WASHINGTON, Feb. 23, 2012 National results indicate that tree cover in urban areas of the United States is declining at a rate of about 4 million trees per year, according to a U.S. Forest Service study published recently in Urban Forestry & Urban Greening.
Tree cover in 17 of the 20 cities analyzed in the study declined while 16 cities saw increases in impervious cover, which includes pavement and rooftops. Land that lost trees was for the most part converted to either grass or ground cover, impervious cover or bare soil.
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.
"Our urban forests are under stress, and it will take all of us working together to improve the health of these crucial green spaces," said U.S. Forest Service Chief Tom Tidwell. "Community organizations and municipal planners can use i-Tree to analyze their own tree cover, and determine the best species and planting spots in their neighborhoods. It's not too late to restore our urban forests the time is now to turn this around."
The benefits derived from urban trees provide a return three times greater than tree care costs, as much as $2,500 in environmental services such as reduced heating and cooling costs during a tree's lifetime.
Forest researchers David Nowak and Eric Greenfield of the U.S. Forest Service's Northern Research Station used satellite imagery to find that tree cover is decreasing at a rate of about 0
|Contact: Jane Hodgins|
USDA Forest Service - Northern Research Station