According to a new study conducted by the U.S. Forest Service, American cities are rapidly losing their urban tree cover, with up to 36 million trees cut down and not replaced every year. Between 2009 and 2014, American cities lost 175,000 acres of tree cover.
Trees serve important functions for the health of the environment, like providing natural habitat for wildlife as well as the oxygen necessary for us to breathe. In urban environments, trees take on a different set of roles as well. They help to keep urban areas cooler, reducing energy consumption, removing pollutants from the air and water, reducing deforestation, and even reducing poverty and improving overall well-being of city dwellers.
Researchers David Nowak and Eric Greenfield analyzed tree cover in urban areas for this study and in the 5 years the study was carried out, American cities lost 1% of their total treecover. Some cities lost more than others, with significant tree cover decline seen in many areas.
Tree losses were greatest in the state of Oklahoma, with Washington D.C., Oregon, Rhode Island, and Georgia close behind.
The researchers found what you would likely expect; that these trees were replaced with “impervious surfaces” like roads, asphalt, cement, and buildings. Impervious surfaces are ones where water cannot soak into the ground. This increases the likelihood of urban flooding and increased air temperatures during the summer. About 40% of these impervious areas were built in places that trees once grew in.
“Urban forests are an important resource,” says Nowak. “Urban foresters, planners, and decision-makers need to understand trends in urban forests so they can develop and maintain sufficient levels of tree cover—and the accompanying benefits—for current and future generations of citizens.”
The researchers are concerned that little is being done to stop the losses of urban trees. Fortunately this is something that we can all have a hand in helping reverse. Consider putting pressure on your city to increase urban reforestation, and if you have space in your yard, consider planting a tree yourself!