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Tuesday
Nov222016

Maine’s Most Common Tree, a Favorite of Deer and Pests

By JOE RANKIN

Forests for Maine’s Future writer

 

Quickly now. This is a quiz. What is the most common tree species in Maine?

You might have said pine. It is, after all the Pine Tree State. Or the iconic white birch, perhaps. But you’d be wrong. The most common tree in the state is Abies balsamea — the Balsam Fir.

“It’s just everywhere. It defines the word ubiquitous,” said Robert Seymour, a professor of forestry at the University of Maine’s School of Forest Resources.

Balsam Fir TreeIt grows in mixed woods in southern and central Maine. It bolts for the sky on abandoned farmland. It crowds together in nearly pure stands of thousands of acres in northern Maine. It grows high on Maine’s tallest peaks and down in lowland valleys; on well-drained sites and dry uplands. It is a contender in almost every forest ecosystem in the state.

And why is that?

Well, says Seymour, it is a fast-growing tree that matures at a young age. And it produces prodigious quantities of seeds that apparently aren’t as popular with animals as those of other conifers, so more of them sprout.

it wasn’t always as common, though. As Andrew Barton points out in his book “The Changing Nature of the Maine Woods.” Researchers estimate that in pre-settlement times balsam fir made up only 10.5 percent of the trees in the woods over five inches in diameter at breast height, Barton writes. By the early 2000s that was 15.2 percent. Species that could rebound quickly after harvesting or when farmland was abandoned, like fir birch, and red maple all made gains. “In the north 150 years of harvesting has targeted spruce, to the benefit of balsam fir,” Barton writes. Spruce is much slower growing.

Not initially as popular for lumber as spruce, Balsam Fir later became more desirable. “Balsam Fir is a wonderful tree. It grows so well, it’s useful for a lot of products. You can make dimensional lumber out of it, or paper,” Seymour said.

The code SPF stamped on your two-by-four stands for spruce-pine-fir, meaning it could be any of the three.

And fir is a valuable commodity.

In 2014 Maine harvested spruce and fir sawlogs (state figures lump the species together) worth nearly $76 million and nearly $16 million more of spruce and fir pulpwood, according to Ken Laustsen, a biometrician at the Maine Forest Service. Yes, that’s a lot of money, but it’s a lot less than it was prior to the 2008 housing crisis and resulting recession. By comparison, spruce and fir sawlogs harvested in 2006 were worth some $101 million; in 2008 spruce and fir pulpwood harvested was worth nearly $16.8 million.

Harvests are “still very much impacted by the loss of the 2008 recession and the lack of a housing market rebound,” said Laustsen. And, he notes, the 2014 figures don’t reflect the closure or downsizing of most of the state’s paper mills over the past couple of years.

But the value of balsam fir doesn’t stop at two-by material or pulp.Overall Spruce-Fir Harvest Value in Maine

Its fragrant branches are a mainstay of the state’s holiday season wreath industry. Tens of thousands of wreaths, woven in huge wreath factories or small home workshops, are shipped all across the country. And balsam fir is the preeminent Maine-grown Christmas tree. Millions are planted and tended on tree farms, shaped for as long as 12 years before they’re cut to adorn the corner of your living room.

Balsam is Maine’s only native fir. It is one of some 50 fir species in the broader Pine family that grow across North and Central America, Eurasia, and even in the mountains of North Africa.Two things will help you tell whether a tree is a fir or not: the cones are upright, like you were holding your hand up in front of your face, and the needles are flattened.

Some species live for centuries and grow to tremendous sizes — European Silver Fir, or Pacific Fir, or Noble Fir. Not Balsam. “It is incredibly susceptible to heart and root rot. It’s more of a size thing than an age thing. If you can find a 12-inch diameter fir on an upland site in northern Maine there’s a good chance they have heart rot. A fir could live 150 years, if they miss it.”

Kevin Smith, supervisory plant physiologist at the U.S. Forest Service’s Northern Research Station in Durham, N.H., said the fungi that infest larger firs include the “bleeding stereum” and armillaria root disease. “Traditionally, these diseases have led to considering Balsam Fir to have a pathological rotation age of 60 to 80 years,” Smith said. Pathological rotation is a forestry term that means the point where a stand of trees is losing as much wood to decay as it is gaining in new growth.

One interesting thing about fir, said Smith, is that, at higher elevations on mountainsides stands can contain fir waves”, where swaths of balsam have died and are regrowing. The waves — dying trees at the leading edge, younger ones coming in at the lower edge — gradually march across the landscape.

The waves start, Smith explains, with some sort of disturbance that creates a gap in the canopy “leading to greater exposure to wind on the leeward side of the gap. The wind exposure rocks the leeward trees, damaging roots, and allowing decay infections to enter into the trees. As the exposed trees decline, die and fall, a new leeward front is exposed and subjected to the same stresses. Regeneration occurs in the killed zone and follows the movement of the wave across the hillside.” Studies show that at susceptible upland sites, the return interval for fir wave mortality is about 60 years.

Balsam fir is, unfortunately, also the favorite food of the spruce budworm, the larvae of a nondescript gray moth native to North America. The budworm periodically ravages the spruce-fir forests of Canada and the northern U.S. in cycles that go from three to seven decades.

Why, you might ask, is it called the spruce budworm if it prefers balsam fir? Balsam budworm would trip off the tongue better, don’t you think?

Well, the budworm was named that because it was first identified on specimens found on a spruce tree in, of all places, Virginia, said Maine State Entomologist Dave Struble.

But the budworm definitely prefers fir, with a secondary preference for white spruce, Struble said.

“This is largely tied to the initial early spring feeding by the 2nd instar larvae, which mine into one-year-old needles,” Struble said. The fir and white spruce needles are larger, providing a better habitat, and an earlier source of food since they tend to break bud earlier, he said. “After the larvae have completed that stage and begin feeding on the new foliage of the  expanding shoots under the bud caps any of the spruces as well as fir appear to provide necessary nutrition.”

Then there’s balsam woolly adelgid, a tiny wingless pest imported from Europe around 1900 on nursery stock and first identified in Maine in 1908. The adelgid spread rapidly and is now found across the continent. It causes tremendous damage to many kinds of fir. It has already obliterated Balsam’s close relative, the Fraser Fir, from the southern Appalachian Mountains, where it had hung out for thousands of years after the last glaciers retreated northward.

The adelgid has killed entire stands of Balsam Fir in Maine, according to the Maine Forest Service. “While the heaviest damage has occurred within 30 miles of the coast, damage may also be seen as far north as southern Aroostook, northern Penobscot and southern Piscataquis counties,” the MFS said on its website.

Temperatures of minus 20 Fahrenheit kill off the adelgid, which is why its depredations have largely been confined to warmer areas of the state. But with a warming planet the adelgid is likely to spread, said Seymour, adding that it has the potential to be worse than the budworm. “It’s an insidious pest. the tree can be healthy and you go back two years later it’s stone cold dead,” he said.

Balsam Fir Showing Signs of Spruce Budworm InfestationSo, it could be that one of the most abundant trees in the Maine landscape could, in a few decades, be a lot less so, thanks to climate change and an imported pest.

If that happens one animal would really miss it — the white-tailed deer. Deer congregate for the winter in dense stands of spruce, fir and cedar. There they are protected from the wind, able to use trails, and don’t have to deal with as much snow, since the trees intercept some of it. Such “deer yards” have shrunk significantly over the past few decades. An all-out adelgid infestation wouldn’t help.

Balsam fir “has a lot of value to wildlife species,” said Seymour, “including woodpeckers and invertebrates. Just the fact that’s it growing up and dying has a lot of benefits to the ecosystem. If it were killed off we’d miss if it was gone. I would anyway.”

 

Joe Rankin writes on forestry and nature from his home in New Sharon, where his 70 acres of woods includes a lot of balsam fir.