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51.
In El Salvador a growing permaculture movement attunes small-scale farming activities to principles of ecological observation. The premise is twofold: close-grained appreciation of already-interacting biophysical processes allows for the design of complementary social and agricultural systems requiring minimum energy inputs. Secondly, the insistence on campesino smallholders as actors in the design of sustainable food systems directly addresses decades of “top-down” developmental interventions, from Green Revolution experiments in the 1960s and 1970s to international food security programmes in the 1990s. Permaculture connects food insecurity to the delegitimisation of smallholder innovation and insists that, through sharing simple techniques, campesino farmers can contribute towards future-oriented questions of environmental sustainability. This repositioning is brought about through the mobilisation of pedagogical techniques that legitimise the experiences and expertise of small-scale farmers, while standardising experimental methods for testing, evaluating and sharing agroecological practices. Like food sovereignty and food justice movements, Salvadoran permaculture links hunger with longer histories of (uneven) capital accumulation and dispossession and renders campesino farmers its protagonists. By modelling a form of expertise premised in intimate involvement with specific environments, permaculture goes still further, seeking to dislodge a pervasive knowledge politics that situates some as knowers and innovators, and others as passive recipients. This grounds human rights in an ethos of caring for the “more-than-human” world and places emphasis on a corollary right as part of food justice, increasingly being demanded “from below”: the right to know.  相似文献   
52.
A variety of tools can be employed in support of environmental policy objectives, but achieving preferred outcomes also requires the cooperation of private landholders and others with vested interests in the land. The Land Stewardship project in the state of Victoria, Australia, is an initiative devoted to exploring the ways in which private landholders could be encouraged towards more sustainable land management. Following the view that the success of policy initiatives is contingent on effective stakeholder engagement, a component of the Land Stewardship project involved a dialogue with landholders about policy tools (e.g., regulation, economic instruments) that might be deployed to encourage improved land management practices. This paper provides an account of the views and attitudes of landholders, as revealed in a series of three workshops, which consisted of discussions about the factors influencing agriculture, participants' interpretations of sustainability, and policy methods. The focus of the paper is on what landholders believe to be the strengths and limitations of standard policy tools, and the essential requirements for these tools to deliver the best land management outcomes. One of the main findings of the project was a 'preference hierarchy' in respect of policy methods, according to which the strongest support was expressed for voluntary and education-based tools, followed by market-based instruments, with command-and-control regulation identified as a measure of 'last resort'. In the paper we reflect also on how the views and outlook of landholders should be positioned relative to other inputs in the design of policy interventions.  相似文献   
53.
Fused-silica-lined (FSL) canisters and SUMMA polished (SUMMA) canisters were compared for the recoveries and the stabilities of 58 volatile organic compounds (VOCs) at low ppbv (volume/volume) levels under various humidified conditions using a three-stage preconcentration method followed by GC-MS analysis. The target VOCs included non-polar VOCs (e.g. halogenated hydrocarbons and aromatic hydrocarbons) and polar VOCs (e.g. alcohols, ketones, esters, ethers, nitriles and thiols). The three-stage preconcentration method was initially optimized for simultaneous analysis of non-polar and polar VOCs because determination of canister stability is dependent on the accuracy of analytical measurements. The method showed good linearity over the concentration range from 1 to 25 ppbv for all target analytes, and the correlation coefficients were higher than 0.9974. The method detection limits ranged from 0.023 to 0.39 ppbv. The test mixtures loaded in both type of canisters (n = 3) had concentrations of 1.7-2.5 ppbv per compound at ambient pressure under various humidified conditions (%RH = 1.6, 8.0, 27, 39, 53 and >99% with excess water present). All canister samples were initially analyzed on day 0 (after 6-12 h). The effect of competitive adsorption of water vapor and polar VOCs on active sites of interior surface was remarkably observed for SUMMA canisters. Polar VOCs had a greater requirement for water vapor to be present. The RH percentages that ensured good recovery on day 0 were RH > 8% for non-polar VOCs and RH > 27% for polar VOCs (except alcohols under the condition of RH > 99%). All thiols were not recovered from SUMMA canisters under all conditions. FSL canisters showed good recoveries of more than 86% for all VOCs under all conditions on day 0 (except alcohols under the condition of RH > 99%). The recoveries of alcohols in both canisters under the condition of RH > 99% displayed relatively low recoveries in the range 25-76% because of the partitioning effect into condensed water. The canister samples under the conditions of RH 8.0, 27, 53 and > 99% were analyzed for the stability test on days 3, 7, 14 and 28 after loading. All non-polar VOCs were reasonably stable in the FSL canisters under all examined conditions over 28 days. However, several polar VOCs that have relatively lower vapor pressure, e.g. MIBK, butyl acetate and alcohols except ethanol, showed unstable characteristics under relatively dry conditions (RH 8 and 27%) during 28 days. RH > 53% was needed to ensure good stabilities of all analytes except thiols with the recoveries of > 80% over 28 days for both canisters. Although the FSL canister showed good recoveries of more than 86% for thiols on day 0, drastic degradations were observed after day 3 and they were not detected after day 14.  相似文献   
54.
Section 305(b) of the United States’ Clean Water Act (CWA) requires states to assess the overall quality of waters in the states, while Section 303(d) requires states to develop a list of the specific waters in their state not attaining water quality standards (a.k.at impaired waters). An integrated, efficient and cost-effective process is needed to acquire and assess the data needed to meet both these mandates. A subset of presentations at the 2002 Environmental Monitoring and Assessment Program (EMAP) Symposium provided information on how probability data, tools and methods could be used by states and other entities to aid in development of their overall assessment of condition and list of impaired waters. Discussion identified some of the technical and institutional problems that hinder the use of EMAP methods and data in the analysis to identify impaired waters as well as development needs to overcome these problems.  相似文献   
55.
A survey of land taken out of production from the early 1990s onwards under the European Union's set-aside policy in England was carried out in 2008, to record plant communities in set-aside of different ages, effects of distance from the field edge, sowing and soil type. Communities were classified using the Countryside Vegetation System (CVS), Ellenberg indicators and Grime CSR strategy. Species richness declined with distance from the field boundary. Annuals declined with age of set-aside. In older set-aside, perennials dominated, 40-50% of species were grasses, and grasses covered over 70% of the area. Sown areas had a higher proportion of grass species and a lower proportion of wind-dispersed species. Perennial forbs increased over time in naturally regenerated swards but decreased on sown swards. Annuals and grasses were more prevalent on light soils, with more bare ground on heavy soils. Most transects fell into CVS aggregate classes ‘tall grassland/herb’ and ‘fertile grassland’. Ellenberg fertility values decreased initially but then stabilised. Competitor scores increased, and ruderal scores declined, with age. In general, the rate of change declined with age. Although few sites had plant communities of significant conservation interest, the value of set-aside is likely to be primarily to maintain botanical diversity in intensively farmed areas, as well as providing food and habitat for fauna.  相似文献   
56.
During 2021, Parties to the Convention on Biological Diversity (CBD) are expected to meet in Kunming, China, to agree on a new global biodiversity framework aimed at halting and reversing biodiversity loss, encouraging the sustainable use of biodiversity, and ensuring the equitable sharing of its benefits. As the post-2020 global biodiversity framework evolves, parties to the convention are being exposed to a range of perspectives on the conservation and sustainable use of biodiversity, relating to the future framework as a whole or to aspects of it. Area-based conservation measures are one such aspect, and there are diverse perspectives on how new targets might be framed in relation to these measures. These perspectives represent different outlooks on the relationship between human and nonhuman life on Earth. However, in most cases there is a lack of clarity on how they would be implemented in practice, the implications this would have for biodiversity and human well-being, and how they would contribute to achieving the 2050 Vision for Biodiversity of “living in harmony with nature.” We sought to clarify these issues by summarizing some of these perspectives in relation to the future of area-based biodiversity conservation. We identified these perspectives through a review of the literature and expert consultation workshops and compiled them into 4 main groups: Aichi+, ambitious area-based conservation perspectives, new conservation, and whole-earth conservation. We found that although the perspectives Aichi+ and whole earth are in some cases at odds with one another, they also have commonalities, and all perspectives have elements that can contribute to developing and implementing the post-2020 global biodiversity framework and achieving the longer term CBD 2050 Vision.  相似文献   
57.
Responding differentially to kin and non-kin is known to be adaptive in many species. One example is the inclusive fitness benefits of reducing aggression toward closer relatives. Little is known, however, about the ability of animals to assess differential degrees of genetic relatedness and to respond accordingly with differential levels of aggression. In the present study, we tested whether aggressiveness between body mass-matched pairs of fire salamander (Salamandra infraimmaculata) larvae covaried with the genetic similarity between them. We quantified aggressiveness at three levels of genetic similarity by selecting pairs within and across pools from recently genotyped populations. We also assessed aggression between pairs of siblings. Aggression and associated injuries decreased as genetic similarity increased across the groups. These findings suggest that cannibalistic salamanders can assess their degree of genetic relatedness to conspecifics and vary their behavioral responses depending on the degree of similarity between them along a genetic relatedness continuum.  相似文献   
58.
Reproductive success within populations often varies with the timing of breeding, typically declining over the season. This variation is usually attributed to seasonal changes in resource availability and/or differences in the quality or experience of breeders. In colonial species, the timing of breeding may be of particular importance because the costs and benefits of colonial breeding are likely to vary over the season and also with colony size. In this study, we examine the relationship between timing of breeding and reproductive performance (clutch size and nest success) both within and between variable sized colonies (n = 18) of fairy martins, Petrochelidon ariel. In four of these colonies, we also experimentally delayed laying in selected nests to disentangle the effects of laying date and individual quality/experience on reproductive success. Within colonies, later laying birds produced smaller clutches, but only in larger colonies. The general seasonal decline in nest success was also more pronounced in larger colonies. Late laying birds were generally smaller than earlier laying birds, but morphological differences were also related to colony size, suggesting optimal colony size also varies with phenotype. Experimentally delayed clutches were larger than concurrently produced non-delayed clutches, but only in larger colonies. Similarly, delayed clutches were more likely to produce fledglings, particularly later in the season and in larger colonies. We suggest that the reduced performance of late breeding pairs in larger colonies resulted primarily from inexperienced/low quality birds preferring to settle in larger colonies, possibly exacerbated by an increase in the costs of coloniality (e.g., resource depletion and ectoparasite infestations) with date and colony size. These findings highlight the importance of phenotype-related differences in settlement decisions and reproductive performance to an improved understanding of colonial breeding and variation in colony size.  相似文献   
59.
Cultural adaptation is one means by which conservationists may help populations adapt to threats. A learned behavior may protect an individual from a threat, and the behavior can be transmitted horizontally (within generations) and vertically (between generations), rapidly conferring population-level protection. Although possible in theory, it remains unclear whether such manipulations work in a conservation setting; what conditions are required for them to work; and how they might affect the evolutionary process. We examined models in which a population can adapt through both genetic and cultural mechanisms. Our work was motivated by the invasion of highly toxic cane toads (Rhinella marina) across northern Australia and the resultant declines of endangered northern quolls (Dasyurus hallucatus), which attack and are fatally poisoned by the toxic toads. We examined whether a novel management strategy in which wild quolls are trained to avoid toads can reduce extinction probability. We used a simulation model tailored to quoll life history. Within simulations, individuals were trained and a continuous evolving trait determined innate tendency to attack toads. We applied this model in a population viability setting. The strategy reduced extinction probability only when heritability of innate aversion was low (<20%) and when trained mothers trained >70% of their young to avoid toads. When these conditions were met, genetic adaptation was slower, but rapid cultural adaptation kept the population extant while genetic adaptation was completed. To gain insight into the evolutionary dynamics (in which we saw a transitory peak in cultural adaptation over time), we also developed a simple analytical model of evolutionary dynamics. This model showed that the strength of natural selection declined as the cultural transmission rate increased and that adaptation proceeded only when the rate of cultural transmission was below a critical value determined by the relative levels of protection conferred by genetic versus cultural mechanisms. Together, our models showed that cultural adaptation can play a powerful role in preventing extinction, but that rates of cultural transmission need to be high for this to occur.  相似文献   
60.
The mitigation of climate change requires reductions in the amount of CO2 emitted into the atmosphere. One way to achieve this in the short run is through the implementation of CO2 capture and storage (CCS) technology. The viability of CCS not only depends on technical and regulatory issues, but also on public attitudes. Communication plays an important role in shaping these attitudes. This paper reports on two experiments performed to examine effects of emphasis framing in CCS communications, meaning that greater weight is given to advantages of CCS over disadvantages or vice versa. Although emphasis framing can be effective in shaping attitudes, our findings suggest that there may be long-term costs to using this communication technique as it can be perceived as manipulative. Moreover, emphasis framing is judged as relatively illegitimate when the source is expected to be impartial rather than biased.  相似文献   
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