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291.
CARLOS CARROLL JOHN A. VUCETICH MICHAEL P. NELSON DANIEL J. ROHLF MICHAEL K. PHILLIPS 《Conservation biology》2010,24(2):395-403
Abstract: The U.S. Endangered Species Act (ESA) defines an endangered species as one “at risk of extinction throughout all or a significant portion of its range.” The prevailing interpretation of this phrase, which focuses exclusively on the overall viability of listed species without regard to their geographic distribution, has led to development of listing and recovery criteria with fundamental conceptual, legal, and practical shortcomings. The ESA's concept of endangerment is broader than the biological concept of extinction risk in that the “esthetic, ecological, educational, historical, recreational, and scientific” values provided by species are not necessarily furthered by a species mere existence, but rather by a species presence across much of its former range. The concept of “significant portion of range” thus implies an additional geographic component to recovery that may enhance viability, but also offers independent benefits that Congress intended the act to achieve. Although the ESA differs from other major endangered‐species protection laws because it acknowledges the distinct contribution of geography to recovery, it resembles the “representation, resiliency, and redundancy” conservation‐planning framework commonly referenced in recovery plans. To address representation, listing and recovery standards should consider not only what proportion of its former range a species inhabits, but the types of habitats a species occupies and the ecological role it plays there. Recovery planning for formerly widely distributed species (e.g., the gray wolf [Canis lupus]) exemplifies how the geographic component implicit in the ESA's definition of endangerment should be considered in determining recovery goals through identification of ecologically significant types or niche variation within the extent of listed species, subspecies, or “distinct population segments.” By linking listing and recovery standards to niche and ecosystem concepts, the concept of ecologically significant type offers a scientific framework that promotes more coherent dialogue concerning the societal decisions surrounding recovery of endangered species. 相似文献
292.
JOSEPH D. WHITE KEVIN J. GUTZWILLER WYLIE C. BARROW LORI JOHNSON‐RANDALL LISA ZYGO PAMELA SWINT 《Conservation biology》2011,25(3):536-546
Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes. 相似文献
293.
利用紫外-可见光谱与三维荧光光谱,结合拉格朗日混合单粒子轨道模型及火点图,研究了重庆2013年夏、冬两季雨水DOM光谱特征,并对其来源进行解析.结果表明,雨水DOM与水体、土壤DOM具有类似性质光谱特征,证明降雨DOM也是陆地及水环境中DOM地化特征的重要贡献者.雨水DOM中DOC含量为0.88~12.80 mg·L-1,CDOM含量在3.17~21.11m-1之间,夏、冬两季降雨DOM差异明显(P0.05).与夏季相比,冬季降雨DOM分子量较小,芳香性程度较低,腐殖化程度也更低,输入主要以本地和短距离输送为主;而夏季DOM来源较分散.尽管吸收和荧光光谱可用于解析雨水DOM组成和来源,但在光谱特征的解析和来源识别上与其他来源DOM有所区别,传统"内、外源区分"并不适用于雨水DOM. 相似文献
294.
Mikoaj Piniewski Sirkka Tattari Jari Koskiaho Olle Olsson Faruk Djodjic Marek Gieczewski Pawe Marcinkowski Marta Ksiniak Tomasz Okruszko 《Ambio》2021,50(3):706
Riverine nutrient loads are among the major causes of eutrophication of the Baltic Sea. This study applied the Soil & Water Assessment Tool (SWAT) in three catchments flowing to the Baltic Sea, namely Vantaanjoki (Finland), Fyrisån (Sweden), and Słupia (Poland), to simulate the effectiveness of nutrient control measures included in the EU’s Water Framework Directive River Basin Management Plans (RBMPs). Moreover, we identified similar, coastal, middle-sized catchments to which conclusions from this study could be applicable. The first modelling scenario based on extrapolation of the existing trends affected the modelled nutrient loads by less than 5%. In the second scenario, measures included in RBMPs showed variable effectiveness, ranging from negligible for Słupia to 28% total P load reduction in Vantaanjoki. Adding spatially targeted measures to RBMPs (third scenario) would considerably improve their effectiveness in all three catchments for both total N and P, suggesting a need to adopt targeting more widely in the Baltic Sea countries.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01393-x) contains supplementary material, which is available to authorized users. 相似文献
295.
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297.
利用1980—2013年间的城镇人口与碳排放数据,选取城镇化进程中影响碳排放的城镇化水平、城镇建设用地面积、第三产业增加值、人均可支配收入、城镇人均绿化面积等因素,实证分析了城镇化对我国碳排放的影响程度,并利用格兰杰夫因果关系与误差修正模型分析了二者的因果关系与时间效应。最后,从降低工业碳排放、加快低碳城镇化试点建设、推进低碳社区发展,促进新能源发展等方面提出了相关建议。 相似文献
298.
我国京津冀地区近年频遭大气PM2.5污染侵扰,相关研究表明,既使关闭建筑外窗,大气中PM2.5仍可以通过渗透通风方式进入室内污染环境.为定量评价建筑渗透通风及无室内污染源条件下建筑结构(如外窗缝隙结构、房间建筑结构等)对室内ρ(PM2.5)的影响规律,基于北京市东城区、朝阳区6个不同建筑结构的房间室内外ρ(PM2.5)实时监测数据,重点比较分析了建筑结构对室内外ρ(PM2.5)关联特性的影响规律.此外,根据颗粒物穿透特性及沉降特性机理,提出了反映建筑外窗缝隙结构(如缝高、缝深)的无量纲特征参数AP与反映房间建筑结构(如层高、开间、进深)的无量纲特征参数Ak.在前期提出的室内ρ(PM2.5)预测模型基础上,进一步构建了二者(AP与Ak)对室内ρ(PM2.5)影响的评价模型,并通过实测数据验证了模型的正确性.结果表明:当室外PM2.5污染程度与气象条件一定时,建筑结构对I/O[室内外ρ(PM2.5)之比]影响较大,其范围在0.4~0.7之间;随着建筑外窗气密性等级的提高,对应室内ρ(PM2.5)呈显著的下降趋势.建筑外窗缝隙结构对室内ρ(PM2.5)影响程度远大于房间建筑结构,敏感性分析结果表明,当建筑外窗缝高每降低50%或缝深每提高50%,对应室内ρ(PM2.5)约可下降33.6%与31.9%.研究显示,气密性等级较高的建筑外窗缝隙缝高往往较小、缝深较长,渗透通风条件下对控制室内ρ(PM2.5)水平作用更显著。 相似文献
299.
近年来随着水环境模拟领域的发展出现了较多水环境数学模型,目前日益成熟的WebGIS技术是使模型使用变得简单化和直观化的一大途径.是在通过Flex和ArcGIS Server搭建WebGIS系统平台的基础上,利用PHP进行WebGIS和水环境模拟模型的数据交互,实现系统平台和数值模型的松散耦合.用户在浏览器端进行模型输入条件的设置,模型在远程服务器端进行运行计算,反馈的模拟结果通过RIA在WebGIS中进行多元化动态展示.该方法对一般模型具有适用性,可降低模型使用门槛,提高模拟结果展示和分析能力. 相似文献
300.
开展城市饮用水源地生态系统健康状况评价,为建立流域尺度的长效保护机制提供依据.以郑州尖岗水库为研究对象,构建水域生境结构、水生生物、陆域生态格局和生态功能等共6类16项评价指标,采用综合指数法开展评估.尖岗水库水域、陆域和流域综合生态健康标准化评估值分别为54.17、59.21和57.19,评价等级均为"一般",河道连通性、森林覆盖率是流域生态健康的主要限制因子.人类活动对尖岗水库生态系统健康状况产生了强烈影响,生态环境正处于负向演替和生态退化阶段. 相似文献