Wednesday, December 28, 2016

Finding the Massachusetts Champion Yellow Birch Tree

By mid-morning on a snappy early-December day, Jared Lockwood, Arnie Paye, and I were leaving a warm vehicle and trudging off into unfamiliar woods in part of the Monroe State Forest near the Vermont border in Massachusetts. Our mission was to locate and explore an old hemlock stand described to us by friend and old-growth forest expert Bob Leverett, to evaluate its potential inclusion in an old-growth forest documentary film.

First, Old Growth Hemlocks

Small, but older hemlocks
 Unaware that there was a trail nearby we could have followed, we instead plunged into thick forest and bushwhacked our way across a steep slope, enveloped in both sun and snow flurries. It quickly became evident that this was an older forest than the typical second growth woods so common in this region. Hemlocks were tipping us off to that fact with their rugged, aging bark. They weren't the largest diameter hemlocks to be found in this forest, yet their bark, trunk, and limb characteristics were clues to their advanced age, likely 200 or more years in many cases.

A hemlock soon to be downed by wind?
One old hemlock we encountered will soon be hugging the ground, judging by a huge crack in its trunk. It's hard to imagine it surviving the winds and snow loads of another winter.








Counting Tree Rings

Beneath one small, dead hemlock, there was a 21/2 inch diameter branch that had fallen from it. I cut a small disk off the trunk end of it, and brought it home to count its rings to get some idea of the age of the tree. Its annual rings were extremely close together, indicating that this tree had grown quite slowly (which is in keeping with the aged look of its bark, and small stature). It was necessary to use a microscope to count the rings; the count was between 150 and 160! 
Annual rings of 150-yr-old hemlock branch

Now, that's just the age of that particular branch, which had been attached to the trunk at roughly 15 feet up. The trunk itself was about 10 inches in diameter, and the total tree height was perhaps 25 feet. This was a small tree, one that most anybody would not look twice at. Yet it was quite old. Hemlocks are very shade tolerant, and if they're shaded by surrounding trees as they get their start in life, they can remain alive and grow almost imperceptibly for easily a hundred years or more. At some point, the overhead canopy may open up when a neighbor tree goes down, and the hemlock will be "released" by the sudden increase in sunlight reaching it, allowing its growth rate to increase dramatically. So, we know that this now-dead hemlock was at least 150 to 160 years old; we would add to that the number of years it took the tree to grow from a seed to the height where that branch had been. We don't know that number in this case, but it could be as much as another hundred years. We would have to count the rings in the trunk just above ground level to know the actual age of the tree. Another nearby hemlock has been dated to over 201 years old, yet it is only 4.5 feet in circumference (or, approximately 17 inches in diameter). Yet another is over 230 years old.
Hemlock, 201+ years old

Old Growth Yellow Birches

We were enjoying this exploratory hike. Like a treasure hunt, it excited us at each ridge line and ravine we crossed. Discovering "new" charismatic old trees with your buddies, well, it doesn't get much better than that for me (ok, finding a restaurant that makes great Belgian waffles might top it).

One of the stately old yellow birches
We were quite pleasantly surprised to find so many impressive, old yellow birches (Betula alleghaniensis) on this mountainside. When these hardy, northern trees put on some years, perhaps a century-and-a-half or more, they become unfamiliar to most people in New England who would recognize young birches (because old birches are no longer common). With age, they lose that loose, curly, papery bark that is so characteristic of yellow (a.k.a. golden, or sometimes silver) birch. The strippy bark is shed, and the underlying layers develop plates, often with intricate swirling patterns for a period of time, until even greater age obscures that.
Yellow birch bark, at middle age

Weather-beaten crown of an old cherry tree





Yellow Birch, 218+ years old



The Champion Yellow Birch

Not terribly far into our hike, the best discovery of the day (no-- the year) suddenly loomed out of the snowy, dark hemlock forest right in front of us. There it was, a magnificently shaped, tall, straight yellow birch. Its most striking feature was its gracefully flared base, formed by large buttress roots that keep it propped up, arrow-straight,
The MA State Champ Yellow Birch
in the frequent high winds that buzz-cut the treetops around it. Many of its neighbors have had their crowns unceremoniously pared back by wind and storm.

Jared Lockwood measures the champ
This monarch too, no doubt, has been shaped by those same forces, at both its upper and lower ends. But that's what gives old growth trees the gnarly, ancient look they often eventually attain. This impressive specimen is the largest-girth yellow birch we know of in Massachusetts, and anywhere nearby. Jared Lockwood meticulously measured the tree, adhering to standards set by American Forests (the organization that maintains the national big tree registry). Those standards call for measuring a tree's trunk circumference at a point 4.5 feet above the ground (commonly referred to as "circumference at breast height", or cbh). If the tree is on sloping ground, the point midway between the slope at the high side of the tree and that at the low side is the point from which one should measure up 4.5 feet.

You can see by the photo that this tree has a significant flare at its base. Because of that, it makes a big difference where you measure the circumference. We determined that this tree is 12.78 feet cbh. It was difficult to see the tree's topmost twig, but Jared measured its height to 86.8 feet, using a laser instrument. The average spread of the crown came in at 57.4 feet.

Champion trees are determined via a formula that considers a tree's height, circumference, and crown spread, and yields a number of points; highest point score wins the title for that species. The formula is as follows;

Point Score = Trunk Circumference (in inches) + Height ( in feet) + ¼ Average Crown Spread (in feet).

Our old growth tree earns a score of 254.5 big tree points, and qualifies to be the Massachusetts state champion yellow birch. You can get a better look at the tree in the short video below (video player may not be visible on some browsers or mobile devices).

Mission Accomplished

Our day's mission was to locate a certain old hemlock stand. After leaving the champion birch, we pressed on and eventually found those hemlocks, and they were worth the hike. But, what we found along the way turned out to be even more impressive and exciting.

So, it was an unexpectedly rewarding day, but then, a hike in an old growth forest never fails to make my day.

More Great Trees of Massachusetts

 and watch the accompanying videos on our New England Forests youtube channel:

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