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921.
Effect of closed areas on distribution of fish and epibenthos 总被引:2,自引:1,他引:1
922.
923.
Roger Few 《The Geographical journal》2000,167(2):111-124
Critical analyses of public involvement in conservation projects in developing countries commonly point toward imbalances of power between project agencies and communities and the persistence of top-down patterns of decision-making. Taking an actor-oriented research approach, this paper probes beneath the surface patterns to analyse the complex socio-political mechanisms at work in the negotiating arena represented by public participation in project planning. The discussion is based on a case study of community involvement in the planning of protected areas in Belize. Detailed analysis of the power relations and tactical interactions between different actors in the negotiating arenas revealed that planner/community relations in the case study were dominated by a process identified as 'containment'. Containment refers to a strategic management of public involvement by the planning agencies, and it hinged on three fundamental social actions: avoidance of conflict; exclusion of dissent; and control over knowledge and procedure. Actions by local stakeholders that served to undermine containment constitute 'counter-containment'. The paper discusses these mechanisms in depth, before developing a comparative analytical framework of containment and counter-containment to help explain disparities in planning progress between different sites. 相似文献
924.
我国北方沙区退化植被的恢复机理 总被引:43,自引:23,他引:20
通过讨论我国北方沙区退化植被的恢复机理,认为气候驱动机制、植被自我修复机制、土壤环境变化和景观格局的驱动机制是我国北方沙区退化植被自然恢复的四个主要机制。其中,气候机制决定着植被恢复演替的方向和终点,是植被恢复的外在驱动机制;植被的自我修复机制决定着植物恢复的起始速度和演替速度,是植被恢复的内在驱动机制;而景观驱动作用只发生于斑块较小且呈镶嵌分布的退化植被区,对于面积很大且连片分布的流沙裸地其作用微弱;土壤条件的改善既是植被对土壤作用的结果,又反馈于植被的演替,它决定着群落演替的阶段性和群落类型,自始自终伴随着植被的演替过程。 相似文献
925.
中国山区经济发展差异与非农产业的贡献 总被引:20,自引:3,他引:17
以地区 (市) 作为基本研究单元,选取大小兴安岭、燕山、太行山区、沂蒙山区、武陵山区、东南丘陵、喀斯特山区、横断山区、祁连山区等具有典型性的中国山区,定量分析2000年中国山区经济发展态势以及影响和制约山区经济发展的深层次因素,并与平原地区和经济发达地区进行宏观、中观层面上的多方位对比分析。结果显示: 中国山区人均GDP的区域变化特征与山区非农产业人均增加值发展态势呈正相关;各类山区农业产业人均增加值表现为一条无差异曲线,即山区居民家庭收入的差距,主要来自非农产业,农业产业收入退于次要地位,非农产业人均增加值决定中国山区的经济发展的空间分异。 相似文献
926.
陕西秦岭国家级生态功能保护区土壤侵蚀的遥感分析 总被引:2,自引:0,他引:2
生态环境问题的调查是生态功能保护区规划的基础,本文介绍了利用1∶25万TM卫星遥感图像查明了陕西秦岭山地土壤侵蚀类型、土壤侵蚀强度及空间分布特征,分析了影响土壤侵蚀的主要因素及发展趋势,为生态功能保护区的准确划分提供依据。 相似文献
927.
利用引水区和黄河上游地区25个站1951—2000年50 a的气温和降水逐日资料,分析了研究区域降水的时空分布特征;把引水区和黄河上游地区分成7个小区,利用小波分析的方法研究了各小区气温和降水的多时间尺度特征.结果表明:黄河上游和南水北调西线引水区夏、秋、冬三季降水以同步的变化为主,其次为黄河上游与引水区之间存在反位相的变化.春季降水主要表现为黄河上游与引水区之间存在反位相的变化,其次才表现为一致的变化.各区的气温均以同步升温为主.降水具准3 a和准22 a周期,气温的振荡周期主要是2~5 a的小周期和准11 a的周期.引水区和黄河上游地区近50 a来夏季的降水在一致变化的基础上也有着明显的区别. 相似文献
928.
929.
Spatial and temporal variability of groundwater dynamics in a sub‐Mediterranean mountain catchment
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The temporal and spatial dynamics of groundwater was investigated in a small catchment in the Spanish Pyrenees, which was extensively used for agriculture in the past. Analysis of the water table fluctuations at five locations over a 6‐year period demonstrated that the groundwater dynamics had a marked seasonal cycle involving a wetting‐up period that commenced with the first autumn rainfall events, a saturation period during winter and spring and a drying‐down period from the end of spring until the end of the summer. The length of the saturation period showed great interannual variability, which was mainly influenced by the rainfall and evapotranspiration characteristics. There was marked spatial variability in the water table, especially during the wetting‐up period, which could be related to differences in slope and drainage area, geomorphology, soil properties and local topography. Areas contributing to runoff generation were identified within the catchment by field mapping of moisture conditions. Areas contributing to infiltration excess runoff were correlated with former cultivated fields affected by severe sheetwash erosion. Areas contributing to saturation excess runoff were characterized by a marked spatial dynamics associated with catchment wetness conditions. The saturation spatial pattern, which was partially related to the topographic index, was very patchy throughout the catchment, suggesting the influence of other factors associated with past agricultural activities, including changes in local topography and soil properties. The relationship between water table levels and stream flow was weak, especially during the wetting‐up period, suggesting little connection between ground water and the hydrological response, at least at some locations. The results suggest that in drier and human‐disturbed environments, such as sub‐Mediterranean mountains, saturation patterns cannot be represented only by the general topography of the catchment. They also suggest that groundwater storage and runoff is not a succession of steady‐state flow conditions, as assumed in most hydrological models. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
930.
城市功能区复合程度是城市发展规划、评价城市区域发展均衡性的重要参考。本文以深圳市为研究对象,首先,划分渔网单元与微博签到数据求交计算样方单元各类签到数据比例。其次,采用香农熵对复合程度进行定量化描述并连接渔网赋予属性值。最后,基于Arc GIS由粗至细进行可视化呈现和分析。结果表明,提出的方法能够有效地表示城市功能区的复合情况,具有较强的可操作性。 相似文献