Ludwig?s Ratchet and the Collapse of New England Groundfish Stocks

The stocks of principal groundfish species off New England have collapsed, creating economic hardship and dislocation in fishing communities from Rhode Island to Maine. In this article we analyze the causes of this collapse using the ?ratchet effect? described by Ludwig, Hilborn, and Walters (1993) as a framework. According to Ludwig, Hilborn, and Walters, powerful economic and political interests drive fisheries to overcapitalize and overexploit despite scientific evidence that stocks are declining. When the fishery is no longer economically viable, governments provide financial assistance to minimize economic hardship. When stocks increase there is another rush to invest, and the cycle repeats itself. The history of groundfish management in New England conforms well to this model. Optimism among fishers and government over U.S. control of this fishery in 1977 stimulated successive rounds of investment that built up excessive fishing capacity despite warnings from scientists that stocks were becoming weaker. Management regimes designed by the New England Fishery Management Council were ineffective in constraining fishing effort. Collapse of the stocks has led to severe restrictions on fishing and to government assistance. We suggest that the integration of science, management, and harvesting sectors through ecosystem-based management offers the best means of avoiding similar situations in the future.     

英国纽卡斯尔市停车管理策略及对中国的启示

随着城市机动化水平的不断提高,中国大中型城市已出现严重的停车供需矛盾,停车难随之成为城市交通中亟待解决的问题。英国纽卡斯尔市在停车管理方面进行了长期摸索与系统的方案设计,已形成具有城市特色并行之有效的停车管理策略。详细阐述纽卡斯尔市在停车政策法规、差别化停车供应和收费政策、管理与保障措施、停车换乘系统,以及停车诱导信息系统方面的实践和经验。结合中国城市停车现状,提出停车规范化、收费标准化、管理差别化、共享停车等停车管理建议。同时,应构建以人为本的停车配建理念,推动新能源汽车发展。     

Car availability change in England and Wales 1971–1981

The aggregate dynamics of car ownership have overshadowed the dynamics of car ownership and availability at the personal and household level. These dynamics have only recently been investigated in more depth. This paper contributes to this work by probing a special data source, theLongitudinal Study (LS) produced by the Office of Population Censuses and Surveys, for the changes in household car availability.The paper describes the LS and explains its special format, as a Census-based ~1% sample of the population of England and Wales.The analysis focuses on the car availability dynamics of a number of groups defined by changes in their life cycle position. Special attention is given to those households where the LS member remains a dependent child throughout the study period.The results show that all studied household types increase and decrease their car holdings, but that there are patterns in this process, which vary from group to group. In particular, the size of the previous car fleet has a different influence on the current fleet size from life cycle group to life cycle group.The paper argues in its conclusion to incorporate these differentials into the further work on car ownership and car ownership change.The work reported here was performed, while the author was a staff member of the Centre for Transport Studies, Imperial College, London.     

基于传统与现代的英国城市桥梁

该文系统地介绍了笔者考察英国期间,对伦敦、诺丁汉、考文垂和利兹等城市的城市桥梁建设的总体印象和分类考察的情况。重点展示了英国在城市桥梁建设上体现传统与现代上有机结合的成功作法,力求为国内同行们提供有借鉴意义的资料和启示,以期促进我国城市桥梁建设的健康发展。     

英国城市有轨电车及运营线路纵览

对英国当前8座城市9个有轨电车运营网络的27条线路及运用车辆进行系统的调查,涉及运营线路条件、车辆总体参数、转向架配置及车辆制造商信息等,在此基础上,总结英国有轨电车及运营线路的特点,车辆型式多样,既有高地板、40%低地板、70%低地板,也有100%低地板,这些车辆从采用的转向架角度来看,传统轮对式转向架、独立轮横向耦合、独立轮纵向耦合、轮毂电机的转向架均有。线路方面也全部采用槽型轨与"T"型轨相结合的形式,提高了旧有铁路利用率。这些信息为总体把握英国有轨电车的发展动态,以及发展国内有轨电车事业提供参考。     

Matching biological traits to environmental conditions in marine benthic ecosystems

The effects of variability in environmental conditions on species composition in benthic ecosystems are well established, but relatively little is known about how environmental variability relates to ecosystem functioning. Benthic invertebrate assemblages are heavily involved in the maintenance of ecological processes and investigation of the biological characteristics (traits) expressed in these assemblages can provide information about some aspects of functioning. The aim of this study was to establish and explore relationships between environmental variability and biological traits expressed in megafauna assemblages in two UK regions. Patterns of trait composition were matched to environmental conditions and subsets of variables best describing these patterns determined. The nature of the relationships were subsequently examined at two separate scales, both between and within the regions studied. Over the whole area, some traits related to size, longevity, reproduction, mobility, flexibility, feeding method, sociability and living habit were negatively correlated with salinity, sea surface temperature, annual temperature range and the level of fishing effort, and positively associated with fish taxon richness and shell content of the substratum. Between the two regions, reductions in temperature range and shell content were associated with infrequent relative occurrences of short-lived, moderately mobile, flexible, solitary, opportunistic, permanent-burrow dwelling fauna and those exhibiting reproductive strategies based on benthic development. Relationships between some traits and environmental conditions diverged within the two regions, with increases in fishing effort and shell content of the substratum being associated with low frequencies of occurrence of moderately mobile and moderately to highly flexible fauna within one region, but high frequencies in the other. These changes in trait composition have implications for ecosystem processes, with, for example, reductions in permanent-burrow dwellers within one of the regions potentially compromising the ability of the assemblages to process and store chemicals and waste products. However, the connections between environmental conditions and trait composition are complex and incorporate many factors. Experimental investigations will be necessary to determine the extent and consequences of these important relationships.     

英国停车换乘交通对策的实践与借鉴

以英国停车换乘(P&R)发展为例,从交通特征、土地利用、环境、商业开发以及社会问题等角度客观分析总结P&R的实施效果,并结合上海综合客运枢纽的规划中37处P&R枢纽的设置,探讨了英国经验对于上海发展P&R的借鉴。