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541.
Yeya Lake Wetlands are the largest site for wintering birds in Beijing, where common cranes(Grus grus)winters every year. The land cover of the wetlands has undergone distinct changes from 2006 to 2009 as a result of human activities. In 2006, a survey of the presence/absence of the birds was completed using a line-transect method.A predictive model of habitat suitability was derived by using logistic regression and geographic information system.Then, this habitat suitability model was applied in 2009 under the land use change to test the effectiveness of the model and compare the habitat suitability between 2 years. The negative associations between Grus grus presence and increasing elevation, distances to grassland, to farmland, to bush, and to road suggested a preference for low lying areas in close proximity to food and cover. While the positive associations with distances to buildings and to water suggested a preference for low disturbance areas. The areas of suitable habitats increased from 2006 to 2009, and the spatial model was effective in both years. Habitat preference of Grus grus varied in land use types, therefore habitat suitability dynamics might possibly relate to land use change and thereby be predictable through a geographic information system approach. Although the obtained model had a good fit in both years, it was suspected that if frequent human activities continued, the number of Grus grus might decrease or disappear in this area. According to the field survey, the spacious water area was essential for wintering birds and the risks from loss of lake water and unfavorable crop practices might dramatically change the quality of each type of land use.  相似文献   
542.
In Nepal, nearly half of the total land is covered by forest, which holds a potentially important position in promoting rural livelihoods and in alleviating rural poverty. The rural landscape that encompasses an agrarian economy, a fragile ecology, and a complex and differentiated society is changing rapidly in Nepal today. Although poverty alleviation has been one of the top priorities for national development since 1976, poverty still remains widespread, persistent and it is also an acute problem in Nepal, where people are in a state of deprivation with regard to incomes, clothing, housing, healthcare, education, sanitary facilities and human rights. Thus, Nepal is considered as one of the poorest countries in South-Asia, with 25.2% people living below the poverty line. The objective of this study was to assess changes in poverty of forest users brought on by the community forestry program, in order to analyze the level of participation in community forestry management activities. For this study, Bajhang district was chosen as the study site, which is one of the poorest and most remote districts in the country of Nepal. Different Participatory Rural Appraisal methods such as face-to face interviews, focus group discussions and key informants’ interviews including secondary data were used to gather information. The findings showed that the forest users’ participation in meetings, discussion and other activities, like community forestry management or silvicultural operation related to community forestry, was high. The assessment found that 42.3%, 32.6% and 25.1% of respondents strongly agreed, agreed and were neutral, respectively, towards the idea that poverty reduction from community forests had occurred. The results showed almost all the respondents were depended upon agriculture and/or forest resources for their livelihoods. Different ecosystem services such as ethnomedicines, aesthetic value and ecotourism, control of soil erosion/land-slides, water recharge and soil fertility have increased due to the decomposition of leaf litter. This was apparent from the formulation of community forests. Poverty in rural areas of the country is still higher than in urban areas and the incidence of poverty is the highest in the Far western Province where this research was conducted, Therefore, the government, policy makers and other stakeholders should work hand-in-hand to effectively reduce the poverty that persists in Nepal.  相似文献   
543.
中国电子信息产业创新的集群网络模式与演化路径   总被引:2,自引:1,他引:1  
周灿  曹贤忠  曾刚 《地理研究》2019,38(9):2212-2225
流空间背景下,多空间尺度网络耦合对创新至关重要已达成学界共识。综合运用区位熵与社会网络分析,识别32个电子信息产业集群,进而基于1985—2015年合作申请发明专利数据,运用卡方检验和Infomap社区发现算法,借助Pajek和ArcGIS等软件,揭示中国电子信息产业创新合作空间模式,探讨创新网络空间组织演化规律。结果表明:① 中国电子信息产业创新合作呈现集群互联的模式,集群区域的创新主体更倾向于同本地和其他集群区域的创新主体合作,这与非集群区域的创新主体结网方式明显不同,印证了关系经济地理学者提出的全球集群网络论断。② 集群创新网络社区的空间组织从位于集群地理边界内,本地化特征显著,演化为超越集群地理边界,呈现等级差异明显的核心-边缘层级式特征,反映出地理邻近对集群主体创新结网影响程度的动态变化。  相似文献   
544.
Can  Eray 《Natural Resources Research》2020,29(3):1773-1785
Natural Resources Research - In underground mining establishments and in all processes of underground coal mining from investigation activities to production activities, geodetic measurements and...  相似文献   
545.
Yao Li  Liu  Can  Ou  Gengxin  Wang  Zhaowei  Korus  Jesse  Jiang  Ran 《Water Resources》2020,47(5):846-854
Water Resources - This study explores the statistical relationship between spectral reflectance and hydraulic conductivity (K) of fluvial sediments in two Nebraska rivers. The spectral reflectance...  相似文献   
546.
破坏性地震发生后,地震灾情快速评估作为地震应急指挥技术系统中的核心模块能够为各级政府和应急管理部门地震应急指挥决策提供重要的信息服务,是地震应急救援与指挥决策重要的支撑平台。随着学者对地震应急领域几十年的研究,已经具备了开发新一代地震灾害快速评估系统的条件。本文基于甘肃省分震级地震烈度衰减模型、分区域的地震灾害人员伤亡评估模型、地震应急专题图设计等研究基础,研发了新一代甘肃省地震灾害快速评估原型系统,实现了软件自动触发、分震级地震影响范围估计、分区地震灾害人员伤亡计算,自动生成地震灾情评估报告,提高了系统的自动化水平和计算结果的精度。该软件能够提升甘肃省地震灾害快速响应能力,能够为甘肃省地震灾害应急救援和指挥决策提供更为科学可靠信息服务。  相似文献   
547.
According to national early warning practice for geo-hazards from 2003 to 2005, it is systematically concluded that the basic characteristics of geo-hazards, early warning method and forecast result based on the geological maps of China in a scale 1∶6 000 000. With the contrast of different characters between sustained rainfall and typhoon rainfall inducing geo-hazards, the disaster reduction result and some problems are preliminarily analyzed. Some basic recognition is that early warning to geo-hazards is feasible, national scale forecast is only to call attention, but can't immediately be used to disaster reduction decision-making. And, the future direction is to build a united disaster reduction framework of early warning system including national, provincial and county levels based on weather factors in different scale of area.  相似文献   
548.
549.
对东秦岭地区河南嵩县一带进行地质调查,发现了一系列具有一定规模的含稀土碱性碳酸岩矿脉并在其中发现一种特殊的钡解石矿物.依据该钡解石主量元素组成,计算分子式为Ba104Cao81Sral4(CO3)2,为锶钡解石,LA-ICP-MS分析表明其富Na、K、Fe、Mn、Pb、REE、Y等元素,稀土元素总量最高为4 080× ...  相似文献   
550.
In this paper, the Einstein field equations have been solved for inhomogeneous cylindrically symmetric space times with string source. Certain physical and geometrical properties of the models have been examined.  相似文献   
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