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141.
Wild game and other renewable resources in tropical rainforests inhabited by indigenous peoples are currently often exploited in unsustainable ways. This article shows, for a Kichwa community in the Ecuadorian Amazon, that this can to some extent be explained as a 'tragedy of the commons'. However there are also other mechanisms at work. In particular, there has been some unawareness of the impact of hunting on game populations, and the expansion of fallows at the expense of old growth forest is a result of population growth that increases the need for farmland, and thus decreases the socially optimal area of old growth forest. Whereas many resources are harvested under conditions resembling open access, there have long been established rules for the harvest of thatch leaves, and the community has recently also adopted several measures in order to regulate hunting. Obviously, experiences of resource scarcity may spark conservationist thinking and behaviour. This is a process that scientists can and should support.  相似文献   
142.
Subjective annoyance response to diesel engine sound during idling conditions was evaluated by 80 participants. Eight different sound spectra were presented to the participants at a constant level of 80 dB(A) in a paired comparison procedure. Stereo-recorded sound stimuli were played back through a pair of loudspeakers in an anechoic room. Four objective parameters of loudness, sharpness, impulsiveness, and roughness were found to be the determining factors that cause subjective annoyance. An annoyance prediction model for the test stimuli of an idling diesel engine was developed on the basis of these factors. The objective parameters and their interactions have a significant effect on the annoyance prediction model. The spectral distribution indicated by test participants to be pleasant can be used as a basis for appropriate modification of engine sound. A single microphone measurement in free field conditions can be used to estimate objective parameters for defining the cause of annoyance.  相似文献   
143.
Experience with fire safety engineering under a performance-based fire safety regulation regime shows that the majority of the analyses performed are scenario based. A comparison with purely pre-accepted performance requirement is made in order to assess the relative safety level of the alternative design compared with the pre-accepted design. We find this approach problematic because it undermines the value of performing analyses. The approach accepts oversimplification and justifies unrealistic assumptions on the basis that it will not affect the comparison. This distances the analyses from reality and reduces their value to answer a yes/no question on acceptability. The considerable time and resources spent on searching for and analyzing a pre-accepted design could be spent on analyzing the design at hand. If fire safety analyses are to have any real impact on design, it is necessary that regulators strengthen the position of analytical design. This must include a provision of a clear set of performance goals, which are possible to transform into quantitative evaluation criteria by the engineers, to avoid comparisons with pre-accepted performance requirements.  相似文献   
144.
This article presents a model for local energy planning and its application in a full-scale experiment in a Swedish municipality. The model is based on legal requirement, research findings and standards of good practice and includes a combination of analytical and procedural tools intended to support rational decision-making: external scenarios, a citizens’ panel, life cycle analysis and qualitative environmental assessment (EA). The application of the model indicates that the decision-support tools selected can give several new and valuable inputs to local energy planning, such as local knowledge and values through citizen dialogue and comprehensive EAs. However, the experiment also shows that there are several challenges involved in applying the tools, for example, it is difficult to get citizens and the industry to participate and that it is complicated to combine several different tools for decision-making into a single planning process. Moreover, the experiences from the application suggest that the model for local energy planning show great potential but needs to be improved before it can be used as a standard of good practice.  相似文献   
145.
Climate change is an important new challenge for local authorities. This study analyses the potential for using the Swedish mandatory process for risk and vulnerability analysis (RVA) as a vehicle to improve local climate adaptation work. An advantage with RVA is its comprehensive approach in dealing with all relevant threats and all vital functions of society. In order to test the applicability of incorporating climate adaptation into RVA, we studied practical experiences from three Swedish municipalities. In all municipalities, a pre-study to identify relevant climate-induced events was performed. In one municipality, this was followed by a more detailed analysis of the potential impacts of these events on the functions of the various administrations and companies within the local authority. Problems identified in successful integration of climate change into the municipal RVA process were lack of sufficient knowledge to identify the impacts of climate change on the level of the respective specialist or district administration and lack of resources to perform the analysis. There were also some difficulties in including a long-term perspective relevant for climate adaptation into RVA, which usually focuses on current threats. A positive outcome was that work on extreme climate events in RVA provided a traceable method to identify events with a potentially great impact on the function of local society and results that could be fed into other ongoing processes, such as spatial planning and housing plans.  相似文献   
146.
Many voluntary incentive programs for provision of forest ecosystem services (ES) have low participation rates, insufficient enrollment areas, and inefficient ecological outcomes. Understanding participation behavior in such programs has therefore become a crucial part of policy success. We synthesized a large body of literature on the behavior of nonindustrial private forest owners based on surveys of stated (intended) participation or data on actual participation in existing or hypothetical programs. Using metaregression analysis, we examined how methodological, program-characteristic, and economic-incentive variables affected participation rate estimates. Participation rates tended to be overestimated when landowner participation was elicited in hypothetical choice situations (compared with real situations) and when dichotomous choice surveys (compared with census data) were used. The marginal effect sizes were quite large, for example, a 31% increase with use of stated choices in hypothetical scenarios, and practitioners should therefore be aware of them. However, use of choice experiment surveys in a modified scenario based on existing programs had no effect on participation when all other determinants were controlled for. Participation rates decreased significantly as length of the contract increased and when there was no withdrawal option. These results suggest that perpetual contracts have a lower negative impact on participation than time-limited contracts with a duration of over 50 years. We confirmed that as compensation amounts increased, participation increased. One-time up-front payments were more effective in increasing initial participation than annual payments for contracts of over 5 years. We identified the robust determinants and the effect sizes of those determinants on landowner participation rate estimates, thereby contributing to a better understanding of forest owner behavior and offering useful insights to enable researchers and resource managers to improve the design and efficiency of new and existing forest ES programs.  相似文献   
147.
Spliid NH  Helweg A  Heinrichson K 《Chemosphere》2006,65(11):2223-2232
Filling and cleaning of pesticide sprayers presents a potential risk of pollution of soil and water. Three different solutions for handling sprayers have been suggested: Filling and cleaning in the field, filling and cleaning on hard surfaces with collection of the waste water, and filling and cleaning on a biobed, which is an excavation lined with clay and filled with a mixture of chopped straw, sphagnum and soil with turf on top, and with increased sorption capacity and microbial activity for degradation of the pesticides. In the present study the degradation and leaching of 21 pesticides (5 g of each) was followed in an established full-scale model biobed. Percolate was collected and analysed for pesticide residues, and the biobed material was sampled at three different depths and analysed by liquid chromatography double mass spectrometry (LC-MSMS). During the total study period of 563 days, no traces of 10 out of 21 applied pesticides were detected in the percolate (detection limits between 0.02 and 0.9 μg l−1) and three pesticides were only detected once and at concentrations below 2 μg l−1. During the first 198 days before second application, 14% of the applied herbicide bentazone was detected in the leachate with maximum and mean concentrations of 445 and 172 μg l−1, respectively. About 2% of the initial mecoprop and fluazifop dose was detected in the percolate, with mean concentrations of 23 μg l−1, while MCPA and dimethoate had mean concentrations of 3.5 and 4.7 μg l−1, respectively. Leachate concentrations for the remaining pesticides were generally below the detection limit (0.02–0.9 μg l−1, below 1% of applied). Sorption studies of five pesticides showed that compounds with a low Kd value appeared in the leachate. After 169 days, all pesticides in the biobed profile were degraded to a level below 50% of the calculated initial dose. Pesticides with Koc values above 100 were primarily found in the uppermost 10 cm and degraded slowest due to the low bioavailability. The 11 most degradable pesticides were all degraded such that less than 3% remained in the biobed after 169 days.

Following second pesticide application of the biobed, leachate was sampled 215 and 365 days after the treatment. This showed the same pesticides to be leached out and at concentrations comparable to those of the first treatment. The same pesticides as after the first treatment were retained in the biobed.  相似文献   

148.
Fisheries management across the world is moving toward an ecosystem-based approach, implying that fishery effects on nontarget species should be taken into account. However, such effects are often not well understood, partly because, they can be difficult to distinguish from impacts of environmental fluctuations. We evaluated the effects of an industrial sand lance (Ammodytes marinus) fishery off the North Sea coast of the United Kingdom, which has been opened and closed in a quasi-experimental fashion, on sand-lance-dependent breeding seabirds. Controlling for environmental variation (sea surface temperature, abundance of larval sand lance, and size of adult sand lance), we found that, when the fishery was operating, breeding productivity in the intensively studied seabird colony on the Isle of May was significantly depressed for one surface-feeding seabird species, the Black-legged Kittiwake (Rissa tridactyla), but not for four diving species. Analyzing Kittiwake data from 12 colonies inside and outside the closure zone in a replicated before-after control-impact design, we again found that breeding productivity was significantly depressed in the closure zone when the fishery was active, whereas no effect was found in the control zone. Furthermore, Kittiwake breeding productivity was negatively correlated with fishery effort during the fishery period in the closure zone, but not in the control zone. The contrasting findings in the two zones could be related to environmental differences or to the fact that only one study colony in the control zone was exposed to high fishery effort within the typical foraging range of Kittiwakes during the breeding season. The strong impact on Kittiwakes, but not on diving species, could result from (1) inherently high sensitivity to reduced prey availability, (2) changes in the vertical distribution of sand lance at lower densities, (3) sand lance showing avoidance behavior to fishery vessels, or a combination of some or all of these factors. These findings indicate that local fishery closures can benefit sensitive predators and should be considered as a tool for future ecosystem-based fisheries management.  相似文献   
149.
The influence of different N:P supply ratios on cell accumulation, chemical composition and toxicity of the marine haptophyte Chrysochromulina polylepis was examined in semi-continuous cultures. A non-axenic strain of C. polylepis was exposed to five different N:P supply ratios (N:P = 1:1, 4:1, 16:1, 80:1 and 160:1, by atoms), in order to create a range of N- and P-limited conditions. The toxicity per cell in C. polylepis was determined on four occasions at steady state cell density using the haemolytic activity of the cells expressed as saponin nanoequivalents. Haemolytic activity was demonstrated in all treatments, and increased in the algae when cell growth was nutrient limited (N:P = 1:1, 4:1, 80:1 and 160:1), compared to cells grown under non-limiting conditions (N:P = 16:1). This occurred regardless of the growth-limiting nutrient (N or P) and became more pronounced as nutrient limitation increased. In P-limited cultures the haemolytic activity per cell increased linearly with the cellular N:P ratio, whereas the N-limited cultures showed an opposite trend. The haemolytic activity per cell showed an inverse relationship with both cellular N and cellular P content. Cells limited by P showed a higher haemolytic activity than cells limited by N. The results suggest that toxicity in C. polylepis is strongly influenced by the physiological state of the algae. This may partially explain the large variability previously observed in the toxicity of C. polylepis blooms. The potential ecological significance of our findings is also discussed. Received: 18 November 1998 / Accepted: 5 July 1999  相似文献   
150.
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