Can you see the difference in the two satellite photos above? Piedmont, California, (left) is definitely greener than West Oakland, California (right). According to Tim DeChant, a blogger at Per Square Mile, these urban trees reveal income inequalities between neighborhoods. In a variety of examples comparing two neighborhoods—one relatively poor, the other relatively wealthy—DeChant hopes to show that income differences are visible from space.
DeChant draws his theory on research published a few years ago, which argues that there is a tight relationship between per capita income and urban forest cover. The study found that “for every 1 percent increase in per capita income, demand for forest cover increased by 1.76 percent. But when income dropped by the same amount, demand decreased by 1.26 percent.” It also found that as population grew, the urban forest area also increased, but at a slower pace than population growth.
The reason behind the leafy manifestations of this income gap: Wealthier cities can afford to maintain more trees both on public and private lands. Moreover, rich people usually reside on larger plots of land that can support more and bigger trees. While tree cover is also dependent upon the geographic location of the city, and the ecology of the area, and the age of neighborhood, income-based differences in tree cover are political in nature as well. As DeChant says, “Compounding the inequality is the fact that most tree planting programs are local. Urban forestry has sailed largely under the federal government’s radar.” While the U.S. Forest Service has a community forestry program, it is highly underfunded.
Urban trees provide many benefits, including shading streets and houses which lowers ambient air temperature in summer and reduces cooling costs, creating habitats for birds and animals, and scrub the air of pollution and particulates, which can potentially reduce the rates of asthma. In some cases, trees have also been found to reduce crime rates. Many cities around the country are boosting efforts to increase urban trees. New York City aims to double the number of trees to 1 million, and Chicago has planted over 600,000 trees over the last twenty years. London aims to plant 20,000 new trees before the Summer 2012 Olympics.
While this is a good effort, it doesn’t address the relationship between wealth and trees, nor does it help poor cities increase their urban forests. To DeChant, this is exactly the point: trees are not a luxury to be purchased by the wealthiest, but rather an important benefit in urban life.
Photo credits: Google Maps, DigitalGlobe, GeoEye, U.S. Geological Survey, USDA Farm Service Agency