that results in the runoff increase.
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    Simulating Net Primary Production of Agricultural Vegetation in China(Ⅱ):Model Validation and Estimation of Net Primary Production
    WANG Yu, HUANG Yao, ZHANG Wen, YU Yong-qiang, WANG Ping
    2006, 21 (6):  916-925.  doi: 10.11849/zrzyxb.2006.06.008
    Abstract ( )   PDF (739KB) ( )   Save
    Models for simulating crop net primary production(NPP)have been developed well over the last three decades,while few of them are successfully put into practice in the agro-ecosystem of China.The objectives of this paper are to validate an existing model Crop-C developed by the authors,and to estimate crop NPP in China by employing Crop-C.Crop-C was validated against independent measurements from literature and the derived NPP from crop yields documented in national statistical yearbooks.Six crops of rice,wheat,maize,cotton,soybean and rapeseed,planted in approximately two thirds of agricultural soils in China,were involved in the validation.Model validation indicated that NPP of the six crops can be well simulated from weather,soil and N fertilization in various regions of China.A comparison between the simulated and the observed NPP resulted in a correlation coefficient(R2)of 0.80(n=786).By linking the Crop-C to GIS database,crop NPP in mainland China was estimated from 1980 to 2000.The GIS database includes soils,weather,N fertilization and some other related parameters that were interpolated or rasterized into grid layers.Model estimates indicated that the NPP increased from 472.9Tg C in 1980 to 607.2Tg C in 2000.Higher NPP occurred in eastern and southern China,and lower NPP appeared in most parts of northwestern and southwestern China.Nevertheless,NPP increased significantly in northern China and some parts of northwestern China from 1980 to 2000 as the consumption of synthetic fertilizer increased.It was concluded that Crop-C can reasonably simulate NPP for crops of rice,wheat,maize,cotton,soybean and rapeseed with common available datasets of climate,soil and nitrogen fertilizer application.NPP of agricultural vegetation in China could be estimated by coupling Crop-C to regional databases with a high spatial resolution.In addition,NPP of Chinese agricultural vegetation increased significantly from 1980 to 2000 according to the regional estimates.
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    Variations of Soil Water Replenishment in Manasi River Basin over the Last 40 Years
    MO Xian-kun, LI Tian-hong, LI Zhen-shan
    2006, 21 (6):  926-933.  doi: 10.11849/zrzyxb.2006.06.009
    Abstract ( )   PDF (361KB) ( )   Save
    Based on the soil water balance principle,this paper uses GRID data structure in the Geographical Information System(GIS)and its spatial analysis to establish a distributed hydrolo-gical model by selecting Manasi River basin in Xinjiang as a study area.Four significant factors influencing soil water replenishment,specifically precipitation,runoff,irrigation and groundwater were introduced in the model according to geographical characteristics of the study area.With this model,the temporal and spatial distributions of soil water replenishment from 1961 to 2000 were analyzed.The results showed that:(1)soil water replenishment is the greatest in June to August and the least in February in a year;(2)it varies with the precipitation in the last 40 years and reached two apexes in the 1960s and 1980s;(3)it was the greatest in oasis and the least in desert which was a bit less than in the mountain areas;and(4)the contribution of precipitation to soil water replenishment is always around 50% regardless of in wet or dry seasons.The contribution of irrigation was 36% and 0 in the two scenarios,while that of runoff remains at a low level all the time.
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    Spatial Pattern of Biological Soil Crusts and its Changes in Gurbantunggut Desert during the 1970 to the 2000
    YANG Wei, CHEN Jin, ZHANG Yuan-ming, WANG Xue-qin
    2006, 21 (6):  934-941.  doi: 10.11849/zrzyxb.2006.06.010
    Abstract ( )   PDF (496KB) ( )   Save
    The biological soil crusts,especially lichen crusts,are well developed in Gurban-tunggut Desert,the largest fixed and semi-fixed sandy desert in China.Together with vascular plant,biological soil crusts become an important factor relating to sandy surface fixation.The objective of this paper is to analyze the variation of the biological soil crust distribution in Gurbantonggut desert from the 1970s through to the 2000s.In this study,43 samples including lichen dominated biological crust,bare sand,litter and green vegetation were collected.The reflectance spectra of these samples were measured and a new biological soil crust index(BSCI)was used to detect and map the lichen-dominated crusts by remotely sensed data including four Landsat ETM+ images,four Landsat TM images and five Landsat MSS images,acquired in the 1970s,the 1980s and the 2000s respectively.Based on the maps of the biological soil crust distribution in the 1970s,the 1980s and the 2000s,we calculated the landscape indexes of biological soil crust using software Fragstats and analyzed the variations of the crust distribution and their landscape features.The results showed that:(1)the biological soil crust was mainly distributed in the southeast part of this desert,but became gradually sparse toward northern and western parts of this desert.The crusts in the southeast part decreased remarkably,while in the north and central parts of the desert it developed very well during the 1970s to the 1980s.(2)There was an increasing trend for crusted areas during the 1970s to the 1980s in general,and the crusted areas displayed a decreasing trend during the 1980s to the 2000s.The climate change and increasing human activities resulted in such a trend.(3)An increasing landscape fragmentation,irregularity of patch shape and bigger isolation between patches were observed during the 1970s to the 2000s because of the significant human disturbance.
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    Biomass Allocation and Net Primary Productivities at Treeline Ecotone on the Changbai Mountains,Northeast China
    DENG Kun-mei, SHI Pei-li, YANG Zhen-lin
    2006, 21 (6):  942-948.  doi: 10.11849/zrzyxb.2006.06.011
    Abstract ( )   PDF (204KB) ( )   Save
    Increasing severity of environment and altitude in mountain ecosystems can affect relative and absolute biomass-allocation patterns in plants.Biomass allocation and net primary productivities were examined in two alpine treeline stands,i.e.Larix Changbaiensis mixed forest and Betula ermanii forest(1900 m a.s.l)on the Changbai Mountains in Northeast China.The biomass and their productivity were measured based on average standard tree with canopy and quadrat-harvesting method for shrub layer and herb layer.The total biomass and net primary production(NPP)of the Larix Changbaiensis mixed forest were 15.16t/ha and 1.68t/(ha·a)respectively,with 3.72,10.34 and 1.1t/ha of biomass allocation and with 0.43,0.46 and 0.79t/(ha·a)of NPP in canopy,shrub and herb layers as well.And the total biomass and NPP of the Betula ermanni forest were 19.44t/ha and 2.58t/(ha·a)respectively,with 5.14,12.68 and 1.62t/ha of biomass and 0.80,0.56 and 1.23t/(ha·a)of NPP in canopy,shrub and herb layers respectively.In comparison with counterparts at lower altitudes,the relative and absolute stem mass decreased significantly with increasing altitude,the ratio of branch and leaf mass to total arbor biomass increased with altitude for larch and birch.However,root ratio and root to shoot ratio present different responses.Root ratio of larch increased a lot but birch had no significant difference.The increase of leaf ratio is favorable for carbon uptake and carbon balance in severe environment at treeline ecotone.Variation in stem mass was caused by multi-stem plasticity and krummholz due to snow accumulation and heavy wind.Net primary productivities of larch mixed forest and birch forest decreased sharply at treeline in comparison with lower altitudinal stands,whilst the ratio of root production was much higher than that of lower altitude.This made it profitable to take water and nutrients in soil.
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    Wetland Changes in the Middle and Lower Wuyuer River,Songnen Plain since the 1970s
    HUANG Fang, ZHANG Shu-wen, Jan de Leeuw, ZHANG Yang-zhen
    2006, 21 (6):  949-956.  doi: 10.11849/zrzyxb.2006.06.012
    Abstract ( )   PDF (379KB) ( )   Save
    The middle and lower Wuyuer River in Songnen Plain is one of the concentrative and extensive distribution areas of inland wetlands in Northeast China.Located between 45°53.3'~48°3.06'N and 122°59.3'~125°42.1'E,it covers an area of 2.53×106ha.Wetlands in this region perform important natural functions in improving water quality,providing flood control,maintaining environment and assisting groundwater recharge.The vast expanse of marshes and numerous lakes and ponds constitute a remarkable natural heritage and serve as an important wintering site for migratory birds.In the past several decades,land cover in the region underwent dramatic changes and the progressive loss and conversion of wetlands has become a key conservation issue.Based on Landsat MSS,TM/ETM imagery and GIS technology,using the theory and methods of landscape ecology,the landscape change of wetlands in the middle and lower Wuyuer River since the mid 1970s was analyzed.The results showed that area of marsh decreased from 39.51×104 ha to 32.04×104ha,while the area of cropland increased 12.97×104ha during 1976-2000.About 5.58×104ha and 3.40×104ha of marsh land were cultivated to dryland and paddy field individually,and 8.10×104ha of dryland were converted into paddy field.Due to shortage of water supply in the whole watershed,wetlands have dried up.About 8 097.7ha of marsh land were turned into dry grassland and 1 039.58ha degraded to saline-alkalined land.The loss of grassland was 16.93×104ha,of which 40% was opened up to cropland and 22.3% degraded into hardly-used land.The degenerated area of moderate coverage grassland reached 2.26×104ha,while low coverage grassland degenerated at a higher annual loss rate of 1.93%.The number and size of marsh patch decreased significantly and the shape of patch tended to be more irregular and complicated,which indicated that the wetland landscape became more fragmental.The loss and degradation of wetlands were closely related to warmer and drier regional climate.The study indicates that noticeable changes in wetland were resulted from climate fluctuation and intensive human activities including irrational reclamation,overgrazing,ditches drainage,road construction and so on.
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    The Impact of Hydrological Characteristics of the Yellow River Coastline Changes in the Yellow River Delta
    CUI Bu-li, CHANG Xue-li, CHEN Ya-lin, DONG Qiong, LI Wei-qing
    2006, 21 (6):  957-964.  doi: 10.11849/zrzyxb.2006.06.013
    Abstract ( )   PDF (420KB) ( )   Save
    The Yellow River delta as a frequently changing area has been studied by using 3S techniques for us to best understand coastline dynamics of the Yellow River estuary.According to the trait of near-infrared wave which has the lowest reflecting ratio in water,the yearly coastline dynamics had been extracted by remote sensing technique during 1976 to 2002.Consequently,the overlay analysis of annual change of coastlines,supported by GIS technique,showed that the coastline stretching distance,the coastline length,and the renewed land area had fluctuated increasing trends in the research period.The changing trends could be divided into three stages obviously in more detailed temporal scales,the first was linear increase stage from 1976 to 1985,the second was fluctuating stage from 1986 to 1996,and the third was decreasing stage during 1997.Due to observation data of the Lijin Hydrological Station which is located in the Yellow River estuary,dynamics of the sediment carrying capacity of the Yellow River had been studied in the same temporal scale.There were significant yearly changing trends during research period,the carrying capacity of the 15 years changed more than 15kg/m3 during this period of time,and the maximum yearly changing rate of the carrying capacity reached 33.04kg/m3 between 1987 and 1988.In the general,the changing trend of the carry capacity of the Yellow River fluctuatedly decreased in the research period.Correlation analysis indicated that relationship between the hydrological characteristics of the Yellow River and the renewed-land amplification was most significant(significant check is more than 0.01 level.),the relation could be expressed as linear regression model.Findings also illustrated that there was a equilibrium point while runoff reached 135.32×108m3,the amount of sediment discharged was 3.517×108t,and the carrying capacity was 19.64kg/m3,all relating to the hydrological characteristics of the Yellow River.
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    Effects of Land Use on Soil Properties in Ziwuling Region
    QIU Li-ping, ZHANG Xing-chang
    2006, 21 (6):  965-972.  doi: 10.11849/zrzyxb.2006.06.014
    Abstract ( )   PDF (381KB) ( )   Save
    Land use exerts great influence on soil properties,including soil physical,chemical and biological properties,which in turn impact soil quality.In this paper,field investigation and laboratory analysis were conducted to reveal the relationship between land use conditions and changes of soil quality,which will provide valuable evidence for land management and eco-environment rebuilding.We studied major soil chemical properties and soil enzymatic activities under four land use conditions,i.e.forest land,farmland,ploughed abandoned land and unploughed abandoned land,in Ziwuling secondary forest area,and analyzed the relationship between land use and soil chemical and biological properties based on soil quality.The results showed that significant difference existed among soil organic matter,total nitrogen,total phosphorous contents,pH values,and activities of soil urease,invertase and alkaline-phosphatase in surface soils at different land use conditions.The major lower soil nutrients and enzymatic activities were observed in farmland,while the higher nutrients and enzymatic activities were observed in forest land.The major soil properties,exceptx pH values,were reduced with the increase of soil depth in soil profiles.The statistical analysis showed that significant or marked significant correlationship existed among soil organic matter,total nitrogen,total phosphorus,ammonia nitrogen,urease,invertase,alkaline-phosphatase and catalase.Soil degraded index(SQI),which was calculated based on forest area,indicated that soil quality has been greatly degraded in farmland and ploughed abandoned land.The soil degraded index in surface layer(0-20cm)were 44.86% and 43.10%,respectively.However,soil quality has been improved in deep layer soil(20-130cm)in unploughed abandoned land.
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    Organic Carbon Distribution and Storage of Soil Aggregates under Land Use Change in Jianghan Plain,Hubei Province
    TAN Wen-feng, ZHU Zhi-feng, LIU Fan, HU Rong-gui, SHAN Shi-jie
    2006, 21 (6):  973-980.  doi: 10.11849/zrzyxb.2006.06.015
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    Soil aggregates determine the fertility and productivity of soils,and possess the ability to protect soil organic carbon by physical entrapment.The land use change will affect the capacity of the soil to act as both a source and a sink of organic matter and nutrients.However,limited literature on soil organic carbon in aggregates with different sizes under land use change were reported.The objective of the present study was to elucidate aggregate composition,organic carbon(OC)distribution and storage of orchard soil,dryland soil,paddy soil,and dryland and paddy rotation soil from Jianghan plain.The results showed that the percentage of soil micro-aggregates in the following order:2-20μm,<2μm and 20-50μm.Soil micro-aggregates in <50μm size group occupied 80.8%-94.1% of the total soil micro-aggregates.The organic carbon contents under different land uses was the highest in 200-2 000μm fractions of aggregates.Furthermore,OC contents in >50μm fraction were higher than those in <50μm fraction.However,69.8%-86.6% of the total organic carbon was mainly found in the aggregates with a size of <50μm.Especially,35.2%-45.9% of the total organic carbon was concentrated in the aggregates with sizes of 2-20μm.So the fine micro-aggregates possessed the high ability of carbon sink,and the organic carbon content in coarse micro-aggregates responded easily to land use change.The content of active soil organic carbon in 2-20μm fraction of different aggregates was the lowest,and their differences between <2μm and 20-50μm was slight.The content of active soil organic carbon was higher in paddy field than that under dryland cultivation.It was proposed that 2-20μm fraction of aggregates was regarded as characteristic aggregates due to its high retention of soil organic carbon.These results will help to reveal the regional soil organic carbon sequestration.
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    Change of Natural Runoff and Contribution of the Natural and Artifical Factors to the Upper Reaches of Wei River
    WANG Xi-qin, ZHANG Yuan, ZHANG Yan-hui
    2006, 21 (6):  981-990.  doi: 10.11849/zrzyxb.2006.06.016
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    Since the 1960s,the quantity of inflow entering Shanxi Province in the upper reaches of the Weihe River has decreased steadily,and in the 1990s,the quantity of natural runoff was only 60% of that in the 1960s.This article analyzed the relationship between natural runoff and precipitation,as well as quantified the extent to that effect of rainfall and non-rainfall on the decreased natural runoff.The result indicated that both rainfall and non-rainfall contributed to the decreased natural runoff in the upper reaches of the Weihe River,and the contribution rate of non-rainfall factors increased from the 1970s,becoming the major reason resulting in the decreased natural runoff in the upper reaches of the Weihe River.This article also analyzed the relationship between natural runoff and temperature,and the correlation coefficient of both is more than 0.47.It further analyzed the influence made by natural and artificial factors,in the case of abstract the factor of air temperature from non-precipitation factor.The results showed that natural factors contributed most before the 1980s,while it was replaced by artificial factors after the 1980s.The extent of the influence of the latter intensified gradually due to runoff decrease resulting from human activity modified underlying surface.
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    Research on Urban Ventilation Channel Based on Climate Regulation
    LI Kun, YU Zhuang
    2006, 21 (6):  991-997.  doi: 10.11849/zrzyxb.2006.06.017
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    Wind,floating climate factor in nature,is one of the important components of urban eco-systems.Wind environment can promote communication between hot and cool air and be a media between metropolitan and ecological area.It can also enhance the ability of cities to suit hot climate.Basing on simulation CFD,this paper focused on a new way of the saving-energy design in urban planning.This way intended to build a few kinds of urban ventilation channels.The methods for increasing area's quality of ventilation and reaching the aim of lowing down the temperature of hot-island in summer and saving energy by using natural resources and efficient planning is introduced.This paper also discusses the issues of ventilation channels' feasibility,necessity,building types and so on.Then it displays a series of computer-aided research in wind field.
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