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201.
ABSTRACT

Recent debates about the concept of planetary boundaries recall longstanding concerns about whether ecological limits are compatible with ecological democracy. The planetary boundaries framework (originally set out in Rockström et al., 2009a, 2009b) defines values for key Earth-system processes such as climate change and biodiversity that aim to maintain a ‘safe’ distance from thresholds or levels that could endanger human wellbeing. Despite having a significant impact in policy debates, the framework has been criticised as implying an expert-driven approach to governing global environmental risks that lacks democratic legitimacy. Drawing on research on deliberative democracy and the role of science in democratic societies, we argue that planetary boundaries can be interpreted in ways that remain consistent with democratic decision-making. We show how an iterative, dialogical process to formulate planetary boundaries and negotiate ‘planetary targets’ could form the basis for a democratically legitimate division of labour among experts, citizens and policy-makers in evaluating and responding to Earth-system risks. Crucial to this division of evaluative labour is opening up space for deliberative contestation about the value judgments inherent in collective responses to Earth-system risks, while also safeguarding the ability of experts to issue warnings about what they consider to be unacceptable risks.  相似文献   
202.
ABSTRACT

Concepts of ecological and environmental democracy seek to reconcile two normative ideals: ensuring environmental sustainability while safeguarding democracy. These ideals are frequently conceived as being in conflict, as democracy is perceived as too slow and cumbersome to deliver the urgent large-scale collective action needed to tackle environmental problems. Theories addressing the democracy-environment nexus can be situated on a spectrum from theories of ecological democracy that are more critical of existing liberal democratic institutions to theories of environmental democracy that call for reforming rather than radically transforming or dismantling those institutions. This article reviews theoretical and empirical scholarship on the democracy-environment nexus. We find continued theoretical and empirical diversity in the field, as well as vibrant debates on democratising global environmental politics, local material practices, and non-human representation. We argue for stronger dialogue between environmental political theory and empirical, policy-oriented research on democracy and sustainability, as well as further exploration of complementarities between ecological and environmental democracy. We identify four main areas of challenge and opportunity for theory and practice: public participation and populism; technocracy and expertise; governance across scales; and ecological rights and limits.  相似文献   
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The authors highlight the importance of the trippage of a returnable bottle to the current beverage container debate. Results of recent surveys of consumers and retailers are presented, which show that the reasons for low trippages in the UK are more complex than the conventional diagnosis that ‘consumers cannot be bothered to return bottles’. In many instances consumers thought that the ‘returnable bottle was ‘non- returnable’ and many consumers found it difficult to return bottles to the shops. Making it easier for consumers to return the bottle would appear to be a more effective method of raising trippage than increasing the deposit levels.  相似文献   
206.
Factors influencing sediment availability are assessed and erosion rates are quantified for an off‐highway vehicle (OHV) trail system in the Ouachita Mountains of Arkansas. As of May 2012, the Wolf Pen Gap trail system included 77.0 km of "trails" which consist of county roads; open and closed Forest Service roads; and open and closed OHV trails. For a given trail length, the sediment volume available to be eroded is determined by bare trail width and sediment depth. Four condition types are defined that group trail sections based on statistically different trail widths or depths. Trail construction method appears to influence sediment availability differences more than erosion potential (as indexed by trail slope gradient and length). The range for annual trail erosion rates is estimated as 75 and 210 tonne/ha/yr. The high and low rates are obtained using two independent methods. The 210 tonne/ha/yr rate is computed from mean sediment capture at 30 sediment traps installed for 0.5–1.0 year. The 75 tonne/ha/yr rate is computed assuming all available trail sediment measured in a one‐time sampling is eroded over the next year. We argue in support of this assumption and suggest both rate values may be conservative. Trail erosion rates and sediment trap observations indicate frequent trap cleanout will be needed to continue sediment capture from All Terrain Vehicle trails.  相似文献   
207.
ABSTRACT: Removal of streamside vegetation changes the energy balance of a stream, and hence its temperature. A common approach to mitigating the effects of logging on stream temperature is to require establishment of buffer zones along stream corridors. A simple energy balance model is described for prediction of stream temperature in forested headwater watersheds that allows evaluation of the performance of such measures. The model is designed for application to “worst case” or maximum annual stream temperature, under low flow conditions with maximum annual solar radiation and air temperature. Low flows are estimated via a regional regression equation with independent variables readily accessible from GIS databases. Testing of the energy balance model was performed using field data for mostly forested basins on both the west and east slopes of the Cascade Mountains, and was then evaluated using the regional equations for low flow and observed maximum reach temperatures in three different east slope Cascades catchments. A series of sensitivity analyses showed that increasing the buffer width beyond 30 meters did not significantly decrease stream temperatures, and that other vegetation parameters such as leaf area index, average tree height, and to a lesser extent streamside vegetation buffer width, more strongly affected maximum stream temperatures.  相似文献   
208.
Influence of Geoengineered Climate on the Terrestrial Biosphere   总被引:3,自引:0,他引:3  
Various geoengineering schemes have been proposed to counteract anthropogenically induced climate change. In a previous study, it was suggested that a 1.8% reduction in solar radiation incident on the Earths surface could noticeably reduce regional and seasonal climate change from increased atmospheric carbon dioxide (CO2). However, the response of the terrestrial biosphere to reduced solar radiation in a CO2-rich climate was not investigated. In this study, we hypothesized that a reduction in incident solar radiation in a Doubled CO2 atmosphere will diminish the net primary productivity (NPP) of terrestrial ecosystems, potentially accelerating the accumulation of CO2 in the atmosphere. We used a dynamic global ecosystem model, the Integrated Biosphere Simulator (IBIS), to investigate this hypothesis in an unperturbed climatology. While this simplified modeling framework effectively separated the influence of CO2 and sunlight on the terrestrial biosphere, it did not consider the complex feedbacks within the Earths climate system. Our analysis indicated that compared to a Doubled CO2 scenario, reduction in incident solar radiation by 1.8% in a double CO2 world will have negligible impact on the NPP of terrestrial ecosystems. There were, however, spatial variations in the response of NPP-engineered solar radiation. While productivity decreased by less than 2% in the tropical and boreal forests as hypothesized, it increased by a similar percentage in the temperate deciduous forests and grasslands. This increase in productivity was attributed to a 1% reduction in evapotranspiration in the Geoengineered scenario relative to the Doubled CO2 scenario. Our initial hypothesis was rejected because of unanticipated effects of engineered solar radiation on the hydrologic cycle. However, any geoengineering approaches that reduce incident solar radiation need to be thoroughly analyzed in view of the implications on ecosystem productivity and the hydrologic cycle.  相似文献   
209.
Ecological interactions of conifers and coniferophagous bark beetles are determined in part by terpenoids (isoprenoids), which are major defense metabolites of conifer oleoresin. Curiously, similar compounds are important aggregation pheromones of conifer-attacking bark beetles. Terpene synthases are responsible for generating the enormous variety of terpenoid carbon skeletons found in nature. These catalysts convert short-chain prenyl diphosphates to a diverse assortment of hemiterpene, monoterpene, sesquiterpene, and diterpene natural products. While terpene synthases have frequently been characterized from plant and microbial sources, they have not yet been described in animals. Here we report the discovery of a monoterpene synthase activity in an insect, the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae). Cell-free assays of I. pini revealed that geranyl diphosphate (GDP) is converted to the acyclic monoterpene myrcene in whole-body extracts from males, but not females. Furthermore, the monoterpene synthase activity in males can be induced by prior treatment with juvenile hormone III (JH III) or by feeding on phloem from the host trees, Jeffrey pine (Pinus jeffreyi Grev. &; Balf.) or red pine (Pinus resinosa Ait.). The sex-specificity and endocrine induction of this activity argue for its involvement in the biosynthesis of monoterpenoid pheromones mediated by enzymes from insect tissue. This discovery is the first example of a monoterpene synthase in the Metazoa and evokes exciting new questions about the origin, evolution, and occurrence of terpene synthases.  相似文献   
210.
Community involvement is fundamental to the management of multijurisdictional river basins but, in practice, is very difficult to achieve. The Murray-Darling basin, in Australia, and the Mekong River basin in Southeast Asia are both cooperatively managed multijurisdictional river basins where the management authorities have expressed an aim of community involvement. In the Murray-Darling basin vigorous efforts have promoted a culture of community consultation throughout each of the state jurisdictions involved, although true participation has not necessarily been achieved. In the Mekong basin the community is much more diverse and the successes so far have been largely at the local level, involving action in subsections of the basin. These case studies suggest that community involvement in the form of community consultation across large multijurisdictional river basins is achievable, but more comprehensive participation is not necessarily possible.  相似文献   
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