Before high-rise office buildings and multi-storied apartments began sprouting up in urban centers across the United States, the tallest structures there were often trees -- stalwart vestiges of a terrain yet untamed. But now, with cities becoming ever more crowded with people and concrete, those urban trees are losing ground at an alarming rate.
According to a recent study conducted by the U.S. Forest Service, some 4 million trees are disappearing from urban areas in the U.S. each year, victims of expanding swaths of pavement and rooftops. After examining forest coverage in 20 metropolitan areas, researchers determined that nearly all were shedding trees, and most were replacing them with impervious cover, dimming hopes they would be recovered.
The USDA breaks down the worst offenders:
Of the 20 cities analyzed, the greatest percentage of annual loss in tree cover occurred in New Orleans, Houston and Albuquerque. Researchers expected to find a dramatic loss of trees in New Orleans and said that it is most likely due to the devastation of Hurricane Katrina in 2005. Tree cover ranged from a high of 53.9 percent in Atlanta to a low of 9.6 percent in Denver while total impervious cover varied from 61.1 percent in New York City to 17.7 percent in Nashville. Cities with the greatest annual increase in impervious cover were Los Angeles, Houston and Albuquerque.
For Michael T. Rains, director of the Northern Research Station responsible for the urban tree analysis, healthy arboreal coverage in cities makes for much more than picturesque postcards:
“Trees are an important part of the urban landscape. They play a role in improving air and water quality and provide so many environmental and social benefits. As our Forest Service Chief says, ‘…urban trees are the hardest working trees in America.’ This research is a tremendous resource for cities of all sizes throughout the nation.”
One such benefit of urban trees cited by the Forest Service is cut and dry cost savings. According to the agency, caring for trees yields a return three times greater than cutting them down thanks to their help in reducing heating and cooling costs.
In light of the troubling loss of urban forest coverage across the country assessed in the study, researchers say that it would be much worse if it weren't for community efforts to plant trees.