首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
The use of environmental safety standards is being increasingly advocated, and economists are being increasingly required to adapt their policy models to take account of such standards, e.g. by the use of transferable environmental damage quotas. The use of these standards may be a consequence of a greater desire to achieve more sustainable development and preserve the natural wealth available to future generations. An important means to this goal is to preserve biodiversity and genetic variability. Safe minimum standards for conservation of wildlife have been suggested as a way to achieve this. Sometimes safe minimum standards for conservation of species are defined in terms of their minimum viable populations and their minimum habitat requirements. However, as a review of recent scientific literature indicates, these safe minimum standards are very uncertain.Environmental safety standards have been integrated into economics in a variety of ways, e.g. via constraints to ensure sustainability at the macro-level, via minimum safety standards necessary to ensure survival of species. Despite the commendable support which safe minimum standards appear to give for nature conservation, they involve conceptual problems and uncertainties as outlined in this paper. In fact, safe minimum standards for the conservation of species do not exist — no standard ensures the continued existence of any species. This is not to deny that an improvement in standards can up to a point increase the probability of survival of a species for a specified period of time. It implies that minimum standards need to be cast in terms of those required to achieve a particular probability of survival of the targeted species for a specified period. It may, however, be impossible to achieve the goal specified, e.g. the probability of survival of a species aimed for, may be greater than can be achieved for any attainable standard. In general, the paper makes it clear that standards suggested by natural scientists and others need to be subjected to careful serutiny before they can be used as a reliable basis for economic policy.  相似文献   

2.
The Precautionary Principle is in sharp political focus today because (1) the nature of scientific uncertainty is changing and (2) there is increasing pressure to base governmental action on more “rational” schemes, such as cost-benefit analysis and quantitative risk assessment, the former being an embodiment of ‘rational choice theory’ promoted by the Chicago school of law and economics. The Precautionary Principle has been criticized as being both too vague and too arbitrary to form a basis for rational decision making. The assumption underlying this criticism is that any scheme not based on cost-benefit analysis and risk assessment is both irrational and without secure foundation in either science or economics. This paper contests that view and makes explicit the rational tenets of the Precautionary Principle within an analytical framework as rigorous as uncertainties permit, and one that mirrors democratic values embodied in regulatory, compensatory, and common law. Unlike other formulations that reject risk assessment, this paper argues that risk assessment can be used within the formalism of tradeoff analysis—a more appropriate alternative to traditional cost-benefit analysis and one that satisfies the need for well-grounded public policy decision making. This paper will argue that the precautionary approach is the most appropriate basis for policy, even when large uncertainties do not exist, especially where the fairness of the distributions of costs and benefits of hazardous activities and products are a concern. Furthermore, it will offer an approach to making decisions within an analytic framework, based on equity and justice, to replace the economic paradigm of utilitarian cost-benefit analysis.  相似文献   

3.
竞争-耐胁迫-杂草型植物对策理论及其应用研究进展   总被引:1,自引:0,他引:1  
竞争-耐胁迫-杂草型植物(CSR)对策理论主要研究植物对环境胁迫和干扰的适应性特化。从功能生态学角度讲,CSR理论是通过解释各种功能性状协同变异的主导维度来反映植物的生态对策。而物种所采取的生态对策将决定其在群落中的生态位,并最终会影响生态系统过程与功能。自1974年Grime首次提出CSR对策的概念以来,CSR对策思想就受到了生态学家很大的关注,经过近半个世纪的发展,目前已经形成了比较完整的理论和研究方法体系。试图在回顾CSR理论及其研究方法发展的基础上,阐述其基本内涵,并重点从功能性状变异空间、植物适应性、群落过程和生态系统特性等4个方面概述CSR理论及其分析模型的验证及应用,梳理其最新研究进展。CSR理论已经得到了很多研究的广泛验证并应用于多种尺度上的植物生态学研究,但仍有一些方面值得进一步发展完善,如第四区缺失问题、功能性状变异主轴以外的变异、CSR对策与功能性状种内变异和谱系关系的联系等方面需要深入研究。  相似文献   

4.
5.
Realist philosophies of science posit a dialectical relation between theoretical, explanatory knowledge and practical, including taxonomic knowledge. This paper examines the dialectic between the theory of descent and empirical, Linnaean taxonomy which is based on a logic of traditional classes. It considers the arguments of David Hull to the effect that many of the practical problems of empirical classification can be resolved by means of an ontology based upon the theory of descent in which species taxa are regarded as individuals rather than as classes or natural kinds.Contra Hull, it is argued that this view is, at best, only partially consistent with taxonomic practice and that it cannot sustain experimental practice which presupposes that species taxa be regarded as natural kinds. An outline is given of a possible alternative dialectic between a field theory of morphogenesis and a rational systematics involving a logic of relations.  相似文献   

6.
Industrial Ecology and Ecological Engineering   总被引:1,自引:0,他引:1  
Ecological engineering (EE) and industrial ecology (IE) strive to balance humanity's activities with nature. The disciplines have emerged separately but share theoretical foundations and philosophies on how to address today's complex environmental issues. Although EE and IE share motive, goals, theories, and philosophies, there are many differences. These similarities and differences may make for a strong symbiotic relationship between the two fields. The goals of this article are (1) to compare and contrast the two fields to identify opportunities for collaboration and integration and (2) to suggest three cross-disciplinary focal areas that bridge EE and IE.
The first symbiotic area, ecosystem engineering for byproduct recovery, is defined as the design, creation, and management of living ecosystems (e.g., forests, wetlands) that utilize the by-products of industrial systems. Examples of this exist, including constructed wetlands for lead recovery and phyto-mining of nickel tailings. The second symbiotic focus is entitled "ecosystem analogues for industrial ecology", which fits with a founding principle of IE to strive to have industry emulate the energy efficiencies and material cycles of natural ecosystems. This focal area quantifies the ecological analogy and exploits the tremendous library of design alternatives that nature has developed over thousands of years to deal with varied resource situations. The third focal area is termed "eco-system information engineering." The means by which living ecosystems have created robust knowledge systems and information cycles should be understood in terms useful for managing current society's information explosion. As industrial society evolves toward the information society, holistic models are needed that account for the available energy and material resources required to operate effective information ecosystems, such as service industries.  相似文献   

7.
传统的遗传流行病学和基因定位的研究设计往往局限于单一的(通常是简单的)数据结构和过分简化的流行病学模型。然而,当实际情况稍微复杂一些的时候,这些简单的方法几乎注定要失败,因此,我们应该重新建构思维方式,应考虑何种的病因学模型会与我们所知道的进化,表现型的表达以及基因型-表现型的相互关系相符,当基因定位的策略充分利用选择偏倚来使P(基因型Ⅰ表现型的;选择偏倚)的预测值达到最大,用分离分析试图对外显率函数或P(表现型Ⅰ基因型)作无偏估计,因而一般而言,没有一个值可以完全充分地被另一个值所推估,一个常见的,关于基因组计划得以“改变世界”的误解甚至使得严谨的科学家们都忽略了以下的科学事实;他们努力地为基因定位策略上的巨额支出辩护,却忽略了基因定位策略的本身就是极度取决于一些难以验证的前题假设,将不同实验设计方案的数据合并起来定会使估计参数和检验假设的自由度增加,虽然仍然需要大样本数的资料库,但采取以上策略可提供更多的信息以检测出真实情况,以往传统的研究方法只针对病因变异量的某一特定方面;双生子法侧重于研究在一个家庭内分享共同的环境因素之下遗传因素的作用;寄养子研究侧重于在控制遗传因素之下,不同家庭环境间的变异性;移民流行病学分析侧重于在控制遗传因素之下,不同文化环境间的变异性;而家系分析则侧重于检测较大的亲缘族系中的复杂遗传性相关,不同的研究着重不同成份的变异量,很显然,一个综合性的研究将可对特微病因学提供更多关于自然,养育因素以及它们之间交互作用的信息,同样地,这些信息可用来辅助基因定位和基因型-表现型相关性的研究,我们目前正以外朝鲜族家庭为对象进行此类研究,这些外朝鲜族家庭包括位于哈萨克斯坦,韩国,中国(延边0的朝鲜族家庭以及寄养于美国及欧洲的朝鲜人,我们亦希望能取得这些寄养人位于韩国的血亲的资料。  相似文献   

8.
Scientific theories seek to provide simple explanations for significant empirical regularities based on fundamental physical and mechanistic constraints. Biological theories have rarely reached a level of generality and predictive power comparable to physical theories. This discrepancy is explained through a combination of frozen accidents, environmental heterogeneity, and widespread non-linearities observed in adaptive processes. At the same time, model building has proven to be very successful when it comes to explaining and predicting the behavior of particular biological systems. In this respect biology resembles alternative model-rich frameworks, such as economics and engineering. In this paper we explore the prospects for general theories in biology, and suggest that these take inspiration not only from physics, but also from the information sciences. Future theoretical biology is likely to represent a hybrid of parsimonious reasoning and algorithmic or rule-based explanation. An open question is whether these new frameworks will remain transparent to human reason. In this context, we discuss the role of machine learning in the early stages of scientific discovery. We argue that evolutionary history is not only a source of uncertainty, but also provides the basis, through conserved traits, for very general explanations for biological regularities, and the prospect of unified theories of life.  相似文献   

9.
A scientific field matures as its theoretical underpinnings consolidate around unified theories: conceptual structures consisting of a few general propositions that encompass a wide domain of phenomena and from which can be derived an array of models. We demonstrate this process with a synthetic theory of ecological gradients and species richness. Our unified theory rests on four propositions. First, variation in some environmental factor effects variation in the number of individuals creating a gradient. Second, in a uniform environment of fixed area, more individuals lead to more species. Third, the variance of an environmental factor increases with its mean for sites of equal area. Fourth, all nonmonotonic relationships (i.e., hump shaped or U shaped) require a trade-off in organismal performance or in population characteristics with respect to the environmental gradient. We identify 17 models that link environmental gradients with diversity, show their relationship to our framework, and describe issues surrounding their empirical testing. We illustrate how a general theory can be used to build new models such as that for the U-shaped productivity-diversity relationship. Finally, we discuss how our theory could be unified further with other theories of diversity and indicate other areas of ecology that are ripe for unification. By providing an example of the process of theory unification, we hope to encourage such efforts throughout ecology.  相似文献   

10.
Many phenotypes respond physiologically or developmentally to continuously distributed environmental variables such as temperature and nutritional quality. Information about phenotypic plasticity can be used to improve the efficiency of artificial selection. Here we show that the quantitative genetic theory for 'infinite-dimensional' traits such as reaction norms provides a natural framework to accomplish this goal. It is expected to improve selection responses by making more efficient use of information about environmental effects than do conventional methods. The approach is illustrated by deriving an index for mass selection of a phenotypically plastic trait. We suggest that the same approach could be extended directly to more general and efficient breeding schemes, such as those based on general best linear unbiased prediction. Methods for estimating genetic covariance functions are reviewed.  相似文献   

11.
杨萍  杨永峰  杨宜男  程亚文  王立  王原 《生态学报》2023,43(22):9206-9217
鸟类栖息地会随着季节迁徙而改变,基于此对以珍稀濒危鸟类保护为主要目标的自然保护区进行动态分区管理,能够有效提高土地利用效率,协调生物多样性保护与其他生态系统服务功能利用。通过MaxEnt模型分析预测安徽升金湖国家级自然保护区鸟类繁殖季和越冬季的栖息地范围,并采用空间叠加分析方法得到动态分区方案。结果发现:繁殖季鸟类栖息地适宜性受到人口密度、丰水期土地利用类型、距居民点距离、距道路距离等环境因素的影响;越冬季鸟类受到距道路距离、人口密度、距枯水期水体距离、枯水期土地利用类型等环境因素的影响。运用ArcGIS水文工具分析出升金湖国家级自然保护区汇水单元作为其动态区划单元,根据鸟类栖息地季节性变化的特点结合分析结果叠加分析,将安徽升金湖国家级自然保护区划分为核心栖息地保护区、繁殖季栖息地保护区、越冬季栖息地保护区和一般控制区。核心栖息地保护区要进行全年严格保护,繁殖季栖息地保护区和越冬季栖息地保护区在相应鸟类栖息时段严格管控、非栖息时段可合理利用,一般控制区则全年可允许合理的行为活动。季节性动态分区方案注重解决安徽省升金湖国家级自然保护区生态环境保护和社区发展之间的矛盾问题,便于未来保护区生态保护规划决策的制定和实施,进一步丰富了以季节性栖息物种为主要保护对象的自然保护区的动态功能分区研究理论与方法体系,为制定提高自然保护区空间利用效率的生态管理策略提供了参考依据。综上,建议在升金湖国家级自然保护区生态环境保护和社区发展中,依据保护区季节性动态分区特征,实行分区管制,制定对应的生态环境保护和发展的措施。  相似文献   

12.
城市生态系统的动力学演化模型研究进展   总被引:5,自引:0,他引:5  
郁亚娟  郭怀成  刘永  黄凯  王真 《生态学报》2007,27(6):2603-2614
从系统分析出发,对城市生态系统的动力学演化模型的发展历程、建模的方法和步骤过程、软件开发方法和目前的模型软件等进行了总结。归纳了城市生态系统的动力学演化建模的方法,主要包括模型定义、模拟、实现、验证、分析和应用等六大步骤。目前国内外用于城市生态系统动力学演化模型的主要方法有:基于数理模型的方法、生态控制论和灵敏度模型、系统动力学模型、多目标规划法等。已经开发的用于城市生态系统的动力学模拟的软件可以划分为两类:基于土地利用和交通规划的专业模型和基于系统动力学和灵敏度模型的一般软件。总结了常用的城市演化模型软件,讨论了模型的研究对象和应用范围。分析了城市生态系统的动力学演化模型建模的不确定性的来源,并指出:向宏观和微观两极化发展是城市生态系统动力学演化模型的发展趋势之一,而与人工智能和地理信息系统等新方法的集成是发展的另一趋势。城市生态系统动力学演化模型的开发前景在于对不确定性问题的定性、定量分析,而多模型的耦合和集成是发展的必然趋势。  相似文献   

13.
Koch's postulates have shaped our understanding of infectious diseases; however, one of the tangential consequences of them has been the emergence of a predominantly monomicrobial perspective concerning disease aetiology. This orthodoxy has been undermined by the growing recognition that some important infectious diseases have a polymicrobial aetiology. A significant new development in our understanding of polymicrobial infections is the recognition that they represent functional ecosystems and that to understand such systems and the outcome and impact of therapeutic interventions requires an understanding of how these communities arise and develop. Therefore, it is timely to explore what we can learn from other fields. In particular, ecological theory may inform our understanding of how polymicrobial communities assemble their structure and their dynamics over time. Such work may also offer insights into how such communities move from stable to unstable states, as well as the role of invasive pathogens in the progression of the disease. Ecological theory offers a theoretical framework around which testable hypotheses can be developed to clarify the polymicrobial nature and dynamics of such infections in the face of environmental change and therapeutic interventions.  相似文献   

14.
Null models that place species ranges at random within a bounded geographical domain produce hump-shaped species richness gradients (the "mid-domain effect," or MDE). However, there is debate about the extent to which these models are a suitable null expectation for effects of environmental gradients on species richness. Here, I present a process-based framework for modeling species distributions within a bounded geographical domain. Analysis of null models consistent with the mid-domain hypothesis shows that MDEs are indeed likely to be ubiquitous consequences of geographical domain boundaries. Comparing the probability distributions of range locations for the process-based and randomization-based models reveals that randomization models probably overestimate the contribution of MDEs to empirical patterns of species richness, but it also indicates that other testable predictions from randomization models are likely to be robust. I also show how this process-based framework can be extended beyond null models to incorporate effects of environmental gradients within the domain. This study provides a first step toward an ecological theory of species distributions in geographical space that can incorporate both "geometric constraints" and effects of environmental gradients, and it shows how such a theory can inform our understanding of species richness gradients in nature.  相似文献   

15.
The paper describes some invariant relations of the Polistinae population structure, including resistance to abiotic and biotic factors that occurs against the background of the hierarchy of biological systems and increasing autonomy of their functioning. A decrease in the dependence on the hostile environment is shown to be due to the activity of foundresses and workers adjusting to external rhythms, developing specialized responses to predators and parasites (predictable external noise of biotic nature), and creating new information. The population organization of Polistinae wasps is considered in the framework of Anokhin’s theory of functional systems and systemogenesis. There are specific processes in the population that unite individual colonies and their reproduction; they are accompanied by the formation of an advanced feedback and functional systems. Systemic processes can be simultaneously regarded as “adaptation” (reflecting the organization of environmental elements) and as “adaptiveness” (reflecting the organization of the activity of intra-colony processes and the organization of reproduction). The organization of the colony activity and reproduction in functional systems reflects the future survival rather than the preceding phenomena and events. The behavior of individuals in a colony is determined not only by the effects of abiotic and biotic factors (via transformation of cues into behavioral programs), but also by previous adaptations (stored in the “memory” as images of still absent events). General progress, limited or partial progress, and narrow specialization in the organization of polistine colonies and populations are considered using the examples of morphofunctional, environmental, energy and information criteria. The emphasis on invariant relations makes it possible to more fully describe biological systems in terms of such general categories as isomorphism, homeostasis or self-organization, and also enables us to use more effectively the theory of general functional systems in studying social insects.  相似文献   

16.
Biologists and economists use models to study complex systems. This similarity between these disciplines has led to an interesting development: the borrowing of various components of model-based theorizing between the two domains. A major recent example of this strategy is economists’ utilization of the resources of evolutionary biology in order to construct models of economic systems. This general strategy has come to be called “evolutionary economics” and has been a source of much debate among economists. Although philosophers have developed literatures on the nature of models and modeling, the unique issues surrounding this kind of interdisciplinary model building have yet to be independently investigated. In this paper, we utilize evolutionary economics as a case study in the investigation of more general issues concerning interdisciplinary modeling. We begin by critiquing the distinctions currently used within the evolutionary economics literature and propose an alternative carving of the conceptual terrain. We then argue that the three types of evolutionary economics we distinguish capture distinctions that will be important whenever resources of model-based theorizing are borrowed across distinct scientific domains. Our analysis of these model-building strategies identifies several of the unique methodological and philosophical issues that confront interdisciplinary modeling.  相似文献   

17.
Background and AimsWhile trait-based approaches have provided critical insights into general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g. root porosity, low root/shoot ratio and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g. through the expression of leaf economics traits and size-related traits, respectively. However, we do not know whether and how these trait dimensions are connected.MethodsBased on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions: leaf economics traits and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms.Key ResultsWe found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated with flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor specific without generic adverse effects on plant functioning (e.g. causing trade-offs on leaf economics traits).ConclusionsThe trait expression across multiple dimensions promotes plant adaptations and coexistence across multifaceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including, for example, methane emissions) are species and habitat specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension.  相似文献   

18.
Cooperation between organisms can often be understood, like trade between merchants, as a mutually beneficial exchange of services, resources or other ‘commodities’. Mutual benefits alone, however, are not sufficient to explain the evolution of trade-based cooperation. First, organisms may reject a particular trade if another partner offers a better deal. Second, while human trade often entails binding contracts, non-human trade requires unwritten ‘terms of contract’ that ‘self-stabilize’ trade and prevent cheating even if all traders strive to maximize fitness. Whenever trading partners can be chosen, market-like situations arise in nature that biologists studying cooperation need to account for. The mere possibility of exerting partner choice stabilizes many forms of otherwise cheatable trade, induces competition, facilitates the evolution of specialization and often leads to intricate forms of cooperation. We discuss selected examples to illustrate these general points and review basic conceptual approaches that are important in the theory of biological trade and markets. Comparing these approaches with theory in economics, it turns out that conventional models—often called ‘Walrasian’ markets—are of limited relevance to biology. In contrast, early approaches to trade and markets, as found in the works of Ricardo and Cournot, contain elements of thought that have inspired useful models in biology. For example, the concept of comparative advantage has biological applications in trade, signalling and ecological competition. We also see convergence between post-Walrasian economics and biological markets. For example, both economists and biologists are studying ‘principal–agent’ problems with principals offering jobs to agents without being sure that the agents will do a proper job. Finally, we show that mating markets have many peculiarities not shared with conventional economic markets. Ideas from economics are useful for biologists studying cooperation but need to be taken with caution.  相似文献   

19.
Although individual‐level variation (IV) is ubiquitous in nature, it is not clear how it influences species coexistence. Theory predicts that IV will hinder coexistence but empirical studies have shown that it can facilitate, inhibit, or have a neutral effect. We use a theoretical model to explore the consequences of IV on local and regional species coexistence in the context of spatial environmental structure. Our results show that individual variation can have a positive effect on species coexistence and that this effect will critically depend on the spatial structure of such variation. IV facilitates coexistence when a negative, concave‐up relationship between individuals’ competitive response and population growth rates propagates to a disproportionate advantage for the inferior competitor, provided that each species specialises in a habitat. While greater variation in the preferred habitat generally fosters coexistence, the opposite is true for non‐preferred habitats. Our results reconcile theory with empirical findings.  相似文献   

20.
By evaluating tires from a perspective of industrial metabolism, potential novel and practical ways to reduce their environmental impact can be found. This may be achieved by focusing on technological issues such as choosing materials, designing products, and recovering materials, or by looking at institutional and social barriers and incentives such as opening waste markets or changing consumer behavior. A model is presented for the life cycle of truck tires in Western Europe that is dynamic in nature and values both environmental and economic consequences. Various scenarios are simulated including longer tire lifetimes, better maintenance of tire pressure, increased use of less-expensive Asian tires, and increased use of fuel efficiency-enhancing tires ("eco-tires"). Tentative results indicate that, among other things, more than 95% of the overall environmental impact during the life of a tire occurs during the use of the tire, due to the impact of tires on automotive fuel efficiency. Better maintenance of tire pressure and use of eco-tires produce greater environmental and economics benefits than more-durable and/or less-expensive (Asian) tires. These results imply that the emphasis in environmental policies related to tires should shift from the production and the waste stages to the consumption stage. It also suggests that the focus on materials throughput and associated improvements through factor 4 or factor 10 advances in reduction in mass are less important than the quality of the tires and their management.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号