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291.
292.
Sun Kee Hong 《环境科学学报(英文版)》1999,11(2):181-187
Throughthestatisticsandtheanalysisoflandscapemap,changesoflandsuseregimeandlandscapestructureduring20yearswereinvestigatedin... 相似文献
293.
1IntroductionLandscapeconnectivity,asoneimportantparametertodescribetheecologicalprocesesandecologicalfunctionsinlandscapeeco... 相似文献
294.
1IntroductionLandscapefragmentationanditsimpactsonbiologicaldiversityhavebeenthehighlyconcernedtopicsintherecentyearsbiologi... 相似文献
295.
Landscape fragmentation by urbanization in the
Netherlands:optionsand ecological consequences 总被引:5,自引:0,他引:5
W. Bert. Harms 《环境科学学报(英文版)》1999,11(2):141-148
1Introduction:thestudyareaFig1ThestudyareaTheeconomicactivitiesoftheNetherlandsareconcentratedinthewestofthecountry,thesoca... 相似文献
296.
西藏色季拉山野生观赏树木资源及其开发利用 总被引:5,自引:0,他引:5
西藏色季拉山区野生观赏树木资源丰富,有40科75属190余种。种类最多的科是蔷薇科、杜鹃花科、忍冬科、虎耳草科和豆科。种类最多的属是杜鹃花属、忍冬属、李属、绣线菊属和子属。其中花木占47.6%,花果木占24.6%,果木占11.0%。花木中白花者占46.4%。果木中红果者占80.9%。75.3%的种类生于森林型生境。74.4%的花木夏季开花。生于阳生灌丛型生境的种类最易被驯化。黄牡丹、多蕊金丝桃、小叶子、素馨花和巨柏等应首先开发。 相似文献
297.
1 BriefdescriptionofoilspillimpactanalysissystemAslongascrudeoilsare producedoffshoreandtransportedacrosstheseasbyshipsorpipelines,thereisariskofoilspillswiththepotentialtocausesignificantenvironmentaldamage .The“ExxonValdez”incidentinAlaska ,andotheroi… 相似文献
298.
汾河流域景观破碎化时空演变特征 总被引:3,自引:0,他引:3
以1990年、2000年、2015年遥感影像解译数据为基础,利用Fragstats 4.2软件分别采取标准法和移动窗口法获取最佳分析尺度;在此基础上探索各景观指数空间分异特征,揭示流域景观破碎化时空演变过程;采用空间自回归模型分析景观破碎化的影响因子。结果表明:随着粒度和幅度的改变,部分景观指数呈现一定规律性,90 m栅格大小、900 m方形窗口尺寸为研究区最佳分析尺度;斑块密度、蔓延度、有效网格大小、香农多样性指数在三个时期均存在空间集聚效应,且空间集聚类型分布形态具有较强的相似性;1990-2015年汾河流域景观破碎化空间分布格局发生明显变化,破碎化集聚区域呈现碎斑化;坡度、高程、距建设用地距离是影响三个时期流域景观破碎化的主要影响因素。 相似文献
299.
Spillover of Agriculturally Subsidized Predators as a Potential Threat to Native Insect Herbivores in Fragmented Landscapes 总被引:3,自引:0,他引:3
Abstract: Habitat loss and fragmentation can have strong negative impacts on populations of some native species. Spillover of generalist natural enemies from the surrounding landscape matrix is one mechanism potentially generating such effects, yet this has been rarely studied in insects. We examined the influence of habitat conversion to agriculture on the abundance and potential effects of predatory coccinellid beetles on native insect herbivores within 12 grassland remnants in central Nebraska (U.S.A.). Results of sweep sampling revealed that coccinellids were three to six times more abundant at native grassland sites embedded within cropland-dominated landscapes compared with control sites in grassland-dominated landscapes over the 3 years of the study. Exclusion experiments further demonstrated that predation intensity was strongly related to coccinellid abundances across sites and that coccinellids can dramatically reduce densities of a native aphid herbivore. In contrast to studies of specialized insect parasitoids, which have generally found reduced enemy pressure in fragmented landscapes, our results suggest that native herbivores may in some cases experience increased consumer pressure in landscapes with increasing habitat loss because of spillover of generalist predators from surrounding cropland habitats. 相似文献
300.
DAVID M. MARSH† GRAHAM S. MILAM† NICHOLAS P. GORHAM† NOELLE G. BECKMAN† 《Conservation biology》2005,19(6):2004-2008
Abstract: Roads can fragment animal populations by disrupting movement among formerly continuous habitats. Although models have demonstrated that disrupted movement can contribute to long-term extinction, there are few empirical data on the effects of roads on animal movement. We used displacement and homing experiments to determine whether forest roads are barriers to the movement of terrestrial salamanders. We displaced 1471 red-backed salamanders ( Plethodon cinereus ) across five forest roads and compared return rates to those of salamanders displaced equal distances toward the forest interior. Roads significantly reduced the return rate of salamanders, with a mean reduction of 51%. Steep roadside verges further reduced return rates, particularly for salamanders moving downhill across verges. The permeability of roads to salamander movement did not appear to be related to road surface type. Gravel roads had both the highest and lowest observed permeability with the two paved roads intermediate between these. We conclude that narrow forest roads are partial barriers to salamander movement and that steep roadside verges may exacerbate these effects. 相似文献