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501.
Abstract: The unit of trade in ecosystem services is usually the use of a proportion of the parcels of land associated with a given service. Valuing small changes in the provision of an ecosystem service presents obstacles, particularly when the service provides non‐use benefits, as is the case with conservation of most plants and animals. Quantifying non‐use values requires stated‐preference valuations. Stated‐preference valuations can provide estimates of the public's willingness to pay for a broad conservation goal. Nevertheless, stated‐preference valuations can be expensive and do not produce consistent measures for varying levels of provision of a service. Additionally, the unit of trade, land use, is not always linearly related to the level of ecosystem services the land might provide. To overcome these obstacles, we developed a method to estimate the value of a marginal change in the provision of a non‐use ecosystem service—in this case conservation of plants or animals associated with a given land‐cover type. Our method serves as a tool for calculating transferable valuations of small changes in the provision of ecosystem services relative to the existing provision. Valuation is achieved through stated‐preference investigations, calculation of a unit value for a parcel of land, and the weighting of this parcel by its ability to provide the desired ecosystem service and its effect on the ability of the surrounding land parcels to provide the desired service. We used the water vole (Arvicola terrestris) as a case study to illustrate the method. The average present value of a meter of water vole habitat was estimated at UK£12, but the marginal value of a meter (based on our methods) could range between £0 and £40 or more. 相似文献
502.
对我国沿海地区1~3a强震危险性给出三级层次分析结果。首先分析地震大开势,其次分区研究强震概率增益,最后以华南为例对小层次即潜在震源未来1~3a强震概率进行计算。 相似文献
503.
化工厂排放SO2对周围植物的影响 总被引:6,自引:0,他引:6
对某厂区及常年盛行风下风向地区植物受SO2危害情况进行了调查,并测定了部分植物叶片中的硫含量。从植物叶片中的硫含量可间接地判断大气被SO2污染的程度及植物对SO2吸收与抵抗能力的强弱。 相似文献
504.
505.
Elwyn S. Krous Joseph P. Wagner Harold L. Parkinson Milton S. Sachs 《Journal of the American Water Resources Association》1971,7(4):810-822
ABSTRACT .A case study was performed to evaluate potential applications of desalted saline water for agriculture using 2 distillation type processes and 2 membrane type processes. The investigation determined the costs and benefits associated with desalting saline water at concentrations of 1,500, 900, 400, 200, and 50 ppm. Benefits from desalting are generated by shifts to more profitable crops, reduced costs for drainage, and reduction in fertilizer and labor requirements with better quality water. Costs are based on the project features such as desalting plants, raw water diversion facilities, storage reservoirs, conveyance and distribution systems, brine disposal, blending facilities, and gypsum addition systems. Hydrologic studies determined the crop irrigation requirements, water demand schedules, desalted water storage requirements, brine disposal requirements, and size of facilities required. Reconnaissance design layouts were made for producing desalted water using a combination of 14 schemes. The study also included a review of irrigation practices. The benefit-cost ratios range from 0.4 to 1.0 for 1,500 ppm irrigation water to 0.8 to 1.0 for 50 and 200 ppm water. Investment costs per acre are high, ranging from $12,900 to $20,900. Irrigation benefits are based on the increase in production from a desert condition with no water supply to the irrigation conditions studied. 相似文献
506.
507.
大巴山地处川、陕、渝的接合部,大气质量较好;由于特殊的地质构造,这里矿产资源较丰富;生物资源极其丰富,局部保存有原始森林,具有重要的科研、经济价值;旅游资源也极其丰富,是开展生态旅游和红色旅游的极好地区. 相似文献
508.
509.
江津润湿时间的温度分布研究 总被引:3,自引:1,他引:2
采用直接读取、4点统计、24点统计三种方法研究了江津试验站1998年的润湿时间的温度分布,研究表明,可以利用全年每天2、8、14、20点的4个数据统计年润湿时间的温度分布;江津地区润湿时间的温度分布特征主要为:(1)99%的年润湿时间是在5℃至30℃温度范围,每月润湿时间的温度波动一般为15℃;(2)在(0~5)℃、(5~10)℃、(10~15)℃、(15~20)℃、(20~25)℃、(25~30)℃、(30~35)℃区间内,4点统计法各区间润湿时间的百分比分别为0.34%、13.4%、24.5%、18.3%、26.0%、17.4%、0.0%。 相似文献
510.