Though Arbor Day has come and gone, let’s take a look at some new data about where trees are planted, and where they aren’t.

Whether pleasure or irritant, trees turn out to be a telling barometer of income inequality. Our nation’s capital is a case study.

What the tree ratings mean

As the map shows, a clear fault line has emerged in Washington, D.C., following the Potomac River. In the northwest quadrant of the city and into the Virginia and western Maryland suburbs, trees are abundant and the land well-planted. To the east, the tree canopy is much sparser, and there is far more open land.

In the lower-income areas of Washington — which has one of the highest levels of income inequality among the nation’s cities — nearly 40 percent of residents live in places with fewer trees and more empty spaces. Meanwhile, 80 percent of residents in upper-income areas live in well-planted neighborhoods. The density of tree canopy in neighborhoods is also affected by such factors as the education level of residents and the number of renters versus owners. More affluent, educated homeowners are often more likely to advocate for trees to be planted in public parks and along streets near their homes, experts say.

“By and large, in areas where people have more disposable income, you’ll see greener areas and a better understanding of what trees and greenery provide,” said Mark Buscaino, executive director of Casey Trees, a nonprofit that has been working to restore Washington’s tree canopy for more than a decade.

So why not plant more?

Many people are unaware of the benefits of trees — like mitigating air pollution, reducing mental stress, saving energy by shading homes and slowing stormwater.

Urban foresters find that before hoisting their shovels to plant in underserved areas, they must frequently persuade residents that trees are important. They say they often get pushback from people like southwest Washington resident Doris Gudger, 61, who worry about whether the city will help maintain the trees. “To me, the trees create more problems than when they weren’t there,” says Gudger, who suffers from allergies. Other fears are more mundane: The leaves would be a pain to rake. Shade would draw drug dealers. And, as Gudger said, soon would follow affluent gentrifiers and higher taxes, pushing out older residents like herself.

Washington, D.C., has often been praised for its urban forest, boosted by trees on the federally owned Mall. But only 36 percent of the overall canopy remains, a decrease from 50 percent in 1950. The decline is due in large part to development. The city and nonprofit groups have been trying to plant at least 8,600 trees a year in an effort to increase the canopy to 40 percent in the next two decades.

— The Washington Post

Sources: University of Vermont Spatial Analysis Laboratory; USDA Forest Service; Casey Trees; Sandia National Laboratories; Montgomery, Prince George’s and Fairfax counties; satellite imagery via Google Earth Pro.