“Ecology” is another one of those words that I’ve hearing more and more, used in ways that you might not immediately associate with the field of ecology. The “ecology of innovation” for example, is a term that describes the actors, interactions, and environmental conditions necessary to foster the propagation of innovative ideas (see for example, this article). Relating to the field of urban planning, I’ve come across three main aspects of urban ecology: the quantitative/modeling studies, the sociological and historical conceptual frameworks, and the urban ecological design principals. These three aspects make up the “ecology” of urban ecology because they influence and interact with each other, are evolving, and exist within a broader context which shapes them all.
Quantitative/Modeling Studies. The (biological) field of ecology offers some very robust models for explaining animal and plant populations, growth, and succession that are very appealing to urban researchers to try to explain urban physical phenomena, such as urban heat island effect, or changes in hydrological patterns and environmental impact, as well as modeling the growth and form of cities. Urban ecology in this vein attempts to extend the traditional field of ecology to include humans and human-influenced geographies (such as cities). A great place to start for this kind of research is the work of: Marina Alberti (University of Washington), Steward Pickett’s article on resilience (Cary Institute), and Nancy Grimm (Arizona State University).
Sociological/Historical Conceptual Frameworks. Students of urban and planning history and theory will be most familiar with this aspect of urban ecology through the Chicago school’s concentric ring model of the city, created by sociologists Ernest Burgess and Robert Park in 1925. The concentric ring model is based on the ecological concept of “zonation”, which differentiated climates and species, as well as explained organism development. The point was to provide a spatial explanation for human community structure that paralleled those in the plant and animal worlds. Similar theories include von Thunen’s agricultural zones, Christaller’s Central Place Theory, and Hoyt’s Sector Theory. Historian Martin Melosi has a great article tracing the history of urban ecology as an useful explanatory framework for both urban growth and environmental context in history and sociology. Jennifer Light’s The Nature of Cities is also a great place for understanding the historical motivation of social scientists to build off of ecological concepts. These models are meant to be used more metaphorically than the above models, which draw more on ecology’s quantitative models. The prevalence of ecology-based words such as “blight” and “resilience” is evidence of the pervasiveness of the analogy of cities to biological organisms and “natural” ecosystems.
Urban Ecological Design Principles. The third main area of urban ecology comes from the design world and the (especially recent) heightened awareness to build human communities and settlements in accordance with the natural environment. It reflects a normative value system of what designers should take into consideration in their work. This was the area of urban ecology that I was originally exposed to, through my work as a civil and environmental engineer in a sustainability-oriented firm. The stormwater management and wastewater treatment designs we produced we intended to increase and in some cases, restore sites’ ecological function. We researched native ecosystems and designed multifunctional stormwater, wastewater, landscape and energy facilities as analogs to those original ecological services. Ian McHarg and his seminal work Design with Nature could be considered the father of urban ecological design. Tim Beatley’s writing on biophila in urban environments is an example of the need to incorporate nature in urban environments. I also recently read Urban Ecological Design by Palazzo and Steiner, which I would also group into this area of urban ecology. In addition to being aware of environmental factors, ecological design is also ecological in the design process, which is usually iterative and involves a web of interrelated stakeholders (as opposed to the conventional, technocratic, expert-driven linear model of design).
The three areas are related, and like possessing their own “ecology” seem to possess their own growth and context. Although the social sciences have largely discounted ecological models for their inability for their overemphasis on the natural-ness of blight and decline and closed, rational systems, analogies have continued for open systems, relating energy and material flows to “urban metabolism” for example. Recent natural disasters stress the idea of “resiliency”, for which ecological design (distributed wastewater facilities and energy infrastructure, for example) is a solution. A fascinating 2007 study also found that the size of cities can be related to social phenomena, like the average speed of walking, via exponential growth equations common in biology. So, it seems, our tendency to think of ourselves and our cities as somehow separate from nature seems to be declining, and the ‘ecology’ of urban ecology continues to resonate.