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691.
We develop a reserve design strategy to maximize the probability of species persistence predicted by a stochastic, individual-based, metapopulation model. Because the population model does not fit exact optimization procedures, our strategy involves deriving promising solutions from theory, obtaining promising solutions from a simulation optimization heuristic, and determining the best of the promising solutions using a multiple-comparison statistical test. We use the strategy to address a problem of allocating limited resources to new and existing reserves. The best reserve design depends on emigration, dispersal mortality, and probabilities of movement between reserves. When movement probabilities are symmetric, the best design is to expand a subset of reserves to equal size to exhaust the habitat budget. When movement probabilities are not symmetric, the best design does not expand reserves to equal size and is strongly affected by movement probabilities and emigration rates. We use commercial simulation software to obtain our results.  相似文献   
692.
The lagoon of Biguglia (northeastern Corsica) is one of a number Nature Reserve. Anthropogenic activities are increasing over its watershed however. The present study aims to examine the state of health of the lagoon with the example of two pollutants (Cd and Cu). Water samples were collected in spring and summer 1997. The trace metal fluxes between the various compartments were measured. Transfer processes from the watershed to the lagoon were also examined. The temporal evolution of Cd and Cu content is assessed on the one hand by comparing the present data with former reference work (1992). On the other hand, a 5-box model is implemented in order to reduce the complex functioning of the lagoon to a system of differential equations. With the help of a numerical resolution method, the increase of metallic concentration levels is estimated since 1992. On the basis of 1997 data, two hypotheses are compared. The hypothesis that takes into account a growing increase of anthropogenic activities on the watershed gives, by extrapolation, results that are closer to field measurements. However, even with this hypothesis, the cadmium content in the lagoon is underestimated. This may signify that for this metal the evolution of the lagoon pollution is more important than a linear increase.  相似文献   
693.
国内外生态环境观测研究台站网络发展概况   总被引:2,自引:1,他引:1  
生态环境观测研究台站是开展生态环境研究的重要手段。《国家环境保护"十二五"科技发展规划》将国家环境保护野外观测研究站作为"十二五"能力建设重点内容。分析了目前国内外主要生态环境监测网络,如区域尺度的全球环境监测系统(GEMS)、全球陆地观测系统(GTOS)、国际长期生态研究网络(ILTER)、全球通量观测网络(FLUXNET)和国际生物多样性观测网络(GEO·BON),以及国家尺度的美国长期生态研究网络(US-LTER)、英国环境变化监测网络(ECN)和中国生态系统研究网络(CERN)的发展历程、观测研究进展;总结了生态环境监测网站的发展趋势,即重视台站的联网观测研究,注重观测标准化和规范化及数据共享,重视观测手段智能化与自动化,注重综合观测与模型模拟相结合;提出国家环境保护生态监测台站网络是现有国家环境监测网络的拓展和完善,也是今后开展区域生态环境综合监测与评估的重要基础。  相似文献   
694.
综述了我国不同介质中挥发性有机物(VOCs)的环境监测方法标准,介绍了样品采集和前处理、分析方法、质量保证与质量控制等技术内容,以及VOCs监测技术的研究进展。分析了国内VOCs监管控制的现状和重点需求,并在此基础上提出了健全VOCs环境标准体系、完善分类监管的优先控制物种清单、尽快实现VOCs监测工作的常态化、推广应用先进的VOCs监测技术等建议。  相似文献   
695.
土地利用变化及林业(LUCF)活动是生态固碳最重要手段。研究确定LUCF温室气体排放核算制度和方法,对平衡碳排放、开展全国统一碳市场交易具有重要基础作用。在综述LUCF温室气体核算理论和方法基础上,借鉴IPCC指南和《省级温室气体清单编制指南(试行)》推荐的基本方法,构建了符合地域特色的LUCF温室气体排放核算制度和方法。采用2014年第九次国家森林资源清查数据,以全国低碳试点省陕西省为实证对象,初步核算了陕西省LUCF温室气体的净排放量,并从排放能力、排放结构和空间特征等角度揭示了陕西省LUCF温室气体的排放特征。结果显示:(1)2014年,陕西省LUCF温室气体净吸收量为1 698.42万t CO_2e,其中森林及其他木质生物质碳贮量净吸收1 852.67万t CO2e,森林转化净排放154.25万t CO_2e。(2)乔木林等优势树种,是陕西省LUCF温室气体排放中重要的固碳源(吸收源)。(3)陕南地区是重要固碳贡献区,陕北地区森林固碳能力较差。最后,针对LUCF温室气体排放核算制度和方法不够完善、森林固碳能力差异较大、区域固碳分化严重等问题,提出了健全温室气体核算制度、平衡森林资源空间分布、改善固碳树种结构等加强陕西省LUCF活动应对气候变化统计核算制度和能力建设的基本措施。  相似文献   
696.
自然保护区是受特殊保护和管理的一类特殊的可靠性系统。本文从可靠性视角出发,利用冲击模型方法和MATLAB随机模拟技术,以贵州草海为例分析自然保护区系统的寿命行为和失效规律。分析结果表明:(1)20世纪50年代以前,草海系统受到的人为干预相对较少,可靠性长期保持相对稳定。以人类活动为主的冲击影响始于20世纪50年代末,对保护区生态功能产生了强烈干预。(2)在1958—1980期间,政府出于防涝减灾考虑的引流排水行为扮演了系统的主要冲击,对其可靠性产生了毁灭性影响。(3)在1980年之后的30多年里,周边农民出于造田增地需求的排水毁林自发性活动则形成草海保护区的新一轮冲击,并持续影响着系统的生态功能。(4)目前草海在调节气候、缓解灾害、保持生物多样性方面的生态功能已严重弱化。如果最近几十年的人为冲击模式不能得到有效缓解,保护区系统极有可能在近期内再次发生功能性崩溃。  相似文献   
697.
Interbasin transfers (IBTs) are man‐made transfers of water that cross basin boundaries. These transfers are used to distribute water resources according to supply and demand. The objectives of this work were to quantify the number of IBTs that exist in the United States (U.S.) and to examine the distribution of IBTs and potential causes associated with any observed clustering of IBTs. Defining “basin” was important to enable determination of which transfers qualify as “interbasin.” A variety of definitions are employed by states, with no federal definition. The most recent national studies of IBTs were conducted by the U.S. Geological Survey (USGS) in 1985 and 1986 using USGS Hydrologic Unit Code (HUC) definitions of basins. To build a 2016 inventory of IBTs in the U.S., and to identify where they most commonly occur, the USGS National Hydrography Database (NHD) was utilized in conjunction with the Watershed Boundary Dataset (WBD). Transfers across HUC6 basin boundaries were considered interbasin. Geographical information analysis with the NHD and WBD databases revealed that there are a total of 2,161 man‐made waterways crossing HUC6 basin boundaries in the U.S. IBTs are somewhat concentrated: Florida, Texas, and North Carolina account for over 50% of the total identified IBTs. For some states, identified IBTs are locally clustered. Analysis of these clusters suggests a variety of reasons that IBTs have been built, including population, drainage, and agricultural factors.  相似文献   
698.
This paper explores whether ambitions to open up the traditional Swedish model of top-down conservation methods to local influences are indicative of an actual transition in governance of Swedish national park policy (NPP), and examines whether such a shift entails an increase in local influence over local interests and needs. Methodologically, we analyse a combination of governance types and incorporate theoretical definitions of power and accountability. The establishment of new governance arrangements – where power is shared, interactions promoted and accountability is directed downwards – indicates that Sweden's NPP is undergoing a change in its mode of governance. This change also seems to include ceding some influence to local interests, and the possibility of combining conservation with the utilisation of certain natural resources. The results of our research also provide valuable insights into when the establishment of shared-governance arrangements are likely to succeed; in short, this seems more likely when there are established sectors sited in a robust legal framework and where strong international commitments potentially play a role. In conclusion, we contend that when seeking diversified governance arrangements it is not enough simply to take local practices and customs into consideration – they have to be strengthened.  相似文献   
699.
The adoption and enforcement of building codes is considered the most effective tool in safeguarding lives and property against earthquakes. There would appear to be a vital regulatory role for government in the enforcement of building codes, but this is somewhat at odds with the neoliberal agenda of ‘rolling back the state’. This paper explores constraints to the implementation of building codes in the context of changing roles and responsibilities of local authorities in Bihar in India. In-depth interviews were conducted with key stakeholders across major urban centres in north Bihar. Some factors, such as: code complexity; competition between the public and private sectors for qualified personnel; and low public risk perception were found to be less significant in Bihar than has been noted elsewhere, while other factors such as: the cost of earthquake-resistant measures; political interests; corrupt practices; and lack of government capacity were important. Additional factors were also revealed by the research, some of which are exacerbated by the neoliberal climate of urban governance. While the recent 2014 byelaws represent an improvement in the system and a degree of re-regulation, ambiguities create opportunities for failures arising from ‘normalised irresponsibility’.  相似文献   
700.
甘肃自然保护区因其资源的原生性和独特性而具有发展生态旅游的优势条件,其景观多样性丰富,具有较高的旅游价值。从优势、劣势、机遇和挑战四个方面分析甘肃自然保护区生态旅游发展,结果表明,甘肃自然保护区发展生态旅游优势明显,存在一定的限制因素,机遇与挑战并存,据此对甘肃自然保护区发展生态旅游提出了合理的目标定位、强化科学规划、加强资源保护和加强合作、建立多渠道融资机制、突出品牌特色、发展高端旅游产品的对策。  相似文献   
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