Effects of urbanization and land use on fish communities in Valley Creek watershed, Chester County, Pennsylvania

Valley Creek watershed, located in southeastern Pennsylvania, is a small, fourth-order stream that empties into the Schuylkill River at Valley Forge National Historic Park, thirty-five kilometers northwest of Philadelphia. The 64 km² watershed has been under extreme urbanization pressure over the past 30 years, resulting in rapidly increasing impervious surface cover and decreasing open space. The purpose of this study was to document some of the effects of urbanization on fish assemblages by quantifying the fish communities at fifteen sites throughout the watershed. Long-term effects of continued urbanization were identified, as data from the present study were compared to similar work completed nearly ten years earlier. There has been a shift in species composition from intolerant, coldwater species to more tolerant, eurythermal species. Currently, Valley Creek is supporting a naturally reproducing population of brown trout, but there has been a marked decline in relative abundance and range since 1993. Increased stream temperature from urban run-off is one of the primary issues in Valley Creek. Species composition was unique at each of the 15 stations owing to the effect of local land use in each station’;s drainage area. Fish assemblages revealed a patchy, non-continuous pattern of fish distribution.     

Role of urban governance in the process of bus system reform in Seoul

The Seoul Metropolitan Government (SMG) executed an innovative bus system reform in July 2004. The bus lines were reorganized as trunk, feeder, and circular routes; and bus numbers were arranged into eight areas. The monopolized route systems were reorganized as a semi-public operation, with a route tendering system to induce competition. A unified fare system was introduced taking into account transfers between buses; buses and the subway, and other modes of public transportation, all with the development of a new transportation card system. Exclusive median bus lanes were constructed in three major corridors. The main purposes of this paper are to (1) discuss the background and necessity of the bus system reform; (2) review the composition and functions of the Bus System Reform Citizen Committee (BSRCC), which instigated the reform; (3) analyze the role of BSRCC as a type of urban governance; and (4) provide policy implications. The study employs three techniques—literature reviews of the realities of bus service, in-depth interviews with stakeholders to analyze the roles and benefits of the BSRCC, and participant observation via a BSRCC member. All these help to shed light on a new form of urban governance which broke from the execution lead only by officials of the SMG.     

建国初期毛泽东对"三农"问题的若干认识

“三农”问题是中国革命与社会主义革命和建设中的基本问题。建国初,毛泽东在开国奠基、恢复经济过程中,通过土地改革、互助合作等方式对解决“三农”问题的途径和道路进行了重要探索,为解决当今中国的“三农”问题,提供了极为丰厚的历史教益。     

农民法律意识对依法治农目标实现的制约因素分析

依法治农是依法治国的关键,而依法治农的前提和基础是提高农民法律意识,农民法律意识的淡薄缘于中国社会现状、民主与法制健全程度及权利保护机制等多方面原因,因此,应加大普法力度、加强农民思想道德建设、重视农村教育,建立法治环境,到司法公正。     

加入WTO对中国农业的影响及对策分析

农业调整涉及新时期的农业发展战略 ,也取决于对 WTO及世界农产品贸易自由化态势的较好把握。由于我国农业工业化进程缓慢 ,集约化经营水平不高 ,市场农业还没有真正形成 ,入世对我国农业不可避免地带来深刻的影响。本文从加入 WTO一年多来对我国农产品价格、农业生产结构及政府管理体制三方面的影响 ,提出了我国农业存在的问题 ,有针对性地分析了我国农业应采取的对策。     

论张之洞的农业近代化思想与实践

学习西方技术,推进农业发展是近代思想家的共识,清末张之洞提出系统农业近代化的思想,他在农业生产方式,农作物产品结构,农业科技等方面都提出具有近代特色的见解,并倡导进行近代农业实践活动,对推进晚清农业近代化进程产生积极的影响。     

加入WTO对恩施州农业的影响和发展对策

我国加入WTO后,农业是受影响最大的产业之一。恩施州的农业发展面临许多的机遇和挑战,为此必须采取一系列的措施,调整策略,走有恩施特色的农业发展之路。     

Notes on the evolution and organization of the urban ecosystem

The continual spread of human settlements over the world’s surface has transformed the natural environment on a global scale. Human’s intervention has changed primary ecosystems (protoecosystems or euecosystems) into anthropoecosystems. The spread of urban ecosystems, cultivated surfaces (agroecosystems), and various areas differentiated by their level of anthropization has facilitated the progressive reduction of euecosystems. The evolution of urban areas over the course of history with transformations of cities and surrounding territory, has created very complex mosaics. A proper study of the city, drawing together historical, cultural, social, and other factors, as well as abiotic ones (urban climate, soil, water, air), requires appropriate, uniform terminology for expressing the complex relationships existing among these factors. We therefore propose that the city (or metropolis) be considered as a set of ecosystems, a “synecosystem”. The entire urban area should be termed a “synbiotope”. It is divided into numerous partial biotopes (macro-, meso- and microbiotopes), the result of modifications wrought through the historical and cultural vicissitudes of the human population. Urban biotopes host not only humans, but also a characteristic vegetable and animal component, the “biosyncoenosis”, formed of numerous plant and animal communities, selected on the basis of the environmental conditions of the individual biotopes, which differ from each other in structure, dynamics, age, and position in the urban space. This terminology should facilitate study of the biotic component and its connection to the urban territory, as well as interpretation of results obtained in the different disciplines in terms of the human population’s quality of life.     

晚清时期我国农业领域的向外国学习

晚清时期,向外国学习已扩展到农业领域,并形成了不小的潮流,使晚清的农业出现了前所未有的新变化。这种状况的出现并非偶然,既反映了中国传统农业自身的变革要求,又是国人对农业重要地位重新认识的结果。     

论甘肃沿黄灌区农业的高效持续发展

本文认为通过实行“三扩大”，大力发展玉米、间套、蔬菜和设施农业，引导农业向集约高效方向发展是甘肃沿黄灌区农业发展的必然趋势．论述了持续高产高效农业与科技进步的关系，提出采取优化品种结构、时空结构、要素组配等措施，实行全方位增加农业投入，进而实现沿黄灌区农业高产、高效、持续发展