An Urban Species

A few years ago, for the first time in our history as a species, Homo sapiens became a predominantly urban species, as people worldwide shook off the dust of rural life and moved to town. We crossed the halfway mark sometime in 2007 or 2008, according to a United Nations estimate, en route from being about 30 percent urban in 1950 to 60 percent urban by 2030. The trend is even more advanced in the United States. About 80 percent of Americans now live in urban areas, which also sprawl across a rapidly expanding share of the American landscape. In less than a lifetime, from 1990 to 2050, the U.S. Forest Service estimates that urban land area will more than triple, from 2.5 percent to 8.1 percent of the lower 48 states. In Connecticut and three other Northeastern states, the land will be more than 60 percent urban by mid-century, up from about 35 percent now.

So what does it mean to become a city-dwelling species? And how should it change the way we think about the forest in the city?

Until recently, even scientists did not pay much attention to this epochal shift in the way people live. “When I was an undergraduate, if you wanted to do urban ecology and examine the design of cities and the relationship between people and the environment, it was a path to obscurity,” says Morgan Grove, an urban forester with the U.S. Forest Service. “It was considered trivial and unimportant. That’s not what ecologists did.” Places with lots of people were the antithesis of nature, an attitude dating back at least to Thomas Jefferson, who once described great cities as “pestilential to the morals, the health and the liberties of man.” Outside the scientific world, planting street trees in cities tended to be little more than an Arbor Day photo opportunity for local politicians and an afterthought in urban budgets.

But that attitude has changed dramatically over the past few years. City planners and politicians have begun to see trees and “green infrastructure” as a practical alternative to costly technological fixes—for traffic calming, controlling air and water pollution, reducing energy demand and urban heat-island effects, preventing floods and adapting to climate change. Likewise, psychologists and social scientists have begun to pay attention to new evidence that trees can make people feel better about where they live, reducing stress, lowering crime rates, improving educational outcomes and helping to minimize asthma hospitalizations and heat-wave deaths. Even ecologists, who once could not see the urban forest for the buildings, have come around. Their recent research suggests that cities are more important to biodiversity than previously thought—and with a little planning could become much more so even as urban areas expand.  (To be continued.)

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