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Species with relatively narrow niches, such as plants restricted (endemic) to particular soils, may be especially vulnerable to extinction under a changing climate due to the enhanced difficulty they face in migrating to suitable new sites. To test for community-level effects of climate change, and to compare such effects in a highly endemic-rich flora on unproductive serpentine soils vs. the flora of normal (diorite) soils, in 2007 we resampled as closely as possible 108 sites originally studied by ecologist Robert H. Whittaker from 1949 to 1951 in the Siskiyou Mountains of southern Oregon, USA. We found sharp declines in herb cover and richness on both serpentine and diorite soils. Declines were strongest in species of northern biogeographic affinity, species endemic to the region (in serpentine communities only), and species endemic to serpentine soils. Consistent with climatic warming, herb communities have shifted from 1949-1951 to 2007 to more closely resemble communities found on xeric (warm, dry) south-facing slopes. The changes found in the Siskiyou herb flora suggest that biotas rich in narrowly distributed endemics may be particularly susceptible to the effects of a warming climate. 相似文献
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Landscape corridors, strips of habitat that connect otherwise isolated habitat patches, are commonly employed during management of fragmented landscapes. To date, most reported effects of corridors have been positive; however, there are long-standing concerns that corridors may have unintended consequences. Here, we address concerns over whether corridors promote propagation of disturbances such as fire. We collected data during prescribed fires in the world's largest and best replicated corridor experiment (Savannah River Site, South Carolina, USA), six -50-ha landscapes of open (shrubby/herbaceous) habitat within a pine plantation matrix, to test several mechanisms for how corridors might influence fire. Corridors altered patterns of fire temperature through a direct connectivity effect and an indirect edge effect. The connectivity effect was independent of fuel levels and was consistent with a hypothesized wind-driven "bellows effect." Edges, a consequence of corridor implementation, elevated leaf litter (fuel) input from matrix pine trees, which in turn increased fire temperatures. We found no evidence for corridors or edges impacting patterns of fire spread: plots across all landscape positions burned with similar probability. Impacts of edges and connectivity on fire temperature led to changes in vegetation: hotter-burning plots supported higher bunch grass cover during the field season after burning, suggesting implications for woody/herbaceous species coexistence. To our knowledge, this represents the first experimental evidence that corridors can modify landscape-scale patterns of fire intensity. Corridor impacts on fire should be carefully considered during landscape management, both in the context of how corridors connect or break distributions of fuels and the desired role of fire as a disturbance, which may range from a management tool to an agent to be suppressed. In our focal ecosystem, longleaf pine woodland, corridors might provide a previously unrecognized benefit during prescribed burning activities, by promoting fire intensity, which may assist in promoting plant biodiversity. 相似文献
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Nicola Ellen 《生态毒理学报》2004,26(1):19
Safeway是英国第4大超级市场连锁店,在全国有480家连锁店,年销售额约为90亿英镑,另外还有与英国石油公司(BP)合营的50家庭院便利店. 相似文献
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Two groups of part-time employees were compared to full-time employees on several organizationally relevant reactions and behaviours in order to replicate and extend research on potential employment status differences. After controlling for demographics, it was found that there were mean differences between the groups; however, no evidence was found for differences in how the various groups ‘process’ organizational experience. Based on the results, implications for managing part-versus full-time employees are discussed. 相似文献
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Arne Aar?s Gunnar Horgen Ola Ro Ellen L?ken Geir Mathiasen Hans-Henrik Bj?rset Stig Larsen Magne Thoresen 《International journal of occupational safety and ergonomics》2005,11(1):25-47
The Norwegian MEPS (musculoskeletal--visual--psychosocial--stress) study included 3 groups: data entry, data dialogue (female) and data dialogue (male). Before intervention, the data entry group reported significantly more symptoms and signs of musculoskeletal illness and had longer periods in front of the video display terminal (VDT) without a break. The ergonomic intervention consisted mainly of ergonomic information and training. After intervention, the data dialogue female group reported a significant reduction in shoulder pain in parallel with a reduction in trapezius load. Increasing the understanding in how to adjust the work stand and chair may have been contributing factors to reducing the pain level. There was a significant reduction in eye problems in all groups; the greatest reduction in eye symptoms was seen in the groups who had new optometric corrections. 相似文献
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Scott MJ Brandt CA Bunn AL Engel DW Eslinger PW Miley TB Napier BA Prendergast EL Nieves LA 《Environmental management》2005,35(1):84-98
The Groundwater Protection Project at the US Department of Energy Hanford Site in Washington State is currently developing the means to assess the cumulative impact to human and ecological health and the regional economy and cultures from radioactive and chemical waste that will remain at the Hanford Site after the site closes. This integrated system is known as the System Assessment Capability (SAC). The SAC Risk/Impact Module discussed in the article uses media- and time-specific concentrations of contaminants estimated by the transport models of the integrated system to project potential impacts on the ecology of the Columbia River corridor, the health of persons who might live in or use the corridor or the upland Hanford environment, the local economy, and cultural resources. Preliminary Monte Carlo realizations from the SAC modeling system demonstrate the feasibility of large-scale uncertainty analysis of the complex relationships in the environmental transport of contaminants on the one hand and ecological, human, cultural, and economic risk on the other. Initial impact results show very small long-term risks for the 10 radionuclides and chemicals evaluated. The analysis also helps determine science priorities to reduce uncertainty and suggests what actions matter to reduce risks. 相似文献
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The educational and research roles of universities in environmentally conscious technologies are discussed from a historical perspective. The American university system, and in particular its interactions with government and industry, is compared with that of the United States' main trading partners including Japan, the NAFTA countries, and Western Europe. Examples of federally funded U.S. programs related to green design are also tabulated. The role of universities within the framework of society, politics, and economics is discussed in regard to emerging concepts such as sustainable development, life-cycle analysis, and design for environment, as well as the functioning of local recycling infrastructures. The means by which universities can contribute to environmentally conscious technology are summarized, as are the demands placed on the next generation of engineers. 相似文献