U.S. Forest Service scientists recently released an assessment that shows forest land has expanded in northern states during the past century despite a 130% population jump and relentless environmental threats. At the same time, Forest Service researchers caution that threats to forests in the coming decades could undermine these gains.

According to the Forests of the Northern United States report, forest coverage in the United States has increased by 28% across the region that includes Minnesota, Iowa, Missouri, Wisconsin, Illinois, Indiana, Michigan, Ohio, West Virginia, Pennsylvania, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire and Maine.

Forested land currently accounts for 42% of the northern land area. Population in the region rose from 52 to 124 million people during the past 100 years, while northern forest coverage expanded from 134 to 172 million acres. Total U.S. forestland remained essentially unchanged during that time.

“While it’s heartening to see our northern forests thriving in great times of change, we should also use this report as a reminder to remain vigilant about working together across all lands to make sure these positive trends continue,” said U.S. Forest Service Chief Tom Tidwell. “Forests have rebounded over the last century, but there are significant threats that could undo many of the gains. Forest Service research including a study released in 2010, have already indicated this. Our future research will delve more deeply into those threats.”

Outlined in the report are current conditions, recent trends, opportunities and threats affecting the most densely populated and forested part of the country. This information lays the groundwork for a 50-year outlook on northern forests, which the Forest Service is expected to release in 2013.