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1.
The Sacramento-San Joaquin Delta, the landward reach of the San Francisco Estuary, provides habitat for threatened delta smelt, endangered winter-run Chinook salmon, and other species of concern. It is also the location of huge freshwater diversion facilities that entrain large numbers of fish. Reducing the entrainment of listed fishes into these facilities has required curtailment of pumping, reducing the reliability of water deliveries. We reviewed the first 5 years (2001–2005) of the Environmental Water Account (EWA), a program instituted to resolve conflicts between protecting listed fishes and providing a reliable water supply. The EWA provided fishery agencies with control over 0.2–0.4 km3 of water to be used for fish protection at no cost to users of exported water, and fish agencies guaranteed no disruption of water supply for fish protection. The EWA was successful in reducing uncertainty in water supply; however, its contribution to the recovery of listed fishes was unclear. We estimated the effectiveness of the EWA to be modest, increasing the survival of winter-run Chinook salmon by 0–6% (dependent on prescreen mortality), adult delta smelt by 0–1%, and juvenile delta smelt by 2–4%. Allocating EWA water for a single life stage of one species could provide larger gains in survival. An optimally allocated EWA of equal size to the median of the first 5 years could increase abundance of juvenile delta smelt up to 7% in the springs of dry years. If the EWA is to become a long-term program, estimates of efficacy should be refined. If the program is to be held accountable for quantitative increases in fish populations, it will be necessary to integrate scientific, possibly experimental, approaches.  相似文献   

2.
Ecological restoration is increasingly becoming a primary component of broader environmental and water resources management programs throughout the world. The New Zealand Department of Conservation implemented Project River Recovery (PRR) in 1991 to restore unique braided gravel-bed river and wetland habitat in the Upper Waitaki Basin in New Zealand’s high country of the South Island, which has been severely impacted by hydroelectric power development. These braided rivers are highly dynamic, diverse, and globally important ecosystems and provide critical habitat to numerous native wading and shore bird species, including several threatened species such as the black stilt. The objective of this study was to review and summarize PRR after more than 10 years of implementation to provide information and transfer knowledge to other nations and restoration programs. Site visits were conducted, discussions were held with key project staff, and project reports and related literature were reviewed. Primary components of the program include pest plant and animal control, wetland construction and enhancement, a significant research and monitoring component, and public awareness. The study found that PRR is an excellent example of an ecological restoration program focusing on conserving and restoring unique habitat for threatened native bird species, but that also includes several secondary objectives. Transfer of knowledge from PRR could benefit ecological restoration programs in other parts of the world, particularly riverine floodplain and braided river restoration. PRR could achieve even greater success with expanded goals, additional resources, and increased integration of science with management, especially broader consideration of hydrologic and geomorphologic effects and restoration opportunities.  相似文献   

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Given the projected threat that climate change poses to biodiversity, the need for proactive response efforts is clear. However, integrating uncertain climate change information into conservation planning is challenging, and more explicit guidance is needed. To this end, this article provides a specific example of how a risk-based approach can be used to incorporate a species’ response to climate into conservation decisions. This is shown by taking advantage of species’ response (i.e., impact) models that have been developed for a well-studied bird species of conservation concern. Specifically, we examine the current and potential impact of climate on nest survival of the Lewis’s Woodpecker (Melanerpes lewis) in two different habitats. To address climate uncertainty, climate scenarios are developed by manipulating historical weather observations to create ensembles (i.e., multiple sequences of daily weather) that reflect historical variability and potential climate change. These ensembles allow for a probabilistic evaluation of the risk posed to Lewis’s Woodpecker nest survival and are used in two demographic analyses. First, the relative value of each habitat is compared in terms of nest survival, and second, the likelihood of exceeding a critical population threshold is examined. By embedding the analyses in a risk framework, we show how management choices can be made to be commensurate with a defined level of acceptable risk. The results can be used to inform habitat prioritization and are discussed in the context of an economic framework for evaluating trade-offs between management alternatives.  相似文献   

5.
Government agencies responsible for pest animal management often assume that their views and assumptions about the benefits of control are widely shared, especially if these pests are exotics. This was certainly the case when tens of thousands of feral Asian water buffalo (Bubalus bubalis) were to be culled in Australias Kakadu National Park as part of a national Brucellosis and Tuberculosis Eradication Campaign (BTEC). Implementation of the campaign sparked considerable dispute between officials and aboriginal and non-aboriginal interests about the risks posed by buffalo relative to their value as a potential resource. Drawing upon a variety of written and oral sources relating to the era of buffalo control in Kakadu, this paper critically analyzes the way in which detriment caused by buffalo was appraised and managed under the BTEC program. In particular, the paper focuses the ways in which the BTEC program affected aboriginal people in Kakadu, who view buffalo as a source of customary and economic benefit as well as a source of change on their lands. The paper then considers what lessons can be learned from the BTEC for the development of sensible feral management objectives and strategies. It is argued that effective management of feral animals such as buffalo will require environmental managers to engage with local people and involve them in the definition and management of pest animal damage and methods of control.  相似文献   

6.
Bear bile has long been used in the Asian traditional pharmacopoeia. Bear farming first started in China ~30 years ago in terms of reducing the number of poached bears and ensuring the supply of bear bile. Approximately 13,000 bears are today captivated on Asia’s bear farms: their teeth are broken and the claws are also pulled out for the sake of human safety; the bears are imprisoned in squeeze cages for years; and a catheter is daily inserted into a bear’s gall bladder or a tube is implanted inside its body in order to collect the dripped bile—captive bears moan in severe pain whenever the bile is extracted. When the bears cannot produce sufficient bile, they are often left to die of starvation. It must be impossible to justify the bile extraction from living bears because (1) medicinal/herbal alternatives are similar to bear bile; (2) there is no evidence to suggest that bear farming has any beneficial effects on wild bear populations; and (3) ethical problems lie not only in the painful bile extraction but also the whole lifecycle of captive bears. In conclusion, human welfare (health care) based on traditional medicine is upheld by sacrificing bear welfare. Since a trial calculation suggests that it is economically unfeasible to keep a proper balance between bear welfare and the traditional pharmacopeia, the cultivation of herbal alternatives seems to be a possible solution to phase out bear faming and maintain the practice of traditional medicine in Asia.  相似文献   

7.
Methods for defining and retrieving reference conditions for large rivers were explored with emphasis on hydromorphologic and biologic quality indicators. For a set of four large rivers in the European Western Plains ecoregion, i.e., the rivers Meuse, Loire, Allier, and Dordogne, reference reaches were selected based on geomorphologic characteristics. A survey of riparian land use, vegetation, and bed geometry was done for the selected reaches. Responses of the riparian landscape to hydromorphologic conditions were determined with a set of existing and newly developed measures of riparian dynamics and forest development. Strong correlations were observed at the reach and local levels between the ratios of width to depth and embankment and the developed measures of riparian dynamics and forest. Boundary conditions for riparian forest development were determined for the hydromorphologic and biologic indicators of riparian dynamics and vegetation structure. These conditions also proved useful for determining the presence of sustainable populations of Populus nigra and Salix purpurea. From this agreement between abiotic and biotic boundary conditions, a set of useful reference conditions was determined, and a framework for the definition of reference and good status conditions subsequently evolved. Finally, a proposal for assessment and monitoring the proposed indicators is discussed for its applicability.  相似文献   

8.
The Conversion of Cropland to Forest and Grassland Program (CCFG), which was initiated by the Chinese government in 1999, is a cropland retirement program with integrated objectives for ecological preservation and local development. The purpose of this article was to study the influencing factors of attitude and economic strategies in rural households toward the CCFG. Rural households’ knowledge, attitude and economic strategies toward the CCFG were investigated through a questionnaire survey in Qira, China. Influencing factors of attitude and strategies of households were analyzed using a logit model technique. The analysis indicated that household’s income level, environmental knowledge of the program, and program implementation were significant influencing factors in a household’s attitude toward the CCFG, while major influencing factors of household strategies were their regional background and availability of income generation sources. Meaningful association was not found between attitude and strategy choices. Rich households had more strategy choices, while poor households were usually confined to low input strategies with uncertain income. To sustain their livelihood, the poor need extra assistances in marketing, loan granting, employment training, information, and technical services.  相似文献   

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