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91.
Microstegium vimineum is an invasive grass introduced from Asia that has spread throughout riparian areas of the eastern United States threatening native riparian vegetation. Postemergence (POST) herbicides registered for aquatic use were evaluated for control of M. vimineum on two riparian restoration sites in the Piedmont and Upper Coastal Plain of North Carolina. This study found that standard and lower than standard rates of diquat, fluridone, flumioxazin, glyphosate, imazamox, and imazapyr reduced weed stem density and biomass at 6 and 30 weeks after treatment (WAT). Both rates of bispyribac and penoxsulam provided less control of M. vimineum. Visual ratings showed both rates of diquat, flumioxazin, imazamox, and imazapyr controlled 63‐100% of M. vimineum at 6 WAT and 84‐100% at 30 WAT. Fluridone and glyphosate provided slightly less control. Bispyribac and penoxsulam treatments provided less control at 6 and 30 WAT compared to the other treatments. Plots treated with both rates of diquat, flumioxazin, imazamox, and imazapyr were nearly devoid of all vegetation at 30 WAT. Recommendations include POST application of lower than standard rates of diquat, flumioxazin, fluridone, glyphosate, imazamox, and imazapyr on riparian restoration sites infested with M. vimineum. Immediate vegetation management measures including temporary and permanent plant cover should be employed on treated sites where weeds are completely eradicated to prevent erosion.  相似文献   
92.
Urban stream restoration continues to be used as an ecological management tool, despite uncertainty about the long‐term sustainability and resilience of restored systems. Evaluations of restoration success often focus on specific instream indicators, with limited attention to the wider basin or parallel hydrologic and geomorphic process. A comprehensive understanding of urban stream restoration progress is particularly important for comparisons with nonurban sites as urban streams can provide substantial secondary benefits to urban residents. Here, we utilize a wide range of indicators to retrospectively examine the restoration of Nine Mile Run, a multi‐million dollar stream restoration project in eastern Pittsburgh (Pennsylvania, USA). Examination of available continuous hydrological data illustrates the high cost of failures to incorporate the data into planning and adaptive management. For example, persistent extreme flows drive geomorphic degradation threatening to reverse hydrologic connections created by the restoration and impact the improved instream biotic communities. In addition, human activities associated with restoration efforts suggest a positive feedback as the stream restoration has focused effort on the basin beyond the reach. Ultimately, urban stream restoration remains a potentially useful management tool, but continued improvements in post‐project assessment should include examination of a wider range of indicators.  相似文献   
93.
Creating False Images: Stream Restoration in an Urban Setting   总被引:1,自引:0,他引:1  
Stream restoration has become a multibillion dollar business with mixed results as to its efficacy. This case study utilizes pre‐ and post‐monitoring data from restoration projects on an urban stream to assess how well stream conditions, publicly stated project goals, and project implementation align. Our research confirms previous studies showing little communication among academic researchers and restoration practitioners as well as provides further evidence that restoration efforts tend to focus on small‐scale, specific sites without considering broader land use patterns. This study advances our understanding of restoration by documenting that although improving ecological conditions is a stated goal for restoration projects, the implemented measures are not always focused on those issues that are the most ecologically salient. What these projects have accomplished is to protect the built environment and promote positive public perception. We argue that these disconnects among publicized goals for restoration, the implemented features, and actual stream conditions may create a false image of what an ecologically stable stream looks like and therefore perpetuate a false sense of optimism about the feasibility of restoring urban streams.  相似文献   
94.
Intact riparian ecosystems are rich in biological diversity, but throughout the world, many have been degraded. Biodiversity declines, particularly of vertebrates, have led to experimental efforts to restore riparian forests by thinning young stands to accelerate creation of large diameter live trees. However, many vertebrates depend on large diameter deadwood that is standing as snags or fallen to the forest floor or fallen into streams. Therefore, we reviewed the sizes of deadwood and live trees used by different vertebrate species to understand which species are likely to benefit from different thinning treatments. We then examined how riparian thinning affects the long‐term development of both large diameter live trees and deadwood. To this end, we used a forest growth model to examine how different forest thinning intensities might affect the long‐term production and abundance of live trees and deadwood. Our results suggest that there are long‐term habitat tradeoffs associated with different thinning intensities. Species that utilize large diameter live trees will benefit most from heavy thinning, whereas species that utilize large diameter deadwood will benefit most from light or no thinning. Because far more vertebrate species utilize large deadwood rather than large live trees, allowing riparian forests to naturally develop may result in the most rapid and sustained development of structural features important to most terrestrial and aquatic vertebrates.  相似文献   
95.
本文主要对官地水电站高陡边坡植被混凝土前期绿化试验成果进行分析,以寻求在干湿季节明显、雨量集中、干旱季节漫长、温度高、蒸发量大等干热河谷气候特征条件下的最佳生境构筑方法,为官地水电站乃至雅砻江流域水电工程高陡边坡生态恢复提供技术依据。  相似文献   
96.
Hydrologic analysis for coastal wetland restoration   总被引:1,自引:0,他引:1  
Increasing recognition of the value of tidal wetlands has led to interest in how to restore and enhance areas that have been modified by human activity. The policy of recognizing restoration or enhancement as mitigation for destruction of other wetlands is controversial. Once policy questions are separated from technical questions, the steps in a successful project are straightforward A key element in the design of a successful project is quantitative hydraulic and hydrologic analysis of alternatives. Restoration projects at two sites in California used a combination of empirical geomorphic relationships, numerical modeling, and verification with field observations. Experience with these and other wetland restoration projects indicates the importance of longterm postproject monitoring, inspection, and maintenance  相似文献   
97.
2008年3月至2009年9月对紫阳湖生态修复效应进行了全程跟踪监测及诊断指示研究。研究表明,通过水生生物群落构建,水生态环境有了明显改善,全湖水质达到地表水IV标准,透明度上升到100 cm左右,叶绿素a下降到10 mg/m3以下。生态修复后各指标50%的效应时间序列为Chla、DO、SD、TP、NH3-N、TN和COD。研究认为,Chla/SD作为湖泊水质指数(LQI)是检验生态修复效果较敏感的指标,可用于浅水富营养湖泊生态修复后水质的诊断和评价。  相似文献   
98.
Abstract: Ecological restoration is a key component of biological conservation. Nevertheless, unlike protection of existing areas, restoration changes existing land use and can therefore be more controversial. Some restoration projects negatively affect surrounding landowners, creating social constraints to restoration success. Just as negative off‐site impacts (i.e., negative externalities) flow from industrial areas to natural areas, restoration projects can generate negative externalities for commercial land uses, such as agriculture. Negative externalities from industry have led to government regulation to prevent human health and environmental impacts. Negative externalities from restoration projects have elicited similar legal constraint on at least one large‐scale conservation project, riparian restoration in the Sacramento River Conservation Area. The negative externalities of restoration that are perceived to be the direct result of specific goals, such as endangered species management, are likely to be more contentious than externalities arising from unintended phenomena such as weed invasion. Restoration planners should give equal consideration to off‐site characteristics as to on‐site characteristics when choosing sites for restoration and designing projects. Efforts to control externalities can lead to off‐site ecological benefits.  相似文献   
99.
The application of the psychological contract to workplace safety   总被引:1,自引:0,他引:1  
INTRODUCTION: Psychological contracts of safety are conceptualized as the beliefs of individuals about reciprocal safety obligations inferred from implicit or explicit promises. Although the literature on psychological contracts is growing, the existence of psychological contracts in relation to safety has not been established. The research sought to identify psychological contracts in the conversations of employees about safety, by demonstrating reciprocity in relation to employer and employee safety obligations. The identified safety obligations were used to develop a measure of psychological contracts of safety. METHOD: The participants were 131 employees attending safety training sessions in retail and manufacturing organizations. Non-participant observation was used to collect the data during safety training sessions. Content analysis was used to analyze the data. Categories for coding were established through identification of language markers that demonstrated contingencies or other implied obligations. RESULTS: Direct evidence of reciprocity between employer safety obligations and employee safety obligations was found in statements from the participants demonstrating psychological contracts. A comprehensive list of perceived employer and employee safety obligations was compiled and developed into a measure of psychological contracts of safety. A small sample of 33 safety personnel was used to validate the safety obligations. CONCLUSIONS AND IMPACT ON INDUSTRY: Implications of these findings for safety and psychological contract research are discussed.  相似文献   
100.
Marine coastal ecosystems, commonly referred to as blue ecosystems, provide valuable services to society but are under increasing threat worldwide due to a variety of drivers, including eutrophication, development, land-use change, land reclamation, and climate change. Ecological restoration is sometimes necessary to facilitate recovery in coastal ecosystems. Blue restoration (i.e., in marine coastal systems) is a developing field, and projects to date have been small scale and expensive, leading to the perception that restoration may not be economically viable. We conducted a global cost–benefit analysis to determine the net benefits of restoring coral reef, mangrove, saltmarsh, and seagrass ecosystems, where the benefit is defined as the monetary value of ecosystem services. We estimated costs from published restoration case studies and used an adjusted-value-transfer method to assign benefit values to these case studies. Benefit values were estimated as the monetary value provided by ecosystem services of the restored habitats. Benefits outweighed costs (i.e., there were positive net benefits) for restoration of all blue ecosystems. Mean benefit:cost ratios for ecosystem restoration were eight to 10 times higher than prior studies of coral reef and seagrass restoration, most likely due to the more recent lower cost estimates we used. Among ecosystems, saltmarsh had the greatest net benefits followed by mangrove; coral reef and seagrass ecosystems had lower net benefits. In general, restoration in nations with middle incomes had higher (eight times higher in coral reefs and 40 times higher in mangroves) net benefits than those with high incomes. Within an ecosystem type, net benefit varied with restoration technique (coral reef and saltmarsh), ecosystem service produced (mangrove and saltmarsh), and project duration (seagrass). These results challenge the perceptions of the low economic viability of blue restoration and should encourage further targeted investment in this field.  相似文献   
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