Fishes and the environmental status of South African estuaries

Abstract More than 100 fish species are associated with southern African estuaries, many of which are caught by recreational anglers and/or commercial fishermen. Mismanagement of either a catchment or an estuary invariably leads to an impoverished system which is of little value to fishes or people. By taking this cause-and-effect scenario to its logical conclusion, it should be possible to assess the ‘state’ of an estuary by monitoring the biological ‘health’ of the aquatic community. Fishes are a dominant and highly visible component of the estuarine fauna and, by virtue of their key positions in the aquatic food web, can reflect either natural or anthropogenic alterations to the environment. In addition, their mobility enables them to respond rapidly to both deteriorating and improving estuarine conditions. Such attributes may assist scientists and managers in being better able both to assess the magnitude of detrimental impacts, and to monitor the ecosystem response to ameliorative actions. This paper attempts to show that an understanding of the biology and ecology of fishes associated with estuaries can lead to the identification of threats to the environment and result in improved management of these systems. The use of fish communities as an indicator of estuarine health is also examined, and ways of incorporating biological and ecological data into decision-support systems are discussed. The adoption of a set of environmental quality objectives for South African estuaries, together with a system of appropriate environmental quality standards, is recommended.     

Fraxinus nigra (black ash) dieback in Minnesota: Regional variation and potential contributing factors

Extensive tree dieback is a recurrent issue in many regions. Crown dieback of Fraxinus nigra Marsh. (black ash; brown ash) in the northeastern and north central United States is an example. F. nigra is a widely distributed hardwood that is often the dominant species in wetland forests from Manitoba to Newfoundland and West Virginia to Indiana. Widespread crown dieback of F. nigra has been noted in many regions, but there are few quantitative assessments of dieback extent or relationship to potential causes. Most F. nigra dieback episodes are not associated with specific disease or pest agents. Drought, excessive soil moisture, cohort senescense, and road influences, have all been suggested as potential contributing factors. Our objectives were to (1) quantify variable dieback across northern Minnesota, a region described as having extensive dieback, (2) determine the relationship between dieback and site moisture, (3) relate dieback to tree age/size distributions, and (4) assess whether dieback was related to road proximity. Given the increasing threat of Agrilus planipennis (emerald ash borer) in the region, it is important to know the current health status of F. nigra populations before widespread infestation occurs. Many stands in our study exhibited high incidences of crown dieback. However, the incidence of dieback was variable across the region. Spatial variability in dieback was associated with site wetland characteristics; more dieback occurred on jurisdictional wetlands and on sites with a higher wetness index and a deeper depth to a perching layer. Dieback was also positively correlated with mean stand diameter, and tree diameters were generally correlated with age, suggesting that stands with larger and older individuals experienced more dieback. Cohort senescence is a possible explanation for this trend. Finally, dieback occurred with higher frequency nearer to roads. The road influence could be related to hydrological alterations or perhaps toxicity from road deicing salt. The fact that dieback is more severe close to roads may contribute to a general perception that black ash dieback is more severe throughout the region than our study suggests. Collectively, our results indicate that the healthiest F. nigra stands in our study region are likely to be younger and located on relatively drier sites and farther from roads, compared to stands with significant crown dieback.     

基于WebGIS的森林健康评价与区划专家支持系统的设计与实现

为了解决森林经营单位森林健康状况的评价问题,利用综合因子评价法建立了改进的林分级森林健康评价指标体系,并基于ArcGISServer开发了森林健康评价与区划专家支持系统．以八达岭林场为例进行了森林健康评价与区划．结果表明,该系统可辅助实现森林经营单位健康状况判定、区划、出图、查询和统计等功能,并可以根据已有数据自定义评价指标体系及实时生成评价结果．     

增强居民小区保健功能的园林绿地设计应用研究

通过对微地形、绿化隔离带和园林芳香植物的保健功能及其设计要点进行研究,结果表明,多用、巧用微地形能够遮挡小区内部不良视觉构筑物,扩大绿视率和促进植物的生命活动;灵活设置绿化隔离带能够有效阻挡小区外围的不良视觉环境,吸附粉尘废气并降低噪音;有针对性地集中栽种园林芳香植物,具有一定的保健功能;在外围设置密闭的环状绿带延缓芳香物质的消散,可以有效提高居民对芳香物质的摄入量。     

浅析外来生物入侵与林业外来有害生物防控

本文通过对外来生物入侵的危害、机制和途径的论述,从江西主要林业外来生物入侵现状分析入手,并结合森林健康理论,提出了林业对外来有害生物防控的对策.     

森林生态系统健康和评价初探

介绍了森林健康、森林健康评价的概念和森林健康的特征,综述了国内外对森林健康和评价的研究现状,同时总结了我国森林健康和评价面临的主要问题以及发展趋势。     

基于Big6模型的卫生政策研究信息资源采集策略

首先介绍了Big6模型的概念、特点及其流程,然后基于Big模型将卫生政策知识服务平台资源采集过程分成任务定义、确定采集策略、采集信息、运用信息、整合信息和过程评价6个阶段,并对各阶段的具体内容进行了分析,以提高采集流程的规范性和完整性。     

利用VPN网络平台服务社区医疗卫生单位

从分析我国社区医疗卫生服务的现状、特点入手,确定了地方医学情报机构对社区医疗卫生单位信息服务的定位,提出了利用VPN网络平台服务社区医疗卫生单位的设想。     

中文医药卫生科技查新常用数据库收录期刊的比较分析

对医药卫生科技查新工作中常用的中国生物医学文献数据库、中国期刊全文数据库、重庆维普中文科技期刊数据库和万方数据知识服务平台收录的期刊资源进行了对比分析,客观地描述了各数据库的收录特征以及数据库收录高质量期刊、医药卫生核心期刊比例和重复情况,并对数据库的未来发展做了SWOT分析,以期能为从事医药卫生科技查新人员和文献数据库研发人员提供指导和借鉴。     

医学图书馆应坚决清除非法医药卫生类出版物

 

介绍了非法医药卫生类书刊的出版方式和国家公布取缔的27种非法医药卫生类期刊；阐述了非法医药卫生类期刊的危害和坚决取缔非法医药卫生类出版物，严防其流入医学图书馆。