吉林省发展绿色食品的农业生态环境优势分析   总被引：5，自引：1，他引：5  

孙道玮  俞穆清  田卫  冯立权  董致祥 《地理科学》2002,22(2):226-231

发展绿色食品生产是吉林省实施“生态省”建设工程的主导产业之一，本文按照绿色食品产地环境质量标准要求，客观评价了吉林省发展绿色食品的产地环境条件，得出吉林省具有发展绿色食品生产的显著农业生态环境优势。基于吉林省良好的农业生态环境质量，结合区域自然条件和资源优势，将全省分为东部山区、中部松辽平原区、西部松嫩平原区和大、中城市郊区四种区域类型，并分别提出了其发展绿色食品生产的宏观策略。  相似文献   

北江大堤植草护坡效应研究   总被引：8，自引：0，他引：8  

夏汉平  敖惠修  刘世忠  王广奎 《热带地理》2002,22(4):359-362

北江大堤在航运的浪涛侵蚀以及洪水和雨水的冲蚀下，部分河段边坡已变得支离破碎，对广州和珠江三角洲地区的防洪安全构成了严重威胁。香根草和百喜草都能耐较长时间的水淹，并都有较强的抗逆性。结合土石方工程，并辅以三维网覆盖，将香根草和百喜种在北江两岸的边坡上。结果，这一护坡措施不仅有较地防止了洪流冲蚀和雨水侵蚀，较好地起到了固土护坡作用，而且绿化美化了河岸边坡，成功解决了河湖水库的河岸带难以植被覆盖的难题。  相似文献   

The Space That Race Makes     

David Delaney 《The Professional geographer》2002,54(1):6-14

This essay is a revision of a paper prepared for an NSF workshop on race and geography. Participants in the workshop were asked to offer their views on the topic and our suggestions for further research. This contribution explores some aspects of the relationship and relevance of geography to the question of race in North America. It touches on three “places” that constitute the discipline: the place of research, the place of teaching, and the workplace. With respect to research, it suggests some promising lines of inquiry. Among these are studies of the relationship of scale to the politics of identity and studies of “passing” in connection with studies of geographies of experience and geographies of power.  相似文献   

The Spaces of Conservation and Development around Lake Nakuru National Park,Kenya     

Robert Daniels  Thomas J. Bassett 《The Professional geographer》2002,54(4):481-490

Geographically or sociologically defined resource management units, such as buffer zones or community resource management territories, seek to harmonize local land–use practices with protected–area management objectives. The geographically restricted nature of these models often results in simplistic representations of society–nature relations over time and space. Conservation areas are misrepresented as ecologically and socially homogeneous, as well as politically neutral. This study examines the limits of a spatially defined conservation and development project designed around the physical geographical unit of the watershed at Lake Nakuru National Park, Kenya. It argues that politically motivated violence that has plagued the area since the early 1990s has severely undermined the suitability of such narrowly defined conservation territories. Specifically, the case study points to the permeability of the Lake Nakuru watershed to national and regional political forces that ultimately constrain participation in conservation activities. The spaces of conservation and development must be enlarged to include these extralocal arenas and processes if environmental problems are to be effectively addressed.  相似文献   

Regulating Land Use Conflict on the Urban Fringe: Two contrasting case studies from the Australian poultry industry     

STEVEN HENDERSON 《The Australian geographer》2003,34(1):3-17

Land use conflict involving farm externalities represents an increasing policy concern in Australia as agricultural activities intensify and as the nation's metropolitan areas continue to expand outwards. A review of the rural-urban fringe literature reveals a noticeable absence of research exploring the intensity of conflict experienced by farmers. Similarly, inadequate attention has been given to the policies adopted by government to manage conflict. This article contrasts the regulatory system that has been implemented to manage conflict involving poultry farming on the metropolitan fringe of two Australian state capitals: Perth, Western Australia and Sydney, New South Wales. Spatial variation in the nature of government intervention is uncovered. In the discussion that follows reasons are identified to help explain such variation including state ideology, metropolitan growth, industry activism, geographical constraints and farm characteristics. It is concluded that where agricultural industries experience internal political divisions and a geographically dispersed membership it becomes more difficult to influence government policy.  相似文献   

罕见矿物--六方球方解石的发现及特征     

彭苏萍  丁述理  王贤君  刘钦甫 《矿物学报》2003,23(1):45-50

大庆油田部分三元复合驱抽油井结垢现象比较严重。井中结垢损害抽油设备，增加了生产成本。通过运用XRD，IR，SEM和化学分析手段对抽油井垢的研究发现，垢的主要化学成分为CaO和SiO2，其含量分别为67％和28％，油井垢中的主要矿物成分是罕见矿物——六方球方解石。六方球方解石呈微晶状(1—10μm)，并常常以微晶聚集的球粒状出现，同时伴生有无定形SiO2。呈游离态的SiO2和有机质对于六方球方解石的形成起到了重要作用。  相似文献   

生态地理建模中的多尺度问题   总被引：29，自引：0，他引：29  

岳天祥  刘纪远 《第四纪研究》2003,23(3):256-261

本文在分析生态地理建模内涵的基础上,讨论了生态地理建模中的尺度转换问题、跨尺度相互作用问题、空间尺度与时间尺度的关联问题和多尺度数据处理问题.由于生态地理问题的非线性、生态环境的异质性和随机事件,简单的线性尺度转换方法远不能满足生态地理建模的要求.为了从根本上解决生态地理建模中的时空尺度问题,除需要运用微分几何学和等级理论等经典方法外,还需要引入格点生成法和网格计算等现代理论和技术手段.  相似文献   

景观指数的粒度变化效应   总被引：66，自引：0，他引：66  

赵文武  傅伯杰  陈利顶 《第四纪研究》2003,23(3):326-333

本文以延河流域的1:250000和1:500000土地利用图为对象,以景观格局分析程序Fragstats3.3为分析工具,探讨了不同比例尺条件下景观指数随粒度增加的变化特征.研究结果表明,随着粒度值由25m到400m的逐渐增加,除斑块丰富度外的景观指数均具有明显的尺度效应,其中聚集度和集合度没有尺度转折点,其他指数具有明显或不明显的尺度转折点.对比分析1:250000和1:500000土地利用格局指数的计算结果可以发现:1)尺度转折点不是一个值,而是一个相对较小的区间;2)尺度转折点与研究图件的比例尺有关,比例尺越大,所发生的第一次尺度转折点的粒度就越小;3)第一尺度域是选择适宜粒度的较好取值范围.对延河流域1:250000土地利用图进行景观指数计算的适宜粒度范围是70～90m,1:500000土地利用图的适宜粒度范围是90～120m.  相似文献   

Methodology for construction, calibration and validation of a national hydrological model for Denmark   总被引：13，自引：0，他引：13  

Hans Jrgen Henriksen  Lars Troldborg  Per Nyegaard  Torben Obel Sonnenborg  Jens Christian Refsgaard  Bjarne Madsen 《Journal of Hydrology》2003,280(1-4):52-71

An integrated groundwater/surface water hydrological model with a 1 km² grid has been constructed for Denmark covering 43,000 km². The model is composed of a relatively simple root zone component for estimating the net precipitation, a comprehensive three-dimensional groundwater component for estimating recharge to and hydraulic heads in different geological layers, and a river component for streamflow routing and calculating stream–aquifer interaction. The model was constructed on the basis of the MIKE SHE code and by utilising comprehensive national databases on geology, soil, topography, river systems, climate and hydrology. The present paper describes the modelling process for the 7330 km² island of Sjælland with emphasis on the problems experienced in combining the classical paradigms of groundwater modelling, such as inverse modelling of steady-state conditions, and catchment modelling, focussing on dynamic conditions and discharge simulation. Three model versions with different assumptions on input data and parameter values were required until the performance of the final, according to pre-defined accuracy criteria, model was evaluated as being satisfactory. The paper highlights the methodological issues related to establishment of performance criteria, parameterisation and assessment of parameter values from field data, calibration and validation test schemes. Most of the parameter values were assessed directly from field data, while about 10 ‘free’ parameters were subject to calibration using a combination of inverse steady-state groundwater modelling and manual trial-and-error dynamic groundwater/surface water modelling. Emphasising the importance of tests against independent data, the validation schemes included combinations of split-sample tests (another period) and proxy-basin tests (another area).  相似文献   

基于DEM的河流多尺度显示研究   总被引：6，自引：0，他引：6  

沈涛  苏山舞 《测绘科学》2003,28(2):20-22

进行了基于DEM的河流多尺度显示方法的研究和试验。采用斯特拉勒算法对河流线进行分级,通过DEM提取河流的高差、集水面积等属性信息,并以此为基础提出了对河流的主支流的自动判别的方法,最终以国家基础地理信息的全国1∶25万数据库为数据源实现了实验区域河流的多尺度显示。  相似文献