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1.
Characteristics of urban natural areas and surrounding landscapes were identified that best explain winter bird use for 28 urban natural areas in southern Ontario, Canada. The research confirms for winter birds the importance of area (size) and natural vegetation, rather than managed, horticultural parkland, within urban natural areas as well as percent urban land use and natural habitat in surrounding landscapes. Alien bird density and percent ground feeding species increased with percent surrounding urban land use. Higher percent forest cover was associated with higher percentages of forest, bark feeding, small (<20 g) and insectivorous species. Natural area size (ha) was related to higher species richness, lower evenness and higher percentages of insectivorous, forest interior, area-sensitive, upper canopy, bark feeding, and non-resident species. Higher number of habitat types within natural areas and percent natural habitat in surrounding landscapes were also associated with higher species richness. Common, resident bird species dominated small areas (<6.5 ha), while less common non-residents increased with area, indicative of a nested distribution. Areas at least 6.5 ha and more generally >20 ha start to support some area-sensitive species. Areas similar to rural forests had >25% insectivores, >25% forest interior species, >25% small species, and <5% alien species. Indicator species separated urban natural areas from rural habitats and ordination placed urban natural areas along a gradient between urban development and undisturbed, rural forests. More attention is needed on issues of winter bird conservation in urban landscapes.  相似文献   

2.
本文分别从市场准入、价格、服务质量以及风险等方面,对城市环境基础设施市场化运营中的政府规制进行了具体分析。  相似文献   

3.
In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Besides technical solutions to abate air pollution, urban vegetation is increasingly recognized as an alternative ameliorative method by removing some pollutants mainly through dry deposition process. This paper assesses the capability and monetary value of this ecosystem service in Guangzhou city in South China. The results indicated an annual removal of SO(2), NO(2) and total suspended particulates at about 312.03Mg, and the benefits were valued at RMB90.19 thousand (US$1.00=RMB8.26). More removal was realized by recreational land use due to a higher tree cover. Higher concentration of pollutants in the dry winter months induced more removal. The lower cost of pollution abatement in China generated a relatively subdued monetary value of this environmental benefit in comparison with developed countries. Younger districts with more extensive urban trees stripped more pollutants from the air, and this capacity was anticipated to increase further as their trees gradually reach final dimensions and establish a greater tree cover. Tree cover and pollutant concentration constitute the main factors in pollutant removal by urban trees. The efficiency of atmospheric cleansing by trees in congested Chinese cities could be improved by planting more trees other than shrubs or grass, diversifying species composition and biomass structure, and providing sound green space management. The implications for greenery design were discussed with a view to maximizing this ecosystem service in Chinese cities and other developing metropolises.  相似文献   

4.
Despite a general decrease in Dutch environmental emission trends, it remains difficult to comply with European Union (EU) environmental policy targets. Furthermore, environmental issues have become increasingly complex and entangled with society. Therefore, Dutch environmental policy follows a pragmatic line by adopting a flexible approach for compliance, rather than aiming at further reduction at the source of emission. This may be politically useful in order to adequately reach EU targets, but restoration of environmental conditions may be delayed. However, due to the complexity of today’s environmental issues, the restoration of environmental conditions might not be the only standard for a proper policy approach. Consequently this raises the question how the Dutch pragmatic approach to compliance qualifies in a broader policy assessment. In order to answer this question, we adapt a policy assessment framework, developed by Hemerijck and Hazeu (Bestuurskunde 13(2), 2004), based on the dimensions of legitimacy and policy logic. We apply this framework for three environmental policy assessments: flexible instruments in climate policy, fine-tuning of national and local measures to meet air quality standards, and derogation for the Nitrate Directive. We conclude with general assessment notes on the appliance of flexible instruments in environmental policy, showing that a broad and comprehensive perspective can help to understand the arguments to put such policy instruments into place and to identify trade-offs between assessment criteria.  相似文献   

5.
The Environmental Liability Directive (ELD) establishes a framework of liability based on the ‘polluter-pays’ principle to prevent and remedy environmental damage. The ELD requires the testing of appropriate equivalency methods to assess the scale of compensatory measures needed to offset damage. The aim of this paper is to contribute to fill the existing knowledge gap on the application of the value equivalency approach for damage compensation in this context. We analyze the toxic spill damaging the Doñana National Park (Spain) in 1998. The welfare losses associated with the resource damage are estimated using non-market valuation and compared to the value of the compensatory measures taken after the accident. Our results show that the in-kind compensation may have been insufficient to offset the welfare losses. We conclude that a more comprehensive knowledge of the human welfare effects caused by environmental damage is of substantial importance to determine compensatory remediation, as insufficient information in this respect can lead to erroneous decisions causing loss to society.  相似文献   

6.
Continued resource degradation in various areas of the Great Lakes has led to doubts of the adequacy of conventional science and management approaches. The need for a more holistic approach, identified as an ecosystem approach, appears now to be more widely accepted although progress with implementation is slow. We argue here that ecosystem science is an integral part of an ecosystem approach and is a prerequisite to effective management planning.One of the problems of implementing an ecosystem approach is forging the link between ecosystem based research and management. For Green Bay, Wisconsin, USA, certain structural and functional qualities of the ecosystem have been used to define operational guides and to formulate management objectives. These objectives are being utilized in the development of a remedial action plan for Green Bay.Deceased 5 February 1986.  相似文献   

7.
Santiago, Chile has the distinction of having among the worst urban air pollution problems in Latin America. As part of an atmospheric pollution reduction plan, the Santiago Regional Metropolitan government defined an environmental policy goal of using urban forests to remove particulate matter less than 10 microm (PM(10)) in the Gran Santiago area. We used cost effectiveness, or the process of establishing costs and selecting least cost alternatives for obtaining a defined policy goal of PM(10) removal, to analyze this policy goal. For this study, we quantified PM(10) removal by Santiago's urban forests based on socioeconomic strata and using field and real-time pollution and climate data via a dry deposition urban forest effects model. Municipal urban forest management costs were estimated using management cost surveys and Chilean Ministry of Planning and Cooperation documents. Results indicate that managing municipal urban forests (trees, shrubs, and grass whose management is under the jurisdiction of Santiago's 36 municipalities) to remove PM(10) was a cost-effective policy for abating PM(10) based on criteria set by the World Bank. In addition, we compared the cost effectiveness of managing municipal urban forests and street trees to other control policies (e.g. alternative fuels) to abate PM(10) in Santiago and determined that municipal urban forest management efficiency was similar to these other air quality improvement measures.  相似文献   

8.
Currently popular concepts such as sustainable development and sustainability seek the integration of environment and development planning. However, there is little evidence that this integration is occurring in either mainstream development planning or environmental planning. This is a function of the history, philosophies, and evolved roles of both. A brief review of the experience and results of mainstream planning, environmental planning, and ecosystem science suggests there is much in past scientific and professional practice that is relevant to the goal of integrated planning for environment and development, but still such commonly recommended reforms as systems and multidisciplinary approaches, institutional integration, and participatory, goal-oriented processes are rarely achieved. “Ecosystem approaches,” as developed and applied in ecology, human ecology, environmental planning, anthropology, psychology, and other disciplines, may provide a more transdisciplinary route to successful integration of environment and development. Experience with ecosystem approaches is reviewed, their advantages and disadvantages are discussed, and they are compared to traditional urban and regional planning, environmental planning, and ecosystem science approaches. Ultimately a synthesis of desirable characteristics for a framework to integrate environment and development planning is presented as a guide for future work and a criterion for evaluating existing programs.  相似文献   

9.
The impacts of agricultural land use are far-reaching and extend to areas outside production. This paper provides an overview of the ecological status of agricultural systems across the European Union in the light of recent policy changes. It builds on the previous review of 2001 devoted to the impacts of agricultural intensification in Western Europe. The focus countries are the UK, The Netherlands, Boreal and Baltic countries, Portugal, Hungary and Romania, representing a geographical spread across Europe, but additional reference is made to other countries. Despite many adjustments to agricultural policy, intensification of production in some regions and concurrent abandonment in others remain the major threat to the ecology of agro-ecosystems impairing the state of soil, water and air and reducing biological diversity in agricultural landscapes. The impacts also extend to surrounding terrestrial and aquatic systems through water and aerial contamination and development of agricultural infrastructures (e.g. dams and irrigation channels). Improvements are also documented regionally, such as successful support of farmland species, and improved condition of watercourses and landscapes. This was attributed to agricultural policy targeted at the environment, improved environmental legislation, and new market opportunities. Research into ecosystem services associated with agriculture may provide further pressure to develop policy that is targeted at their continuous provisioning, fostering motivation of land managers to continue to protect and enhance them.  相似文献   

10.
For the last three and half decades, Botswana has been widely acclaimed to be one of sub-Saharan Africa's longest and most stable liberal democracies, coupled with and sustained by a growing economy. One of the major contradictions, however, within this development scenario, has been the neglect of environmental problems in the country in general, and urban environmental issues in particular. Part of the problem fueling the misconception of environmental issues in Botswana is the state's domination of the country's environmental agenda. This is linked to the power disjunction in decision-making and policy processes between state and nonstate actors over the most appropriate course of action to tackle the problems. Without adopting appropriate analytical frameworks, it is possible that the problem of urban environmental mismanagement in Botswana will persist. This article examines some of the major urban environmental issues in Botswana from neighborhood, citywide, and urban–rural interface perspectives. Further, the elite theory of public policy is used to explain constraints on policy change in the urban environmental management arena in Botswana.  相似文献   

11.
In developing countries, large dam projects continue to be launched, primarily to secure a time-stable freshwater supply and to generate hydropower. Meanwhile, calls for environmentally sustainable development put pressure on the dam-building industry to integrate ecological concerns in project planning and decision-making. Such integration requires environmental impact statements (EISs) that can communicate the societal implications of the ecological effects in terms that are understandable and useful to planners and decision-makers. The purpose of this study is to develop a basic framework for assessing the societal implications of the river ecological effects expected of a proposed large dam project. The aim is to facilitate a comparison of desired and potential undesired effects on-site and downstream. The study involves two main tasks: to identify key river goods and services that a river system may provide, and to analyze how the implementation of a large dam project may alter the on-site capacity and downstream potentials to derive river goods and services from the river system. Three river goods and six river services are identified. River goods are defined as extractable partly man-made products and river services as naturally sustained processes. By four main types of flow manipulations, a large dam project improves the on-site capacity to derive desired river goods, but simultaneously threatens the provision of desirable river goods and services downstream. However, by adjusting the site, design, and operational schedule of the proposed dam project, undesirable effects on river goods and services can be minimized.  相似文献   

12.
Fast economic and social changes in recent years in China have brought massive expansion, redevelopment, and restructuring of cities. These changes offer cities the opportunity to improve environmental quality through urban green spaces (UGSs) and to address the challenges of meeting community aspirations. This study explored peoples’ minds concerning UGSs in Guangzhou city in south China in relation to the following: (1) knowledge and perception of 25 ecosystem services and 8 negative impacts; (2) attitude toward site condition and management; (3) expectation of landscape design; and (4) preference ranking of venues. A questionnaire was designed to solicit opinions from 340 respondents randomly chosen from residents living in the study area. The results indicated widespread recognition of ecosystem services and strong support of UGS programs. Negative responses were weakly expressed. Amelioration of urban microclimate and environmental quality were emphasized. Environmental functions stressed in publicity programs, together with aggravating environmental problems in the city, tended to focus respondents’ attention on UGS benefits. Wildlife habitat, species conservation and other natural ecosystem services drew limited concerns. Awareness of economic benefits was very low. Visual-landscape contributions with strong preference for naturalistic design and recreational benefits were highlighted. Compared with other countries, Guangzhou residents were characterized by visual–scenic–recreation orientation and pragmatic–utilitarian perception of UGSs, reflecting underlying differences in the understanding of inherent ecosystem services of green spaces. Relevant UGS policies and practices could adopt the approaches of market survey, citizen participation, and precision planning in order to meet increasingly mature and refined demands. Citizens’ understanding of high-order ecosystem services could be enhanced to encourage appreciation of nature and their associated benefits.  相似文献   

13.
Urban ecological systems: scientific foundations and a decade of progress   总被引:9,自引:0,他引:9  
Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.  相似文献   

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