From SpaceTrees Reveal Income Difference


Research published a few years ago shows a tight relationship between per capita income and forest cover. The study’s authors tallied total forest cover for 210 cities over 100,000 people in the contiguous United States using the U.S. Department of Agriculture’s natural resource inventory and satellite imagery. They also gathered economic data, including income, land prices, and disposable income.

They 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. That’s a pretty tight correlation. The researchers reason that wealthier cities can afford more trees, both on private and public property. The well-to-do can afford larger lots, which in turn can support more trees. On the public side, cities with larger tax bases can afford to plant and maintain more trees. Given the recent problems New York City has had with its aging trees dropping limbs on unsuspecting passers-by—and the lawsuits that result—it’s no surprise that poorer cities would keep lean tree inventories.

Trees shade houses in the summer, reducing cooling bills. They scrub the air of pollution, especially of the particulate variety, which in many poor neighborhoods is responsible for increased asthma rates and other health problems. They also reduce stress, which has its own health benefits. Large, established trees can even fight crime. Fortunately, many cities understand the value trees bring to their cities. New York City is aiming to double the number of trees it has to 1 million. Chicago has planted over 600,000 in the last twenty years.¹ And London has been working to get 20,000 new trees in the ground before it hosts the Olympics. But those cities are relatively wealthy. It’s the poorer ones that probably need trees the most but are the least able to plant and maintain them.

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