Many years ago when I was an anthropology major in college ideas of urban ecology held great interest for me. I return to them now as a biologist, a sustainability consultant, and a lifelong city dweller. Urban ecology seems richer and more complex to me than it ever did. Where once I saw the urban landscape as a primarily social landscape, I see it now as a larger complex of realities both human and non-human that shape the world profoundly.
We can think about urban form as the streets, buildings, and open spaces of the city. But we can't separate these physical presences from the life of the city. Transportation, work, commerce, and play all go on in these "hardscape" spaces and play a mutual role in affecting, and being affected by them. So the urban landscape comprises both structures and the humans and their activities within.
But this framework still seems too simple. So much more is going on. The urban landscape is an open system that interacts with its environment. Light and heat energy, water, and movement all flow through the system. Tons of "stuff" are brought into the urban environment every day and they either stay or leave, sometimes in the same form and sometimes radically altered. Raw and finished materials, carbon dioxide, wastes of every conceivable sort move in and out of the city in a kind of steady-state flow that reminds me of cellular systems in living organisms. Art and ideas are also exported from the urban environment, less tangible but not immaterial.
In my blog "Botany Without Borders" I wrote about non-human life forms in the city. Everything from bacteria to algae, grasses, trees, and animals of every sort have a place in the incredibly complex urban web, all of them in close contact, sometimes intimate contact, with their human contemporaries. Urbanization has, in many ways, exerted a negative, simplifying effect on the larger ecosystem through paving, channeling, building, mining, and dumping. The changes are physical and chemical in nature, and have challenged once diverse lands and waterways. But inside the special ecosystem that is the urban space lies a unique, deep, well of diversity, unexpected perhaps, largely unseen, but powerful in that it influences the urban landscape in many ways we still may not understand.
As we continue to learn more about urban ecosystems the mutual influences inherent in these systems will come to make more sense. As my friend and colleague Margarita Iglesia states, sustainable things tend to stick around. Systems that are unsustainable disappear. So for example in fifty years we'll see with some clarity what the place of the personal automobile was in the urban setting. Our understanding of water use, energy consumption, and land use patterns will also come into better focus. How will issues of density, green space, and recycling be understood? And how will we reconcile urban form, especially in the broader geographical perspective, with global climate change?