Ecological resilience in urban ecosystems: Linking urban patterns to human and ecological functions

Urban ecosystems evolve over time and space as the outcome of dynamic interactions between socio-economic and biophysical processes operating over multiple scales. The ecological resilience of urban ecosystems—the degree to which they tolerate alteration before reorganizing around a new set of structures and processes—is influenced by these interactions. In cities and urbanizing areas fragmentation of natural habitats, simplification and homogenization of species composition, disruption of hydrological systems, and alteration of energy flow and nutrient cycling reduce cross-scale resilience, leaving systems increasingly vulnerable to shifts in system control and structure. Because varied urban development patterns affect the amount and interspersion of built and natural land cover, as well as the human demands on ecosystems differently, we argue that alternative urban patterns (i.e., urban form, land use distribution, and connectivity) generate varied effects on ecosystem dynamics and their ecological resilience. We build on urban economics, landscape ecology, population dynamics, and complex system science to propose a conceptual model and a set of hypotheses that explicitly link urban pattern to human and ecosystem functions in urban ecosystems. Drawing on preliminary results from an empirical study of the relationships between urban pattern and bird and aquatic macroinvertebrate diversity in the Puget Sound region, we propose that resilience in urban ecosystems is a function of the patterns of human activities and natural habitats that control and are controlled by both socio-economic and biophysical processes operating at various scales. We discuss the implications of this conceptual model for urban planning and design.     

Structuring institutional analysis for urban ecosystems: A key to sustainable urban forest management

A decline in urban forest structure and function in the United States jeopardizes the current focus on developing sustainable cities. A number of social dilemmas—for example, free-rider problems—restrict the sustainable production of ecosystem services and the stock of urban trees from which they flow. However, institutions, or the rules, norms, and strategies that affect human decision-making, resolve many such social dilemmas, and thus, institutional analysis is imperative for understanding urban forest management outcomes. Unfortunately, we find that the definition of institutions varies greatly across and within disciplines, and conceptual frameworks in urban forest management and urban ecosystems research often embed institutions as minor variables. Given the significance of institutional analysis to understanding sustainable rural resource management, this paper attempts to bring clarity to defining, conceptually framing, and operationally analyzing institutions in urban settings with a specific focus on sustainable urban forest management. We conclude that urban ecologists and urban forest management researchers could benefit from applying a working definition of institutions that uniquely defines rules, norms, and strategies, by recognizing the nested nature of operational, collective choice, and constitutional institutions, and by applying the Institutional Analysis and Development framework for analysis of urban social-ecological systems (SESs). Such work promises to spur the desired policy-based research agenda of urban forestry and urban ecology and provide cross-disciplinary fertilization of institutional analysis between rural SESs and urban ecosystems.     

Positioning urban rivers within urban ecology

Rivers are important components of many urban systems, and research into urban rivers is increasing internationally, both in scope and intensity. As an introduction to a special section on urban rivers, this short article briefly highlights some key trends in urban river research based on a survey of published articles from Web of Knowledge, before summarising the contributions made by the special section papers. In particular, there has been a general increase in work on urban rivers since the 1990s, with a more dramatic increase from 2001. Most published research has concentrated on water quality and its wider environmental implications; ecologically, many studies have focused on autecology, community ecology or river restoration/rehabilitation, with the main emphasis on macroinvertebrates or fish. Geographically, most studies have taken place in North America (mainly the US) and Asia (mainly China). In the large majority of cases research has been on relatively small rivers within urbanised catchments rather than large, heavily urbanised systems within major towns or cities. Given the wide range of topics and studies relating to urban river research, a detailed meta-analysis of the urban river ecology literature would be a useful endeavour. The six papers included in the special section of this issue provide a sample of some of key and emerging themes within recent urban river research, and originate from a session on the understanding and management of urban rivers held at the Royal Geographical Society (with IBG) Annual Meeting in 2010, at Imperial College London.     

The urban design of a Balinese town: placemaking issues in the Balinese urban setting

This research considers the role of indigenous institutions and conceptions of space in the urban design process for producing culturally appropriate designs for Balinese towns. Employing a pluralistic approach (The Image of the City, MIT Press, Cambridge, MA, 1960; Planning a Pluralist City: Conflicting Realities in Ciudad Guyana, MIT Press, Cambridge, MA, 1976; House Form and Culture, Prentice-Hall, Englewood Cliffs, NJ, 1969, Human Aspects of the Built Form, Pergamon Press, Oxford, 1977), a case study of the town of Gianyar, Bali, Indonesia explores the popular accounts on the operative indigenous conceptions of space in contemporary Balinese urban settings. This exploration aims at providing a ground for reconnecting urban design proposals with their cultural context, thus promoting the spatially expressed localism originating from the diversity of cultures which is currently undermined by the highly standardized process of the Indonesian planning system. In particular, for the town of Gianyar, such an exploration provides a set of placemaking issues which is useful in devising urban design guidelines for achieving a town with more pronounced cultural identity.The research concludes that to achieve culturally appropriate places, the design process has to acknowledge the Balinese Hindu psycho-cosmic concept as the core principle in the design of Balinese townscapes. As such, the existing indigenous cosmic territory, which accommodates the relationship between human (microcosm) and environment (macrocosm), along with its adat law and institution, has to be incorporated in contemporary urban design processes. As a result, urban spatial organization, structure and form will significantly reflect the Balinese cultural identity.     

Restructuring for growth in urban China: Transitional institutions,urban development,and spatial transformation

This research examines government policies and urban transformation in China through a study of Hangzhou City, which is undergoing dramatic growth and restructuring. As the southern center of the Yangtze River Delta, an emerging global city region of China, Hangzhou has been restlessly searching for strategies to promote economic growth and survive the competition with Shanghai. This paper analyzes Hangzhou’s development strategies, including globalization, tourism, industrial development, and urban development, in the context of shifting macro conditions and local responses. We hold that urban policies in China are situated in the broad economic restructuring and the gradual, experiential national reform and are therefore transitional. The paper suggests that China’s urban policies are state institution-directed, growth-oriented, and land-based, imposing unprecedented challenges to sustainability and livability. Land development and spatial restructuring are central to urban policies in China. Last, while Hangzhou’s development strategies and policies to some extent reflect policy convergence across cities in China, local/spatial contexts, including local settings, territorial rescaling and land conditions, are underlying the functioning of development/entrepreneurial states.     

Soil organic carbon stock in different urban land uses: high stock evidence in urban parks

Urban Ecosystems - Urban areas are major producers of atmospheric CO2 emissions, but at the same time they can offset some of the associated C losses by retaining stable organic carbon in their...     

Silphids in urban forests: Diversity and function

Many ecologists have examined the process of how urbanization reduces biological diversity but rarely have its ecological consequences been assessed. We studied forest-dwelling burying beetles (Coleoptera: Silphidae)—a guild of insects that requires carrion to complete their life cycles—along an urban-rural gradient of land use in Maryland. Our objective was to determine how forest fragmentation associated with urbanization affects (1) beetle community diversity and structure and (2) the ecological function provided by these insects, that is, decomposition of vertebrate carcasses. Forest fragmentation strongly reduced burying beetle diversity and abundance, and did so far more pervasively than urbanization of the surrounding landscape. The likelihood that beetles interred experimental baits was a direct, positive function of burying beetle diversity. We conclude that loss of burying beetle diversity resulting from forest fragmentation could have important ecological consequences in urban forests.     

Schulman's urban lesbian: a hobosexual pedestrian rhetoric

The following article reads the protagonist in Sarah Schulman's Girls, Visions and Everything as not only lesbian, but as hobosexual-a concept representative of anti-capitalist practices in both sex and labor. The hobosexual is developed as an extension of the lesbian flaneur, as a concept that requires reading Schulman's urban lesbian at the intersection of class and sexuality. Lila Futuransky's sexual identity is suspended and complicated through an emphasis on her desire for queer mobility; her urban movements connect her to hobo history, but also expose the effects of capitalism that thwart her urban movement.     

Bending the urban flow: a construction-migration strategy

The excess rate of migration to urban centers is a problem affecting over 50 developing countries and 18 developed ones (68% of the world's population). Policies that rely on compulsion or disincentives have mostly failed because they do not deal with the cause of the problem. This paper proposes a strategy of increasing or decreasing the rate of housing construction in different urban areas as a means of stimulating or reducing migration to those areas; in most developing areas priority is given to residential construction in already congested metropolitan areas. 5 assumptions are the basis for this approach: 1) migrants tend to gravitate to the most powerful growth poles; 2) residential construction is a leading sector of regional and urban economies; 3) the encouragement of construction activity will make itself felt indirectly via its effect on construction-related employment; 4) rates of residential construction may be manipulated through government policy affecting the cost of materials, availability of loans, level of unionization, and price of housing; and 5) residential construction is amenable to quick policy action. The central idea of the strategy is that an increase in residential construction will exercise a pull on migrants, increasing job opportunities, raising incomes, lowering housing costs, and improving the chances of home ownership. This idea has been verified by various projects in Hong Kong, Ghana, Venezuela, Brazil, Bahrain, Mexico, Colombia, Poland, USSR, and the UK. In Bahrain low-income housing programs have been used to relocate Bahraini nationals in new outlying suburbs and to promote population growth in rural villages. In Mexico self-help and low-income housing programs have helped to redirect migrants headed for small towns toward smaller communities. There is also evidence to show that building construction has the potential to expand and contribute to economic growth. Some problems of implementation might be finding an adequate economic base, the need to place new communities close to primate cities, the use of large portions of the national budget, and profit-maximizing plans have been detrimental to the speed and development of construction migration. Some benefits for smaller urban areas of construction migrants in developing countries are: 1) emphasis on the development of a labor-intensive industry, 2) little training of workers as needed, 3) it can provide the housing required by industries planning to move to smaller areas, 4) this housing will be cheaper, and 5) incentives will exist to save and invest in the smaller areas.     

Toward increasing avian diversity: urban wildscapes programs

Residential development in urban and suburban settings is a major cause of habitat change affecting avian communities. The effects from land-clearing prior to initiation of construction followed by landscaping focused on traditional aesthetics has reduced habitat diversity at multiple levels. These residential developments generally emphasize the use of ornamental, nonindigenous vegetation with little to no concern for native species and natural vegetation parameters. As a result, avian community composition and diversity is changed. We compared avian communities at three sites in Bexar County, Texas; two residential neighborhoods in the city of San Antonio and an unincorporated undeveloped site, Government Canyon State Natural Area. The residential neighborhoods were a Texas Parks and Wildlife Department certified wildscapes development and a traditionally developed neighborhood. Bird abundance and species richness in the neighborhoods were greater than at Government Canyon State Natural Area (P < 0.01), but no differences existed between the neighborhoods. Bird diversity was greatest at the wildscapes neighborhood (P < 0.01). Further, bird diversity did not differ between the traditional neighborhood and the natural area. Evenness differed among sites (P = 0.006) with the natural area having the greatest value. Bird diversity measures correlated with woody plant density and vertical cover (r = 0.358 to 0.673, P < 0.05) at residential sites. Residential areas incorporating natural landscapes into their design attracted a greater variety of birds than traditionally landscaped residential areas.     

Japanese urban sociology: Development and current trends

This article focuses on current trends in Japanese urban sociology as they developed historically. They can be understood in the distinctive context of Japanese sociology, as the products of an interaction between Western sociological theories and their adaptation to Japan’s own materials. The article begins with the historical context of urban development and provides an overview of the development of urban studies in Japan, including issues in the theory of urbanization, the distinctive character of the neighborhood association, Cbonaikai, and the formation of new local communities in suburban areas. The current trends since the 1980s involve the macro approach to urban restructuring, studies on urban ethnicity, and social network analysis. Overall, it is suggested that the influence of American sociology makes Japanese urban analysis comparative. I thank Claude S. Fischer and Tazuko Hanzawa for their help with editing this paper. Remain-ing deficiencies are mine.     

Wellbeing and urban living: nurtured by nature

Urban Ecosystems - In recent decades, empirical evidence has demonstrated that nature can enable urban environments to support human wellbeing. Research into links between nature and human...     

Linking bird species traits to vegetation characteristics in a future urban development zone: implications for urban planning

Identifying the relationships between species traits and patch-scale vegetation characteristics in areas designated for urban development can improve our understanding of how animal communities may change with urbanization. We explored the implications of this premise to the urban planning process in a mixed-use landscape in Canberra (Australia), prior to its development into new suburbs. We used RLQ analysis to relate bird foraging, nesting and body size traits to patch-scale vegetation characteristics. Relationships between species traits and vegetation characteristics within the development zone suggest that species that forage and nest on the ground and in the understory strata, and smaller-bodied species will be most negatively affected by urbanization. Identifying the relationships between species traits and vegetation characteristics may be used by urban planners to (i) identify potentially critical habitat and species at risk from development, (ii) inform the choice of impact mitigation measures, and/or (iii) distinguish between high and low mitigation measures. Analyses conducted early in the planning process can then be used to allocate proposed land uses in an ecologically sensitive way, and to plan appropriate mitigation measures.     

用城市设计理念塑造优美城市空间

一、前言 作为中国近代工业的发祥地.唐山拥有雄伟瑰丽的三山两河、丰富的物产资源、厚重的历史积淀以及辉煌的建设成就.是我国新兴的现代工业城市之一.