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151.
Wetlands exist in complex ecological conditions that are changeable in time and space in terms of function and structural diversity. In recent decades, wetlands have been exposed to a wide range of threats. Assessment of these threats is essential to develop an understanding of the state of a wetland ecosystem and to develop a suitable management strategy. This paper discusses wetland vulnerability in terms of analysis of human and environmental systems from application of the driver-pressure-state-impact-response (DPSIR) framework. This assessment presented a systematic methodology for assessment of wetland vulnerability in a social-ecological approach applying broad-scale ecosystem services and vulnerability functions. The method combined the hydro-geomorphic approach with estimations of vulnerability indicators and DPSIR analysis. The aim of this paper was to assess vulnerability of wetland ecosystem services and to characterize the threat indicators according to importance, severity, and probability of occurrence. Quantitative and qualitative methods were applied to characterize values for these three indicators. The Multi Criteria Decision Making (MCDM) method was used to prioritize threats and impacts of the wetland on the basis of experts’ opinions. The proposed methodology was applied to the Choghakhor international wetland landscape in south-western Iran. Vulnerability assessment revealed that water requirement of the lowland and the water transfer system were the most important factors threatening the wetland. Agricultural activities, settlements and urban areas, drought, tourism, population growth, and mining activities in the upland were the next most important priorities, in that order. Hydrological balance was determined as the most vulnerable function and was considered as the most important function in the Choghakhor wetland. The DPSIR model was used to determine a management strategy to reduce vulnerability of ecosystem services in response to drivers, pressures, states and impacts indicated by modelling.  相似文献   
152.
The objective of the presented study is the development of a spatially explicit approach for mapping ecosystem services (MapES) by using specific knowledge about the Cerrado biome (Brazilian Savanna). This biome covers an area of about 2 million km2, i.e. nearly 24% of the total area of Brazil, and has come under substantial pressure during the last 50 years caused by strong land-use/land-cover change, mostly due to agricultural expansion and urbanization. Because of its fast transformation rate, there is an enormous demand for knowledge, and its application, about the effects of land-use/land-cover on the capacity of providing or maintaining ecosystem services. The MapES approach was developed using a vast existing knowledge base. After analyzing and structuring this knowledge the relationships between land-use/land-cover and the potential to provide or maintain eight ecosystem services (Erosion Control, Runoff Control, Water Supply, Water Quality Maintenance, Soil Quality Maintenance, Biodiversity Maintenance, Food Production and Energy Production) were parametrized. In addition, the approach was developed as spatially explicit by including landscape properties (soil, slope and distance to river network) in the cell based system. A reference map of potential natural vegetation and a land use map for 2013 for a meso-scale experimental catchment (32.7 km2) were produced. The catchment was used as an example to apply the approach, i.e. assessing and visualizing changes from before human interference to the current land use situation. Finally, a procedure for assessing the potential impacts of land-use/land-cover on ecosystem services considering the methodological limitations of the respective monitoring. The presented approach is easy to understand, to modify and to adapt to other situations and might be therefore used in other context of decision support. It might also help to fill the gap between land use planning and numeric modeling using very complex tools.  相似文献   
153.
In Uganda, information on visitation frequency of pollinator species visiting coffee flowers is absent, although such information is critical for the stability of coffee yield through the enhancement of pollination services. This study was conducted to understand the role played by local and environmental factors on the visitation intensity of coffee flowers by different bee species. Stepwise multiple regressions were used to investigate the effects of light intensity, distance to forest, foraging time of the day, coffee blooming season and abundance of coffee floral resources on the flower visitation frequency of different bee species. Results indicated contrasting responses of different bee species. The most important factors for social bees included forest distance, light intensity and the time of the day, whereas most determinant factors for solitary bee species were the length of the flowering season and the abundance of coffee floral resources. There is a need for developing habitat and landscape management strategies for the conservation of frequent native species in the vicinity of coffee fields to increase the delivery of pollination services to coffee. It is recommended to farmers to grow their coffee farms in the adjacent of forest habitats and related semi‐natural habitats to receive high bee visitations.  相似文献   
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155.
【目的】定量分析麦田自然天敌对麦蚜的控制作用。【方法】系统调查和罩笼接虫法。【结果】龟纹瓢虫Propylaea japonica Thunberg是麦蚜的主要天敌。在麦蚜发生平稳期、盛发期、消退期,自然天敌对麦蚜有稳定的控制作用,控害指数分别为35%、42%和32%。【结论】在制定麦蚜的防治策略时,应充分考虑自然天敌的控害作用,加强对自然天敌的保护利用。  相似文献   
156.
基于1985、1995、2000、2011年的Landsat TM影像解译数据,以河西走廊20个县(市、区)为基本研究单元,运用生态系统服务价值估算法,依据生态系统服务价值指数(ESV)和生态经济协调度指数(EEH),对河西走廊1985—2011年生态经济系统协调度进行评价.结果表明: 研究期间,研究区土地类型结构发生了较大变化,林草地面积减少幅度较大,建设用地和耕地面积增加较快.ESV整体呈下降趋势,研究区东、中部石羊河流域和黑河流域中游ESV变化幅度较大,经济开发方式在本时段发生过显著变化,研究区西部疏勒河流域ESV变化不大.2000年后,研究区经济增长速度明显加快,资源型城市和区域性中心城市是经济增长的热点区,整体上沿走廊中心向两侧递减.研究区生态经济关系整体上经历了“初步恶化-进一步恶化-低度协调”的演变过程,研究区东、中部的石羊河流域和黑河流域中游EEH有较大幅度的变化,生态经济经历了“冲突-进一步冲突-小幅度缓和”的过程,西部疏勒河流域EEH变化幅度较小,石羊河流域和黑河流域高强度的开发模式以及随后的流域综合治理对区域生态经济协调性产生了较大影响.
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157.
158.
Because ecosystems are complex, tradeoffs exist among supplies of multiple ecosystem services, especially between the provisioning and regulating services. In ecosystem processes, net primary production (NPP) is connected with many other processes such as respiration and evapotranspiration. As one key supporting service, NPP is also related to other provisioning and regulating services. This study introduces an analysis framework of ecosystem services tradeoffs from the perspective of varied share of NPP, in the alpine grassland ecosystem of Damxung County on the Tibetan plateau, China. Total NPP was divided into the share of NPP spent on supplying provisioning services and the share used in supporting regulating services. Tradeoffs between provisioning and regulating services were analyzed by quantifying the change of meat provisioning service and the remaining share of NPP used in other ways; the corresponding change in the share of NPP used to support regulating services was also analyzed and compared with other changes in regulating services, such as carbon sequestration and water conservation services. The results show, from 2000 to 2010, the meat provisioning service increased by 199%, but this was at a cost of additional livestock feeding, which used more NPP of the alpine grassland ecosystem. As a result, by 2010 the remaining NPP used for supporting regulating services shrank to 77% of the 2000 level, which was accompanied by a decrease in carbon sequestration and water conservation services by 90% and 67%, respectively. The analysis of tradeoffs from the perspective of variations in the share of NPP used for various services will contribute to the study of mechanisms involved in providing ecosystem services, interactions between the provisioning of various services, and will also help land managers improve the management of ecosystems.  相似文献   
159.

Aim

We sought to survey a large, multi-center patient sample to better characterize/quantify RT utilization at the end of life.

Background

Few objective data exist for radiation therapy (RT) delivery at end of life (EOL).

Materials and methods

Data were retrieved for all patients receiving RT in calendar year 2010 in the Department of Radiation Oncology at Indiana University (IU) and Howard University (HU) hospitals. Specific attention was made of the group of patients receiving RT in the last 30 days of life.

Results

A total of 852 patients received all or part of their RT during 2010 (HU: 139, IU: 713). At time of analysis in early 2012, 179 patients had died (21%). Fifty-four patients (6.3% of total; 30% of expired patients) died within 30 days of receiving their last treatment. Twenty patients (2.3% of total; 11.2% of expired patients) received RT within their last week of life. For both sites, the median time until death from completion of therapy was 12.5 days (range 2–30 days).

Conclusions

Radiation in the last month of life is likely to provide minimal palliation or survival benefit. This, coupled with the financial implications, time investment, and physical costs, suggests that physicians and patients should more strongly consider hospice, and minimize duration of palliative RT courses as far as possible. As with chemotherapy, RT utilization at EOL should be considered for collection as an overuse metric.  相似文献   
160.
AMPA 受体是兴奋性神经递质谷氨酸的非N- 甲基-D- 天冬氨酸型离子型跨膜受体,其介导中枢神经系统快速兴奋性突触传递,在中枢神经系统的信号传导、神经发育以及突触的可塑性等方面有重要的影响。研究表明,多种疾病如神经精神系统疾病、心血管疾病、肿瘤、呼吸系统疾病、内分泌系统疾病的发生发展与AMPA 受体数量或功能的异常密切相关。近年来,AMPA 受体作为一种理想的药物作用靶点,受到了越来越多的关注。结合汤森路透数据库资源——Thomson Reuters Integrity 和Cortellis for Competitive Intelligence,对AMPA 受体的机制、相关药物研究进展、适应证、研发机构、交易、专利、文献等情报进行数据层面的分析。  相似文献   
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