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1.
Reasons for the current siting impasse, including participatory activism, regulatory failure, the multiplication of considered interests, and the “investigative caveat,” are reviewed, and the existing logic of regulator behavior, viewed as a rational choice model, is summarized. Three sets of goals for agency participants are identified: personal goals of agency decision-makers, organizational goals of the agency as a whole, and goals of agency clients; and the incentive system of a new administrative agency structured so as to make satisfaction of these goals contribute toward informed and impartial decision-making. Major structural components of the agency would be a Director, a Corps of Examiners, counsel(s) for special interest(s) of special merit, a Public Counsel, and a Research and Information Office. The model is applied to the case of a regional or state-level agency to handle power plant siting.  相似文献   

2.
Urban green land compensation plays an important role in county development, ecological environment management and many other fields. The concept, methods and principles of urban green land are introduced in this paper. According to the pay fee method, the value and ecological function of various types of urban green land were analyzed. The cost-benefit analysis method (CBAM) was used to estimate different external diseconomy benefits caused by green land loss. The authors applied CBAM to estimate such benefits in the case of Shanghai, China, and calculated the actual compensation value for green land. Results indicated that in 2002, the compensation value for the green land of Shanghai was RMB 8.58 × 105 Yuan/hm2.  相似文献   

3.
李云燕 《生态环境》2011,20(12):1957-1965
基于国家主体功能区划的自然保护区被界定为禁止开发区域,必然要对其进行科学有效地实施生态补偿。本文阐明对我国自然保护区实施生态补偿的必要性,分析生态补偿机制的构建路径,探讨生态补偿标准的确定方法,对生态补偿的方式类型及自然保护区生态补偿机制的实施途径进行深入研究。生态补偿机制的构建路径涉及补偿主体与对象、补偿标准与尺度、补偿方式与途径以及法律保障等内容。生态补偿标准的确定是生态补偿机制建设中的重点与难点问题,需要依据生态保护者的直接投入与损失以及机会成本、生态破坏的恢复成本、生态受益者的获利、生态系统服务的价值等进行核算。其确定方法包括直接成本法、机会成本法、意愿调查法、市场法、生态系统服务功能价值法等。生态补偿的方式和途径是实施生态补偿机制的核心与关键,主要涉及政府与市场两种基本途径。对自然保护区这样的生态保护的重点功能区域,应该充分发挥政府的主导作用,中央与省级财政应加大纵向转移支付力度。同时,应积极引入市场机制,作为生态补偿机制建设的有益补充。  相似文献   

4.
5.
We have re-evaluated the experimental methods and statistical procedures used to determine the relationship between feeding rates of pelagic herbivores and food concentration. Analysis of our own experiments, on Calanus pacificus feeding on Gyrodinium resplendens, and of other published research on this subject suggests the need for improvements in experimental design and methodology. We show that the use of mean concentration is statistically erroneous. First, it produces an artificial increase in the degrees of freedom that may result in the acceptance of nonsignificant regression lines. Second, it negates the value of replication, which is required to estimate sources of error. We present an example of how replication may be used to improve control over sources of error. Furthermore, we recommend the use of initial concentration rather than mean concentration. Finally, we introduce alternative methods to determine clearance and ingestion rates that enable the investigator to use replication and thus to estimate experimental errors.  相似文献   

6.
7.
In line with sustainable development principles, the reactions to modern architecture and planning have led to a new appreciation of traditional cities and urban environments.

Considering the extensive neglect and devastation of local values in our cities and towns, urban development practice in Turkey cannot be said to meet the requirements of sustainability. This paper, therefore, will explore the logic of sustainable development and focus on the components of good urban design which are needed to produce it. Since promoting sustainable lifestyles in our towns and cities depends mainly on the design of the physical environment, the paper will propose a set of key design principles that can deliver sustainable urban development through exploring the qualities of ‘traditional urbanism’ in the Turkish cities as well as examining the latest approaches to urban design.  相似文献   

8.
Computational and experimental approaches are employed for the structural design of a natural windbreak. It is intended to find the optimum tree shelterbelt to obviate the uneven wind speed distribution across the width dimension of a high-level competition rowing channel. The experimental results, obtained in a wind tunnel, and consisting of erosion-technique images and local wind-speed measurements, are used to benchmark the computational model. A good agreement between the two sets of results is obtained. Several windbreak configurations, considering one or two rows of different cross-sectional shape and porosity, are computationally modeled. For the shortest row a rectangular shape, with porosity of 35%, is considered; for the tallest row, which aims the modeling of a poplar tree, a porosity of 87% is assumed at the trunk level, and 60% at the crown. The optimum shelterbelt consists of two rows, composed by bamboo and poplar trees, which allows the attainment of a low and nearly uniform wind flow across the width of the channel.  相似文献   

9.
非稳态条件下藻类种间非生物资源竞争理论及研究进展   总被引:2,自引:0,他引:2  
金相灿  杨苏文  姜霞 《生态环境》2007,16(2):632-638
从理论及实验研究的角度论述了藻类非稳态种间资源竞争研究进展。实验室内稳态条件下的竞争理论得到了大量实验验证,由于自然水体处于非稳状态,非稳态条件下藻类种间资源竞争日益成为藻类水华形成机制研究的重点。主要理论包括Tilman的R*法则和资源比假说,Grover的拾遗者-机会主义者交替竞争假说(VIS),中度干扰假说(IDH)及关键光强(CLIH)假说。这些假说的提出丰富了藻类资源竞争的理论体系,为研究自然状态下藻类增殖和竞争行为奠定理论基础。今后的藻类种间资源竞争的研究重点为非稳态下物理条件变化以及物理、化学和生物资源共同变化下藻类种间关系及生物多样性的研究。  相似文献   

10.
This paper proposes a welfare criterion that balances the need for development and the concern for the least advantaged generations, and explores its implications. This criterion, called the mixed Bentham–Rawls criterion, moderates the effect of discounting, yet permits some degree of intertemporal trade-off. It is a weighted average of two terms: (a) the sum of discounted utilities and (b) the utility level of the least advantaged generation. We derive necessary conditions to characterize growth paths that satisfy our criterion, and show that in some models with familiar dynamic specifications, an optimal path exists and displays appealing characteristics.  相似文献   

11.
Potassium-ion batteries(PIBs) are potential “Beyond Li-ion Batteries” candidates for their resource advantage and low standard electrode potential. To date, the research on PIBs is in its early stages, the most urgent task is to develop high-performance electrode materials and reveal their potassium storage mechanism. For PIBs anode materials, carbon with tunable microstructure, excellent electrochemical activity, nontoxicity and low price is considered as one of the most promising anode materia...  相似文献   

12.
As GIS becomes an increasingly more ‘user-friendly’ tool, and more people recognize the benefits of the technology in their work environment, inevitably greater use will be made of it for a wide range of applications. The ease with which a GIS can now be used often overshadows the complexity underlying this technology and the potential difficulties that can (and do) arise when this is not fully understood. In practice, there are two routes open to the application of GIS technology for environmental studies. The first is to commission new data for the research. The second is to make use of existing data sets. Data are at the heart of any GIS application. A detailed knowledge about the data sources, the method of collection, capture, scale and sampling strategy, especially if the data are to be used in any analysis, modelling or simulation studies, is fundamental to any application. Unfortunately, information about data (metadata) is seldom available, especially for archival or legacy data sets. Furthermore, although it is now relatively easy to acquire digital data, to input, store, manipulate and display this data, and to output the results of any GIS analysis in the practical sense, little consideration is given to the problems associated with data quality and how this will ultimately affect present and future analyses and use of the output for planning and decision-making. The need to raise awareness about data quality for applications is set in the context of the development of an environmental database for the Moray Firth. Northeast Scotland, and more specifically the use of selected data sets from the database to aid in the proposed siting of an artificial reef. Using this example, this contribution explores the problems associated with the use of both existing analog and digital data sets as the basis for environmental applications, the problems of data acquisition, data quality, data standards, error and how these can affect the operational use of the data in GIS analyses. The solution to such problems appears to lie with improved error assessment and reporting. The outcome of this contribution is an attempt to offer guidance and solutions to researchers and applications specialists undertaking similar studies, by suggesting to what extent studies, such as the artificial reef siting, can safely make use of existing data sets without risking the problems associated with judgements based on inadequate information, and generated or inherent error.  相似文献   

13.
王彤  王留锁  姜曼 《生态环境》2010,26(6):1439-1444
生态补偿标准的测算是建立生态补偿机制的核心问题,也是难点所在。研究在对现有生态补偿标准计算方法进行总结分析的基础上,分别从供给方和需求方的角度探索建立了水库流域生态补偿标准测算体系。该体系对基于水库上游水源涵养区生态系统服务功能、生态保护建设总成本和基于下游用水城市意愿支付价格的补偿标准进行了比较分析,最终选择一个既能使水消费者承受得起,又能使生态保护者体会到有所回报的补偿金数额作为上下游协商确定补偿标准的依据。此体系较为全面地对补偿标准进行了测算,使得补偿标准更为公平、合理,进一步完善了水库流域生态补偿标准测算方法。并以大伙房水库流域为例,对其补偿标准进行测算,得出基于研究区生态系统服务功能的补偿标准为64661.3万元,基于研究区生态保护建设总成本的补偿标准为9221.4万元,基于下游用水城市意愿支付价格的补偿标准分别为8637.6万元、12956.4万元,最终认为10000万元是令补偿双方都比较容易接受的一个价格,可作为确定补偿标准的依据。  相似文献   

14.
This paper explores the prospects for combining elements of the ecological and policy sciences to form a substantive and effective science of ecological policy design. This exploration is made through a case study whose specific focus is the management problem posed by competition between man and an insect (the spruce budworm, Choristoneura fumiferana) for utilization of coniferous forests in the Canadian Province of New Brunswick. We used this case study as a practical testing ground in which we examined the relative strengths, weaknesses, and complementarities of various aspects of the policy design process. Where existing approaches proved wanting, we sought to develop alternatives and to test them in turn. In particular, we used a combination of simulation modeling and topological approaches to analyze the space-time dynamics of this ecosystem under a variety of natural and managed conditions. Explicit consideration was given to the development of invalidation tests for establishing the limits of model credibility. An array of economic, social, and environmental indicators was generated by the model, enabling managers and policy makers to evaluate meaningfully the performance of the system under a variety of management proposals. Simplified versions of the models were constructed to accomodate several optimization procedures, including dynamic programming, which produced trial policies for a range of possible objectives. These trial policies were tested in the more complex model versions and heuristically modified in dialogue with New Brunswick's forest managers. We explored the role of utility functions for simplifying and contrasting policy performance measures, paying special attention to questions of time preferences and discounting. Finally, the study was shaped by a commitment to transfer the various models and policy design capabilities from their original academic setting to the desks and minds of the practicing managers and politicians. An array of workshops, model gaming sessions, and nontraditional communication formats was developed and tested in pursuit of this goal.This paper reports some specific management policies developed, and some general lessons for ecological policy design learned in the course of the study.  相似文献   

15.
The net agglomeration and disamenities approaches to the measurement of agglomeration economies are merged. The net agglomeration view is represented by a labor demand function derived from Segal (D. Segal, Rev. Econ. Stat. 48, 339–350 (1976)). The disamenities view is represented by an upward-sloping labor supply function derived from Izraeli (O. Izraeli, Urban Stud. 14, 275–290 (1977)). Three cases are simulated. Case I is the benchmark case and assumes a linear homogeneous production function, no agglomeration economies, and no perceived environmental quality differences between cities. Cases II and III combine Segal and Izraeli by introducing agglomeration economies, an upward-sloping labor supply function, and a change in the level of air pollution. The results demonstrate the feasibility of isolating the output of market goods and environmental goods within a common framework.  相似文献   

16.
Raubenheimer D  Mayntz D  Simpson SJ  Tøft S 《Ecology》2007,88(10):2598-2608
In recent years it has become clear that intraguild predation (where predators feed on other predators) has important consequences for food webs, and yet very little is known about its nutritional or functional bases. In the most detailed study of the nutritional basis of foraging by a predator to date, we used geometrical analysis to test the ability of the generalist invertebrate predatory beetle, Agonum dorsale (Carabidae), to forage selectively for lipid and protein over a 10-day period following emergence from winter diapause, and we measured associated changes in body lipid and nitrogen content. Over the first 48 hours, beetles that were offered two nutritionally imbalanced but complementary foods self-selected a diet high in lipids, and thereafter the proportion of protein in the selected diet increased. Beetles confined to a single food with excess lipid (higher lipid:protein ratio than the self-selected diet) regulated intake to meet lipid requirements, while suffering a shortfall of protein. Those given diets with a lower lipid:protein ratio than the self-selected diet showed a progressive tendency across the 10-day experiment to over-ingest protein, thereby reducing the lipid deficit in their diet. Body composition changed markedly during the experiment, with the lipid content of the self-selecting insects increasing over the first 48 hours from 14% to 46% by dry mass, and thereafter remaining stable. We discuss some implications of our results for the understanding of intraguild predation.  相似文献   

17.
《Ecological modelling》2007,200(1-2):79-88
The movement of organisms is usually leptokurtic in which some individuals move long distances while the majority remains at or near the area they are released. There has been extensive research into the origin of such leptokurtic movement, but one important aspect that has been overlooked is that the foraging behaviour of most organisms is not Brownian as assumed in most existing models. In this paper we show that such non-Brownian foraging indeed gives rise to leptokurtic distribution. We first present a general random walk model to describe the organism movement by breaking the foraging of each individual into events of active movement and inactive stationary period; its foraging behaviour is therefore fully characterized by a joint probability of how far the individual can move in each active movement and the duration it remains stationary between two consecutive movements. The spatio-temporal distribution of the organism can be described by a generalized partial differential equation, and the leptokurtic distribution is a special case when the stationary period is not exponentially distributed. Empirical observations of some organisms living in different habitats indicated that their rest time shows a power-law distribution, and we speculate that this is general for other organisms. This leads to a fractional diffusion equation with three parameters to characterize the distributions of stationary period and movement distance. A method to estimate the parameters from empirical data is given, and we apply the model to simulate the movement of two organisms living in different habitats: a stream fish (Cyprinidae: Nocomis leptocephalus) in water, and a root-feeding weevil, Sitona lepidus in the soil. Comparison of the simulations with the measured data shows close agreement. This has an important implication in ecology that the leptokurtic distribution observed at population level does not necessarily mean population heterogeneity as most existing models suggested, in which the population consists of different phenotypes; instead, a homogeneous population moving in homogeneous habitat can also lead to leptokurtic distribution.  相似文献   

18.
林木根系衰老研究方法与机制   总被引:2,自引:1,他引:2  
张建锋  周金星 《生态环境》2006,15(2):405-410
根系衰老研究方法主要有根窗直接观测和挖根取样间接观测。在整株水平上,树木同化碳的能力,碳在不同器官间的分配,尤其是在地上部分和地下部分间的分配比例,对根的萌生和衰老起着重要作用;地上部分的生长过程和健康状况也对根系的生长和寿命有很大影响;当树木的生长环境受到某种胁迫时,树木的抵抗力下降,容易招致病原菌的危害,造成根系衰老和死亡。在生态系统水平上,干旱洪涝、干扰等胁迫和树木一土壤间的养分循环都会引起树木生长环境的改变,对根系的衰老过程发生作用;季节变化使树木的地上部分和地下部分的生理活动处于不同的旺盛期,从而使碳的分配方式有些改变,影响到根系的生长;土壤中养分的存在形式,某些离子的浓度也直接影响到根的寿命;病原菌对根系的危害与土壤中养分含量变化有关。所以,衰老过程受环境条件的影响,伴随着代谢,RNA和蛋白质合成速率的下降和(或)膜与细胞器结构的改变。  相似文献   

19.
森林生态系统的水文调节功能及生态学机制研究进展   总被引:2,自引:2,他引:2  
森林水文调节功能是森林所实现的重要服务功能之一,可是由于森林资源被无节制的开采利用,导致人们不断遭受森林破环所带来的洪旱灾害。因此关于森林生态水文功能研究已成为生态学和水文学的研究重点之一。近年来,国内外对森林水文调节过程及其生态学机制进行了广泛深入的研究,所以文章从森林的水文过程出发,对林冠截留、树干流、凋落物层截留、林地水分涵养和蒸发蒸腾及其影响因子的国内外研究现状进行了归纳分析,研究认为林地各冠层均能够截留降雨,降低雨水动能,从而减少地表径流的产生和对地表的冲击;凋落物层能蓄留水分、抑制蒸散、减缓地表径流;而树干流改变降雨水平空间格局,影响水分入渗以及土壤水源涵养。森林结构复杂,明显改变了降雨分配过程,而森林水文过程及调节功能又受到森林结构的制约,因此定量定性探讨森林生态系统的结构、过程与水文调节功能之间关系,是未来森林生态水文功能研究的重点。  相似文献   

20.
Nest concealment varies strongly within populations of many species. Although some studies have revealed the beneficial effects of concealment in mitigating predation pressure on nests, other studies were unable to find similar effects. One potential reason for the mixed results is that parental behaviour may compensate for the effects of nest cover, and specifically designed experimental studies are needed to reveal this compensation. I studied the effects of concealment on the probability of nest survival in the blackcap (Sylvia atricapilla), by experimentally manipulating the degree of nest-foliage cover. There was a significant effect of the treatment depending on nest type and the phase of nesting. Whereas there was no effect of concealment on nest survival in natural nests, there was a positive effect in real nests baited with plasticine clutches (i.e. without parental activity). Parents probably behaviourally compensated for poor concealment in natural nests (nest guarding, defence). In line with this, there was no effect of concealment on nest survival during incubation, whereas there was probably a positive effect in the nestling phase. Parents spent more time on the nest during incubation (80%) than during the care of nestlings (40%) and, consequently, had more opportunities to compensate for poor cover. In general, we cannot use single measures of behaviours or states (nest concealment) as an indication of predation risk because of the capacity for compensation in other behaviours.Communicated by C. Brown  相似文献   

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