共查询到19条相似文献，搜索用时 156 毫秒
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于2008年采用植被常规调查方法,对磨刀溪干流3个引水式电站对河岸植物的影响进行调查研究,按影响情况,各电站设3个采样点.用植物生活型、物种多样性等参数,衡量小水电对河岸植物群落的影响.共采集到维管植物157种,其中乔木21种,灌木19种,草本植物117种.结果表明:各样地之间河流生境物理因子(流速、水深、底质类型、底质异质性)之间存在显著性差异;总的物种丰富度和草本植物的物种丰富度在各样地间存在显著性差异,乔木和灌木物种丰富度差异不显著;物种多样性方面,各样地之间差异性显著;湿生植物物种丰富度分析表明,小水电的修建,造成坝下样地湿生植物成分较低,与坝上样地和电站出水口样地有明显差异.研究认为,引水式电站的修建使河流河岸植被的连续性受到干扰,不利于河流生物多样性的保护. 相似文献
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生物多样性是指生命有机体及其借以存在的生态复合体的多样性.生物多样性包括遗传多样性、物种多样性和生态系统的多样性三层含义.遗传多样性,即指所有遗传信息的总和;物种多样性,即生命机体变化的多样化;生态系统的多样性,即栖息地、生物群落和生物圈内生物过程的多样化.相应的生物多样性保护也在环环相扣的多个生物空间等级层次上进行,即景观和生态系统总和体层次、群落层次、物种层次、基因层次[1]. 相似文献
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在新疆160多万km2土地上,分布着众多珍稀物种和独特自然景观的特殊地域.动植物资源丰富、种类繁多,高等植物3500多种,其中药用植物1116种,开发利用的有120多种;饲用植物930种,常见的有382种;森林资源有乔木89种,其中针叶林8阔叶林49种,经济林32种,主要造林树种约57种.灌木有57种,野生脊椎动物近700种,其中两栖爬行类48种,鸟类428种,兽168种,土著鱼类53种.列为国家重点保护植物的有21种,重点保护动物有48种,其中有一类保护动物28种,二类保护动物种.1980—2002年,已建立各类自然保护区26个,属国家级的保护区6个,分别为阿尔金山自然保护区、喀… 相似文献
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青藏铁路沿线高寒草甸植物群落特征对人为干扰梯度的响应——以风火山高山嵩草草甸为例 总被引：5，自引：1，他引：4
选择风火山地区受到人为干扰的高寒草甸,对处于不同干扰梯度的高寒草甸植物群落,用样带法进行调查.共调查5条样带,50个样方.统计植物的科属组成,计测其群落盖度、频度指标以及物种丰富度指数、多样性指数及均匀度指数等.对不同干扰梯度上的植物群落结构及其物种组成特点进行分析,结果表明:青藏铁路沿线的高寒草甸随着人为干扰的强度的增加,植物群落的科、属、种组成趋向单一;群落中起显著作用的物种趋向是高山嵩草→高山嵩草和矮嵩草→早熟禾和扇穗茅→早熟禾→羊茅和早熟禾;按照植物种群的重要值对干扰梯度的响应,该地区植物种群可被划分为3类响应模式,即忍耐型种、敏感型种和扩展型种.随着干扰强度的增加,物种丰富度指数和物种多样性随着干扰增加而降低.干扰梯度与有机质含量、全氮、水解氮、全磷、速效磷均呈显著相关,但是与全钾和速效钾相关关系不明显. 相似文献
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东天山喀尔里克山北坡-淖毛湖植物群落物种多样性研究 总被引：2，自引：0，他引：2
以东天山喀尔里克山北坡-淖毛湖为研究区,探讨了该区山地-荒漠生态系统的植物种类组成、植被类型及群落物种多样性特征.结果表明:该区共有高等植物33科93属133种,植物生活型组成以草本植物居多.群落物种多样性测度指数的主成分分析结果显示,物种丰富度指数(R)、Pielou均匀度指数(Jsi)、Shannon-Wiener多样性指数(H)和Simpson优势度指数(C)能很好地描述群落结构和组成特征.其中,多样性指数、均匀度指数和丰富度指数的变化趋势基本一致,优势度指数则和前三者呈负消长的关系.随着海拔升高,群落物种多样性指数、丰富度指数和均匀度指数变化均呈现单峰分布格局,即植物群落的物种多样性在山前荒漠生态系统和高海拔山地生态系统中较低,而在中海拔地区达到最大. 相似文献
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近代由于气候的变暖,工业化进程的加快,人口的激增,森林的过度砍伐,草场的超载过牧,化学制品的滥用,环境的污染,生态环境遭到了严重破坏,生物物种灭绝速度较单纯自然状态下的速度要快1000倍。生物物种灭绝对人类生产、生活,甚至对人类生存都构成巨大的威胁。因此,应对气候变化,保护生物多样性,防止物种灭绝,已成为全球性的紧迫任务;中国是世界生物物种资源最丰富的国家之一。中国生物多样性形势总体严峻。中国政府高度重视生物多样性保护工作,先后颁布一系列法律法规,已收到巨大成效;保护生物多样性确保世界粮食安全,是全球人民的普遍愿望。生物灭绝关系人类存亡。人类要秉承天人合一的理念,与大自然和谐相处。 相似文献
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广西龙虎山植物功能群物种多样性垂直格局 总被引：1，自引：1，他引：0
以样带法沿海拔梯度调查了广西龙虎山自然保护区植物群落、常绿植物功能群及落叶植物功能群物种多样性。垂直格局分析表明:乔木层α多样性垂直格局没有随海拔变化的明显规律;乔木层α多样性垂直格局在常绿植物功能群与落叶植物功能群之间差异较大,而在常绿植物功能群与群落物种多样性格局之间比较一致;乔木层β多样性垂直格局在群落、常绿植物功能群、落叶植物功能群之间大体一致;植物物种多样性垂直格局是垂直梯度上多种环境因子综合作用及不同植物功能群对垂直梯度环境因子不同响应的结果。地形和岩性的生态梯度分析表明:α多样性垂直格局与地形变化较一致,但没有随岩性变化而变化的明显规律;群落β多样性、落叶植物功能群β多样性与常绿植物功能群的β多样性垂直格局随岩性变化的趋势大体一致,但没有表现出随地形变化的明显趋势。 相似文献
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唐古拉山南麓多年冻土退化与嵩草草甸变化的关系 总被引：9，自引：4，他引：9
测定了分布于唐古拉山南木麓两道河－聂荣高地多年冻土岛和冻土退化后，季节冻土区的两种嵩草草甸群落中各物种的重要值以及群落生态优势度，物种多样性，结合冻土环境对比分析得出，诸多物种重要值发生了明显变化，物种多样性，生态优势度有所增高，这是该区独特的生境特征所导致，另外，草场的特性也发生了改变，应引起畜牧生产者的关注。 相似文献
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《Geoforum》2015
The World Conservation Union (IUCN) publishes the Red List of Threatened Species, the most authoritative information available globally on the conservation status of species. However, the status of globally threatened species remains controversial at local levels because many of them are not protected as part of national statutory law. Such anomalies are examples of controversies in implementing the much-hyped environmental slogan “think globally, act locally”. Here we provide a comparative review between globally threatened species as listed by the IUCN Red List found in Nepal and those of nationally protected species under Nepalese law. We discovered a significantly higher diversity of globally threatened mammals and birds in Nepal than would be expected relative to their global ratios. We established remarkable disparities in species conservation in Nepal: (1) a large number (an average of 85% of species of five taxonomic groups: mammals, birds, amphibians, fishes and reptiles) of IUCN-listed globally threatened species found in Nepal are not protected by national law; (2) most protected species listed are mammals (70%), but more than half of globally-threatened mammals found in Nepal are not protected; and (3) amphibians and fish are not protected, although they represent 12% of the total number of globally-threatened species found in the country. Such large gaps in Nepalese conservation law are an indication of unresponsive and inefficient conservation planning. The Government of Nepal and international conservation partners should: (1) emphasize knowledge-based conservation strategies for all taxonomic groups; and (2) prioritize updating the lists of protected species. 相似文献
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Hydrogeologic delineation of habitats for endangered species: the Comal Springs/River System 总被引：1，自引：0，他引：1
We delineate 18 distinct habitats for the endangered fountain darter in the Comal Springs/River system based upon a combination
of vegetative, geologic, and hydrologic criteria. Comal Springs are the largest natural discharge from the Edwards aquifer
of central Texas; they issue along faults which penetrate the confined portion of the aquifer. The springs are the head of
the Comal River which is an important economic and recreational resource to the local community. The spring/river system is
the home of the fountain darter, a federally listed endangered species. Previous studies of this system were on a large scale
and lacked detail necessary for characterization. The fountain darter and other fauna in the Comal Springs/River system are
threatened by the possibility of diminished flows and the concomitant habitat change. The 18 habitats are defined by the dominant
species of vegetation, the substrate, and the flow conditions. Human alterations and spring discharge control the morphology
of the river and the substrates. Stream velocities determined substrate conditions and, thus indirectly, the distribution
of vegetation and habitats. In this system, hydrochemical parameters were uniform as were the soils adjacent to the stream;
these factors were not important to the habitat delineation. The range of stream velocities necessary to maintain the habitats
can be estimated with the Hjulstrom diagram. The darters were associated with a number of these habitats. We surmise that
significant alteration of the system's habitats will occur if discharge conditions change.
Received: 22 January 1996 · Accepted: 4 March 1996 相似文献
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Adolphe Nfotabong-Atheull Ndongo Din Farid Dahdouh-Guebas 《Estuaries and Coasts》2013,36(6):1181-1192
Qualitative and quantitative characterization of mangrove vegetation structure and dynamics is required for assessment of coastal habitat vulnerability. Changes in mangrove forests around Douala, Cameroon, have been documented using aerial photography between 1974 and 2009. The distribution pattern of tree species was also assessed in 2009 following the point-centered quarter method (PCQM+) protocol. Pristine mangroves observed in 1974 had been disturbed markedly in 2003 and 2009. Some of the pre-existing mangroves were entirely replaced by settlements, road, and crops (maize, bean, banana, oil palm, green vegetables, and sugar cane plantations). From 1974 to 2003, 39.86 % of mangrove forests have disappeared; the net loss of 22.10 % occurred between 2003 and 2009 alone. Mangrove forest area had decreased 53.16 % around Douala over a 35-year period from 1974 to 2009 concurrent with a substantial increase of settlements (60 %), roads (233.33 %), agriculture areas (16 %), non-mangrove areas (193.33 %), and open water (152.94 %). Field survey showed that almost one third of the quadrants in the remaining mangrove forest were empty. The disrupted mangrove forest has an overall mean height, absolute density, and basal area of 19.80 m, 158 trees ha?1, and 110.44 m2 ha?1, respectively. In comparison with scientific literature on mangrove degradation, this puts the mangroves around Douala at the top of the “peri-urban mangrove degradation” list. In addition, beyond listing of mangrove plants on the Red List of Threatened Species which will seldom lead to widely distributed species being listed, we call for the creation of a Red List of Locally Threatened Ecosystems, which in contrast is likely to list mangroves as an ecosystem under critical risk of (local) extinction in many countries around the globe, in particular, peri-urban sites. 相似文献
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喀斯特区常见的出露石牙对水分和养分的再分配影响了植物物种的分布与适应特征。为了解出露石牙对中国特有珍稀濒危植物四药门花(Loropetalum subcordatum)的分布与叶表型性状的影响，用样带法对贵州茂兰国家自然保护区内四药门花个体根部和周边最近石牙与土表连接处的距离进行调查、并选择距石牙不同距离的乔木植株叶片进行表型特征测量。根据四药门花植株的分布特征，将其与石牙距离分为三组（0 cm、0.1~10 cm、≥10 cm）进行分析。结果表明:①本次共调查到四药门花个体515株，其中胸径≥1 cm的388株（75.3%）。胸径最大值为17.5 cm，该植株距石牙7 cm。胸径≥1 cm植株距石牙0 cm、0.1~10 cm、≥10 cm植株数分别为89株平均胸径3.44±2.26 cm、21株平均胸径4.38±4.55 cm和278株平均胸径3.93±2.75 cm；幼苗和幼树距离石牙0 cm有19株、0.1~10 cm有62株、≥10 cm有46株。②茂兰四药门花种群叶长106.60±19.28 mm、叶宽47.53±10.10 mm、叶宽/长0.45±0.08、叶厚0.32±0.05 mm、叶柄长12.82±3.35 mm、叶柄径1.43±0.35 mm。距石牙0 cm组、0.1~10 cm组和≥10 cm组四药门花的叶长、叶宽、叶柄径差异不显著（P>0.05），叶厚、叶宽/叶长、叶柄长差异极显著（P<0.01）。石牙出露深刻影响了四药门花的分布和植物的适应特征。 相似文献
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植物地境及物种地境稳定层 总被引：9，自引：0，他引：9
植物地境是其生境的重要组成部分.地境结构的系统分析应作为探索植物与其地境生态关系的重要手段之一.植物地境具有鲜明的耗散结构特征, 内部的宏观稳定性和层次性是适应外界环境的自组织结果, 并与植物根群的“层片”结构相契合.每一“层片”代表一个特定的地下小环境.若地境具有多个“层片”, 说明该地境拥有可被多种植物利用的多样小环境.根群作为根系的主功能区, 是联系植物与地境的纽带.与植物的根系相比, 根群的“层片”现象更清晰.通过根群的“层片”, 不同植物实现资源分割, 避免过激竞争, 能够长期共存.基于地境耗散结构特征分析和各物种根群所处深度范围的统计结果, 首次建立了物种地境稳定层的概念.某一物种根群所处的位置即为该物种的地境稳定层.物种地境稳定层可作为地境生态功能分层的基本单位.较之地境全剖面各指标的平均值, 地境稳定层内理化指标组态更为真实地反映了植物生存的地下环境, 可用以确定物种的生存域; 不同植物的生理和生活习性是对其稳定层内指标组态量值及动态变化规律的一种响应; 地境所能提供的稳定层的多寡及组态对地表植物群落的结构具有一定的控制作用; 地境稳定层的消失和产生, 可导致对应物种的消亡和入侵, 造成植物群落的演替. 相似文献
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Zejin Shi Leixun Lu Guan Yin Hongyu Long Wenjie Li Huaixin Yang 《International Geology Review》2017,59(7):905-917
The remains of trilobites and other species were unexpectedly discovered in a volcanic ash layer beneath the Permian–Triassic Boundary (PTB). Based on a biostratigraphic investigation of the Zhongliangshan section in Chongqing, South China, the quantity of the species gradually decreased with subsequent volcanism. This finding provides an opportunity to further understand the disappearance of trilobites and the evolution of the mass extinction event. The temporal coincidence between the volcanic eruption event and the loss of trilobites and other species supports the idea of a cause-and-effect relationship. The species remains in the ash bed appeared before the disappearance of Clarkina yini and the climax of the negative carbon isotope excursion, which implies that the onset of the mass extinction occurred at the end-Permian. The explosive volcanic events caused massive releases of CO2, toxic gases and volcanic ash and resulted in loss of habitat for certain species in the Tethys domain. This phenomenon may have led to the abrupt death of trilobites and the catastrophic collapse of biodiversity. 相似文献
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荔波小七孔岩溶植被的研究 总被引：2，自引：2，他引：0
通过实地调查、样方统计、标本采集等,对荔波小七孔地区岩溶植被的生境条件、区系组成、群落学特征等进行了初步的分析研究。结果表明: 该区植被区系十分丰富,在12km2 的范围内,自然分布的维管束植物高达375种,分别隶属于117科、272属;地理成分也相当复杂,既有世界分布、泛热带分布、热带美洲和热带亚洲间断分布、热带亚洲至热带非洲分布,又有北温带分布、东亚和北美间断分布、西亚至中亚分布和中国特有分布。此外,区内岩溶植被多元顶极演替特征也很明显,常绿阔叶、落叶阔叶与常绿落叶阔叶混交林共存。小七孔的这种植被群落特征主要由其气候、土壤、小生境差异及其相互配置的不同而引起。 相似文献