MONTPELIER, Vt. — The age of forest landowners across the country is increasing and the size of parcels they own is shrinking – and that has state, federal and private experts fearing for the long-term health of millions of acres of American woodlands.

The concerns of forestry professionals are more subtle than the typical worries over large-scale development: as the parcels of land get smaller, the people who own them might not have the same commitment to the forests as the previous landowners.

“Our alarm bells are starting to go off, not because landowners are suddenly older, but because it’s been going on long enough now that we are really beginning to see the impacts,” said Mary Sisock, an assistant professor of extension forestry at the University of Vermont, who has worked on the issue across the country.

Owners of smaller parcels are less likely to invest in forestry management plans, and managing for wildlife is more difficult than on larger plots, Sisock said. And once the land gets cut up it’s more likely it will be developed, and once developed there’s no chance it will ever again be a working forest, she said.

Brett Butler, the coordinator of the U.S. Forest Service’s National Woodland Survey, says there’s a common misconception that the majority of forest land is owned by the government. Nationally, more than half of the 766 million acres of forest land is owned privately by proprietors whose average age is 62.5.

“It’s really families and individuals that control the fate and the future of the forests,” Butler said.

Sisock previously worked with a project developed at Oregon State University called “Ties to the Land,” which was designed to help landowners and their heirs plan for the future.

Variations of that program are now in use in almost two dozen states. Allen and Ginny Nipper — owners of about 500 acres in Louisiana and Arkansas — started a business helping people plan after attending one such seminar. Now they work across the south, from Texas to the Carolinas.

Allen Nipper said the most important thing is getting different generations to talk, so children and parents understand what they each want.

“We tell them the best love parents can show the kids is to not put them in a bind,” he said.

Vermont is emblematic of the problem. Seventy-seven percent of the forest land is owned by people 55 and over and 15 percent of the owners are over 75, according to preliminary statistics from the Forest Service’s 2013 survey. Since 2006, the number of private owners has increased by 7 percent and the parcels are getting smaller, Sisock said.

Though many forest landowners are deeply attached to their property, that affinity can be harder to pass on than a legal deed.

“Many of the offspring, grandchildren, are more urbanized and don’t have the interest or the roots in the land,” said Putnam “Put” Blodgett, the president of the Vermont Woodlands Association. “It’s also a subject people don’t like to talk about, their demise, and they keep putting it off.”

Blodgett, 83, now of Hanover, New Hampshire, was raised on a farm in Bradford, Vermont, about 20 miles up the Connecticut River. In the mid-1950s he bought 670 acres from his parents.

Over the years he’s harvested more than 3 million board feet of logs, 4,622 cords of pulp, more than 900 cords of firewood and almost 3,000 tons of wood chips.

“I was married to the land more or less, and I decided I would keep it in forests because that is a feeling of mine that is so important, to conserve the forest,” said Blodgett.

Blodgett worked with his children to come up with a plan acceptable to all. Now one son lives on a small portion of the land, he formed a limited liability company and put a conservation easement on the land that prohibits development and mandates professional forest management.

Clint Bentz started thinking about the issue almost a quarter-century ago after his parents said they wanted to sell their 700 acres in the foothills of the Cascade mountains.

“The basic problem is we don’t live along enough to benefit from our own work,” said Bentz, of Scio, Oregon, who is a driving force behind the “Ties to the Land” curriculum.

“All the work that I’m doing on my family forest is for the benefit of somebody who isn’t even born yet,” he said. “It’s not even my children, it’s their children.”