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1.
青藏高原城乡建设用地和生态用地转移时空格局   总被引：1，自引：0，他引：1  
青藏高原作为中国重要的生态环境保护地,城镇化和生态环境的变化受到广泛关注。本文基于1990-2015年土地利用数据,进行生态用地和城乡建设用地之间的转移分析,通过核密度以及标准差椭圆分析进行空间转移强度的定性研究。结果表明：① 1990-2015年青藏高原生态用地显著地向城乡建设用地转移,是城乡建设用地向生态用地转移量的54.6倍,其中2000-2005年和2010-2015年是用地转移的热点时期;② 城乡建设用地与生态用地之间的转换在空间上呈现逆向状态,生态用地向城乡建设用地的转移分布逐渐从青藏高原的周边区域向腹地蔓延;城乡建设用地向生态用地的转移最初出现在青藏高原的腹地,逐渐向外围扩张;③ 生态服务功能越大的生态用地,越容易被人类占用,随之发生用地类型的转移,侵占后的土地很难反向转移为具有高生态服务功能的生态用地。  相似文献   

2.
本文以济南市泉水补给区为研究对象,利用GIS空间分析方法,在其景观变化分析的基础上,参照中国陆地生态系统的生态服务价值系数,估算了泉水补给区生态服务功能价值变化,重点分析景观变化对研究区生态服务功能的影响,进而为区域可持续发展和城市建设提供理论支持。结果表明:(1)20世纪90年代以来,泉水补给区耕地和草地景观面积呈减少趋势,林地、园地和建设用地景观面积大幅增加,其中,以林地面积增加最大;从景观类型转化看,耕地与其他景观类型相互转化较为密切,特别是与建设用地和园地之间的转化;林地面积的增加主要来源于草地和耕地;(2)泉水补给区生态服务功能价值主要由林地和耕地景观生态服务价值构成,其变化对该研究区生态服务价值变化起决定作用;从生态服务价值构成类型来看,该地区土壤形成与保护服务功能单项价值所占比重最大,约占总服务功能价值的20%;(3)90年代以来,该地区总生态服务价值呈增加趋势;从单项服务价值变化来看,水源涵养、废物处理和食物生产服务功能价值则呈现出减小趋势,其中,以水源涵养减幅最大,为4.01%,主要是由该区建设用地增加,地面硬化面积增多而引起的。研究认为,济南市南部山区作为重要的泉水补给区,其生态服务功能尤为重要,特别是水源涵养功能,因此,研究区水源涵养服务功能价值的降低应在今后南部山区开发过程中得到足够的重视与保护,逐步增加泉水补给区的整体生态效益。  相似文献   

3.
Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and forecast forest cover and other land-use changes for the protection and conservation of mountainous environment. The present study deals with the assessment of forest cover and other land-use changes in the mountain ranges of Dir Kohistan in northern Pakistan, using high resolution multi-temporal SPOT-5 satellite images. The SPOT-5 satellite images of years 2004, 2007, 2010 and 2013 were acquired and classified into land-cover units. In addition, forest cover and land-use change detection map was developed using the classified maps of 2004 and 2013. The classified maps were verified through random field samples and Google Earth imagery (Quick birds and SPOT-5). The results showed that during the period 2004 to 2013 the area of forest land decreased by 6.4%, however, area of range land and agriculture land have increased by 22.1% and 2.9%, respectively. Similarly, barren land increased by 1.1%, whereas, area of snow cover/glacier is significantly decreased by 21.3%. The findings from the study will be useful for forestry and landscape planning and can be utilized by the local, provincial and national forest departments; and REDD+ policy makers in Pakistan.  相似文献   

4.
We analyzed the characteristics and trends of land-use change in and near the coastal zone of the Yangtze River Delta (YRD) during five periods (1995, 2000 2005, 2010, and 2015) using remotely sensed Landsat imagery. Using automatic supervised classification combined with visual interpretation, we obtained land-use information for five study areas (Nantong, Shanghai, Jiaxing, Ningbo, and Zhoushan). Significant land-use changes have occurred in this area between 1995 and 2015, characterized in particular by large reductions in cultivated land and rapid increases in urbanized land. In addition, land reclamation was very active in this period as an effective supplement to the increased demand for land development: since 1995, 1622 km2 of land was reclaimed from near-coastal regions in the study area. This increase in urbanization was jointly driven by population, economic, transportation, and policy factors. Urban areas expanded from the center outward in concentric rings, with infrastructure guiding the radial expansion of development along transportation corridors, thus forming a network of connections. Due to the influence of national land regulation policies, the expansion rate of development in the YRD gradually diminished after 2010. This indicates that the area’s resource and environmental carrying capacity has reached a saturation stage in which urbanization has transitioned from broad and incremental expansion to the intensive use of land resources.  相似文献   

5.
This study investigated and simulated land use patterns in Beijing for the year 2000 and the year 2005 from the actual land use data for the year 1995 and the year 2000,respectively,by combining spatial land allocation simulation using the CLUE-S model,and numerical land demand prediction using the Markov model.The simulations for 2000 and 2005 were confirmed to be generally accurate using Kappa indices.Then the land-use scenarios for Beijing in 2015 were simulated assuming two modes of development:1) urban development following existing trends;and 2) under a strict farmland control.The simulations suggested that under either mode,urbanized areas would expand at the expense of land for other uses.This expansion was predicted to dominate the land-use conversions between 2005 and 2015,and was expected to be accompanied by an extensive loss of farmland.The key susceptible to land-use changes were found to be located at the central urban Beijing and the surrounding regions including Yanqing County,Changping District and Fangshan District.Also,the simulations predicted a considerable expansion of urban/suburban areas in the mountainous regions of Beijing,suggesting a need for priority monitoring and protection.  相似文献   

6.
Sutainable use of natural resources is different from sustainable development.As the most important natural resource,sustainable use of land resource is the essential guarantee of sustainable development.The nature of sustainable use of land resource is to retain the quantity and productivity of land resource from generation to generation.The evaluaton of sustainable use of land resource is an important method to ensure land-use to get onto the sustainable track.Furthermore,building index system is the key of the evaluation.In view of tendency of the evaluation indexes chosen so widely,the evaluation indexes should include only three kinds in the researches on the evaluation of sustainable use of land resourece.The first is the stock and structure index of land resource,viz,Areas quantity structure of land resources.In China,it is especially paid attention to the per person index of landquantity and rate between cultivated land farmland.The second is the productive index of land,which includes the productivity,potentiality,stability and renewal situation of land.The third is the sustained index of land environment .On the evaluation research of areal level,we should lay particular emphasis on statistic indexes.With a case of Guangxi Zhuang Autonomous Region in China,the evaluation index system of sustainable land-use in county area has been built in this thesis,Using the weighted average method to calculate the means of sustainable land-use in each county,according to the land-using situation,all counties in the autonomous region have been divided into three types.(1)Sustainable Pattern contains 18 counties,which have higher land resource productivity,stronger sustained abilities of land environment.The economic benefits of land-using in these conties are obviously higher.These counties have gotten highly intensive farming,and tyey are all in the good circumstance.(2)Basically Sutained Pattern contains 48 counties,which productivity of land resource is of middle level.In part of counties are obviously higher.These counties can rapidly enter in a good circumstance.(3)Critically Sustained Pattern contains 14 counties,which are mostlyin the karst mountain areas.They have less stock of land resource,lower productivity and more extensive culitivation.The productivity of land renewing has been hindered.so it urgently need to be renovated.At last,the writers have explored the basic ways of sustainable use of land resource in Guangxi,China-(1)Retain the stock of land resource and strictly manage farmland uses.(2)Strengthen the value accounting of land resource,and control the farmland occupation of non-agricultural controction.(3)Depend on technology advanced,optimize the land-using structure,and promote the productive level.(4)Carry out land management all-round,and improve the ecological environment of land resource.(5)Enhance evaluation researche and land monitoring ,and promote the sustainable utilization level of land resource.  相似文献   

7.
FLUS模型是一种新型的土地利用变化模拟模型,应用前景广阔。本文通过在FLUS模型的人工神经网络(Artificial Neural Network,ANN)训练模块中引入空间自相关因子来改进模型,以珠江三角洲地区为例,基于2009年、2015年土地利用数据和一系列驱动因子对改进的模型进行了验证,并利用该改进的FLUS模型模拟了2035年研究区在3种情景下土地利用变化格局。结果表明:①引入空间自相关因子后各地类发生概率分布的预测精度更高,耕地、林地、建设用地、水体和未利用土地的拟合优度ROC值分别从0.819、0.928、0.885、0.855和0.861提高到0.857、0.934、0.890、0.863和0.978;②改进的FLUS模型的模拟精度有一定的提高,Kappa系数从0.732提高到0.744,FOM系数从0.077升到0.106;③情景模拟表明,3种情景下珠江三角洲建设用地和林地均将增加、而耕地均呈减少趋势。但不同情景下模拟的土地利用格局也存在显著差异:基准情景下,建设用地明显扩张且大幅侵占耕地。耕地保护情景下,耕地面积保持在合理水平,建设用地蔓延扩张趋势得到遏制,土地利用布局总体趋向合理。生态保护情景下,耕地、林地和水体得到较好保护,建设用地布局更为合理,土地利用可持续性明显提高。  相似文献   

8.
A crucial region for China's ‘Grain-forGreen Policy' is located within a traditional farmpastoral area, between 2000 to 3000 m above sea level, on the eastern Qinghai-Tibetan Plateau.However, the responses of soil organic carbon(SOC) to different land-use patterns in this region are unclear. Here, we determined the SOC(0–20 cm) content of grasslands and forests that are being converted from farmlands, as well as in abandoned arable land and arable land in this region. The factors influencing the reclaimed lands were analyzed along altitudes from 2030 to 3132 m. Our results showed that SOC content was higher for grassland and abandoned arable land than forest and arable land. The SOC content increased with the increase in altitude for total land-use patterns. Further, the grassland and abandoned arable land had higher SOC content than the forest with almost parallel trends along the increase in altitude. However, the proportion of regulated factors of altitude and species richness varied among forest, grassland, and abandoned arable land. Our results indicated that the land-use pattern of returning farmland to grassland and abandoned arable land was more effective in terms of the SOC storage in the superficial layer in this altitude range in the Qinghai-Tibetan Plateau, thereby being beneficial to optimizing land management in this region.  相似文献   

9.
生物多样性是人类赖以生存与发展的基础。中国生物多样性保护优先区域集中分布着中国绝大多数的生物物种,如何保护好这些区域的生态系统和生物多样性,是实现可持续发展急需解决的问题。本文基于2010年和2015年的2期土地利用/覆被数据,应用人类干扰指数,分析了中国生物多样性保护优先区域人类干扰的程度及变化。结果表明：① 2015年中国生物多样性保护优先区域人类干扰程度以微度和轻度为主,15个优先区处于微度干扰,占优先区总面积的84.10%,13个处于轻度干扰,占优先区总面积的6.65%;华北平原黄土高原区和华东华中丘陵平原区人类干扰程度较高,而西南高山峡谷区、蒙新高原荒漠区和青藏高原高寒区人类干扰程度很低;② 2010-2015年,占优先区总面积84.54%的区域人类干扰程度基本持衡,人类干扰程度发生增加和下降的面积大致冲抵,生物多样性保护优先区域整体变化不大,华南低山丘陵区和东北山地平原区人类干扰程度较高,且升幅超过1%,华北平原黄土高原区降幅最大,为0.15%;③ 人类干扰程度较高且变化幅度大的区域,主要受经济发展对生态系统干扰及土地利用程度加深的影响,对农田、居民点及工矿交通用地的需求增加,退耕还林等部分生态工程实施有利于减少人类对生态系统的干扰程度。总体上看,全国32个生物多样性保护优先区域整体上人类干扰程度较低且变化幅度较小,且人类干扰程度高的区域分布较集中,说明国家生态保护各项政策与措施的实施对生物多样性保护起到了良好的促进作用,有利于生物多样性的保护。  相似文献   

10.
退耕还林（草）等生态工程对区域用地结构及生态系统服务功能产生了重要影响。本研究基于RUSLE模型,并辅以遥感监测与GIS空间分析方法,对北方农牧交错带西段2000-2015年退耕状况及其引起的土壤保持功能变化分3个时段（2000-2005年、2005-2010年及2010-2015年）进行了探究。结果表明：北方农牧交错带西段地区2000-2015年耕地面积净减少1663.83 km2,以转为林地、草地、建设用地为主,其中耕地转林、草地净减少面积为1113.64 km2,草地和未利用地是新增耕地的主要来源;15年间土壤保持功能提升显著,退耕还林（草）工程的实施使土壤保持量增加了56.50×104 t,2005-2010年由退耕所带来的土壤保持增加量在3段时期中最高;不同坡度等级的生态退耕引起的土壤保持增加量差别较大,总体随着坡度升高呈下降趋势,但在25°以上的陡坡耕地由退耕还林（草）带来的土壤保持效益又有所升高。研究对于评估北方农牧交错带西段地区实施退耕还林（草）等工程的生态效益具有重要意义,并能为区域生态保护与修复工程的建设规划提供科学依据。  相似文献   

11.
Understanding the effects of land cover changes on ecosystem carbon stocks is essential for ecosystem management and environmental protection, particularly in the transboundary region that has undergone marked changes. This study aimed to examine the impacts of land cover changes on ecosystem carbon stocks in the transboundary Tumen River Basin (TTRB). We extracted the spatial information from Landsat Thematic Imager (TM) and Operational Land Imager (OLI) images for the years 1990 and 2015 and obtained convincing estimates of terrestrial biomass and soil carbon stocks with the InVEST model. The results showed that forestland, cropland and built-up land increased by 57.5, 429.7 and 128.9 km2, respectively, while grassland, wetland and barren land declined by 24.9, 548.0 and 43.0 km2, respectively in the TTRB from 1990 to 2015. The total carbon stocks encompassing aboveground, belowground, soil and litter layer carbon storage pools have declined from 831.48 Tg C in 1990 to 831.42 Tg C in 2015 due to land cover changes. In detail, the carbon stocks decreased by 3.13 Tg C and 0.44 Tg C in Democratic People’s Republic of Korea (North Korea) and Russia, respectively, while increased by 3.51 Tg C in China. Furthermore, economic development, and national policy accounted for most land cover changes in the TTRB. Our results imply that effective wetland and forestland protection policies among China, North Korea, and Russia are much needed for protecting the natural resources, promoting local ecosystem services and regional sustainable development in the transnational area.  相似文献   

12.
西藏自治区特殊的高寒生态系统对人类活动具有高度敏感性,定量评估系列政策实施下西藏生态系统调节服务对人类活动强度变化的响应有助于西藏生态政策和空间规划的调整完善。本研究基于西藏1980年和2015年土地利用现状数据及1992—2013年DMSP/OLS夜间灯光指数数据,借助GIS空间分析功能分析了居民点用地和夜间灯光强度的变化;并结合生态系统调节服务空间数据,利用相关分析对居民点用地和夜间灯光变化所反映的人类活动强度变化对西藏生态系统水土保持和防风固沙服务的影响进行研究。结果表明：① 1980—2015年,西藏新增居民点用地212.06 km2,减少居民点用地44.99 km2,其中,新增居民点用地中62%为城镇用地,减少的居民点用地中95.88%为农村居民点;居民点用地变化主要发生在藏南河谷区;② 自治区内居民点用地扩张一定程度上直接导致夜间灯光强度增加,“一江两河”流域土地整治工程和农牧民安居工程等促进了当地人类活动强度增加,区内部分乡镇因进城务工和易地扶贫搬迁造成了当地人类活动强度的下降;③ 西藏2015年防风固沙服务较1990年有整体增强趋势,水土保持服务除藏东高山峡谷区外均有大幅度退化趋势;④ 对居民点用地进行的还林、还草整治工程等人类活动有利于促进生态系统防风固沙服务的恢复;人类活动强度的增加极易导致水土保持服务的退化,“一江两河”流域体现最为明显。研究能为西藏国土空间规划和生态政策的制定和调整提供参考。  相似文献   

13.
城市土地利用优化配置分析应用——以济南市为例   总被引：13，自引：0，他引：13  
对城市土地资源进行优化配置,提高城市土地利用的集约程度,是当前城市土地利用研究领域中的热点问题。本文以济南市为研究区,通过构建系统动力学模型对济南市土地利用的数量结构进行预测,在此基础上,利用ArcGIS软件的二次开发语言编写程序,实现了济南市土地利用的空间优化配置,为济南市城市内部土地资源的合理开发与利用,提供决策参考。  相似文献   

14.
As an important means regulating the relationship between human and natural ecosystem,ecological restoration program plays a key role in restoring ecosystem functions.The Grain-for-Green Program(GFGP,One of the world’s most ambitious ecosystem conservation set-aside programs aims to transfer farmland on steep slopes to forestland or grassland to increase vegetation coverage)has been widely implemented from 1999 to 2015 and exerted significant influence on land use and ecosystem services(ESs).In this study,three ecological models(In VEST,RUSLE,and CASA)were used to accurately calculate the three key types of ESs,water yield(WY),soil conservation(SC),and net primary production(NPP)in Karst area of southwestern China from 1982 to 2015.The impact of GFGP on ESs and trade-offs was analyzed.It provides practical guidance in carrying out ecological regulation in Karst area of China under global climate change.Results showed that ESs and trade-offs had changed dramatically driven by GFGP.In detail,temporally,SC and NPP exhibited an increasing trend,while WY exhibited a decreasing trend.Spatially,SC basically decreased from west to east;NPP basically increased from north to south;WY basically increased from west to east;NPP and SC,SC and WY developed in the direction of trade-offs driven by the GFGP,while NPP and WY developed in the direction of synergy.Therefore,future ecosystem management and restoration policy-making should consider trade-offs of ESs so as to achieve sustainable provision of ESs.  相似文献   

15.
As a result of rapid urbanization in China, urban sprawl has increased rapidly, and land-use regulation and smart urban growth are equally important. Spatial function regionalization can provide the scientific groundwork for the regulation of land use and protection. This paper probes the system of evaluation indices and applies the methods of spatial analysis and classification clustering to the calculation of the ecologically significant value and economically significant value in each evaluation unit. After use of a classification matrix integrated by the two significant values, city space can be divided into four functional types, namely, feasible development area, moderate development area, moderate conservation area and prohibited exploiting area, and these are the basis for spatial development and control.  相似文献   

16.
在国家大力推进新型城镇化和落实城市群空间规划的背景下,评价城市群土地生态安全水平,并以此为限制条件预测城市群未来土地利用格局,对城市群可持续发展具有重要意义。本文以环鄱阳湖城市群为研究对象,对城市群土地生态安全格局和变化进行分析,根据土地生态安全评价结果设置自然发展情景和生态保护情景,结合多分类Logistic回归和多标准评价方法(MCE),构建CA-Markov模型,预测2种情景下2030年土地利用格局并进行对比分析。研究结果表明:①2005、2010和2015年,环鄱阳湖城市群网格平均生态安全值分别为0.574、0.573和0.571,空间布局上呈现"中部低、东西高"的特征;②预测2030年,自然发展情景下新增城镇用地主要位于九江市、上饶市和南昌市,生态保护情景下限制城镇用地和其他建设用地向土地生态安全高值区扩展,使得城镇用地和其他建设用地扩展更加集中;③预测生态保护情景下,高生态安全区面积比自然发展情景下多39.39%且分布更加均匀,包括鄱阳湖周边区域、九江市中部以及新余市和吉安市,城市群生态安全得到有效保护。该研究可为环鄱阳湖城市群土地利用规划及生态保护提供参考。  相似文献   

17.
Ecological migration is the process of increasing the population density in the immigration area and transferring the ecological pressure from emigration area to immigration area. This process may result in significant changes in land use and land cover in the area of immigration and have an important effect on ecosystem services. Therefore, scientifically revealing the effects and differentiation mechanisms of ecological migration on ecosystem services is becoming an important issue related to the implementation of the national ecological migration strategy in China. This study employed the Hongsibu District as a typical example of ecological migration. Hongsibu District is located in the central Ningxia steppe and desert steppe areas. Remote sensing data covering five periods from the period before ecological migration in 1995 and after migration in 2000, 2005, 2010, and 2015 was used to measure the value of ecosystem services(ESV). A geographical detector model and the value of ecosystem services model were used to diagnose the dynamic mechanism of the effects of land use change on ecosystem services. The results showed that: 1) The development of large-scale ecological resettlement has caused the area of cultivated land and urbanized land area to increase significantly in the area of immigration, while the grass area decreased significantly. 2) The overall value of the Hongsibu ecosystem services increased in a form of a ‘V'. Among them, during the period of 1995–2005, the overall ESV decreased and had an annual rate of change of-0.67%. During the period of development 2005–2015, the ESV increased steadily, with an annual rate of change of 0.79%. 3) The proportion and total ESV in soil formation and protection, waste treatment, and biodiversity conservation of the Hongsibu District decreased from 57.61% in 1995 to 56.17% in 2015, indicating that the region's ecological regulation function slightly decreased. 4) The ESV in the Hongsibu District, showed a low distribution pattern of ecosystem services increasing from northeast to southwest, and the capacity of three townships, Hongsibu, Taiyangshan, and Liuquan, to provide ecosystem services gradually declined over time. The ecological service function of Xinzhuangji Township and Dahe Township gradually improved. 5) The sensitivity index of the ESV of each land use type was less than 1, indicating that the environment lacks flexibility in providing a strong ESV index in Hongsibu, which shows that the research results are reliable and believable. 6) During the study period, the decisive force of the change of land use on ecosystem services in Hongsibu District was: grassland(0.9934), climate regulation(0.9413), soil formation and protection(0.9321) and waste treatment(0.9241).  相似文献   

18.
This investigation is an analysis of the influence of landform instability on the distribution of land-use dynamics in a hydrographical basin, located in the Mexican Volcanic Belt mountain range (central Mexico), currently affected by substantial changes in land use and deforestation. A landform map was produced, in addition to seven attribute maps - altimetry, drainage density, slope, relief energy, potential erosion, geology and tectonics - which were considered as factors for determining landform instability through Multi-criteria Evaluation Analysis. Likewise, the direction and rhythm of land-use dynamics were analyzed in four dates - between 1976 and 2000 - and cross tabulations were made between them, in order to analyze the trends and processes of land-use dynamics. Afterwards, the databases obtained were cross tabulated with the landform variables to derive areas, percentages and correlation indices. In the study area, high-instability landforms are associated with most ancient volcanic and sedimentary landforms, where high altitude, drainage density, slope and potential to develop gravitational and fluvial processes are the major factors favouring a land-use pattern, dominated by the conservation of extensive forest land, abandonment of human land use and regeneration of disturbed areas. In contrast, low-instability landforms correspond to alluvial plains and lava hills covered by pyroclasts, where low potential erosion to develop fluvial processes, added to water and soil availability and accessibility, have favoured a land-use pattern dominated by the expansion of agroforestry plantations and human settlements, showing a marked trend towards either intensification or permanence of the current land use and with little abandonment and regeneration.  相似文献   

19.
Land-use change is an important aspect of global environment change. It is, in a sense, the direct result of human activities influencing our physical environment. Supported by the dynamic serving system of national resources, including both the environment database and GIS technology, this paper analyzed the land-use change in northeastern China in the past ten years (1990–2000). It divides northeastern China into five land-use zones based on the dynamic degree (DD) of land-use: woodland/grassland — arable land conversion zone, dry land — paddy field conversion zone, urban expansion zone, interlocked zone of farming and pasturing, and reclamation and abandoned zone. In the past ten years, land-use change of northeastern China can be generalized as follows: increase of cropland area was obvious, paddy field and dry land increased by 74.9 and 276.0 thousand ha respectively; urban area expanded rapidly, area of town and rural residence increased by 76.8 thousand ha; area of forest and grassland decreased sharply with the amount of 1399.0 and 1521.3 thousand ha respectively; area of water body and unused land increased by 148.4 and 513.9 thousand ha respectively. Besides a comprehensive analysis of the spatial patterns of land use, this paper also discusses the driving forces in each land-use dynamic zones. The study shows that some key biophysical factors affect conspicuously the conversion of different land-use types. In this paper, the relationships between land-use conversion and DEM, accumulated temperature (⩾10°C) and precipitation were analysed and represented. We conclude that the land-use changes in northeast China resulted from the change of macro social and economic factors and local physical elements. Rapid population growth and management changes, in some sense, can explain the shaping of woodland/grassland — cropland conversion zone. The conversion from dry land to paddy field in the dry land — paddy field conversion zone, apart from the physical elements change promoting the expansion of paddy field, results from two reasons: one is that the implementation of market-economy in China has given farmers the right to decide what they plant and how they plant their crops, the other factor is originated partially from the change of dietary habit with the social and economic development. The conversion from paddy field to dry land is caused prmarily by the shortfall of irrigation water, which in turn is caused by poor water allocation management by local governments. The shaping of the reclamation and abandoned zone is partially due to the lack of environment protection consciousness among pioneer settlers. The reason for the conversion from grassland to cropland is the relatively higher profits of farming than that of pasturing in the interlocked zone of farming and pasturing. In northeastern China, the rapid expansion of built-up areas results from two factors: the first is its small number of towns; the second comes from the huge potential for expansion of existing towns and cities. It is noticeable that urban expansion in the northeastern China is characterized by gentle topographic relief and low population density. Physiognomy, transportation and economy exert great influences on the urban expansion. Foundation item: Under the auspices of Knowledge Innovation program Key Project of the Chinese Academy of Sciences (KZCX-2-308). Biography: LIU Ji-yuan (1947 - ), male, a native of Shanghai Municipality, professor, Director General of Institute of Geographical Sciences and Natural Resources Research, the Chinese Academy of Sciences. His research interests include environment and resources, remote sensing and geography.  相似文献   

20.
Labile organic carbon(LOC) and carbon management index(CMI), which are sensitive factors to the changes of environment, can improve evaluating the effect of land management practices changes on soil quality. The objective of this study was to investigate the effects of land use types and landscape positions on soil quality as a function of LOC and CMI. A field study in a small watershed in the red soil hilly region of southern China was conducted, and soil samples were collected from four typical lands(pine forest(PF) on slope land, barren hill(BH) on slope land, citrus orchard(CO) on terrace land and Cinnarnornum Camphora(CC) on terrace land) at a sampling depth of 20 cm. Soil nutrients, soil organic carbon(SOC), LOC and CMI were measured. Results showed that the LOC and CMI correlated to not only soil carbon but also soil nutrients, and the values of LOC and CMI in different land use types followed the order CC PF CO BH at the upperslope, while CO CC BH PF at mid-slope and down-slope. With respect to slope positions, the values of LOC and CMI in all the lands were followed the order: upper-slope down-slope midslope. As whole, the mean values of LOC and CMI in different lands followed the order CC CO PF BH. High CMI and LOC content were found in the terrace lands with broadleaf vegetations. These results indicated that the terracing and appropriate vegetations can increase the carbon input and lability and decrease soil erosion. However, the carbon pools and CMI in these lands were significantly lower than that in reference site. This suggested that it may require a long time for the soil to return to a highquality. Consequently, it is an efficient way to adopt the measures of terracing and appropriate vegetations planting in improving the content of LOC and CMI and controlling water and soil loss in fragile ecosystems.  相似文献   

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