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221.
M. ZACHARIAH PEERY†† STEVEN R. BEISSINGER SCOTT H. NEWMAN† ESTHER B. BURKETT‡ TONY D. WILLIAMS§ 《Conservation biology》2004,18(4):1088-1098
Abstract: We identified six approaches to diagnosing causes of population declines and illustrate the use of the most general one ("multiple competing hypotheses") to determine which of three candidate limiting factors—food availability, nesting site availability, and nest predation—were responsible for the exceptionally poor reproduction of Marbled Murrelets ( Brachyramphus marmoratus ) in central California. We predicted how six attributes of murrelet demography, behavior, and physiology should be affected by the candidate limiting factors and tested predictions with field data collected over 2 years. The average proportion of breeders, as estimated with radiotelemetry, was low (0.31) and varied significantly between years: 0.11 in 2000 and 0.50 in 2001. Murrelets spent significantly more time foraging in 2000 than in 2001, suggesting that low food availability limited breeding in 2000. In 2001, 50% of radio-marked murrelets nested and 67% of females were in breeding condition, suggesting that enough nest sites existed for much of the population to breed. However, rates of nest failure and nest predation were high (0.84 and 0.67–0.81, respectively) and few young were produced, even when a relatively high proportion of murrelets bred. Thus, we suggest that reproduction of Marbled Murrelets in central California is limited by food availability in some years and by nest predation in others, but apparently is not limited by availability of nesting sites. The multiple-competing-hypotheses approach provides a rigorous framework for identifying causes of population declines because it integrates multiple types of data sets and can incorporate elements of other commonly used approaches. 相似文献
222.
本文采用万元产值取水量和水重复利用率作为节水指标,通过对山东省主要工业行业用水节水现状进行调查研究,阐述了各行业节水水平和节水经验,分析并预测了节水潜力,总结提出了各行业应采取的主要节水措施和建议。 相似文献
223.
Abstract: Environmental impact assessment (EIA) is the process of identifying potential environmental effects of proposed development and the required mitigation measures. It is one of the most widely used planning tools today, but its ability to promote biodiversity conservation is largely unexplored. We studied the ecological component of the Israeli EIA system by reviewing a representative sample of 52 environmental impact statements (EISs) produced since 1995 and their corresponding guidelines issued by the Ministry of the Environment. Quality of both EISs and guidelines was determined using a simple scoring approach. Lack of quantitative data, meaningful analyses, and ecosystem perspective was apparent throughout. Many EISs failed to perform field surveys and their qualitative nature hampered meaningful impact prediction. Most EISs concentrated on aesthetic mitigation measures and did not assess their feasibility and likely success. Most of these flaws reflect poor standards rather than true scientific limitations. Guideline quality scores were the most important factor determining the quality of EISs; second was the involvement of an ecological consultant in preparing the EIS. We found a decreasing trend of EIS quality scores over time. Improvements in EIA procedures, particularly in ecological guidelines and the incorporation of ecological consultation, are important for upgrading ecological impact assessment so that the potential of EIA to advance biodiversity conservation can be realized. 相似文献
224.
Prioritization for Conservation of Northern European Cattle Breeds Based on Analysis of Microsatellite Data 总被引:2,自引:0,他引:2
225.
水质安全是调水工程顺利实施的关键,为此调水区背负巨大的调水工程的外部经济成本和社会发展代价,必须通过生态补偿政策进行内部化,然而调水工程涉及的范围广、时间长、利益主体多、资金投入大,难以通过一种手段或者现有某种方式建立长效的生态补偿机制。文章从调水工程生态补偿政策建立的目标、标准、责任分担与利益共享、补偿方式角度分析了生态补偿现状及存在的问题,提出了调水工程生态补偿的分阶段推进战略总体思路与实施构想,重点分析了各阶段生态补偿政策的制定标准和要求,为中线调水工程生态补偿政策制定提供了技术支持。 相似文献
226.
227.
Chao‐Hsien Liaw Liang‐Ching Chen 《Journal of the American Water Resources Association》2004,40(4):971-979
ABSTRACT: This work begins by defining rational water use, and then discusses important factors that most strongly influence it. A general model is then developed to enable factories to quantify the ratio of rational industrial water reuse based on the least cost method. The model is established to minimize the cost of water with reference to gross water use and three subsystems ‐ the intake, reuse, and discharge of industrial water. Discharge cost is determined using data from a 1997 survey of 38 factories, and reuse costs are ranked and expressed by a step function. The model is verified using data from a typical semiconductor factory in northern Taiwan's Hsinchu Science Based Industrial Park, whose effective rational water reuse ratio is about 38 percent. A sensitivity analysis shows that improving water reuse technology is the most important factor in determining the rational water reuse ratio, and the price of water is the second most important. When water costs over NT$30 (New Taiwan Dollar, US$1 = NT$34) per cubic meter, increasing reuse becomes significant. The model provides a step towards the scientific management of industrial water. 相似文献
228.
ELIZABETH B. HARPER TRACY A. G. RITTENHOUSE RAYMOND D. SEMLITSCH 《Conservation biology》2008,22(5):1205-1215
Abstract: Much of the biodiversity associated with isolated wetlands requires aquatic and terrestrial habitat to maintain viable populations. Current federal wetland regulations in the United States do not protect isolated wetlands or extend protection to surrounding terrestrial habitat. Consequently, some land managers, city planners, and policy makers at the state and local levels are making an effort to protect these wetland and neighboring upland habitats. Balancing human land‐use and habitat conservation is challenging, and well‐informed land‐use policy is hindered by a lack of knowledge of the specific risks of varying amounts of habitat loss. Using projections of wood frog (Rana sylvatica) and spotted salamander (Ambystoma maculatum) populations, we related the amount of high‐quality terrestrial habitat surrounding isolated wetlands to the decline and risk of extinction of local amphibian populations. These simulations showed that current state‐level wetland regulations protecting 30 m or less of surrounding terrestrial habitat are inadequate to support viable populations of pool‐breeding amphibians. We also found that species with different life‐history strategies responded differently to the loss and degradation of terrestrial habitat. The wood frog, with a short life span and high fecundity, was most sensitive to habitat loss and isolation, whereas the longer‐lived spotted salamander with lower fecundity was most sensitive to habitat degradation that lowered adult survival rates. Our model results demonstrate that a high probability of local amphibian population persistence requires sufficient terrestrial habitat, the maintenance of habitat quality, and connectivity among local populations. Our results emphasize the essential role of adequate terrestrial habitat to the maintenance of wetland biodiversity and ecosystem function and offer a means of quantifying the risks associated with terrestrial habitat loss and degradation. 相似文献
229.
Abstract: Central America is exceptionally rich in biodiversity, but varies widely in the attention its countries devote to conservation. Protected areas, widely considered the cornerstone of conservation, were not always created with the intent of conserving that biodiversity. We assessed how well the protected-area system of Central America includes the region's mammal diversity. This first required a refinement of existing range maps to reduce their extensive errors of commission (i.e., predicted presences in places where species do not occur). For this refinement, we used the ecological limits of each species to identify and remove unsuitable areas from the range. We then compared these maps with the locations of protected areas to measure the habitat protected for each of the region's 250 endemic mammals. The species most vulnerable to extinction—those with small ranges—were largely outside protected areas. Nevertheless, the most strictly protected areas tended toward areas with many small-ranged species. To improve the protection coverage of mammal diversity in the region, we identified a set of priority sites that would best complement the existing protected areas. Protecting these new sites would require a relatively small increase in the total area protected, but could greatly enhance mammal conservation. 相似文献
230.
农牧交错带农业生态服务功能的作用及其保护途径 总被引:10,自引:0,他引:10
目前全球农业生产覆盖全球25%~30%的土地面积,约50%的可利用土地已经被农业占据。如果农业生态系统.特别是生态脆弱区的系统服务功能得不到恢复与保护.那将会拖全球环境保护的“后腿”。由于中国的国情决定了在生态脆弱区环境保护中必须坚持环境保护与发展农业生产“两手抓“。因此.农业生态系统服务功能的恢复、维持应该成为该地区生态环境保护与建设的重要组成部分。农业生产不仅要提高生态系统服务的产品功能,更要恢复和维持其各种维持生命的间接服务功能。本文在分析农业生态系统服务功能退化表现与影响因素的基础上.提出了针对各项服务功能的恢复与维持对策。 相似文献