Biology instructor Matt Landis is attempting to unravel one of the great mysteries of the northern woods
By Tim Etchells '74
Photograph by Dennis Curran
On a day in early June, on the west flank of Mt. Abraham above Lincoln, Vermont, sun streams through a break in the forest canopy. On the ground, Matt Landis shoulders his way through a "dog-hair" fir thicket, where dozens of balsam fir saplings are packed into a space no larger than an average living room.
Landis, an associate in science instruction with Middlebury's biology department, points to one of the taller young trees, just above head-high, and demonstrates how you can measure annual growth by the distance between what are called terminal bud scars, basically marks on the trunk that indicate where a tree stopped growing during a given season; it appears the tree has grown about eight inches in the past year.
And then he stoops to examine a small tree, barely three feet tall—and, Landis says, already doomed. You can see the smaller trees are growing more slowly, their crowns flatter than those of their taller brethren, mostly because they're losing out in the competition for light. "They'll never catch up," he says, "never reach the canopy. It's funny to think that we already know what's going to happen to these trees, even though it might take 25 or 30 years."
This summer, Landis, his biology department colleague Associate Professor Andrea Lloyd, and two Middlebury students, Sarah Fortin '07 and Alyse Forrest '06, will spend a lot of time on Mt. Abe, looking at hundreds of young trees. They'll be trying to explain a phenomenon familiar to anyone who's spent time hiking in, skiing on, or even just gazing up at the Green Mountains: there's one kind of forest on the lower slopes and another on the steeper, rockier, colder upper reaches. Deciduous trees, mostly American beech, sugar maple, and yellow birch, predominate up to an elevation of about 2,500 feet; above that, the forest becomes mostly coniferous, home to red spruce and balsam fir, and some hardy mountain paper birch.
The data that the Middlebury researchers collect this summer, and follow up on in subsequent summers, could eventually help answer questions not only about why there are different forests at different elevations, but also what climate change, a.k.a. global warming, will mean for the future of all our forests. Figuring out the underlying causes of range limits for various species "assumes more importance given a changing climate," Landis says. "How will forests respond?"
In addition to studying saplings, mostly trees less than seven feet tall, throughout their ranges on the side of the mountain, the Middlebury crew will spend a lot of time this summer in "gaps," open spaces in the forest canopy created by disturbances such as wind, ice damage, logging, and fires. The trees that grow fastest in these light-filled gaps, the ones that get to the canopy first, are the winners.
During his early June visit to Mt. Abe, at 4,006 feet the fifth-highest peak in the state, Landis leads a hike up from Lincoln on the Battell Trail (named for Middlebury legend and benefactor Joseph Battell), stopping every few minutes to point out the various components of the forest. Just above the trailhead, at about 1,500 feet, beech, maple, and yellow birch are everywhere. The first red spruce appears at about 1,800 feet, and the first fir tree about 20 minutes later, at 2,400 feet. Another quarter mile up the trail, next to a cold rivulet, a tiny red salamander crawls along the white bark of a fallen paper birch.
Just a little bit higher, the forest is suddenly fragrant with balsams. Under the thicker canopy, it's noticeably cooler and damper. The ground cover has changed, too, with blue bead lilies, carpets of club mosses, wood sorrel, and a delicate painted trillium, its three perfect leaves surrounding a white tri-corner flower, with streaks of red on each petal. Picking up a small piece of club moss, Landis, in worn khakis, a red T-shirt, sturdy leather hiking boots and gaiters, with a full daypack on his back, examines the plant and decides it's specifically shining club moss. A bit later, he leans over to examine a stump left from logging perhaps three decades before, and points out five different species of moss growing in the space of just a few feet.
This summer, Landis and his fellow researchers will be collecting information to help improve their understanding of how and why tree species win and lose in their competition for Green Mountain real estate. Is it all about temperature? Is it the length of the growing season? The acidity or depth of the soil? The moisture-bearing clouds that cover the mountain tops?
The questions are more pressing now, since some scientists have forecast rapid changes in the northern forests should the climate turn significantly warmer and drier. "Some models predict that our beech and maple forests in 100 years will be oak and hickory [species that thrive today at lower latitudes]," Landis says, "that the range of trees will just move north. But there are other reasons to expect this kind of change could take much longer, maybe 1,000 years."
His hope is that the work on Mt. Abe among the thickets of balsam firs and tall stands of yellow birch will be a first step toward building better models and "more accurate predictions of New England forest responses to climate change. . . . There's no question we're going to have a different forest. The big questions are who the winners and losers will be, and how long the transition will take."
Tim Etchells '74, editor for electronic communications at the College, has spent many hours exploring the Green Mountains, on foot, on snowshoes, and on skis, but didn't know a beech from a yellow birch until he met Matt Landis.