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551.
552.
Male dung beetles, Onthophagus taurus, are dimorphic for a secondary sexual trait, head horns. Horned males participate in the production of brood masses while
hornless male do not. Here we examine the reproductive performance of females mated with males exhibiting alternative horn
morphologies. We found that exposure to males may be costly for females in that it reduced the total number of brood masses
produced. However, females paired with horned males produced significantly larger brood masses than females paired with hornless
males or females producing broods alone. We discuss the possible selection pressures that may underly horn evolution in this
genus.
Received: 22 August 1997 / Accepted after revision: 19 January 1998 相似文献
553.
JunJie Wu David Zilberman Bruce A. Babcock 《Journal of Environmental Economics and Management》2001,41(3):333
Resource purchasing funds have become a major tool for environmental protection and resource conservation. These funds use various strategies to target resources for conservation, the choice of which may lead to striking differences in environmental performance. This paper develops an analytical framework to analyze the impact of alternative targeting strategies on different interest groups, including consumers, producers, labor, and environmentalists. We show that ignoring the output price effect of purchasing funds reduces environmental gain and in some cases may make a purchasing fund counterproductive, and we argue that the optimal design of targeting criteria must consider the price feedback effect. 相似文献
554.
Kenneth Strzepek David Yates Gary Yohe Richard Tol Nicholas Mader 《Integrated Assessment》2001,2(3):139-157
A space of “not-implausible” scenarios for Egypt's future under climate change is defined along two dimensions. One depicts
representative climate change and climate variability scenarios that span the realm of possibility. Some would not be very
threatening. Others portend dramatic reductions in average flows into Lake Nassar and associated increases in the likelihood
of year to year shortfalls below critical coping thresholds; these would be extremely troublesome, especially if they were
cast in the context of increased political instability across the entire Nile Basin. Still others depict futures along which
relatively routine and relatively inexpensive adaptation might be anticipated. The ability to adapt to change and to cope
with more severe extremes would, however, be linked inexorably to the second set of social–political–economic scenarios. The
second dimension, defined as “anthropogenic” social/economic/political scenarios describe the holistic environment within
which the determinants of adaptive capacity for water management, agriculture, and coastal zone management must be assessed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
555.
In the last decades the European Union exerted influence on precautionary environmental planning by the establishment of several Directives. The most relevant were the Habitat-Directive, the EIA-Directive, the SEA-Directive and the Water Framework Directive. Comparing these EU policies in the area of environmental precaution it becomes obvious that there is a lot of common ground. Thus, the conclusion seems likely that the European Union, in doing so, has intended to establish general planning concepts through introducing several methodological steps indicated by the regulations. The goal of this article is firstly to point out, which are the common planning principles, converted by methodological elements and secondly examine the consideration of these planning concepts by the implementation and application in the member states. In this context it is analysed whether the connections and divergences between the directives lead to significant differences in the implementation process. To this aim the directives are shortly introduced and significant steps of the processes regulated by them are outlined. In the second steps the national legal implementation in the Alpine states and its consequences for the practical application are discussed. The results show a heterogeneous application of the EU principles. Within the comparative view on the four directives influence and causalities between the national implementation and the practical application were identified, which can be simplified as four types. Since a coherent strategic and methodological concept for improving environmental precaution planning from part of the EU is noticeable, more unity and comparability within the implementation is desirable, particularly in areas with comparable habitats such as the alpine space. Beyond this the trade-off between the directives poses an important task for the future. 相似文献
556.
Lennart J. Lundqvist Sjur Kasa 《Journal of Environmental Planning and Management》2017,60(6):1092-1111
This paper contributes to the current discussion on whether ‘soft’ regulation actually influences policy outcomes by examining the effects of national policy instruments on municipal climate and energy planning. Sweden has experienced shifts in the incentive context over the last decades complementing soft planning regulations with stringent conditions for getting national economic support to local energy and climate action. We hypothesize that when soft regulations are surrounded by detailed conditions for getting state support, there will be higher degrees of local institutionalization of climate and energy strategies. The importance of economic support as part of national policy is confirmed by evidence from local energy and climate strategies and from interviews with local decision-makers. We also find that specific municipal features such as earlier municipal engagement in national support programs and relevant inter-municipal networks function as drivers for the institutionalization of local action. 相似文献
557.
We model climate change as a dynamic game and prove existence of a unique subgame-perfect Nash equilibrium (SPNE) that is also Markov perfect. We interpret this unique SPNE as the business-as-usual (BAU) equilibrium and show that if the countries are not sufficiently symmetric then the familiar trigger strategy equilibria may not be Pareto improvements over the BAU equilibrium and may even lack efficiency properties. We then motivate and introduce a subgame-perfect cooperative agreement as an improvement over the BAU equilibrium in the sense that every country or coalition of countries is better off in every subgame, irrespective of the extent of heterogeneity of the countries. We characterize subgame-perfect cooperative agreements and identify sufficient conditions for their existence. We show that (direct or indirect) transfers between countries to balance the costs and benefits of controlling climate change are a necessity and not a matter of approach. 相似文献
558.
Jari Lyytimäki 《Natural resources forum》2012,36(2):101-108
Indicators are commonly used as tools to identify and highlight socio‐economic and ecological trends and to assess progress towards sustainability. Different quality criteria can be considered for indicators. This paper focuses on the timeliness of indicators used in the evaluation of sustainable development strategies. The analysis is based on indicators included in four assessment reports of the sustainable development strategy of the European Union and three assessment reports of the national strategy of Finland. Furthermore, a web‐based national level indicator portal is analysed. The results show that the timeliness of indicators has generally not improved during the past decade and that indicators used in strategy evaluations have a time lag of approximately two years. It is suggested that more attention should be given to efforts to improve the timeliness of indicators in order to increase the effectiveness of the evaluations. More generally, it is suggested that greater emphasis should be put on the empirical research on actual use of indicators. 相似文献
559.
Sources of contamination of groundwater are often difficult to characterize. However, it is essential for effective remediation of polluted groundwater resources. This study demonstrates an application of the linked simulation-optimization based methodology to estimate the release history from spatially distributed sources of pollution at an illustrative abandoned mine-site. In linked simulation-optimization approaches a numerical groundwater flow and transport simulation model is linked to the optimization model. In this study, topographic and geologic characteristics of the abandoned mine-site were simulated using a three-dimensional (3D) numerical groundwater flow model. Transport of contaminant in the groundwater was simulated using a 3D transient advective-dispersive contaminant transport model. Adsorption or chemical reaction of the contaminant was not considered in the contaminant transport model. Adaptive simulated annealing (ASA) was employed for solving the optimization problem. An optimization algorithm generates the candidate solutions corresponding to various unknown groundwater source characteristics. The candidate solutions are used as input in the numerical groundwater transport simulation model to generate the concentration of pollutant in the study area. This information is used to calculate the objective function value, which is utilized by the optimization algorithm to improve the candidate solution. This process continues until an optimal solution is obtained. Optimal solutions obtained in this study show that the linked simulation-optimization based methodology is potentially applicable for the characterization of spatially distributed pollutant sources, typically present at abandoned mine-sites. 相似文献
560.
This article analyses the factors influencing stakeholder participation in municipal energy and climate planning, together with stakeholder experiences of participation in such processes. The article presents findings from a survey of 60 Swedish municipalities and detailed case studies of energy and climate planning in five Swedish municipalities to explore which stakeholders are involved, how and why they are involved, and the impacts of participation on both stakeholder experiences. The results of this study provide insight into the role of stakeholders in municipal energy and climate planning. The study proceeds as follows: the Introduction is followed by a discussion of theoretical perspectives on stakeholder participation and energy and climate planning. The Methods used to conduct the study are presented, followed by Results and Analysis. In the subsequent Discussion, the authors propose a conceptual approach that may assist municipalities in development of energy and climate strategies. The Analysis and Discussion inform Conclusions in which the authors advocate early and active stakeholder engagement in energy and climate strategy planning and emphasise the possible utility of their conceptual approach in supporting stakeholder participation. 相似文献