Years after logging at his Mariaville woodlot, Bob Seymour expected to see new hardwood trees growing in the understory, such as maple and birch.
In fact, he took it as a given after decades in the Maine woods that natural regrowth would crop up so vigorously he’d have to thin it if any were to reach marketable size.
Instead, almost all of the young trees in some sections are eastern white pines he had planted. He believes that’s largely because deer populations are growing and eating more hardwood saplings, which means fewer trees and less diversity in the future.
“The forest of 50 to 100 years from now is the [trees] that are regenerating when we do these harvests,” he said.
It’s one of the most concerning changes that Seymour, a retired UMaine silviculture professor, has seen in almost five decades of experience researching forest management. He manages the Mariaville woodlot and several others with his wife, fellow professor Jessica Leahy, to demonstrate and document management techniques that are resilient to new challenges and can also be profitable.
Such challenges to understanding and managing the Maine woods have grown in recent years amid climate change, which has brought destructive new pests, fast-moving diseases, invasive plants that take over, and warmer winters that change growing, harvesting and wildlife conditions.
It will take decades to see the extent of how these forces will shape Maine’s key timber industry and its characteristic forests which, unlike in most other states, are largely owned and managed privately. But one thing is clear, according to woodlot owners: current understanding of how to manage forests will have to evolve, and there’s no precedent in human memory for how to do it.
“This ecological memory we have about how things are supposed to work is becoming unreliable,” Seymour said.
One framework he uses for responding to such changes outlines three options: resistance, or conserving species that are already present, like thinning hemlock tree stands so they can grow and have better chances of surviving the woolly adelgid; resilience, such as diversifying woodlands with species from neighboring areas like the white pine Seymour and Leahy plant; and transition, or bringing in new species altogether.
The Mariaville lot isn’t a typical forest because of that. But it’s an example of some changes seen in different areas of the state in growing and changing combinations, as pests and diseases spread east.
Insect issues affected 1.5% of Maine forest land and disease affected another 2% between 2019 and 2024, according to the Maine Forest Service, totalling 622,373 acres. Despite that, forests grew overall, adding up to about 285 million cubic feet.
Common issues emerging for family woodlot owners include pests like hemlock woolly adelgid, browntail moth, and emerald ash borer, along with beech bark and leaf diseases, according to Jenn Hicks, director of communication and outreach for Maine Woodland Owners.
Hemlock woolly adelgid drains the sap from trees, weakening and sometimes killing them; emerald ash borer beetles kill ash trees, and fast-spreading beech leaf disease has joined existing bark diseases to sicken beeches across the state.
Invasive jumping worms that degrade soil are also spreading along the coast, as are invasive plants such as barberry, honeysuckle and Japanese knotweed.
Si Balch, a Brooklin forester who manages about 50 acres of family land, said jumping worms are the only new threat he’s seen at his woodlot — which is made up mostly of softwood, with red spruce joined by some eastern white pine, balsam fir, red cedar and birches.
He’s keeping an eye out for Japanese stiltgrass, a fast-spreading and hard to kill plant recently found in nearby Blue Hill, and knows of significant issues with deer eating down new trees in nearby states. Balch also wonders about changes to natural wildfire patterns and potential increased droughts, though he said he’s not concerned about Maine species surviving.
Away from the coast and southern counties, small landowners may not see all these challenges yet but know they are coming, according to Amanda Egan, executive director of the Maine Woodland Owners organization.
Family woodlots are typically managed for multiple purposes compared to commercial timber operations, she said, which can give more flexibility to try resiliency techniques.
But they’re also more vulnerable because margins are thin; weather, pest and disease impacts are significant for their bottom lines and ability to keep land as woodlots, according to Egan.
Then there’s the weather. Seymour estimates about a third of his trees are now blown down by storms each year — about eight cords on 40 acres — and, while fallen trees are good wildlife habitat, they can’t generally be recovered and used by timber operations.
Warmer, wetter winters are also limiting when loggers can work with heavy machinery. The Maine Forest Service last month released new guidelines for preventing erosion and water pollution while logging as extreme weather events increase.
Its suggestions are welcome but add more costs for an industry already struggling with a dip in the paper and pulp market, Dana Doran, executive director of the Professional Logging Contractors of the Northeast, told Maine Public. He suggested the state offer financial assistance.
Other suggested resiliency practices are also expensive, particularly at a large scale, according to Seymour. Planting new species adds up quickly, as do options for deer protection such as the plastic tubes that shelter young hardwoods.
In December 2025, the Maine Forest Service was awarded $9 million in federal funds to create an incentive program for woodland owners to use silviculture practices to “improve forest health, sustainability and carbon storage.”
Practices like thinning dense forests and removing invasive plants will be eligible for reimbursement, the service said in a January newsletter, noting the program was still being developed.
Some Maine organizations have in recent years taken up “assisted migration,” planting species traditionally found farther south in preparation for warmer conditions ahead here.
Seymour and industry foresters he knows are skeptical of that, he said, citing the risk of investing with little information about how new trees will survive here.
It’s not clear how to get from the forest of today to the forest of that theoretically resilient future, he said. Getting there is a “wicked problem” in the sense that it’s hard to find a solution, according to Seymour, who cited a need for more research and the difficulty of balancing the state’s industry with climate response.
Egan said the market is another uncertainty for woodlot owners, and so is the potential of a use for trees thinned or cut to control pests and diseases. The market is already down for small trees and lower grade wood; Balch, for one, said he hasn’t done much in his Brooklin woodlot lately because of the market.
It’s hard for Seymour to find positive signs on a walk through his woods, he said. But not trying to become more resilient is a guarantee of failure, in his view.
He’s heartened by young, bright new foresters in the field, such as Sandy Walczyk, a former student who said that she’s also seen a marked increase in discussion of climate change topics at industry meetings.
It’s also hard for Egan, of the woodland owners group, to see a bright side yet. That’s especially challenging when looking at a forest that’s been “decimated” or a favorite tree that won’t be in Maine for much longer, she said, describing a “really heavy negative” people have to face.
In a broader view, Balch said the changes starting in Maine forests are evolution at work over decades. Humans have their own values for what those landscapes should look like, he said, but there’s no such thing as a perfect forest.
“This land is going to grow trees,” he said. “You can’t prevent it from growing trees.”
