Showing papers on "Urban ecosystem published in 2001"

Urban ecological systems: linking terrestrial ecological, physical, and socioeconomic components of metropolitan areas

Abstract: Ecological studies of terrestrial urban systems have been approached along several kinds of contrasts: ecology in as opposed to ecology of cities; biogeochemical compared to organismal perspectives, land use planning versus biological, and disciplinary versus interdisciplinary. In order to point out how urban ecological studies are poised for significant integration, we review key aspects of these disparate literatures. We emphasize an open definition of urban systems that accounts for the exchanges of material and influence between cities and surrounding landscapes. Research on ecology in urban systems highlights the nature of the physical environment, including urban climate, hydrology, and soils. Biotic research has studied flora, fauna, and vegetation, including trophic effects of wildlife and pets. Unexpected interactions among soil chemistry, leaf litter quality, and exotic invertebrates exemplify the novel kinds of interactions that can occur in urban systems. Vegetation and faunal responses suggest that the configuration of spatial heterogeneity is especially important in urban systems. This insight parallels the concern in the literature on the ecological dimensions of land use planning. The contrasting approach of ecology of cities has used a strategy of biogeochemical budgets, ecological footprints, and summaries of citywide species richness. Contemporary ecosystem approaches have begun to integrate organismal, nutrient, and energetic approaches, and to show the need for understanding the social dimensions of urban ecology. Social structure and the social allocation of natural and institutional resources are subjects that are well understood within social sciences, and that can be readily accommodated in ecosystem models of metropolitan areas. Likewise, the sophisticated understanding of spatial dimensions of social differentiation has parallels with concepts and data on patch dynamics in ecology and sets the stage for comprehensive understanding of urban ecosystems. The linkages are captured in the human ecosystem framework.

Energy and Climate in the Urban Built Environment

Abstract: Part 1 * On the Built Environment the Urban Influences * Climate and Climate Change * Wind Patterns in Urban Environments * Wind Patterns in Urban Environments * Thermal Balance in the Urban Environment * Heat-island Effect * The Canyon Effect * The Energy Impact of the Urban Environment * Short-wave Radiation * Urban Pollution * The Role of Green Spaces * Appropriate Materials for the Urban Environment * Applied Lighting Technology for Urban Buildings * Active Solar Heating Systems for Urban Areas * Indoor Air Quality and Ventilation in the Urban Environment * Urban Settlements * Part 2 * Guidelines for Integrating Energy Conservation Techniques in Urban Buildings * Examples of Urban Buildings * Appendix * Index

Restoration of Fragmented Landscapes for the Conservation of Birds: A General Framework and Specific Recommendations for Urbanizing Landscapes

Abstract: Humans fragment landscapes to the detriment of wildlife. We review why fragmentation is detrimental to wildlife (especially birds), review the effects of urbanization on birds inhabiting nearby native habitats, suggest how restoration ecologists can minimize these effects, and discuss future research needs. We emphasize the importance of individual fitness to determining community composition. This means that reproduction, survivorship, and dispersal (not simply community composition) must be maintained, restored, and monitored. We suggest that the severity of the effects of fragmentation are determined by (1) the natural disturbance regime, (2) the similarity of the anthropogenic matrix to the natural matrix, and (3) the persistence of the anthropogenic change. As a result, urbanization is likely to produce greater effects of fragmentation than either agriculture or timber harvest. Restoration ecologists, land managers, and urban planners can help maintain native birds in fragmented landscapes by a combination of short- and long-term actions designed to restore ecological function (not just shape and structure) to fragments, including: (1) maintaining native vegetation, deadwood, and other nesting structures in the fragment, (2) managing the landscape surrounding the fragment (matrix), not just the fragment, (3) making the matrix more like the native habitat fragments, (4) increasing the foliage height diversity within fragments, (5) designing buffers that reduce penetration of undesirable agents from the matrix, (6) recognizing that human activity is not compatible with interior conditions, (7) actively managing mammal populations in fragments, (8) discouraging open lawn on public and private property, (9) providing statutory recognition of the value of complexes of small wetlands, (10) integrating urban parks into the native habitat system, (11) anticipating urbanization and seeking creative ways to increase native habitat and manage it collectively, (12) reducing the growing effects of urbanization on once remote natural areas, (13) realizing that fragments may be best suited to conserve only a few species, (14) developing monitoring programs that measure fitness, and (15) developing a new educational paradigm.

A habitat island approach to conserving birds in urban landscapes: case studies from southern and northern Europe

Abstract: Wildlife conservation in urban habitats is increasingly important due to current urbanization trends. We review the different approaches to studying birds in urban landscapes, and point out the impor- tance of the habitat island ecological theory as a research framework for the management and conservation of urban birds. Based on two comprehensive research projects conducted at urban parks in Spain (Ma- drid) and Finland (Oulu and Rovaniemi), several different issues related to bird conservation in cities are discussed, main findings of these projects are presented, and future research needs are suggested. Urban parks are important biodiversity hotspots in cities. Fragmentation conditions have the same deleterious effects to urban birds as in other fragmented landscapes. Park size accounts for species accumulation in urban parks; this pattern being highly nested. Urban parks of 10-35 ha would contain most of the species recorded in cities, but other indicators related to the probabilities of persistence of the target species should be obtained. Wooded streets can increase urban landscape connectivity by providing alternative habitat for feeding and nesting during the breeding season. Because increasing the size of parks is difficult in cities, enhancement of habitat diversity and resource availability for birds within parks (e.g. nest boxes, winter feeding tables, etc.) appears to be a straightforward way of increasing urban bird diversity. However, human disturbance (pedestrians) should be controlled since it can negatively influence many urban birds. We present a conceptual model for urban bird conservation, which includes three aspects (management, environmental education and research) and new alternatives to promote the involvement of different sectors of the society.

Urban Sprawl: Lessons from Urban Economics

Abstract: strong sentiment against the phenomenon known as “urban sprawl” has emerged in the United States over the past few years. Critics of sprawl argue that urban expansion encroaches excessively on agricultural land, leading to a loss of amenity benefits from open space as well as the depletion of scarce farmland resources. The critics also argue that the long commutes generated by urban expansion create excessive traffic congestion and air pollution. In addition, growth at the urban fringe is thought to depress the incentive for redevelopment of land closer to city centers, leading to decay of downtown areas. Finally, some commentators claim that, by spreading people out, lowdensity suburban development reduces social interaction, weakening the bonds that underpin a healthy society.1 To make their case, sprawl critics point to a sharp imbalance between urban spatial expansion and underlying population growth in U.S. cities. For example, the critics note that the spatial size of the Chicago metropolitan area grew by 46 percent between 1970 and 1990, while the area’s population grew by only 4 percent. In the Cleveland metropolitan area, spatial growth of 33 percent occurred over this period even though population declined by 8 percent.2 Similar comparisons are possible for other cities.

The Urban Funnel Model and the Spatially Heterogeneous Ecological Footprint

Abstract: Urban ecological systems are characterized by complex interactions between the natural environment and humans at multiple scales; for an individual urban ecosystem, the strongest interactions may occur at the local or regional spatial scale. At the regional scale, external ecosystems produce resources that are acquired and transported by humans to urban areas, where they are processed and consumed. The assimilation of diffuse human wastes and pollutants also occurs at the regional scale, with much of this process occurring external to the urban system. We developed the urban funnel model to conceptualize the integration of humans into their ecological context. The model captures this pattern and process of resource appropriation and waste generation by urban ecosystems at various spatial scales. This model is applied to individual cities using a modification of traditional ecological footprint (EF) analysis that is spatially explicit; the incorporation of spatial heterogeneity in calculating the EF greatly improves its accuracy. The method for EF analysis can be further modified to ensure that a certain proportion of potential ecosystem services are left for in situ processes. Combining EF models of human appropriation with ecosystem process models would help us to learn more about the effects of ecosystem service appropriation. By comparing the results for food and water, we were able to identify some of the potentially limiting ecological factors for cities. A comparison of the EFs for the 20 largest US cities showed the importance of urban location and interurban competition for ecosystem services. This study underscores the need to take multiple scales and spatial heterogeneity into consideration to expand our current understanding of human–ecosystem interactions. The urban funnel model and the spatially heterogeneous EF provide an effective means of achieving this goal.

Urban Design, Urban Space Morphology, Urban Tourism: An Emerging New Paradigm Concerning Their Relationship

Abstract: The paper concerns the relationships between the physical form of the urban environment and leisure activities. It examines how urban space morphology - i.e. spatial patterns and formal patterns - may have an impact on tourists' attraction and preferences in the contemporary cultural context of urban tourism. Can urban design and the physical form of space in themselves determine anything in urban tourism development?

Value to wildlife of urban-agricultural parks: a case study from Rome urban area.

Abstract: Urban-agricultural parks could have some advantages to wildlife because of less intensive agricultural procedures, absence of hunting pressure, and reduced human disturbance. In this study, the breeding and wintering bird communities and the small mammal community in an urban-agricultural park of Rome were compared to those of a close urban park and a close agricultural area just outside the city. The aim was to assess the best destination and management of wildlife in natural areas at the urban-rural interface. Richness and diversity of bird communities were higher in the urban-agricultural park. Due to habitat features and probably human disturbances, but not to urbanization, predation, and competition factors, the urban park drastically reduces the abundance of decreasing open-land bird species. Abundance of these species was not significantly different in the urban-agricultural park and in the agricultural area. In the urban-agricultural and urban park, bird and mammal pest species were more abundant than they were in the agricultural area. Regarding decreasing abundance of small mammal species, no significant difference among the study areas was observed. Urban-agricultural park is a better choice than urban park for wildlife. Thus, a higher number of preserved urban natural areas should be devoted to urban-agricultural parks. However, to increase the abundance of open-land species and in general wildlife, a less intensive management of cultivated and pasture patches is necessary.

Gardening to reduce hazard: urban agriculture in Tanzania

Abstract: Urban agriculture is an illegal activity in most African towns and cities, as it is seen to be competing with other, higher value, urban land uses. Despite this, food production occurs throughout the African urban environment and is crucial to the urban economy; providing employment, food security and investment opportunity for a large proportion of the urban population. Urban agriculture also adds value to urban land, bringing unused land into production, reversing degradation and improving the urban landscape. In the context of a rapidly expanding urban population, food production in Dar es Salaam is playing a crucial role in sustaining the city, employing 210000 people. Urban agriculture also has an important role to play in providing a viable land use in the hazard lands of Dar es Salaam, as an alternative to squatter housing which exposes the inhabitants to a substantial risk from flooding. This paper looks at the role that urban agriculture plays in Dar es Salaam and identifies the major actors. Copyright © 2001 John Wiley & Sons, Ltd.

Ecological urban dynamics: the convergence of spatial modelling and sustainability

Abstract: Planning professions have focused their attention on continued technological solutions to environmental problems despite discussions relating to the sustainability of the built human community. However, ecological sustainability involves the identification of ecologically sound alternatives to current practices, not necessarily involving technological intervention. In the urban ecosystem this means the identification of the processes of urban change. New theory, tools, and research methods in ecological systems have the potential to improve the dynamics of change in urban environments. A variety of sophisticated computational and theoretical tools exist for characterizing urban systems at a conceptual level, and for visualizing and understanding these characterizations. The theoretical underpinnings and practical application of the integrated, multi-disciplinary,ecological and engineering approach to modelling urbanland use transformation is presented. A new tool, LEAM (Land use Evolution and Impact Asses...

Urban Ecology: Patterns of Population Growth and Ecological Effects

Abstract: Currently, over 50% of the world's population lives in urban areas. By 2050, this estimate is expected to be 70%. This urban growth, however, is not uniformly distributed around the world. The majority of it will occur in developing nations and create megacities whose populations exceed at least 10 million people. Not all urban areas, however, are growing. Some are actually losing populations because of changing economic conditions and population demographics. Whether a city is growing or losing population, governances face unique challenges with respect to infrastructural, water and transportation needs. To meet these challenges, agencies within city government are cooperating by pooling resources and removing conflicting policies, partnering with the private sector to offset costs of infrastructure, and taking new approaches to design infrastructure. By linking ecological theory with urban design, a more integrative approach to create liveable spaces, which are sustainable, can be achieved in rapidly expanding and shrinking urban areas. Key Concepts: Megacities and shrinking cities are our future. In the nineteenth and twentieth centuries, most of the world's population lived in rural areas. With economic shifts people moved into cities to find employment, better health services, and improved education opportunities. Future cities represent major ecological, social and economic challenges and opportunities. Rapid urban growth creates economic incentives but can fragment, destroy or degrade existing natural ecosystems. Similarly, population losses create economic and ecological opportunities for expansion and growth. Integrating ecological theory in urban design can create a framework for sustainable cities that are adaptive and resilient. Often, infrastructure is designed to meet engineering specifications but do not incorporate ecological functionality. By integrating ecological with the engineering, infrastructure can meet regulations at the same time enhancing the environment. Keywords: urban; megacities; shrinking cities; ecological design; resilience

Integrating avian ecology into emerging paradigms in urban ecology

Abstract: We discuss emerging paradigms in the conceptual and methodological approaches to the study of urban ecosystems. We review methods used in urban studies of avian ecology, both historically and in this book, and discuss how the results of these studies can be incorporated into these paradigms. We explore the mechanistic links between the urban environment and between different levels of biological organization, from physiology to individuals to populations to communities and we suggest future approaches to increase the applicability of urban avian ecology to understanding the functioning of cities as ecosystems. These approaches require and will benefit from interdisciplinary research and education.

Everyday ecologies: Cities, nature, and teaching urban ecology

Abstract: Conventional geographical approaches to the city tend to place the study of urban form and urban space squarely within the political-economic and cultural branches of geography. Geographic pedagogy has tended to assume, therefore, that nature is absent from the city or exists only as a backdrop or stage on which urban economic and cultural activities take place. In contrast, there has been a recent groundswell of interest—originating in places as diverse as environmental activism, environmental history, landscape architecture, and environmental education—in reinterpreting the city as a space intimately connected with nature. This article examines the possibilities for integrating this rethinking of the relationship between city and nature into undergraduate education. Specifically, it outlines the rationale, objectives, and design of a course on urban ecology and examines the benefits and challenges of doing urban ecology as part of geographic education.

Urban Forestry in Europe

Abstract: Forest or woodland ecosystems in urban environments are of increasing,particularly social and environmental importance in Europe’s urbanising society. Traditionally,however, forestry science and practice have focused on rural settings. Only recendy have comparative and international studies been initiated on the role of urban forests or woodlands and other urban greens, their use, management and planning.This article presents the main results of a study carried out by the European Forest Institute between 1995 and 1999 on woodland policies, planning and management in selected major European cities. Because the objectives and conditions affecting the management of woodlands in an urban environment differ from those in rural areas, the approaches and techniques developed for rural areas have to be adapted. Some general characteristics and challenges of urban woodland planning and management in Europe are described. These include the wide range of uses and pressures urban foresters have to deal with. By developing innovative woodland planning and management to balance urban demands and woodland resources in high-pressure environments, urban forestry’s experiences may assist forestry at large in better adapting to a changing and urbanising society.

Environmental and Energy Impact of the Urban Forest in Arid Zone Cities

Abstract: The massive presence of trees in urban environments, particularly in regions with dry mesothermal climates, generates a significant environmental impact on the open spaces of the public domain and consequently on the enclosed spaces of the private domain. The paper presents the development and the initial results of the utilization of an analytical-computational model, specifically designed to assess the availability of solar radiation on horizontal and vertical surfaces of the urban environment shaded by trees as function of several interrelated variables descriptive of urban morphologies typical of the city of Mendoza, in central-western Argentina. The data generated by the model's utilization will be essential for future studies, aimed at assessing the incidence of trees on the solar potential of urban buildings and on the intensity of the urban heat island effect in cities of the region.