Have you hugged a tree lately? If not, you might want to show your appreciation with a good squeeze. According to a recent state-by-state US Forest Service study, urban forests are responsible for storing 708 million tons of carbon – a service valued at $50 billion. Each year, our leafy friends capture an additional 21 million tons of carbon to the tune of a $1.5 billion benefit. Led by Dave Nowak, the study was published in the journal Environmental Pollution.
Nowak and his team took field data from 28 cities, six states, and national tree coverage information to calculate the carbon storage in urban areas of the United States. In a previous study done in 2008, total carbon storage from forest land was determined to be 22.3 billion tons. Adding city trees, the number increased to 22.7 billion tons. Rates of sequestration vary across the states depending on the amount of tree cover and growth rate. The states with the largest amount of stored carbon are Massachusetts (39.6 million tons), North Carolina (37.5 million tons), Georgia (42.4 million tons), Texas (49.8 million tons), and Florida (47.3 million tons).
“With expanding urbanization, city trees and forests are becoming increasingly important to sustain the health and well-being of our environment and our communities,” said Tom Tidwell, the U.S. Forest Service Chief. “Carbon storage is just one of the many benefits provided by the hardest working trees in America. I hope this study will encourage people to look at their neighborhood trees a little differently, and start thinking about ways they can help care for their own urban forests.”
The amount of carbon stored in urban trees is expected to increase as cities expand. Urban areas grew from 2.5% of land in 1990 to 3.1% in 2000. However, more development does not always directly translate into more trees being planted. Nowak and co-author Eric Greenfield found that urban tree cover is declining at an overall rate of four million trees annually. To assist with keeping our metropolises healthy, the Forest Service suggests becoming involved in planting campaigns such as those run by the Arbor Day Foundation.