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321.
Although previous research has found weak support for the model of stressful work ‘spilling over’ to negative coping responses during nonwork hours, we argue that a variety of conceptual and methodological problems may partially explain the weak and inconsistent findings. Two important shortcomings are inadequately specified models and a failure to consider nonescapist responses to job-related stress. We therefore propose that there may be escapist (i.e. increased drinking, working through job dissatisfaction for those who believe that alcohol consumption is an effective means to reduce stress) and nonescapist (i.e. decreased drinking for those who are dissatisfied with their jobs but do not believe alcohol is an effective coping strategy) responses to work stress. These hypotheses were tested on a sample of 972 production workers in the Pacific northwest. Results show moderate support for the existence of both escapist and nonescapist responses to job-related stresses. © 1998 John Wiley & Sons, Ltd.  相似文献   
322.
Evaluations of the effectiveness of protected areas often report their inadequate representation of regional variation in environmental conditions, land cover, and biological diversity. One frequent contributory explanation is the heavy reliance placed upon the designation of public as opposed to private lands for statutory protection. Given that protected area designation in Britain has no such constraint, and indeed that more than half of such areas are on private lands, we tested the a priori assumption that within this region the representation of environmental conditions and land cover within statutory protected areas would be more equitable. Despite the reduction in land ownership constraints on where protected areas can be established, a marked bias in protected area coverage remains. Protected areas in Britain tend toward regions of higher elevation, soils of lower economic potential, and coastal/estuarine habitat and fail adequately to represent areas of lower elevation and woodland habitats. Improving the current situation requires not only a more systematic approach to site selection, but a more equitable and diverse portfolio of incentives for private landowners to facilitate the decision to manage sites for conservation.  相似文献   
323.
High-latitude ecosystems store large amounts of carbon (C); however, the C storage of these ecosystems is under threat from both climate warming and increased levels of herbivory. In this study we examined the combined role of herbivores and climate warming as drivers of CO2 fluxes in two typical high-latitude habitats (mesic heath and wet meadow). We hypothesized that both herbivory and climate warming would reduce the C sink strength of Arctic tundra through their combined effects on plant biomass and gross ecosystem photosynthesis and on decomposition rates and the abiotic environment. To test this hypothesis we employed experimental warming (via International Tundra Experiment [ITEX] chambers) and grazing (via captive Barnacle Geese) in a three-year factorial field experiment. Ecosystem CO2 fluxes (net ecosystem exchange of CO2, ecosystem respiration, and gross ecosystem photosynthesis) were measured in all treatments at varying intensity over the three growing seasons to capture the impact of the treatments on a range of temporal scales (diurnal, seasonal, and interannual). Grazing and warming treatments had markedly different effects on CO2 fluxes in the two tundra habitats. Grazing caused a strong reduction in CO2 assimilation in the wet meadow, while warming reduced CO2 efflux from the mesic heath. Treatment effects on net ecosystem exchange largely derived from the modification of gross ecosystem photosynthesis rather than ecosystem respiration. In this study we have demonstrated that on the habitat scale, grazing by geese is a strong driver of net ecosystem exchange of CO2, with the potential to reduce the CO2 sink strength of Arctic ecosystems. Our results highlight that the large reduction in plant biomass due to goose grazing in the Arctic noted in several studies can alter the C balance of wet tundra ecosystems. We conclude that herbivory will modulate direct climate warming responses of Arctic tundra with implications for the ecosystem C balance; however, the magnitude and direction of the response will be habitat-specific.  相似文献   
324.
McCarthy-Neumann S  Kobe RK 《Ecology》2008,89(7):1883-1892
A negative feedback between local abundance and natural enemies could contribute to maintaining tree species diversity by constraining population growth of common species. Soil pathogens could be an important mechanism of such noncompetitive distance and density-dependent (NCDD) mortality, but susceptibility to local pathogens may be ameliorated by a life history strategy that favors survivorship. In a shade-house experiment (1% full sun), we tested seedling life span, growth, and mass allocation responses to microbial extract filtered from conspecific-cultured soil in 21 tree species that varied in abundance and shade tolerance in a wet tropical forest (La Selva Biological Station, Costa Rica). Forty-three percent of the species had significant reductions, and 10% of the species had significant increases in life span, growth, root length, or root surface area when inoculated with microbial extract; 10% of the species experienced opposing reductions and increases in these characteristics. Contrary to expectation, species' local abundance was not related to species-specific responses to microbial extracts from cultured soils. Across species, seedling shade tolerance (survival at 1% full sun) was negatively correlated with susceptibility to the microbial. treatment for both survival and total mass accumulation, thereby exaggerating shade tolerance differences among species. Thus, soil pathogens may contribute to species coexistence through heightening niche differentiation rather than through negative density dependence in common species.  相似文献   
325.
Emery SM  Gross KL 《Ecology》2007,88(4):954-964
While there has been extensive interest in understanding the relationship between diversity and invasibility of communities, most studies have only focused on one component of diversity: species richness. Although the number of species can affect community invasibility, other aspects of diversity, including species identity and community evenness, may be equally important. While several field studies have examined how invasibility varies with diversity by manipulating species identity or evenness, the results are often confounded by resource heterogeneity, site history, or disturbance. We designed a mesocosm experiment to examine explicitly the role of dominant species identity and evenness on the invasibility of grassland plant communities. We found that the identity of the dominant plant species, but not community evenness, significantly impacted invasibility. Using path analysis, we found that community composition (dominant species identity) reduced invasion by reducing early-season light availability and increasing late-season plant community biomass. Nitrogen availability was an important factor for the survival of invaders in the second year of the experiment. We also found significant direct effects of certain dominant species on invasion, although the mechanisms driving these effects remain unclear. The magnitude of dominant species effects on invasibility we observed are comparable to species richness effects observed in other studies, showing that species composition and dominant species can have strong effects on the invasibility of a community.  相似文献   
326.
Environment, Development and Sustainability - More and better collaboration between farmers and other stakeholders has repeatedly been identified as a key strategy for sustainable agriculture....  相似文献   
327.
For cultures around the world, a journey, particularly one undertaken by foot through landscapes that are simultaneously natural and cultural, is both a metaphor for the discovery of the self and the divine and an embodied practice in the physical realm. Here we analyze twenty-six publicly available blogs of thru-hikers of the John Muir Trail in the Sierra Nevada mountains of California, U.S.A. Cognizant of the critiques of the intrusion of technology into wilderness areas, we examine how the communication medium of travel blogs becomes a vehicle for both self-reflection and for sharing spiritual experiences, and how the act of blogging merges virtual and corporeal communities formed among hikers. It is in the intersection of these social networks and mobile communication technologies that we find suggestions of changing relationships between a subculture of tech-savvy and highly connected hikers sometimes called “flashpackers” and the physical landscapes through which they travel.  相似文献   
328.
329.
Integrative research is increasingly a priority within the scientific community and is a central goal for the evolving field of sustainability science. While it is conceptually attractive, its successful implementation has been challenging and recent work suggests that the move towards interdisciplinarity and transdisciplinarity in sustainability science is being only partially realized. To address this from the perspective of social-ecological systems (SES) research, we examine the process of conducting a science of integration within the Southcentral Alaska Test Case (SCTC) of Alaska-EPSCoR as a test-bed for this approach. The SCTC is part of a large, 5 year, interdisciplinary study investigating changing environments and adaptations to those changes in Alaska. In this paper, we review progress toward a science of integration and present our efforts to confront the practical issues of applying proposed integration frameworks. We: (1) define our integration framework; (2) describe the collaborative processes, including the co-development of science through stakeholder engagement and partnerships; and (3) illustrate potential products of integrative, social-ecological systems research. The approaches we use can also be applied outside of this particular framework. We highlight challenges and propose improvements for integration in sustainability science by addressing the need for common frameworks and improved contextual understanding. These insights may be useful for capacity-building for interdisciplinary projects that address complex real-world social and environmental problems.  相似文献   
330.
The primary goal of this study is to compare wet versus dry sampling methods for three different media, (Whatman 41 filter papers, GhostWipes, and SKC Smear Tabs), These media were selected because they are the most commonly used means for the collection of beryllium from contaminated surfaces within the DOE Complex. A range of known concentrations of beryllium was introduced onto a smooth nonporous surface. All three types of media were tested for collection efficiency in both the wet and dry mode and analyzed by inductively-coupled plasma atomic emission spectrometry (ICP-AES).  相似文献   
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