Tree cover in the lower 48 U.S. states amounts to 659 million acres, more than one-third of the country, a U.S. Forest Service study has found.

New Hampshire leads the nation in percentage of tree cover at 89 percent, followed by Maine with 83 percent and Vermont at 82 percent, a Forest Service release reported Monday.

On the opposite end of the spectrum, North Dakota has the lowest percent tree cover with just 3 percent, followed by Nebraska at 4 percent and South Dakota at 6 percent, the release said.

In urban and community areas, as opposed to natural forests, the percentage of tree cover is highest in Connecticut, 67 percent, and lowest in Nevada, 10 percent, Forest Service researchers said.

"Urban forests are a vital part of the nation's landscape," Michael T. Rains, director of the Forest Service's Northern Research Station, said. "Forest Service science is supporting stewardship of urban forests with tools that communities, organizations and home owners can use to better understand the environmental benefits of trees."

Urban and community areas were analyzed for tree cover using aerial photography data from 2005, the Forest Service said.