Amphibian use of constructed and remnant wetlands in an urban landscape

Urban areas are increasing in number, extent, and human population density worldwide. There is potential to mitigate negative impacts of urbanization to native pond-breeding amphibians by providing habitat in both remnant natural and constructed wetlands. This study examines amphibian use of potential breeding sites in natural and constructed ponds in a large metropolitan area to investigate habitat characteristics that are associated with successful breeding. I surveyed 62 ponds over three breeding seasons in Portland, Oregon, measuring eleven habitat characteristics that may influence their successful breeding: pond depth, nitrate level, aquatic refugia, aquatic vegetation, surrounding vegetation, pond permanence, presence of fish and of introduced bullfrogs, surrounding road density and forest cover, and whether they were constructed or remnant natural ponds. Five of the six native pond-breeding species that occur in the region were regularly found breeding in city ponds. Surrounding forest cover and amount of aquatic vegetation were highly associated with breeding, indicating that preserving and planting vegetation likely benefits urban amphibians. Non-native bullfrogs were not associated with native species richness. Surprisingly, whether a pond was natural or constructed was also only weakly associated with native species breeding, and the trend was towards higher presence for all species in constructed ponds. This indicates that novel, human-dominated areas can provide habitat for these species. Consideration of habitat characteristics associated with breeding success in urban pond management will likely benefit native amphibians in these rapidly expanding landscapes.     

Differences in fish harvest,fishing effort,and angling guard activities between urban and natural fishing grounds

Recreational fishing is a very popular outdoor leisure activity. Assessing differences in basic metrics in recreational fishing on different types of fishing grounds is very important for effective fisheries management. This study aimed to discover how basic metrics in recreational fishing (harvest, fishing effort, angling guard activities) differ between urban fishing grounds (located in a densely populated city) and natural fishing grounds (located in the countryside). Data were obtained from individual angling logbooks collected by the Czech Fishing Union on the River Elbe and the River Vltava (Prague and Central Bohemia, Czechia, Central Europe). Study shows that urban and natural fishing grounds showed significant differences in basic metrics in recreational fishing. Urban fishing grounds displayed higher fish harvest in general and higher dominance of intensively stocked fish species in catches of anglers (mainly common carp Cyprinus carpio). High harvest rates of common carp can be mostly explained by intensive fish stocking. The only fish species that showed higher harvest on natural fishing grounds were large-growing piscivorous fish with high ecological demands. However, anglers were harvesting larger fish (average body weight) on natural fishing grounds. In addition, fishing effort was similar on both types of fishing grounds. Inversely, angling guards were more active on natural fishing grounds. In conclusion, differences in basic fisheries metrics between urban and natural fishing grounds seem to be partially driven by intensive fish stocking.

     

Bihari Muharram processions in Dhaka city: religious performance as a means of territorialising urban public space by a disenfranchised ethnic minority

The Biharis in Bangladesh are a heavily persecuted ethnic minority confined to slum like camps for nearly five decades. Using data from ethnographic research carried out in a Bihari camp and its surrounding areas in Dhaka city, this visual essay examines the ways in which the Biharis use religious processions to claim visibility, assert community identity and territorialise urban public space in a city that systematically denies them access to citizen rights.     

The production of space in the negotiation of water and electricity supply in a bosti of Dhaka

Dhaka Water Supply and Sewerage Authority (DWASA) and Dhaka Electricity Supply Company (DESCO) do not provide any direct utility supply in the informal settlements of Dhaka where more than one third of the total city population live. Large numbers of the population thus access utilities from local vendors who maintain relationships with administrative staff of the authorities concerned, political leaders and influential community leaders, thus making the supply available in the settlement and continuing their informal utility business. Access to these utilities is negotiated in the continuously changing arrangements of a complex hybrid institutional sphere and under informal regulation. In this process, the changing nature of the state and urban groups and the complicated and dynamic relationship between and within urban groups indicate that urban governance operates in a ‘third space’ of constant negotiation and contestation. Against this background this paper presents the informal practice of water and electricity supply by a local association, the regulations in place, and the inter-linkage between different forms of regulatory space whose presence is a necessary condition for the continuation of the informal practice.     

Urban croaking: diversity and distribution of anurans in a neotropical city

Anurans are excellent site-specific bioindicators. Although urbanization imposes diverse threats to wildlife species, little is known about its effect on tropical anurans. In this study we assessed the response of anurans to different conditions within an urban area (i.e. highly developed intra-urban residential areas, highly developed peri-urban residential areas, intra-urban abandoned lots, waterway). Our results show that: (1) 36 % of the regional anuran species pool was found within the boundaries of the studied city, (2) species richness peaked in highly developed peri-urban areas, (3) anuran abundance scores were highest in abandoned lots, and (4) highest similarity was found between the anuran community from highly developed peri-urban areas and abandoned lots. Although this study was carried out in a single city, and we only recorded four species, our results suggest that the urban semi-permeability process occurs for anuran communities, plus the fact that abandoned lots seem to offer better breeding habitat for anurans than a polluted waterway.     

The peri-urban fringe: Europe's forgotten rural areas

The EC White Paper — The Future of Rural Society — identifies three “standard problems” of rural areas, but the first, which characterises areas associated with “the pressures of modern development”, receives little attention in the remainder of the document. This paper explains why it is particularly important that the peri-urban areas are not ignored in the development of rural policy. In the first place, the problems of these areas are inextricably linked to those of areas of rural decline and if such links are ignored the resulting partial analysis of rural problems may cause some important policy-options to be overlooked. Second, there continue to be pockets of disadvantage within the peri-urban areas where deprivation is likely to be increased by close proximity to an affluent majority. Finally, the paper analyses the Rural Community Strategy for Berkshire, a nonstatutory document prepared by a group drawn from governmental, quasi-governmental and non-governmental organisations in one peri-urban area of southern England. This shows that while the broad agenda of rural policy issues (covering employment, housing and services), may be very similar to that found in areas of rural decline the rationale for intervention is somewhat different, and transport issues may lie at the heart of the “standard problem” of these areas.     

WAGES,RENTS, AND HETEROGENEOUS MOVING COSTS

The model of compensating differentials in regional labor and land markets was formalized by Roback (1982) . The model interprets regional differences in constant quality wages and rents as compensating firms and residents for inter‐regional differences in amenities. This paper extends the Roback model to allow for moving costs which vary among a city's residents and businesses. This modification of the model generates new interpretations of regional differences in rents and wages. The theoretical results suggest that the interpretation of inter‐city rent and wage differentials as compensating is misguided, that such differentials are inappropriate as weights in Quality of Life (QOL) comparisons, and stresses the importance of local housing market parameters in the determination of these differentials. The importance of amenities is retained, but housing supply becomes the main other determinant of regional rents. Housing supply was ignored in the literature following on Roback's initial insight. We show that interactions between amenities and housing supply will bias QOL rankings. Finally, we support the empirical importance of heterogeneous moving costs by demonstrating the effects of exogenous supply constraints on local housing prices. (JEL R31)     

Nest selection by red-headed woodpeckers across three spatial scales in an urban environment

Forest habitat is important for a variety of woodpecker species, and is under pressure from urbanization. Red-headed Woodpeckers (Melanerpes erythrocephalus; RHWO) were once abundant across Eastern North America, and their populations have been declining since the 1960s. Their distribution encompasses urban centers, and since urban habitats differ from natural forest areas, our goal was to understand RHWO nest-site selection in an urban context. We addressed two main questions 1) what are the characteristics of RHWO nest selection across multiple spatial scales and 2) how do RHWO nest tree characteristics in city parks compare to those in forest preserves? This work was done in Cook County, IL, which includes Chicago, the third-largest city in the USA by population. We examined 34 RHWO nest trees used between 2010 and 2013, their surrounding habitat, and the landscape within a 1 km radius. Used trees and habitats were compared to paired unused trees and habitats, and landscape-scale characteristics were compared to random locations. Advanced decay of the nest tree, low canopy cover and increased presence of fungus on trees in the surrounding habitat were the best predictors of RHWO nesting in the area. Nests were most commonly found in forested areas outside of dense urban areas. However, we did not detect significant differences in the characteristics of the nest trees located in forest preserves and city parks. Our findings are consistent with nest selection studies in rural and natural areas, suggesting that forest habitats in metropolitan landscapes can support RHWO nesting.     

'Reconnecting' the Unemployed

This paper discusses the potential uses of the Internet and other forms of information and communication technology (ICT) as a tool for delivering information services for unemployed people, comparing the experiences and attitudes of jobseekers in peri-urban and remote rural labour markets. The analysis is based upon research carried out in two areas: the first combining a remote rural town with a much larger, more sparsely populated, rural 'travel-to-work area'; the second, a centrally located peri-urban labour market. Survey research undertaken in the study areas gathered responses from 490 unemployed jobseekers. Emerging issues were then followed up during twelve focus groups. The study found that the use of ICT for job seeking remained a marginal activity for most unemployed people, but was much more important in remote rural communities. In these areas, jobseekers were more likely to use the Internet as a search tool and were particularly dependent on telephone helplines provided by the public employment service (PES). However, the study also found that a 'digital divide' was evident within the unemployed client group. Those with low educational attainment, the long-term unemployed, young people and those perceiving their ICT skills to be 'poor' were less likely to use the Internet. Although respondents in rural areas were more likely to use ICT to look for work, they also pointed to the overriding importance of informal, social networks as a means of sharing job information in remote communities. We conclude that ICT may have a future role in the delivery of services for jobseekers, especially in rural areas. However, policies are required to ensure that information provided through ICT-based services is locally relevant, and disadvantaged groups have access to the facilities and training they require.     

Effects of habitat and landscape quality on amphibian assemblages of urban stormwater ponds

Urbanisation is one of the most severe drivers of current global biodiversity loss and has contributed to severe declines in many amphibian species. The aim of this study was to determine whether artificial stormwater ponds, designed to control water flow, can act as refuges for amphibians in urban areas. Moreover, we analysed the influence of habitat and landscape quality on amphibian species richness of 46 stormwater ponds (STOPON) in comparison to 46 control ponds (CONTROL).Our study revealed that environmental conditions clearly varied between STOPON and CONTROL. The most pronounced differences were that STOPON were larger, shallower, sunnier, more isolated by streets and had a greater cover of built-up area and lower cover of arable land surrounding them. Nevertheless, the amphibian assemblages of STOPON and CONTROL were very similar. All nine amphibian species (including three threatened species) detected in this study were found in both pond types. Moreover, species richness (2.8 ± 0.2 vs. 2.3 ± 0.2) and the frequency of each species did not differ between STOPON and CONTROL. The only exception was Pelophylax spp., which occurred more regularly in STOPON. Both habitat and landscape quality affected amphibian species richness; however, the explanatory power of the habitat models was about twice as high as those of the landscape models.In conclusion, stormwater ponds play an important role for amphibians in urban areas. In comparison to CONTROL, the low landscape quality in the surroundings of STOPON seemed to be compensated by a higher habitat quality due to regular management.     

城市多元生鲜市场空间格局的演变及其相互关联——以昆明主城区为例

生鲜市场关系到民生、城乡经济联系和就业等问题,孤立地研究某一类型的生鲜市场具有片面性,不利于理解整个城市的生鲜市场功能和全局管理。通过对昆明市主城区各种生鲜市场实地调查和问卷,运用ArcGIS空间叠加分析、核密度分析和统计分析等多种方法描述了该城市多元生鲜市场的空间格局的形成和演变,归纳不同生鲜市场的特征及其多元生鲜市场共存格局的原因,并对未来演变趋势进行分析,提出此消彼长的互动关联性对各主体所隐含的机遇和挑战,由此说明从地域视角开展的研究,能综合把握全局特征,以及各类型之间的彼此关联性,可弥补以往单一类型研究的不足,并对政府的相关决策进行讨论。     

Drivers of plant biodiversity and ecosystem service production in home gardens across the Beijing Municipality of China

Home gardens have been recognized as repositories of agricultural biodiversity across the world. The influence of socioeconomics and location-specific factors on urban gardening patterns merits continued study. Using Beijing Municipal Province in China, a rapidly urbanizing region, as a case study, we address two questions: 1) How do biodiversity patterns change between different urbanized regions in Beijing? 2) How do ecosystem services provided by Beijing home gardens change with socioeconomic status and location-based preferences of gardeners? We surveyed 104 home gardens in Beijing Municipal Province for plant biodiversity, abundance, and species ecosystem services (ES) (provisioning or cultural uses). The gardens were distributed across three urbanized regions (suburban, peri-urban, and exurban). We found that species biodiversity and abundance shift according to a hierarchy of need from ornamentals (cultural ES) to edibles (provisioning ES) with increasing distance from Beijing. These trends are related to reduced income, lowered food security, and lack of urban markets in exurban regions. Rarefaction curves indicate ornamental species drive β diversity. Ordination also showed a shift in species composition with increasing isolation from the city; Suburban and exurban gardens were the most different, while peri-urban gardens were similar to both others. Only exurban gardens had a positive relationship between species and area. High edible cover and high species density indicates that demand for edibles in exurban regions may be higher than space constraints allows. Our study better quantifies species biodiversity patterns in Beijing, and can inform urban planners about the value and usefulness of home garden space.     

关于建立城市供水安全保障机制的思考

通过对淮安市供水行业现状及存在问题的分析,认为解决该市供水安全保障问题的根本出路在于建立一个以"政府推动、企业主动、市场拉动"为核心的行业发展机制。并就机制构架的建立、措施的落实等提出建议。     

Maritime disputes and seafood regimes: a broader perspective on fishing and the Philippines–China relationship

ABSTRACT

In much discussion surrounding the relationship between maritime disputes and fisheries resources, emphasis is given to the role of fisheries resources as a driver of the dispute or how states use fishing to further their interests through territoriality. Yet a narrow focus on maritime disputes obscures the broader ways in which fishing contributes to interstate relationships. This paper uses a political ecology and food regimes approach to demonstrate how seafood flows between the Philippines and China represent power relations. China exports a significant volume of low-value small fish and molluscs from its distant water fishery. The Philippines exports low numbers of high-value reef fish. Current Chinese aquaculture investments are minimal. Poaching forms another component of this seafood regime, which is marked by environmental unsustainability and unequal relations between the Philippines and China. This analysis highlights the value of seeing fishing and fishery resources as constitutive of a broader politicized environment.     

THE EXTENT OF THE MARKET AND INTEGRATION THROUGH FACTOR MARKETS: EVIDENCE FROM WHOLESALE ELECTRICITY

We document the influence of factor markets in determining the extent of the market, appealing to the Mundell hypothesis that trade in goods and factor markets are substitutes. We confirm this influence using the U.S. wholesale market for electric power. Although the Eastern, Western, and Texas regions cannot trade electricity, inputs such as natural gas move freely across these regions. Through a set of price transmission ratios, and a supply model for natural gas, we find regional electricity shocks do propagate across regions. We conclude output markets institutionally in autarky achieve modest degrees of economic integration through factor markets. (JEL C32, L94, Q41)     

Subcommunity Change in a Changing Metropolis*

Residential areas in cities and suburbs change as they age. The conventional concepts that represent this process are succession and the neighborhood life cycle. In this study we use cohort analysis and multiple regression on small-area data from four censuses to examine population growth patterns among subcommunities in metropolitan Chicago,1940–70. The major findings: among city and suburban areas, cohort is a strong predictor of growth and loss. All suburbs grew early in the period studied, but older suburbs stabilized in the 1960s. Among city areas and suburbs, familism is a strong predictor of growth. Many areas in the city began to lose population in the 1950s, with accelerated loss in the following decade. City areas undergoing racial change in the 1950s lost population rapidly in the following decade. We conclude that the succession model, which is embedded in Burgess' city growth model, no longer accounts for change at the subcommunity level. Thus, the research confirms the life-cycle model but also points to the need for a new macro model of a nongrowing metropolis.     

The historical development of the Mexico City milk supply system: local and global contradictions

In order to help inform interventions in food supply systems, urban areas, and sustainable development, this paper traces the development of the milk supply system to Mexico City. The co-evolution of urban supply and demand factors with policy objectives is dealt with in three distinct periods. (1) The early 20th century in which milk production became an end in itself of cattle raising, with the introduction of new forage crops and the concept of the ‘dairy basin'. (2) The period of the paternalist state is characterised by policy objectives to support Mexican dairy producers and ensure milk supply to the burgeoning urban population. To these ends, there was increasing government intervention in cattle breeding and production systems, distribution and processing of milk, and the importation of powdered milk from international stocks. (3) The neoliberal period included a retreat of the state from quality control enforcement, the inclusion of imported milk the industrialisation process of products for national sale, and concentration of dairy enterprises into fewer hands. While ealier policy objectives have indeed been achieved, three contradictions pose a threat to the systems sustainability: the disarticulation of national supply and demand by means of the financial attractiveness of imported milk stocks; the now minimal contribution of the urban area to its own milk consumption, and the poor quality of industrialised milk products reaching the consumer. It is expected that the system will persist essentially unchanged in the near future, as the various actors involved each act in their own self-interest. Constructive interventions should focus on the contradictions created by the pursual of previous policy approaches, and necessarily address issues of sustainability at various scales.     

Ecosystem services assessment of the urban forests of Addis Ababa,Ethiopia

Addis Ababa is a highland city with varied topography and landscape features. The mountains that surround the city are covered with urban forest of different types. These forests are providing various ecosystem services for the urban and peri-urban population of the city. Apart from surface temperature regulating function of the green spaces of Addis Ababa, no quantitative assessment of the carbon sequestration and soil protection ecosystem services provided by the urban forest has been conducted to date. The aim of this study was to assess selected ecosystem services such as carbon storage potential, habitat support and soil erosion protection provided by different categories of urban forest of Addis Ababa. The result showed that carbon density in the study area varied with forest categories viz. 293tons/ha, 142tons/ha and 132tons/ha in the dense, medium and open forest types respectively. The Shannon-Wiener diversity index is3.24 for Junipers dominated forest, 2.98 for mixed forest and 2.76 for Eucalyptus dominated forest. The formation of soil erosion features is significantly different among the Eucalyptus forest, Juniperus forest and Mixed forest where high incidence of soil erosion was recorded in the Eucalyptus forest. Therefore, irrespective of the environmental factors such as slope, aspect and elevation differences, there is an association between Eucalyptus forest cover and high soil erosion features. To ensure sustainable supply of ecosystem services and maintain a balanced urban environment, all green spaces in the city should be ecologically networked and diversified. Therefore, assessment of ecosystem services provided essential information for effective planning of the green space in terms of species composition and interconnectivity.     

Dining with the Devil: Identity Formations in Juarez,Mexico

This article analyzes popular narratives surrounding the theme of drug lords in the Mexican border city of Juarez and their multifaceted social, ideological, and material effects. This analysis takes into consideration the historical context of eruptions of violence that Juarez has endured in the last few years. Complex formations of the Mexican identity are now being reformulated in hierarchical, gendered, and racialized identities, which project the very strong and powerful social frictions currently emerging from complex socioeconomic factors resulting in mass poverty and migration. These elements are evinced in the narco-narratives within their violent contexts. However, violence in Juarez must not be interpreted as upsurges outside the control of the state, but rather as byproducts of conflict within it (see Das and Poole 2004). Thus, on the border, Juarez becomes a central site, not a periphery, in which economic and political forces materialize in the middle of complex social dynamics.