Writing in Atlantic Cities, Wolfe compares an encounter with a "feral, walkable urbanist" coyote on a Seattle sidewalk with the tactful greening of a former motorway ramp within Madrid's Rio Project.
"Successful integration of nature and the city is a hallmark of sustainability", he notes, "Sometimes it occurs without effort or provocation, while other times it results from projects or plans. In both instances, the natural and artificial merge, morph and redefine urban reality going forward."
He uses the perspective of two landscape architects to explain different ways that city and nature merge. Under one approach, such as changing coyote habitats, surrounding nature merges with urban culture and physical form, two things that need not be as distinct as we might expect. The second, equally compelling approach recognizes that there is nothing natural in the city, and any insertion of nature into the urban fabric that resonates with the public and creates a sustainable result, is defensible, proper and legitimate.
Wolfe concludes with a nuanced view that combines the two perspectives:
[W]hile there is arguably nothing natural in the constructed city, the proposition has its exceptions, or compromises... From multiple perspectives, the role of nature and the city will continue to realign. In fact, before too long, our cities' versions of Madrid’s green, re-purposed motorway ramp may have some non-human users along the way.