Urban ecology, the environmental sciences youngest and most rambunctious cousin, is in a position to influence the design of the cities of the future. Its clout comes from its willingness to think big, to think about the ecology of entire cities as if they were just any other ecosystem. Urban ecologists call this big picture view the “ecology of the city”.
From this disciplinary perspective, Chicago is just another savannah, one where admittedly the commonest species is the human animal.
However, by taking this bird’s eye view of cities, is urban ecology losing sight of the bird-on-the-ground? I mean this quite literally. Is urban ecology losing it roots in natural history? Will the successful cultivation of relationships with decision makers, municipal authorities, city planners and other governmental powers-that-be, come at the expense of urban ecologists’ knowledge about birds, wildlife, beetles and the other creeping things inhabiting the city?
Are we (and I count myself in this troupe) urban ecologists, forgetting the world-fascination, the intense delight, that comes from direct encounters with nature in the city?
Urban ecology is not the first discipline to encounter the tensions accompanying distinctions between the bird’s-eye view and the bird-on-the-ground view of the city. An instructive example found in the work of Michel deCerteau (1925-1986) who makes of this tension a theory of the everyday interactions of people who both conform to and resist the strictures of the culture to which they belong.
In their entry on deCerteau the Routledge Encyclopedia of Philosophy describes him as “a French philosopher trained in history and ethnography, [who] was a peripatetic teacher in Europe, South America and North America.” To describe him as peripatetic is apropos in two senses as the adjective describes a follower of Aristotle, and also signifies one who moves about quite a bit. Etymologically it comes from the Greek patein which is to tread. Followers of Aristotle are referred to as Peripatetics, though the term refers not to a supposed habit of wandering in the Lyceum after the lecturing Aristotle, but to the practice of teaching in a colonnade (a peripatos). Whatever about the Aristotelian influences on his work, deCerteau, a Jesuit priest, was certainly a wanderer both intellectually and physically having taught in many places and written on history, mysticism, everyday life, spiritual life, literary history and so on.
An influential chapter in deCerteau’s book The Practice of Everyday Life is aptly entitled Walking in the City. In it deCerteau illustrated his broader thesis concerning the differences between tactics and strategies. Strategies are concerned with “force-relationships” that can be exercised when an entity can be separated from an environment. A city, a proprietor, a scientific institution serve as deCerteau’s examples here. Each can be held up and inspected as separate analyzable units, each has its own distinct place – its headquarters, or at the very least it occupies lines on a map. Tactics, on the other hand, are not so easily localized. Tactics are usually deployed on the sly, “poached” to use deCerteau’s term, on someone else’s territory.
A simple way of understanding what deCerteau’s is arguing is to contrast those individuals, institutions, or governments who have grand conceptions of the city, with the pedestrians, jaywalkers, flâneurs, who make their own plans, and take up the business of living in the city in ways that are simultaneously constrainted and resisting of these grand designs. He dramatizes the distinction by opening the chapter’s narrative from his perch on the 110th floor of the World Trade Center. From there one get’s a bird’s eye view, indeed a planner’s view, of the entire city. Peering down at the insect-like pedestrians swarming beneath him, he sees in their movement a type of pedestrian-grammar.
The city may be produced by those with visions of the city, but it is consumed in a creative, one might say productive way, by those who walk in the city.
All this rarified talk becomes concrete when one thinks about the everyday practices of pedestrians treading the city streets. The act of walking becomes strange, even given a slight revolutionary tinge, when one recalls how the manners of pedestrians can cut across the designs of city managers, proprietors, planners, and other strategic officers.
Here’s an example: the university quad outside the building where I work in Chicago is provided with a number of helpful pathways to assist us as we traverse the campus. But these best laid plans are subverted by pedestrians who are always finding newer more expedient routes across the quad. The grounds people in turn often concede by paving yet another route and the cycle begins again.
Another example: in downtown Evanston, Illinois, where I live, no matter how much the city fusses over the design of Fountain Square, it seems to appeal to no one. Sometimes a builder builds, and yet they do not come.
Urban ecology which only emerged as a distinct subdiscipline in ecology in the 1970s has made a lot of its own use of the in and of distinction. The distinction is regarded as a significant conceptual leap forward. It places uni-disciplinary, small scale ecological studies on one side, and multidisciplinary, multiscalar studies, especially those that examine the human and non-human aspects of nature simultaneously, on the other.
An influential review by a disciplinary leader, Steward T. A. Pickett from the Cary Institute of Ecosystem Studies in Millbrook New York, and his colleagues, written more than a decade ago identifies types of research belonging to both flavors of urban ecology .
A study of the physical environment, the soil, or the biota of a city or a neighborhood would be considered ecology “in” the city. These studies can be aggregated to allow for generalities to emerge. Cities tend, for instance, to have their own distinctive climatic situations. Rain is more frequently in cities than in the hinterlands. City temperatures tend to increase as population grows up to a certain limit at least. These climatic differences have, in turn, implications for vegetation growing in the city. Spring comes earlier in urban areas. Decomposition of dead organic matter occurs a little faster. Tree cover changes as cities develop (decreasing in forested areas, increasing in desert areas). Urban vegetation is weedier, with more non-natives, but diversity can be high since plant diversity oftentimes follows the money. The richer the human population the lusher is the vegetation. City mammals tend to be moderately sized carnivores. All the above insights emerge from within the “ecology in the city” paradigm.
“Ecology of the city” takes an explicitly systems view of things. By system here is meant a set of entities that interact to make a connected whole. In what manner do the elements of the city the human and non-human aspects of nature interact to contribute to an emergent whole city? Among the examples that Pickett and his colleagues give are studies of the amount of pollutants or carbon taken up (sequestered being the $100 term preferred by ecologists) by all the trees in Chicago. Studies of the flow of crucial nutrients like nitrogen (a key element for the growth of vegetation, but also a contributor to the fouling of water bodies) have been done on the scale of entire cities. For instance, fascinating whole system evaluations of nutrient flow are conducted as part of the Baltimore Ecosystem Study, where Pickett is a project leader. The resource accounting tool of “ecological footprinting”, developed by William Rees and Mathis Wackernagel at the University of British Columbia in Vancouver, Canada, provides another example. Footprinting is not only a way to make us feel miserable about our personal environmental impact; it can used to have an entire metropolitan area hang its head in shame. A simple back of the envelope calculation reveals that the footprint of Chicago is larger than the state in which it is located!
In another influential early review Nancy Grimm, a professor at Arizona State University and a project leader at the Central Arizona – Phoenix Long Term Ecological Research project and her colleagues also utilize the in and of distinction and they identify similar systems-oriented hallmarks of the latter type of study. In particular, they call for integration of social science approaches with more traditional approaches to ecology, and they illustrate what this looks like with a series of increasingly sophisticated conceptual models revealing the interaction of physical, ecological, and social variables. They conclude that without insight into the integration of the human and the ecological perspectives at local and global scales urban ecology will be less effective in guiding public policy and management.
So which of these two flavors of urban ecology is best? The in or the of?
Although none, I think, would make the claim too strenuously that there is a preferred approach, leading urban ecologists, nonetheless, seem to have a preference for the ecology of the city studies. In the view of most of those championing this distinction at the very least more studies of the of type are required since ecological studies in the city have been more common. For instance, in his brief historical overview of urban ecology McDonnell emphasizes the need for more ecology of cities studies in order to advance the discipline and enhance our understanding of the urban environment. In a similar vein, Grimm and colleagues state that “the study of the city as a ecosystem would be a radical expansion of ecology. And who is not on the side of radical expansions?
For the most part I agree with this emerging disciplinary consensus. We need those multidisciplinary, multiscalar, aggregative, holistic, inter-urban studies to really understand the sorts of ambiguous, hybrid, cyborgian affairs that have relatively recently created and in which now we dwell. Cities after all have been around for about 2% of our history as a species and yet more than 50% of people live in them. We have become an urban species and wanting to know the ecological patterns and processes associated with these novel entities is understandable.
Ecology in the cities allows us to appreciate what goes on in the cracks in the pavement, so to speak, but we need larger scale work to appreciate them as systems of interactions between human institutions and the rest of nature.
All of this being said, I have a suspicion that a full-throttled committment to the discipline's (maginally) favored approach – ecology of cities – will result in losses of certain types of knowledge: the knowledge that manifests when a human body meanders through an ecosystem that it is enraptured by. An old-fashioned encounter with beings, coming in touch with what we might call brute reality, must count for something.
In order to be an effective ecologist of the city one needs, increasingly, to master the use of a range of techniques that are relatively novel to ecology. Ecologists, it must be said, have always been savvy users of computer technologies. Modeling approaches, which typically employ high end computing capabilities, have a respectable and productive place in the history of ecology. And ecosystems studies with their focus on processes – production, decomposition, nutrient dynamics – have as a matter of disciplinary focus deliberately blurred distinctions between individual species, and species are the very core of more traditional natural history. So in as much as urban ecology of cities takes a system’s approach it is emphasizes computational, modeling, and processes oriented methodologies.
These days there is more of high-tech widget than old-fashioned nature walk in urban ecology.
In recent weeks I have been re-reading the work of Robert Lloyd Praeger (1865–1953). Praeger was an Irish naturalist, author, and librarian who published over 800 papers and was author of twenty-four books. Though he is best described as a naturalist, his work, like Darwin's, that more famous naturalist and ur-ecologist, is profoundly ecological. In The Way that I Went Praeger describes his basic scientific methodology: he walked!
The Way that I Went, which is 75 years old this year, starts with the sentence, “The way that I went was an Irish way, with extraorbital aberrations, especially in later year, to the extent of a thousand or fifteen hundred miles.” Michael Viney, a wonderful contemporary Irish nature writer, recounts how Praeger fell into a large pot hole in the limestone hills of Fermanagh only to emerge clutching a Green Spleenwort, a plant he wanted for his famous rock garden in his Rathgar backyard (a couple of mile away from the home in which I grew up in Dublin).
Praeger reported that he had “traversed Ireland to and fro from end to end, and from sea to sea. Mostly on foot, for that is to only way to see and get to know intimately any country.” Praeger was a man that knew his plants, and knew them because he wandered through the terrain in which they were found.
An ecologist must walk in the same way that a poet must ruminate; these are the basic techniques of their respective vocations. I recognize that in saying this I risk sounding, or perhaps even being, nostalgic. Moreover, I may seem to be reviving old-fashioned complaints about a loss of appreciation for whole organisms, or even excavating ancient concerns about theory and application distinctions in the sciences. However, I express my concern not (or at least not simply) as a looking back, but in an effort to look at the future of urban ecology. If urban ecology is to have a productive conversation with decision makers it will need to bring with it more than hefty numerical models and complex conceptual frameworks. It will have to drag its muddy boots along the carpets of city hall. It should bring with it a joy in being out in nature, and a deep appreciation for the beings encountered as the ecologist traipses to through the city.
Though there will always be those who know their plants, insects, fungi and so forth those who identify as naturalists are getting fewer and fewer. For the most part it not a component of the training of ecologists, and when it is, it is rarely a substantial component of their work for the long term. By the time she hits 40 the typical ecologist is sitting in her office begging for money. But this may be the fate of all of us, scientist and non-scientist alike, and is probably part of another complaint.
I wish to reassert the primacy of walking as procedure in urban ecology. I do so because walking provides the bird-on-the-ground view, a encounter with reality, that complements the birds-eye perspective that harmonizes well our discipline's ambitions. Urban ecology has the task of Hermes – it must mediate between the pavement and the plan.
Finally, I also advocate walking as a protocol because it is provides a suite of other micro-nutrients that are required for the fitness of the mind. It is hard to imagine what ecology would be without Thoreau’s monumental walks. In Walking (1862) he said “I think that I cannot preserve my health and spirit, unless I spend four hours a day at least, – and it is commonly more than that, sauntering through the woods and over the hills and fields, absolutely free from all worldly engagement.” Though we should be more Thoreauvian in our practice, we need to change direction and instead of heading out of town as Thoreau did, we need to venture into the wildness at the center of city.
 Conley, T(1998). Certeau, Michel de. In E. Craig (Ed.), Routledge Encyclopedia of Philosophy. London: Routledge. Retrieved March 26, 2012, from http://www.rep.routledge.com/article/DE008
 Pickett, S.T.A., M.L. Cadenasso, J.M. Grove, C.H. Nilon, R.V. Pouyat, W.C.Zipperer, and R. Costanza. 2001. Urban Ecological Systems: Linkingterrestrial ecological, physical, and socioeconomic components ofmetropolitan areas. Annu. Rev. Ecol. Syst. 32:127-157.
 Grimm, N.B. J.M. Grove, C.L. Redman, and S.T.A. Pickett. 2000. Integrated approaches to long-term studies of urban ecological systems. BioScience 50:571-584
 McDonnell, M (2011) The history of Urban Ecology – An ecologist’s Perspective. in Urban Ecology patterns processes and applications.
 The Way that I Went (1997) by Robert Lloyd Praeger, Michael Viney (Introduction). Collins Press