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91.
Abstract:  The area of Caricion davallianae alliance in Switzerland has been considerably reduced and fragmented during the last 150 years. We assessed the genetic variability, inbreeding level, and among-population differentiation of two common habitat-specific plant species, Carex davalliana SM. and Succisa pratensis Moench, in 18 Caricion davallianae fen meadows subjected to fragmentation. We used a spatial field design of fen systems (six systems total), each consisting of one large habitat island and two small habitat islands. We used allozyme electrophoresis to derive standard genetic parameters ( A, P, HO, HE, FIS, FST ). In Carex we identified a consistently lower A in isolated habitat islands; furthermore, HE was lower in small habitat islands than in large habitat islands. In Succisa we identified a lower HO in small habitat islands than in larger ones. Small habitat islands were marginally significantly differentiated (  FST ) from large islands for Succisa . For both species, no effects were evident for FIS ; therefore, we argue that genetic drift rather than inbreeding is the main cause of the observed differences. The genetic structure of Carex and Succisa in small habitat islands differed from that in large habitat islands, but differences were small. It appears that the observed differences in genetic variability among fen meadows correspond to observed differences in fitness and demographic traits. We show that habitat fragmentation affects not only the rare species in an ecosystem but also reduces the survival probabilities of common species. One of the main goals of conservation should be to mitigate fragmentation of natural habitats in order to increase population sizes and connectivity.  相似文献   
92.
随着经济全球化、信息化和消费者的成熟,企业面临更为复杂和多变的竞争环境,企业核心竞争力是企业获得持续竞争优势的基础,如何保持持续核心竞争力成为企业成功的关键所在.本文从我国企业的实际情况出发,探讨企业如何提升核心竞争力,参与全球经济竞争。  相似文献   
93.
建设先进的环境监测预警体系,是我们贯彻落实国务院<关于落实科学发展观加强环境保护的决定>和第六次全国环境保护大会精神,针对当前我国环境管理面临的复杂形势和东胜区"打造城市核心区","创建全国环保模范城(区)",确保地区级核心城市环境安全的形势要求以及环境监测肩负的重要历史使命,审时度势提出的一项具有战略性.基础性建设任务.准确可靠的环境监测预警数据,信息,是政府制定法律法规,条例制度,政策标准,规划计划和综合决策的依据.科学的监测手段,可以为政府管理提供科学的决策依据,以对当前复杂的环境形势做出准确判断;而预警监测跟不上,就可能在出现突发污染事件时措手不及.应对无方.贻误战机,给人民群众生命健康安全,经济生活运行,以及社会安定和环境安全带来严重的威胁和损害.并就如何加强环境监测预警体系建设,从专业技术,能力建设,队伍素质等方面提出了建设性的宝贵意见.  相似文献   
94.
介绍了一种安全的应用于PKI系统中的密钥管理方案.该方案采用秘密共享机制备份和恢复私钥,有效地维护了私钥的安全性.同时,该方案采用可验证秘密份额分发协议有效地解决了分发者欺骗问题.  相似文献   
95.
通过研究借鉴多个国家/城市的研究实践,提出了城市空气治理监测网络(UAAMNA)评估管理的方法,包括评估思路与流程,评估关键指标,针对不同污染物的评估方法等.以沈阳市及周边6个城市共46个国控监测站点的监测网络为背景,基于2013~2018年日尺度空气质量数据,考虑监测成本,对沈阳市PM2.5监测网络进行评估,结果表明,沈河区增加1个最高浓度站点,大东区增加1个高人口密度区站点,皇姑区增加1个跨界传输点;在沈阳-铁岭,沈阳-本溪,沈阳-辽阳方向增设跨区域站点.未来建立空气质量监测网络定期评估制度、加强跨区域边界站点布设、实施区分监测点位类型评估、区分污染物类型评估是UAAMN的发展方向.  相似文献   
96.
根据《山东省区域性大气污染物综合排放标准》(DB37/2376-2013)实施要求,开展济南市市域范围大气污染防治三区划定。划定过程以地理信息系统空间分析技术为手段,根据各区域大气环境承载力、人口密度分布和生态环境敏感程度三个因素的空间分布差异,实现三区划分,形成划定初步方案。同时,结合相关规划和重点企业/工业园区空间布局状况,对初步划定方案进行调整,形成三区划定最终方案,并在此基础上提出各分区大气污染控制措施。  相似文献   
97.
The dynamics of habitat distribution in two bird species differing in the level of site tenacity—willow warbler (relatively tenacious) and little bunting (more flexible)—were studied at the boundary of the northern taiga and forest–tundra zones over ten years. The distribution pattern proved to be more uniform in the willow warbler than in the little bunting. Both species occupied their habitats according to a well-known scheme: initially, the birds settled in their favorable floodplain habitats and later; when their abundance increased, in less preferable habitats (terraces above the floodplain, moss bogs, and the tundra). In the case of willow warbler, the process of occupying the floodplain was stepwise: bird density increased sharply, remained at the same level in the next year, then increased again, etc. In the case of little bunting, the degree of floodplain occupation by birds remained high, except for the years when high spring floods interfered with bird settling.  相似文献   
98.
Some species may have a larger role than others in the transfer of complex effects of multiple human stressors, such as changes in biomass, through marine food webs. We devised a novel approach to identify such species. We constructed annual interaction-effect networks (IENs) of the simulated changes in biomass between species of the southeastern Australian marine system. Each annual IEN was composed of the species linked by either an additive (sum of the individual stressor response), synergistic (lower biomass compared with additive effects), or antagonistic (greater biomass compared with additive effects) response to the interaction effect of ocean warming, ocean acidification, and fisheries. Structurally, over the simulation period, the number of species and links in the synergistic IENs increased and the network structure became more stable. The stability of the antagonistic IENs decreased and became more vulnerable to the loss of species. In contrast, there was no change in the structural attributes of species linked by an additive response. Using indices common in food-web and network theory, we identified the species in each IEN for which a change in biomass from stressor effects would disproportionately affect the biomass of other species via direct and indirect local, intermediate, and global predator–prey feeding interactions. Knowing the species that transfer the most synergistic or antagonistic responses in a food-web may inform conservation under increasing multiple-stressor impacts.  相似文献   
99.
Ecological restoration has become an important strategy to conserve biodiversity and ecosystems services. To restore 15% of degraded ecosystems as stipulated by the Convention on Biological Diversity Aichi target 15, we developed a prioritization framework to identify potential priority sites for restoration in Mexico, a megadiverse country. We used the most current biological and environmental data on Mexico to assess areas of biological importance and restoration feasibility at national scale and engaged stakeholders and experts throughout the process. We integrated 8 criteria into 2 components (i.e., biological importance and restoration feasibility) in a spatial multicriteria analysis and generated 11 scenarios to test the effect of assigning different component weights. The priority restoration sites were distributed across all terrestrial ecosystems of Mexico; 64.1% were in degraded natural vegetation and 6% were in protected areas. Our results provide a spatial guide to where restoration could enhance the persistence of species of conservation concern and vulnerable ecosystems while maximizing the likelihood of restoration success. Such spatial prioritization is a first step in informing policy makers and restoration planners where to focus local and large‐scale restoration efforts, which should additionally incorporate social and monetary cost–benefit considerations.  相似文献   
100.
基于行为安全的建筑事故预防量化方法与实证研究   总被引:3,自引:2,他引:1  
在阐述安全行为(BBS)预防事故原理及其应用效果的基础上,选取某工程项目作为试验对象,结合我国建筑业一线工人的特点,对BBS实施中的培训方法、关键行为确认、观察方法3个关键环节进行具体试验。试验中建立了行为变化指数的图线,使用了安全行为指数(SI)来评定一线工人的安全行为及变化趋势。试验结果显示施工现场一线工人作业过程中的SI比基线期提高15%,表明所设计的BBS方法对于提高施工现场一线工人的行为安全性具有明显的效果。  相似文献   
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