Forests have always faced threats.

From natural disturbances like hurricanes and wildfires to native pests and diseases like spruce budworm to shifts in climate over the millennia.

Humanity has been a threat: think about how quickly forests in a large part of Maine were cleared in the 1700s and 1800s to make room for agriculture, or how logging has changed the age, size and species of trees in many forests.

Some threats to the forests of the Northeast were more or less neutralized. The effect of wildfire werePhoto courtesy of State of Maine blunted as firefighting preparedness and surveillance improved. Damage from acid rain was curtailed by reducing power plant pollution.

But these days Maine’s forest faces a raft of challenges or threats — forest fragmentation, over-harvesting, development pressures; climate change; invasive pests, pathogens and plants; a rapidly aging cohort of small woodland owners — at a time when the forest is more important than ever as we try to slow the runaway train of global heating.

“I would put climate change right up at the top,” of the list of threats, said Alec Giffen, a former chief of the Maine Forest Service and now affiliated with both the New England Forestry Foundation and the Clean Air Task Force. “We don’t really know what the consequences are of increased temperatures on forests and forest management.” Many people may assume “we are going to be able to manage them like we have in the past and that might not be true,” Giffen added.

Ecologists know that “climate is the main determinant of why forests look the way they do and why they’re different, with temperature and moisture being the biggest drivers,” said Andrew Barton, a forest ecologist, professor of biology at the University of Maine at Farmington and co-author of the book The Changing Nature of the Maine Woods.

“We know now that the climate has shifted and have every reason to think it’s going to shift more in the future. We know there are going to be some quite drastic changes in the climate of the future, some powerful changes in the next century.”

Barton said that, for forests, the coming climate change will be the biggest challenge Northern Hemisphere forests have faced since the Younger Dryas, a period beginning some 12,900 years ago when the planet abruptly cooled only to begin warming up again 1,300 years later.

Current thinking is that in an era of global heating Maine can expect a longer growing season, milder winters with less snow, drier summers and more of its annual precipitation concentrated in fewer storms in the spring and fall. But no one knows.

We do know that forests are already responding to global heating, with some species moving to higher elevations or northward. While some predict Maine will inherit the forests of southern New England, Barton says that’s not a given. Maine’s future forests may be “no-analog” communities — entirely new blends of species. Like no forest before them.

“I do think that forests are resilient. We will have forests in 100 years, there won’t just be a barren landscape. But it will be very changed and there could be very negative consequences,” Barton said.

Ivan Fernandez, a soils scientist, professor in the University of Maine’s School of Forest Resources and a member of UM’s Climate Change Institute, said uncertainty about what the forests of Maine’s future will look like will “be made even more challenging by the long-lived nature of our forests. Some trees will grow better until they don’t. New pests and pathogens will require greater surveillance of our forest condition and improved information about how to respond to insects and disease. Invasive species from microbes to mammals are likely to have increased opportunities” as climate disruption gives them a competitive advantage.”

Still, with ample water, a longer growing season and increased carbon dioxide, “it is very reasonable to expect that the forests we have in our future will possibly be more productive,” Fernandez said.

Mark Berry, the forest director for The Nature Conservancy, said his main concern isn’t just one threat but “the potential for multiple negative factors to build on each other.” Depending how threats interact, well . . . There’s the potential for “runaway feedback of negative consequences” that could lead to “large-scale loss of forests, large scale carbon emissions and fragmentation of remaining forests,” Berry said.

One of the more serious threats referenced by experts we interviewed is that of invasive species, particularly pests and pathogens.

Forests in the Northeast have seen an onslaught of imported diseases and insect pests over the past couple of centuries: White pine blister rust, Dutch elm disease, beech bark disease, and chestnut blight to name just a few.

But still they keep coming. Emerald ash borer is already here. Southern pine beetle is marching north towardPhoto courtesy of Maine Audubon the state. Spotted lanternfly is spreading in the eastern US.

“We know we can expect one new forest pest or pathogen every two and a half years,” said Allison Kanoti, the Maine state entomologist.

Will exotic pests and diseases gain greater virulence given a warming climate? It’s hard to say, said Kanoti, but the outlook isn’t good. Warmer and wetter springs would likely lead to an increase in fungal diseases like white pine needlecast disease, which has plagued Maine’s white pines every spring for more than a decade.

Warmer and shorter winters could mean more generations per year of pests like hemlock wooly adelgid or woodborers like the native eastern larch beetle, Kanoti said. The browntail moth, which hatches in the summer months, has longer to feed and is “entering winter more robust than in the past.”

Then there are questions about our relationship with the land, and how we value forests.

Much more of northern Maine’s forestland is owned by large landowners, than in southern Maine where the forest is owned by tens of thousands of small landowners.

The decision by paper companies in the 1990s to sell off their large forestland holdings created a tremor of fear in the conservation community. But the shift from paper companies to timberland investors actually opened up possibilities for landscape scale conservation, said Karin Tilberg, the executive director of the Forest Society of Maine.

The paper companies weren’t interested in selling conservation easements; the new investors saw that as part of their revenue stream, said Tilberg. “Now a fifth of Maine, close to 21 percent, is under some form of conservation,” she said.

And there’s a new trend back toward timberland ownership by families and even by conservation groups like the Appalachian Mountain Club.

Some experts caution that issues of forest fragmentation and over-harvesting that date back decades continue to threaten forest health and the wood supply.

The state needs to “just say no to development and fragmentation by corridors and pipelines” in the woods, said Giffen, who also is adamant that over-harvesting needs to be addressed.

Citing research on ideal stand makeup by US Forest Service scientists, Giffen said Maine has anPhoto courtesy of Center for Research on Sustainable Forestry, UMaine overabundance of seedling and sapling-sized trees and much less than the recommended percentage in older, sawtimber-size trees. “We’re pushing the forests right to the max, simplifying them and eliminating certain age classes in doing it,” Giffen said. “We need to back off” and “restock the forest.”

That doesn’t mean Maine shouldn’t harvest trees, said Giffen. He maintains that lumber is part of the climate solution — a board is another type of carbon storage unit, after all. Just that there needs to be a movement toward a more ideal age and size distribution in the woods. That’s where better forestry could come in, Giffen said. The result would be a healthier forest that would preserve biodiversity and could store more carbon.

Theresa Kerchner, the executive director of the Kennebec Land Trust, also worries about the “absence of late successional growth forests on the landscape” and the values they represent. A good long-term goal would be extended harvesting rotations of 80-plus years that favor longer-lived tree species and larger diameter trees, Kerchner said. The challenge is how to get there, given markets and owners’ expectations of returns on investment, she added.

Maybe, she said, carbon storage can change the financial equations.

Given climate change, a forest’s ability to store atmospheric carbon as wood — for decades if not centuries — is becoming very important.

Yet our economic system is still geared toward turning that wood into cash and is moving only slowly toward figuring out a way to financially reward forestland owners for all the other values the forest provides to humanity and the biosphere:  clean water, erosion control, temperature moderation, biodiversity, recreation and carbon storage, among others.

“We have not aligned our financial incentives with what we want as a society,” Giffen said. “We’re living with an antiquated system that will only pay people for timber . . . we need to reward people for the kind of stewardship society wants.”

There have been some sales of “carbon credits” in Maine, but the process is hugely complex and expensive and easily accessible only for large land trusts or large landowners. Small landowners — there are 86,000 family landowners with 10 acres or more in Maine — are generally left out of that equation.

And that’s an equation we need to solve to address some of the fragmentation and overharvesting challenges the forest faces.

The Maine Climate Council is refining a proposal by Tilberg that would set up an incentive-based Maine Forest Carbon Program to reward small landowners for managing their forests for carbon storage and still encourage harvesting for timber.

Giffen is also working to create an investment fund that would marry philanthropic money with private investment to encourage carbon storage, exemplary forestry and improved wildlife habitat.

Giffen believes that “building with wood is a big part of the climate solution.” Kerchner, Tilberg and others agree. Wood products, which are renewable resources, after all, are a vital part of Maine’s economy. And, Tilberg notes, durable wood products store carbon for a long time. She added that in developing carbon programs for landowners in Maine, “we don’t want to inadvertently hurt Maine wood businesses” or move harvesting pressure elsewhere.

Kerchner hopes “we will see increased demand for traditional and new wood products that are dependent on a long-term view of forest management and sustainable forest practices.”

While development in Maine’s woods has traditionally been in the form of rustic camps where people could retreat to recharge, some experts worry that climate change could exacerbate development pressure.

TNC’s Berry said that “people relocating in part due to climate change” is one of the things that concern him. Tilberg said Maine’s cooler climate and ample water supplies might “increase development pressure in ways that we have not imagined. For the first time in a very long time, Maine is losing forestland — about 8,000 acres per year over the last decade.”

Whether it’s these challenges, threats and pressures or others we haven’t seen yet, there’s something theyPhoto courtesy of Yves Levesque all have in common:  we helped create them and it will be up to us to help the forest deal with them. We’re in this together — trees and people.

Kevin Smith, the senior plant physiologist at the U.S. Forest Service’s Northern Research Station in Durham, N.H., has studied forests for more than four decades.

He offers a bit of optimism: “The most positive sign for me in recent decades has been the increased awareness” of average people of the vast array of benefits forests provide. And the willingness of those who manage forests to help connect people to the “wonder, resilience and vulnerability of forests.”


Author’s Note: This will be my last feature for Forests for Maine’s Future. It is my 99th Fresh from the Woods article since 2010. I’ve had a good time writing them and learned a lot. I owe a big thank you to everyone who has shared their expertise and insights about the Maine woods: Scientists, naturalists, conservationists, foresters, logging contractors, land owners and managers, mill owners and managers, state and federal officials and others. See you in the woods!







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