Urban Ecology Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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Urban ecology is the study of the urban ecosystem as an ecological unit that is part of the larger global ecosystem; it is also known as the ecology of cities and towns. Urban ecology examines the relationships between the urban and natural systems and interactions among the biotic components-including humans. It also involves the study of the urban ecosystem’s impact on other ecosystems, seeking to understand relationships with the rural system, particularly transfers of matter and energy and the complementary functions the surrounding space provides. The relationship with the global system derives from the contribution of the city to global environmental change and the use of renewable and nonrenewable natural resources.

As an interdisciplinary field of study, there is a debate among fields regarding an identifiable specific approach. Ecology understands urban ecology as a subfield of the discipline that studies the ecological relations in the unique human-modified environment, adopting a traditional approach and applying conventional theories, or with the perspective of integrating the human system and humans as another species. From this point of view, we can examine the budget of matter and energy flowing through the urban ecosystem and observe a unit that almost wholly depends on external sources of system inputs-food, fuel, water, and building materials-a heterotrophic ecosystem that does have parallel on earth. The outputs-solid waste, wastewater, combustion gases, and heat-are the results of industrial respiration, which is a metabolic process of what resembles a large living organism. The system inputs have varied distant origins while the outputs have varied destinations, thus the city depends on areas much larger than its own surface. This is the ecological footprint, the equivalent area of land required to support the provision of inputs and process the outputs. It measures the dependence of the city on other ecosystems and its sustainability; the more area required the more unsustainable the city.

Sociology and anthropology understand urban ecology as a division of human ecology, the study of how humans relate to their environment. The concept has a sociological origin in the Chicago School of Sociology of the 1920s. Robert E. Park and Ernest W. Burguess conceived the human ecology approach to explain the urban development and spatial segregation within the city of Chicago as the result of the intervention of social and economic forces. Cities were regarded in their theory as environments governed by competition and accommodation forces, inspired by ecology and the ecological factors intervening in a natural ecosystem. From this point of view, groups compete for a scarce resource-the land-and this struggle leads to the division of the urban space into areas with homogeneous social and economic characteristics and to the appropriation of the most valuable areas by the higher rent groups. Naturalist Edward O. Wilson developed the notion of biophilia to define the nongenetic emotional affiliation of human beings to nature and other life forms for having lived within a biological world. This helps to understand the preference for living close to nature, moving to the suburbs, valuing natural landscapes, and ultimately, supporting conservation of ecosystems and species and desiring to manage them efficiently. Biophilia can be promoted by education and experience with wildlife or discouraged by living within a completely industrial environment.

Political studies approach urban ecology by highlighting the role of institutions and identifying economic and social processes as forces implicated in environmental changes at various spatial scales, focusing on man as an agent of change. The field develops into political ecology. Urban ecology becomes a policy to increase the sustainability of the urban system by minimizing the impact on natural systems, promoting restoration plans of degraded habitats and conservation of those areas with a natural habitat. Urban ecology is seen as the conceptual basis of the process of sustainable urban development, a policy to build green cities or ecocities. The goal is to achieve healthier and more liveable cities, maintaining biodiversity and more efficiently managing space and resources, so that the community has not only architectural, social, and economic assets but also environmental ones.

The Urban Ecosystem

The urban ecosystem is the result of human alteration of the natural system and is an environment intensely modified by social and economic development. The components of the urban habitat-climate, soils, hydrology, and biodiversity-are different from the surrounding nonurban areas. However, differences in the urban ecosystem are observed in line with the model of urbanization. Sprawl-the spatially-extended urban expansion over rural land-produces a city model based on high rates of energy consumption and associated disadvantages: Increased travel times and transport costs, pollution, traffic congestion, and broad transformation of the countryside.

The model has a major advantage over the dense city model: The conservation of large undeveloped land areas interspersed with the urban fabric, which locally retain former environmental attributes. These spaces are extremely varied. Green spaces such as natural parks, urban river corridors, formal gardens, recreational areas, sports parks, and street trees are important environmental assets for urban communities as they provide both recreational opportunities and ecosystem services, supporting local species and maintaining air quality. Some are remnants of past landscapes while others have been planted.

The course of urbanization produces a fragmentation of natural habitats, that is, wetland, grassland, woodland, and agricultural land turning into interstitial open spaces of semi-natural vegetation or farm land surrounded by urban, industrial, commercial, or residential land uses. Other areas with significant green space but dedicated to other uses are airports, cemeteries, golf courses, scientific and technological parks, and university campuses. Water courses, water bodies, lakes, and reservoirs are aquatic ecosystems that may or may not be attached to vegetated areas. Other areas offer a much lower environmental quality with low to medium concentrations of waste or pollution and highly variable physical, chemical, and biological soil characteristics: Derelict land, vacant lots, and brownfieldsformer industrial or commercial lands. Still other areas are highly degraded by dumps or densely crossed by infrastructures, yet they attract and keep some wildlife species.

The Cityscape

The mixture of built forms with the residual rural landscape yields a differentiated landscape known as a cityscape. The variety originates from combining land use categories, densities of population, and types of vegetated areas: Paved industrial, residential, commercial, grassy residential, dispersed residential, forested residential, agricultural, green areas, and vacant sites. The extensive network of roads, railroads, distribution pipelines, power lines, and dikes act as barriers that create habitat fragmentation by obstructing normal animal movement, increasing mortality, and isolating habitats and populations, threatening species with extinction. Essentially, this struggle for survival takes place in suburban areas, for city centers have already gone through this phenomenon.

There are a number of alterations and pressures acting upon species and humans in the built environment. The urban climate-the result of the modifications produced by the built structures and the combustion of fossil fuels-is defined by the heat island effect, which is an increase in temperature of up to nine degrees F (five degrees C), an increase in precipitation between five and 10 percent, a reduced total solar radiation, a higher precipitation runoff, a lower precipitation infiltration rate caused by the broad extent of pavement and other impervious surfaces, and a varied regime of wind speeds according to street orientation with respect to predominant wind directions.

Air, Water, and Light Pollution

Air pollution is caused by emissions derived from the burning of fossil fuels and industrial processes used by heavy industry, urban traffic, and household heating systems. Concentrations of complex atmospheric pollutants, gases, and suspended particulate matter create a toxic atmosphere. The deposition of those airborne pollutants, by either wet or dry processes, produces an acidification and nitrification of soils and water bodies. The application of fertilizers to home lawns and urban gardens at similar rates to agriculture adds large quantities of nitrogen and phosphorous to the water bodies. The leading causes of reduced water quality are nonpoint source stormwater, or polluted runoff; sewer overflows; and nontreated wastewater point discharges flowing into water courses. They increase the loadings of nitrogen and phosphorous nutrients, raise temperatures, reduce visibility, and decrease dissolved oxygen levels, producing a decline in wildlife, hypoxia, and, eventually, harmful algal blooms. Artificial night lighting, a form of pollution produced by the illumination of buildings, commercial signage, and streetlights, reaches miles around cities, and has the biological effect of disturbing nocturnal species. Light pollution goes in all directions and interferes with feeding, predation, reproduction, and other activities of populations.

Urban Wildlife

Disturbance is responded to with the settlement of tolerant and adapted species that represent earlier stages of ecological succession in the urban environment. The high frequency of disturbance often causes retrogression, thus these species are tolerant to stress. Species richness-the number, evenness, and relative abundance of species-sharply declines in the urban environment from the human disruption and habitat destruction, while total populations increase, creating a decline in ecological diversity. Specialist species are replaced by fewer synanthropic generalist species, some of them invasive, and benefiting from the more favorable climate, food abundance, and habitat. It has been observed how some wild avian, mammalian, or amphibian species adjust to the new urban environment by occupying emerging and growing ecological niches, a response termed synurbanization. These species are adapted to reduced territories, nonmigratory patterns, frequent changes in habitat and diet, and daily contact with people, for they possess an ecological, demographic, and behavioral plasticity differentiated from the rural populations. This response is progressively increasing diversity in urban wildlife.

Management

A range of measures and approaches have been conceived to implement an urban ecology policy. Habitat management includes landscape and watershed restoration of native forests, riparian woodland, and urban intertidal wetlands. Methods applied are revegetation with native species, stabilization of banks and slopes by reducing runoff, cleanup, and remediation. These measures bring back the functions of earlier habitats in densely settled regions, including water filtration and improvement of water quality by removing pollutants, flood control, and providing green space for recreation. Other measures are linking fragmented urban habitats isolated from each other with a corridor network to strengthen their ecological value, expanding forested areas, facilitating safe wildlife crossing and free movement, and preventing road kill by means of underpasses and overpasses. The creation of new habitat with bioengineering techniques to mitigate the destruction of another has not been demonstrated to be completely successful since it can fail to compensate for the loss because some properties have vanished due to the rarity or complexity of the initial ecosystem.

Urban management measures include regulation of development intensity and patterns using improved land use control and zoning, sewage and stormwater runoff treatment, landfill restoration, and land remediation by removal of contaminants in soil, groundwater, and sediments as well as implementation of transportation policies such as slower speed limits, efficient public transportation, car sharing, park and ride programs, and encouragement of change in fuel consumption.

Economic inequity and segregation across urban neighborhoods has environmental and social implications. Land values are higher next to designed or preserved green spaces, while affordable housing is limited to areas close to infrastructures, industrial areas, commercial areas, and impoverished areas with poorer recreational assets. The socioeconomic status of a family is a limiting factor to accessing housing in middle-class neighborhoods. The exposure to poor ecological conditions in urban middle and low income neighborhoods may decrease the ability to assess the significance of biodiversity, and, thus, decrease support for diversity.

Bibliography:

Marina Alberti, John M. Marzluff, Eric Shulenberger, Gordon Bradley, Clare Ryan, and Craig Zumbrunnen, “Integrating Humans into Ecology: Opportunities and Challenges for Studying Urban Ecosystems,” BioScience (v.53/12, 2003);
Jürgen Breuste, Hildegard Feldmann, and Ogarit Uhlmann, eds., Urban Ecology (Springer-Verlag, 1998); Oliver L. Gilbert, The Ecology of Urban Habitats (Chapman and Hall, 1989);
Gordon McGranahan and David Satterthwaite, “The Environmental Dimensions of Sustainable Development for Cities,” Geography (v.87/3, 2002);
Rutherford H. Platt, Rowan A. Rowntree, and Pamela Muick, eds., The Ecological City: Preserving and Restoring Urban Biodiversity (University of Massachusetts Press, 1994);
Herbert Sukopp, Makoto Numata, and A. Huber, , Urban Ecology as the Basis of Urban Planning (SPB Academic Publishing, 1995).