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1.
区域土地覆被景观特征的幅度效应及其变异规律 总被引：2，自引：0，他引：2
尺度是空间地理现象普遍存在的问题，由于尺度本身的复杂性以及人们认知的局限性，对于尺度问题的讨论仍然有待深入，因此，尺度问题仍然是当前生态学、地理学研究中的热点问题。尺度又包括粒度和幅度两种类型。本文基于2005年广州市的TM遥感影像解译土地覆被类型图，剪裁最大矩形区域景观类型图，沿对角线分别形成不同方向的一系列幅度大小的景观类型图，研究土地覆被景观特征的幅度效应及变异规律。结果表明：景观特征指数的幅度效应及指数之间的差异是明显的，随幅度由小到大，幅度效应减小或趋于平缓，幅度400（144km2）是研究区域景观特征的“临界阈”幅度；景观特征指数的幅度效应及指数之间差异还存在方向性，如PD在NE—SW方向的变化较其它方向大；景观特征指数对幅度效应的程度各异，相对于整体景观而言，指数PD和SHDI在各方向的变幅都较大，而指数FRAC_MN和SHAPE_MN则随幅度的变化只有很小的效应。 相似文献
2.
流域宏观尺度降雨-景观-径流变化的相互作用 总被引：1，自引：0，他引：1
大流域宏观尺度上长时间序列的降雨变化、景观变化、径流变化及其相互作用是近年来研究全球变化的一个重要问题。本文研究泾河流域降雨-景观-径流变化的相互作用，结果表明：①泾河流域中上游主流域40多年来的降水具有微弱下降趋势，降雨倾向率为-4.9mm/10～-11.3mm/10年；泾河流域马莲河分流域，年降雨量表现为不变或微弱下降；②泾河流域1986年～2000年15年之间，景观结构变化不大，一直以草地景观和耕地景观为主。草地景观和农耕地景观二者始终占流域总面积的85%以上，林地景观始终占流域总面积的10%左右，其他景观类型一直占流域总面积的5%左右。在宏观景观格局的变化中，泾河流域中上游主流域，农耕地景观所占比例有所上升，而泾河流域马莲河分流域农耕地景观所占比例维持稳定；③泾河流域中上游主流域年径流量逐年较大幅度地减少，下降速度达到每10年减少1.78m3/s。在泾河流域马莲河分流域，年径流和径流模数在过去30年中基本维持稳定，整个泾河流域年径流量逐年下降；④相应年份内对应的径流和降雨相关性极为显著（P<0.01）。在泾河主流域中上游地区降水每减少10mm，径流可能相应减少70×108m3，在马莲河分流域地区每减少10mm，径流可能减少110×108m3。在泾河流域，若维持景观结构的稳定，则径流的变化趋势会与降雨的变化趋势保持一致。景观结构的微弱变化会改变径流对降雨响应的变化幅度。在景观组成中，耕地景观比例的增加会显著减少径流。 相似文献
3.
基于最佳分析粒度的巴彦县土地利用景观空间格局分析 总被引：2，自引：0，他引：2
适宜的分析粒度是保证土地利用景观格局分析准确的重要环节.本文以黑龙江省巴彦县为研究区,应用遥感、GIS手段及景观指数法,探讨景观指数随分析粒度变化效应,综合面积精度损失评价,确定最佳分析粒度.从景观要素空间组成、空间形态、空间关系及空间构型4个方面分析研究区土地利用景观空间格局.结果表明: 部分景观指数与粒度可拟合为数学函数关系,并确定最佳分析粒度为100m;研究区主要土地利用景观类型为旱地和林地,旱地景观优势明显,是基质景观;水域空间形态最复杂,林地、旱地等农业用地景观形状较不规则,建设用地和园地形状最简单;旱地、建设用地分布很均匀,水田、其他用地分布较合理,各乡镇间林地、草地及水域分布差异较大,园地分布差距极悬殊且斑块间分布离散;景观整体主要由团聚的大斑块组成,异质性小,形状复杂程度适中,破碎化程度不严重,稳定性差,不利于现状土地利用景观空间格局的维持. 相似文献
4.
露天煤矿区的资源开发会导致土地损毁和景观格局破坏,损毁土地的复垦规划和实施也应该考虑景观生态的保护。景观指数作为定量化研究景观格局的手段之一,其本身具有明显的尺度依赖性并存在生态学意义的重叠,因而针对矿区土地损毁与复垦过程进行景观指数尺度效应分析及代表性景观指数筛选是一个重要前提。本文以北方农牧交错生态脆弱区魏家峁露天煤矿区为例,应用景观生态学和传统统计学方法,分析了矿区开采前、开采结束和完全复垦3个阶段的13种格局水平景观指数的粒度效应,筛选了能够反映矿区开采损毁、复垦对景观格局产生影响的10个代表性景观指数。结果表明：除斑块丰富度密度指数外,其余12种景观指数表现出很强的粒度效应,该生态区露天煤矿区景观指数计算的适宜粒度范围为10~15m;最终确定表征该露天煤矿区开采结束后景观格局变化的代表性景观指数为香农多样性指数、景观形状指数、面积加权分维数和几何最邻近距离,表征该露天煤矿区完全复垦后景观格局变化的代表性景观指数为香农多样性指数、景观形状指数、面积加权分维数和聚集度。研究结果可为进一步分析露天煤矿区开采损毁与复垦多阶段、多复垦模式的景观格局变化提供参考,为切实保护矿区土地资源和景观生态提供指导。 相似文献
5.
露天煤矿区土地损毁与复垦景观指数分析 总被引：2，自引：0，他引：2
露天煤矿区的资源开发会导致土地损毁和景观格局破坏,损毁土地的复垦规划和实施也应该考虑景观生态的保护。景观指数作为定量化研究景观格局的手段之一,其本身具有明显的尺度依赖性并存在生态学意义的重叠,因而针对矿区土地损毁与复垦过程进行景观指数尺度效应分析及代表性景观指数筛选是一个重要前提。本文以北方农牧交错生态脆弱区魏家峁露天煤矿区为例,应用景观生态学和传统统计学方法,分析了矿区开采前、开采结束和完全复垦3个阶段的13种格局水平景观指数的粒度效应,筛选了能够反映矿区开采损毁、复垦对景观格局产生影响的10个代表性景观指数。结果表明:除斑块丰富度密度指数外,其余12种景观指数表现出很强的粒度效应,该生态区露天煤矿区景观指数计算的适宜粒度范围为10~15m;最终确定表征该露天煤矿区开采结束后景观格局变化的代表性景观指数为香农多样性指数、景观形状指数、面积加权分维数和几何最邻近距离,表征该露天煤矿区完全复垦后景观格局变化的代表性景观指数为香农多样性指数、景观形状指数、面积加权分维数和聚集度。研究结果可为进一步分析露天煤矿区开采损毁与复垦多阶段、多复垦模式的景观格局变化提供参考,为切实保护矿区土地资源和景观生态提供指导。 相似文献
6.
拉萨河流域湿地系统景观格局多尺度分析 总被引：5，自引：2，他引：3
以2006年中巴遥感影像为数据源提取拉萨河流域湿地类型矢量数据,在此基础上计算湿地景观格局指数。在ArcGIS支持下,基于景观类型、生态系统类型和地貌区3个不同尺度开展湿地景观格局分析。结果表明:不同尺度的湿地景观格局特征不同,高寒草甸湿地景观是流域湿地基质景观,占湿地总面积的77.74%。藏北嵩草沼泽草甸是高原湿地的核心生态系统类型(占65.45%),其斑块面积、斑块数目、斑块密度、斑块形状指数、斑块的聚散程度等景观指数都具有极大值。河源区湿地类型简单,仅5种,斑块破碎度较高。河谷区湿地景观类型丰富(13种),景观多样性指数最大(1.841),生态系统稳定性较弱。当雄盆地区优势度指数最大(1.288),以藏北嵩草沼泽草甸为主,分布较集中,抗干扰能力较强。 相似文献
7.
人类活动对泾河流域村落尺度土地利用格局的影响及冲突 总被引：2，自引：1，他引：2
对流域微观尺度土地利用结构变化研究是进行宏观尺度土地资源研究和管理的基础。本文旨在探讨中国西部黄土高原泾河流域村落尺度土地利用的变化及其驱动因素，识别并分析资源利用和管理中存在的冲突与解决方案。研究所用资料来自社区快速评估(RRA)、参与式社区评估(PRA)、农户问卷调查、小组讨论、统计资料等。应用系统抽样法对泾河流域上游的南庄村和史么村的90个农户进行了问卷调查，同时在各村进行PRA研究。主要研究结果有：①通过PRA方法，首次恢复和直观再现了村落尺度1950年代以来主要土地利用类型图及其变化，与1950年代相比，1985年～1995年代中期林地和草地面积呈增加趋势，主要得益于荒山造林。1996年～2004年代草地和林地面积持续增加，耕地面积下降；②1950年代以来，种植作物的种类逐渐转换为市场需求高的经济作物；③不同时期的政策和市场机制的作用是引起这些变化的主要原因；④尝试性地界定和分析了在土地利用管理中的主要冲突类型，即公众认知与意愿的冲突、耕地面积减少与剩余劳动力增加的冲突、生态移民措施与公众愿意的冲突、上游与下游资源利用与保护的冲突。个人因素如教育程度、性别和年龄影响他们对土地结构变化的认知和愿意。研究建议应重视土地利用变化最明显时期的特点，针对冲突及其产生的原因进行研究，提高资源利用效率。 相似文献
8.
山东半岛典型流域土地利用格局分析 总被引：6，自引：2，他引：4
本文以烟台市1996年土地利用现状图图斑分类和地面调查为斑块属性引导,在3S技术的支持下,对2002年9月9日的ETM影像进行解译分析,选取斑块密度（PD）、形状指数（SI）、景观多样性（DV）和景观均匀度指数（EV）等,对烟台市12个典型流域的土地利用结构进行了分析。结果表明：在斑块尺度上,6种主要土地类型与流域面积和形状指数进行的关联分析表明,灌木林斑块和旱地斑块的相对面积（在0.01水平上）与流域面积的关联程度显著,关联系数分别为0.843和0.796,且呈对数回归关系;水浇地和旱地斑块的相对面积与形状指数关联程度极为显著（在0.01水平上）,关联系数大于0.729。从相互关系来看,在本文所研究的流域面积范围内,灌木林斑块和旱地斑块的相对面积随着流域面积的增大呈增加趋势;而形状指数与水浇地斑块相对面积呈正相关、与旱地斑块相对面积为负相关。在景观尺度上,斑块数量与流域面积的关联程度极为显著（在0.01水平上）,关联系数为0.987,有较高的置信度,斑块数量与流域面积之间存在正相关回归关系。 相似文献
9.
基于2006年Quickbird卫星影像数据解译的沈阳城市绿地分布图,利用GIS技术和景观结构分析软件FRAGSTATS,结合梯度分析方法定量分析了沈阳城市绿地景观格局,并探讨了其幅度效应.结果表明:绿地的空间格局可以应用梯度分析与景观指数采定量.不同的绿地类型沿景观格局梯度确实表现出明显的"空间特征".不同景观指数沿样带的表现也有差异,斑块密度和景观形状指数具有明显的梯度特征,而最大斑块指数,斑块类型百分比,多样性指数和景观聚集度指数则不明显.为了研究绿地景观的幅度效应,尝试了不同的窗口大小,5km的幅度是比较合理的尺度,能够通过景观指标的变化反映城市绿地空间格局. 相似文献
10.
内蒙古锡林郭勒盟景观格局变化对土壤保持能力的影响 总被引：1，自引：0，他引：1
提高土壤保持能力对于维持脆弱的草地生态系统稳定具有重要意义。本文在GIS技术的支持下,采用景观格局分析与逐步回归的统计方法,在流域尺度上对2005—2010年锡林郭勒盟景观格局变化对土壤保持能力的影响进行研究。结果表明：① 不同景观类型的土壤保持能力差异显著,单位面积土壤保持量为林地>农田>草地;② 2005—2010年,锡林郭勒盟林地土壤保持能力减弱,草地和农田土壤保持能力增强;③ 不同景观水平指数及不同斑块类型水平指数对土壤保持能力的影响差异显著;④ 景观水平上,流域土壤保持能力随着斑块数量和香农多样性指数的减小以及景观形状指数和香农均匀度指数的增加而相对增强,其中,斑块数量对土壤保持能力的影响更大;⑤ 斑块类型水平上,在降雨减少而植被覆盖度降低的情况下,随着聚合度的增加,林地土壤保持能力减弱幅度变小,其中,草地土壤保持能力随着最大斑块指数的增加而增强,农田土壤保持能力随着斑块面积百分比的增加以及平均邻接度指数的减小而增强。研究结果对于提高区域景观管理水平,促进水土保持具有借鉴意义。 相似文献
11.
A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
12.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
13.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
14.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
15.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
16.
Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
17.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
18.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
19.
Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
20.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献