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排序方式: 共有212条查询结果,搜索用时 15 毫秒
161.
Genetic improvement of livestock is a particularly effective technology, producing permanent and cumulative changes in performance. This paper highlights some of the options for including mitigation in livestock breeding schemes, focusing on ruminant species, and details three routes through which genetic improvement can help to reduce emissions per kg product via: (i) improving productivity and efficiency, (ii) reducing wastage in the farming system and (iii) directly selecting on emissions, if or when these are measurable. Selecting on traits that improve the efficiency of the system (e.g. residual feed intake, longevity) will have a favourable effect on the overall emissions from the system. Specific examples of how genetic selection will have a favourable effect on emissions for UK dairy systems are described. The development of breeding schemes that incorporate environmental concerns is both desirable and possible. An example of how economic valuation of public good outcomes can be incorporated into UK dairy selection indices is given. This paper focuses on genetic selection tools using, on the whole, currently available traits and tools. However, new direct and indirect measurement techniques for emissions will improve the potential to reduce emissions by genetic selection. The complexities of global forces on defining selection objectives are also highlighted. 相似文献
162.
Mather ME Finn JT Pautzke SM Fox D Savoy T Brundage HM Deegan LA Muth RM 《Journal of fish biology》2010,77(10):2326-2337
Almost three-quarters of the 46 young adult and sub-adult striped bass Morone saxatilis that were acoustically tagged in Plum Island Estuary, Massachusetts, U.S.A., in the summer of 2006 were detected in one or more southern coastal arrays during their autumn migration. On the basis of the trajectories along which these M. saxatilis moved from feeding to overwintering areas, three migratory groups emerged. After leaving Plum Island Estuary, about half of the fish were detected only in a mid-latitude array, Long Island Sound. The other half of the tagged fish were detected during autumn and winter in a more southern array, the Delaware Estuary. This latter group of fish may have used two routes. Some travelled to the Delaware Estuary through Long Island Sound while other fish may have taken a second, more direct, coastal route that did not include Long Island Sound. Consequently, a seemingly homogeneous group of fish tagged at the same time in the same non-natal feeding location exhibited a diversity of southward movement patterns that could affect population-level processes. These three groups that differed in overwintering location and migration route could be movement contingents with migratory connectivity. 相似文献
163.
生态系统服务功能分类与价值评估探讨 总被引:30,自引:2,他引:28
生态系统服务功能及其价值评估研究是当前生态学研究的热点,对于促进生态系统可持续管理具有重要作用。目前,在生态系统服务功能分类及价值评估方面,还没有形成比较系统的理论;在服务价值的评估方面,国内相关研究多数套用现有的一般化计算公式对生态服务功能进行计算,缺少针对性和探索性。总结近年来笔者在这方面的研究得失,并综合前人的研究,将生态系统服务功能进行新的分类,提出“核心”服务功能、“理论”服务价值与“现实”服务价值的概念,并以温州三湿地生态系统服务功能及其价值评估研究作为实例,论证所提出的新概念。生态系统服务功能及价值评估研究的最终目的是为生态系统管理决策者提供信息,因此服务价值评估的意义不在于对每一项服务功能价值的精确估算,甚至不需要计算一个生态系统所有的服务功能价值,而应抓住一个或几个有计算依据的核心服务功能。提出理论服务价值概念的主要目的在于同现实服务价值的比较,量化某服务功能的退化程度,明确后续生态恢复和重建的主要目标,并可在一定程度上作为生态恢复的重要指标。 相似文献
164.
我国棉花抗枯黄萎病品种纤维品质遗传改良评价 总被引:6,自引:1,他引:5
对我国108个抗枯、黄萎病骨干品种的纤维品质进行了分析,整体表现纤维较长,27mm以下的品种较少;比强度平均值较低,但也有少数高强力品种;马克隆值较大,纤维较粗.20世纪60-90年代抗病育种对纤维品质未明显改进,纤维长度、比强度、马克隆值平均值均无显著增长;但纤维长度类型更加丰富,纤维长度最大值有所增加,最高强力品种的比强度值逐渐提高,90年代品种中有较细纤维类型.从中筛选出纤维长度在33mm以上,比强度在33.2cN/tex以上,纤维整齐度在87.1%以上,马克隆值在3.8~4.3之间的品种各10个,筛选出纤维品质指标综合优良的品种9个. 相似文献
165.
《Ethnic and racial studies》2012,35(3):418-435
Abstract This study examines how members of minority groups in Israel cope with stigmatization in everyday life. It focuses on working-class members of three minority groups: Palestinian Arabs or Palestinian citizens of Israel, Mizrahim (Jews of Middle Eastern and North African origin) and Ethiopian Jews. It reveals the use of racial, ethnic and national markers in daily processes of social inclusion and exclusion in one sociopolitical context. Palestinians, a group with a fixed external identity and a limited sphere of participation, were found to use the language of race and racism when describing stigmatizing encounters. Ethiopian Jews, the most phenotypically marked group, strictly avoided this language. For their part, Mizrahi Jews perceived the very discussion of stigmatization as stigmatizing, while often using ‘contingent detachment’ to distance themselves from negative group identities. Despite differences between the communities and the powerful role of the state in establishing symbolic and social boundaries, members of all three groups expressed their intention to achieve or retain avenues for participation in the larger society. 相似文献
166.
Is forest landscape restoration socially desirable? A discrete choice experiment applied to the Scandinavian transboundary Fulufjället National Park Area 下载免费PDF全文
Sviataslau Valasiuk Mikołaj Czajkowski Marek Giergiczny Tomasz Żylicz Knut Veisten Iratxe Landa Mata Askill H. Halse Marine Elbakidze Per Angelstam 《Restoration Ecology》2018,26(2):370-380
Using an economic valuation approach, we assessed people's stated preferences for policy aimed at enhancing restoration of functional networks of naturally dynamic boreal forest habitats as a public good. Active landscape restoration can improve the functionality of boreal forest habitats as green infrastructure, which is essential for biodiversity conservation and delivery of multiple ecosystem services that production forests are poor at providing. In contrast, so far designation of protected areas in Fennoscandia has focused on remnant patches of near‐natural forests, and not on forest landscape restoration. We assessed citizens' preferences for forest landscape restoration in a transboundary region primarily managed for sustained‐yield wood production for the forest industry, and which hosts the transboundary Fulufjället National Parks in Sweden and Norway. We conducted a discrete choice experiment by asking Swedish and Norwegian citizens to choose among two options for the Fulufjället area, including (1) extension of passive protection on one side or both sides of the border, by additional area protection and restoration of forest naturalness, and (2) a status quo option. The scenario assumed that extension of the protected forest area would imply a compulsory tax administered bilaterally by the two countries. Just over half of the sample, in both countries expressed willingness to pay for forest landscape restoration. Alternatives that contemplated larger extensions of forest landscape restoration were assigned higher willingness‐to‐pay. Public awareness and support, combined with spatial planning, are necessary for forest landscape restoration to become a viable tool for biodiversity conservation in Scandinavia. 相似文献
167.
生物多样性经济价值评估的基本方法 总被引:33,自引:1,他引:32
目前,生物多样性经济价值的基本评价方法包括三种类型,一种是基于个人支付意愿(WTP)的直接经济价值评估方法,再一种是利用实际或替代市场的间接经济价值评估方法,第三种是针对生物多样性价值在空间上流动的现象,基于定量分析的过程-效益评价法。 相似文献
168.
Paying for Restoration 总被引:5,自引:0,他引:5
The question of how society is going to pay for restoration has received little open discussion. We review existing literature and examples to explore two questions: How should ecological and economic considerations be balanced in determining expenditures on restoration projects? and How is society going to pay for the substantial costs involved? We discuss a number of different techniques for determining the amount of money to allocate to restoration efforts, including ecosystem replacement costs, quantifying ecosystem services, contingent valuation, and surrogate market price techniques. We then review different strategies for paying for restoration including private funding by the party responsible for the damage, public funding through taxes, voluntary contributions, and various public/private partnerships. We conclude by discussing other considerations in developing strategies to pay for restoration, including uncertainty, time‐scale, evaluating success, and regional planning. 相似文献
169.
Synopsis The diversity of fishes is declining worldwide, largely as the result of habitat alterations created by decisions that foster short-term economic gain. While the best arguments for preserving endangered fishes and ecosystems are non-economic arguments, they have been relatively ineffective. Therefore, it is necessary to provide economic arguments as well. Fish in general have high market values and are a vital source of protein for humans but these values have contributed more to their decline than to their conservation. Fish also have high value as indicators of the health of ecosystems which provide many services to humans, such as clean water. This has not prevented the degradation of aquatic ecosystems, although the value of fisheries has occasionally justified ecosystem protection. Existence values have been developed as a way of putting an economic value on some of the less tangible aspects of fish and ecosystems but they also make it possible to justify extinctions. If the continuous increase in the number of endangered fishes and aquatic ecosystems is to be halted, then the economic costs of environmental degradation to future generations must be included as part of the cost of doing business today (intergenerational value). Political action is needed to protect fishes and aquatic habitats against the day when more benign economic and philosophical systems become predominant.Invited essay 相似文献
170.
《Journal of Industrial Ecology》2004,8(1-2):241-261
Materials flow analysis (MFA) is internationally recognized as a key tool to assess the biophysical metabolism of societies and to provide aggregated indicators for environmental pressures of human activities. Economy-wide MFAs have been compiled for a number of Organisation for Economic Cooperation and Development (OECD) countries, but so far very few studies exist for countries in the South. In this article, the first materials-flow-based indicators for Chile are presented. The article analyzes the restructuring of the Chilean economy toward an active integration in the world markets from the perspective of natural resource use in a time series from 1973 to 2000. Special emphasis is placed on the assessment of materials flows related to Chile's international trade relations. Results show that material inputs to the Chilean economy increased by a factor of 6, mainly as a result of the promotion of resource-intensive exports from the mining, fruit growing, forestry, and fishery sectors. At more than 40 tons, Chile's resource use per capita at present is one of the highest in the world. The article addresses the main shortcomings of the MFA approach, such as weightbased aggregation and the missing links between environmental pressures and impacts, and gives suggestions for methodological improvements and possible extensions of the MFA framework, with the intent of developing MFA into a more powerful tool for policy use. 相似文献