Urban ecology is the study of community structure and organization as manifest in cities and other relatively dense human settlements. Among its major topics, urban ecology is concerned with the patterns of urban community sorting and change by socioeconomic status, life cycle, and ethnicity, and with patterns of relations across systems of cities. Of particular concern is the dynamic evolution of cities and contrast in urban structure across time periods, societies, and urban scale. The notion of community is central to urban ecology; a premise of the ecological approach is that the aggregation of persons into communities has important implications for their life chances, for the behavior of groups, and for aggregate outcomes. A further aspect of community organization lies in its geographic manifestation, although a mere geographic reductionism would not accurately capture the theoretical or empirical approach of the ecological perspective.
A sub area of human ecology – a social science paradigm that seeks to understand the relationship between human organization and its environment, both in terms of physical set ting and sustenance – the study of urban ecology has been interdisciplinary. Work in ecology has touched on sociology, demography, geography, economics, and anthropology, usually emphasizing the urban sectors of those disciplines. And at various times, human urban ecology has been more or less connected to biological ecology.
As Franklin Wilson argued, ecology is one of the oldest specializations within sociology and the intellectual roots of urban ecology can be found in the origins of sociology itself. For example, Emile Durkheim’s The Division of Labor in Society (1893) argued that modern societies are comprised of functionally interdependent units that are necessary for their survival and progress. As an explicit sociological approach, urban ecology is particularly associated with the Chicago School of sociology in the early twentieth century, even though the connection extends to a wide range of scholars and groups interested in cities and in population processes. The massive growth of cities at this time, fueled by the immigration of diverse origin populations, helped spur the interest in urban form and function, and hence urban ecology as a subject of interest.
These early thinkers attempted to establish a parallel for human behavior with the topic of ecology in biology to describe local biotic com munities. Collections of organisms are seen as communities, and the membership and evolution of communities are seen in a framework of interdependence. Sociological approaches almost universally invoke notions of ecology that are at once aggregate, interdependent, and embedded in a spatial and environmental con text. Thus, communities of plants and animals find their parallel in communities of human groups. Both approaches see competition for resources in a spatially delimited setting. A further aspect of the framework is the concept of sustenance, in which one considers the manner in which local organisms, here humans, are sustained by the environment and by organization.
Studies at this time of specific urban communities, such as Louis Wirth’s The Ghetto (1928) and Harvey Zorbaugh’s The Gold Coast and the Slum (1929), and of city form and sub communities more generally, such as Robert Park, Ernest Burgess and Roderick McKenzie’s The City (1925), offer key illustrations of early treatments by the Chicago School, also known as the classical position. Additional concern in this era was with land rents and gradients, which not only helped explain the distribution of social groups, but also connected to the evolving interest in urban economics.
These early notions of human ecology gave way to more statistically intensive and geo graphically driven analyses of human organization in urban physical space. Considerable analysis was devoted in the middle to late twentieth century to the dimensions of urban social structure. These included extensive analyses of patterns of residential segregation, urban growth, and differentiation. The application of factor analysis, or ‘‘factorial ecology’’ in the nomenclature, identified life cycle, socioeconomic status, and ethnicity as key dimensions of urban ecological sorting.
The ecological approach then came under criticism from various quarters, the most notable early critic being Milla Alihan. The biological metaphor was seen as strained, limiting the crucial elements of human volition and cognition. Urban ecology was also at risk of appearing spatially deterministic and attention to the relative spatial position and mapping of social phenomena lent credence to the critique. Furthermore, ecological approaches were criticized methodologically, even generating a phrase, ‘‘the ecological fallacy,’’ that has traversed into general social science parlance. The fallacy is the error of making inferences about individual behavior from analysis of phenomena at the aggregate level.
In the middle of the twentieth century, human (and hence urban) ecology received additional formulations, with perhaps the broadest theoretical treatment arising in Amos Hawley’s Human Ecology (1950). This treatise emphasized the study of the community and the dynamic connections among individuals, human organization, and the environment. Around the same time the widely adopted POET frame work came to the fore: Population, Organization, Environment, Technology. This POET paradigm is also part of the neoclassical or neo orthodox approach and it provides an intellectual rubric for organizing the thinking about urban phenomena and community processes within them.
Much work carried out from the mid twentieth century for the next several decades was ecological in approach, if not always explicit in name. While one stream of research concentrated on the internal structure of cities, another focused on systems of cities and the relationships among them. Analyses of residential segregation by ethnic and socioeconomic group, the relationship between urban economic base and population growth, and some international comparisons of internal urban structure all took place at this time. Similarly, analysis of metropolitan functional specialization, trade, and the comparative growth of urban settlements were undertaken from an ecological vantage point.
These efforts were again followed by critiques from a variety of points, including Marxist and political economy perspectives. Both explicit and implicit criticisms suggested that the ecological approach missed several crucial elements in the study of urban development, structure, and change: the role of the state, local governments, and capital interests. At the same time, the combination of methodological concerns and the availability of microdata made the classic ecological style of aggregate analysis less attractive.
With the reemergence of concerns for urban issues generally and neighborhood issues specifically, various aspects of urban ecology achieved visibility or were reinvented in the late twentieth century. New data forms and methodological developments helped spur this turn. The wider concern for social exclusion, especially as it had a community or spatial manifestation, incorporated the ecological approach. The framework also continues to be relevant and widely used in the study of ethnic groups. In fact, the increasing ethnic diversification of high income societies provides increasing impetus for the ecological approach, as Park’s adage that spatial distance reflects social distance is put to the test in new settings. Interest in residential integration and sorting still involves the analysis of community patterns of ethnic concentration. Moving beyond classical ecology as applied to ethnic and racial groups, contemporary treatments examine dynamic changes in residential environments, such as in residential attainment, where a minority or disadvantaged group achieves residential parity with members of the advantaged majority. Such work is an extension of classical concerns for the process of residential succession.
An additional research theme is the restructuring of urban areas in light of significant transportation, communication, and industrial transformations. Scholars have noted the trend for the spatial decentralization of urban growth (e.g., suburbanization and urban sprawl, land use patterns, and corporate activity). Where limitations in transportation and communications necessitated spatial proximity in the past, current technology, to some extent, liberates producers, suppliers, workers, and consumers from this constraint. Regional factors, including policy variation and climate, may also play a role in shifting urban development. In this context, new urban forms and systems of inter urban hierarchy emerge.
A more methodological avenue of ecological investigation accompanies the exploitation of multi level or contextual data, in which individual data (microdata) is merged with characteristics of neighborhoods or a wider geographic area. Individual (person, household) behavior then, is taken to be predicted not only by individual traits, but also by characteristics of the local community. Indeed, the rapid development of the ‘‘neighborhood effects’’ literature, both substantively and methodologically, can be seen as a major intellectual current within sociology (Sampson et al. 2002), and this current taps directly into the central themes of urban ecology. Similarly, the broad interest in the problem of the macro micro link overlaps significantly with ecologists’ interest in community, in multiple levels of aggregation, and in dynamic interchange. Such studies have examined the determinants of escaping distressed neighbor hoods, the choice of new neighborhood as a function of its ethnic composition, community effects on child development and crime, and the role of neighborhood traits in determining health outcomes.
The multi level ecological approach is involved at a larger geographic scale, as well. The existence of social inequalities in health motivates a vein of research in which metropolitan income inequality is seen as playing a role in health outcomes such as infant and child mortality. Such studies have been carried out in some detail for the US. International comparisons also exist, where the ‘‘ecological’’ or aggregate measure is the level of inequality measured at the country level.
The predisposition of urban ecological analysis to spatial phenomena has made urban ecology readily receptive to the use of geographic information systems (GIS). More than merely mapping, GIS technology applied to urban ecology allows the analyst to redefine communities and networks, and to link micro to macro. Whereas social scientists were once bound by the community aggregation defined by others (such as a census agency’s tract or ward boundaries), the availability of point coordinates assigned to each person or housing unit, and to natural features and economic activities, would allow a more variegated and refined analysis of the relationship between human organization, sustenance activity, community, and territory. Tests for spatial autocorrelation, which examine the effect of proximity, further add to our toolkit for understanding urban structure and organization.
Such technological developments have stimulated a reconnection with biological ecology. Urban ecological analysis provides a framework for examining integrated human natural systems. Indeed, in several institutional and academic settings, the use of the phrases ‘‘urban ecology’’ and ‘‘human ecology’’ explicitly link human behavior to the biological environment. Here again human activity is seen as dynamic and community based, both influencing and influenced by its surrounding environment.
While urban ecology may be identified most clearly with American urban sociology and the Chicago School particularly, its adherents and manifestations are much broader. For example, it has been linked to the work of the French historian Fernand Braudel, who studied social system changes in the Mediterranean. It has been applied in analyses of urbanization in socialist countries as well as in the developing world. The paradigm was used to describe the somewhat inverted settlement patterns in Latin American cities. It has further found occasional expression in describing North African and European cities, where ethnic diversity had not yet achieved so clear a place in urban form. Still, the level of knowledge about urban ecology for settings outside of high income societies is less developed. It is far from certain that the models once applied to North America and Europe (and selected other locations) will apply so readily to other portions of world geography, especially to urban settings in developing countries. Yet themes of internal urban structure, geographical disparities in well being, and community change are relevant to all of these settings.
- Berry, B. J. L. & Kasarda, J. D. (1977) Contemporary Urban Ecology. Macmillan, New York.
- Duncan, O. D. (1959) Human Ecology and Population Studies. In: Hauser, P. M. & Duncan, O. D. (Eds.), The Study of Population: An Inventory and Appraisal. University of Chicago Press, Chicago.
- Frisbie, W. P. & Kasarda, J. D. (1988) Spatial Processes. In: Smelser, N. J. (Ed.), Handbook of Sociology. Sage, Newbury Park, CA, pp. 629-67.
- Hawley, A. (1950) Human Ecology: A Theory of Community Structure. Ronald Press, New York.
- Micklin, M. & Poston, D. L. (Eds.) (1998) Continuities in the Study of Human Ecology. Plenum Press, New York.
- Sampson, R. J.,Morenoff, J. D.,& Gannon-Rowley, T. (2002) Assessing ‘‘Neighborhood Effects’’: Social Processes and New Directions in Research. Annual Review of Sociology 28: 443-78.
- Saunders, P. (2001) Urban Ecology. In: Paddison, R. (Ed.), Handbook of Urban Studies. Sage, London, pp. 36-51.
- Wilson, F. D. (1984) Urban Ecology: Urbanization and Systems of Cities. Annual Review of Sociology 10: 283-307.
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