Wednesday, November 25, 2020

New Film: The Magic Maples of New England


The northeastern quadrant of the United States is fortunate to be treated to an annual spectacle... the fluorescent foliage of fall. Many of our tree species here in New England present a glorious display, but as a group, the maples win the prize for the widest range of colors.

You might think we Yankees would all be confident in our ability to distinguish each local maple species from its kin, given that no other place on Earth can match this pageant. But if you can't, there's no need to cower in shame; you just need to watch our latest film, The Magic Maples of New England. All will be made clear. Plus, you can get another take at the autumn finery!

The film features two forest tree experts: Bob Leverett, co-founder of the Native Tree Society and co-author of The Sierra Club Guide to the Ancient Forests of the Northeast; and dendrochronologist Neil Pederson, Senior Ecologist at Harvard Forest. Each of New England's native maple species is described in detail.

And now, to set the mood for the film, here is an essay by Bob Leverett about one of his favorite trees, "Magic Maple", which inspired the making of this film.



Magic Maple


Robert T. Leverett

Magic Maple's Essence

Magic Maple is a mature red maple ( Acer rubrum ) that grows in the northern part of Mohawk Trail State Forest in the Berkshires of western Massachusetts. Magic stands in a small cove above the Deerfield River, one of the most scenic areas in Massachusetts. Some of the tallest, most statuesque trees in all New England grow in this region.

As we climb uphill from the river, the inviting sounds of the rushing waters put us into a mood of receptivity. We have entered a place that black bear, bobcat, beaver, deer, and even an occasional moose call home. The area around Magic reminds us that not all the East suffers from the impact of daily human activities. Here, nature has reclaimed that which is rightfully hers and is building a monument to herself through a wealth of stately trees.

We ascend, reaching a gently sloping area that served as a sheep pasture in the mid-1800s. We are entering the domain of tall trees growing on an old river terrace, a glacial remnant. A white ash reaches a height of 145.2 feet, as measured by botanist and tree-measurer extraordinaire Jared Lockwood, with one higher on the steep ridge approaching 150 feet. Two white pines approach 160 feet.

Entering this superlative forest, sensitive souls may feel a shift in the energy. It is a feeling that no young forest can inspire.

The steepening contours of the mountain hide spots of exquisite beauty. From a distance, these places can only be imagined. The following springtime image showcases sugar maples and budding oaks.

Maples and Oaks

After a short walk among stately oaks, a few black cherries, and younger red maples, if we are looking in just the right direction, the magic one appears. Even from a distance her wonderfully symmetrical form attracts us. Closer to her trunk, her long lines and smooth curves carry our eyes upward into her out-swept limbs. There is a pleasing flow to each of her branches. Her contours stimulate the inner recesses of our brains that love symmetry.

Magic Maple

Magic is attractive at all times of year, but it is with her crimson spring flowers and autumn fire that she presents her charms in special regalia. At these times, light filtering through her arching limbs and dappled foliage initiates an odd competition in my head. My left-brain faculties set about trying to decode her form and color toward some analytical resolution, but my right brain synapses simply embrace the gestalt. There is no need to think, only to appreciate and enjoy.

Magic Maple is rooted firmly in the earth. She claims a spot that gives her the vigor to hold competing forms at bay. Other trees are just close enough to keep her growing vertically, but far enough away to allow her to extend her limbs farther out to gather extra sunlight for life-sustaining photosynthesis. In over a century of growing, she has developed a long, straight trunk and a large crown. In the photographs, we see her trunk progressively surrounded by spring's bright green cloak. Only weeks before, the forest presented us with the skeletons of trunks, limbs, and branches.

Seeing Magic Maple from a sufficient distance to preclude quick species identification, she taunts the newcomer marginally familiar with local species. Name my type, she exhorts. Am I an ash or an elm? From a distance, features of her form may suggest either. But approaching more closely, her opposite branching rules out elm, leaving us with the slight possibility of ash, but that species has compound leaves and hers are simple. We search for other clues. The upward thrust of her many fine twigs suggest red maple. As we approach more closely, her bark formally announces her identity: she is a red maple, and proud of it.

A clinical examination reveals no major broken limbs. The pattern of large branches, giving way to small, and then to fine twigging, is in the right proportion. We are witnessing the fulfillment of an arboreal blueprint, complete in the details. Though each species has its blueprint genetically encoded, interferences through seasons of growth can cause aberrant forms to develop, sometimes pleasing to the eye, sometimes not.

Monica at Magic Maple
Monica at Magic Maple

In the space beneath her outstretched limbs, she seems to be inviting all to hug her. "I am here to remind all who would dismiss my species that we red maples are proud trees. We have a long heritage of service to all creatures. You humans once considered us your friends. You used our bodies to build your houses and your furniture. Those you call the indigenous people drank our sweet sap. You split and burned our trunks and limbs in winter to keep your dwellings warm. You gloried in our reds in spring and fall. Please don't think ill of us now as you alter the landscape and introduce imbalances that allow us to over-populate, a trait not so different from your own. Remember, we love to seed in where there is disturbance, and in this place, there has been excessive past cutting. But in time, we will adjust our numbers to fit our environment. Will you do the same?"

The area where Magic Maple grows is not old growth, but part of past loggings. Today, Magic Maple has helped to reclaim the land and sends a clear message that her species belongs in the woodlands of New England, left to reach maturity and grow old gracefully. She is a true native with much to offer.

Magic Maple

Magic's Story in Numbers

In December, 2008, Magic's statistics were a respectable 8.1 feet in girth and an impressive 118.9 feet in height. These are worthy statistics for a forest-grown red maple throughout much of the species' geographical range, but especially in New England.

Magic Maple

By Nov, 2016, eight growing seasons later, Magic's girth had expanded to 8.9 feet, an increase of 0.8 feet. This translates to an average annual ring width during the eight years of 0.19 inches. Assuming Magic was around 115 years old in 2016, had she been growing at this rate since being a seedling, her diameter would be 43.7 inches, which translates to a girth of 11.4 feet. Magic has been growing rapidly in her post-century life. In the last four years, Magic has increased her girth from 8.9 feet to 9.5. This represents a remarkable radial growth of 0.29 inches annually! Clearly, Magic has been increasing her annual rate of growth as she has aged, reinforcing her dominance.

However, her height was down to 116 feet; crown damage and a beginning area of decay on her north side signaled to me that Magic had passed her prime. At least, that's what I thought then. Loss of vitality can happen quickly with this species, although trees can linger in gradual decline for decades. The normal life span of Magic's species is on the order of 150 to 225 years. But Magic's current rate of radial growth tells a competing story.

The table below summarizes Magic's growth from 2008 to 2020 with CO2 implications.




Dry Biomass-lbs

Increase in biomass for period-lbs

Corresponding Carbon increase-lbs

Carbon Dioxide Equivalent-lbs

Annualized CO2 Equivalent -lbs





















This table shows the carbon consequences of Magic's remarkable growth, defying the conventional belief that these New England trees slow their growth appreciably after 100 years. To be sure, many do, as competition, insect damage, and disease take their toll, but by no means do all trees slow their growth by 100 years, particularly the dominant ones. Magic's absolute growth surpasses that of much younger, vigorously growing red maples. An example will help.

A red maple 12 inches in diameter and 45 feet tall that grows to a 13-inch diameter (very fast growth) and 47-foot height in a year will sequester approximately 214 lbs of CO2 equivalency. It would take three of these small red maples growing at that very fast rate to equal Magic's current annual increase.

But even if Magic starts going downhill in the near future, her growth accomplishments deserve our admiration, as she shares forest space with impressive examples of white ash, sugar maple, northern red oak, yellow birch, black birch, and black cherry, all seeking to claim the territory as their own. They all grow in individual competition with one another, but they also cooperate in an extensive underground community connected by a lattice work of many species of fungi.

As impressive as the above numeric description of Magic is, it isn't her dimensions that endear her to me and my wife, Monica. Many trees of other species in Mohawk Trail State Forest are larger and taller and quite handsome. But Magic Maple is a projection into physical time and space that artists seek to render on canvas and poets labor to paint in words -- timeless expressions of nature's beauty. To our eyes, Magic is an exquisite manifestation of natural creativity that beckons us to admire her for her beauty.

- ~ -

Saturday, September 19, 2020

Good News for Cathedral Pines of Cornwall, CT

Once touted as the premiere stand of old eastern white pines (Pinus strobus) in New England, the legendary, lofty Cathedral Pines were summarily brought to the ground in 1989 by three (!) tornadoes (apparently, one wasn't enough).


Cathedral Pines, 1970's (Jack Sobon photo)


The 42-acre grove of tall conifers sprouted from seed on agricultural land sometime in the late 1700's, and soared skyward over the next two centuries. A road rambled through the tallest of the pines at the base of a hill, providing the namesake cathedral experience for visitors. That scene was profitable for postcard publishers of the time. In 1982, the forest was designated a National Natural Landmark.

Those tornado winds dramatically changed the view on Essex Hill Rd. Thousands of tons of timber lay on the ground. And, they're still there today, some 31 years later. The Nature Conservancy, who owns and manages the property, allowed the cleanup of logs along the roadside, but, thankfully, decided to let nature recycle the rest of the debris in the forest. 

Dead pine snags on the hill today









Today, you can clamber among the hulks of large, moss-covered pine logs, and sidle up to still-standing, gray, broken, dead pine snags.

The good news

While those imposing roadside columnar pines are no more, there is reason to rejoice in this forest. There are survivors... a number of large, impressive white pines still gracing the hillside. And they've been quietly putting on girth and height, as they sway in the breezes and gales.

This summer, after a conversation about the stand with our old-growth-forest expert and amigo Bob Leverett, Jared Lockwood and I visited the site to see how it has fared. Bob hasn't been there in several years and suggested it could be well worth a road trip. 

We were delighted to find fat, old pines. Several exceed twelve feet in circumference at breast height (cbh), the standard height of 4.5 feet above ground level at which trees are measured. Jared used his LTI TruPulse 200x laser to very accurately measure tree heights as well; in the limited number of pines he had time to measure, he found a height range of 120+ feet to a maximum of 151 feet. That is really good news! To have white pines breaking the 150-foot mark is a cause for celebration; the number of locations in the northeast where pines exceed that height is very limited, but on the increase. 

Jared Lockwood measures 12.5' cbh, 147' tall pine


On a subsequent visit, we were accompanied by Jack Sobon of Windsor, MA, who is an internationally known timber framer, architect, author, and big-tree hunter. Jack had spent many a day measuring the Cathedral Pines during the 1970's and 80's. Using a surveyor's transit and tape measure, he accurately determined heights and diameters. He found many 160-ft-class pines there pre-tornado; the height champ was an awe-inspiring 172-footer, possibly the tallest tree in New England at that time (and today, there are only two known trees exceeding 170 feet in New England; both are white pines in MA). Jack was heartbroken when the great pines went down, and hadn't been back to the site since. 

Before their demise, the pines were providing shade for up-and-coming eastern hemlocks (Tsuga canadensis), which can be found mixed with pines on the site today; the grandest one Jared found is nearly 10 feet cbh, and 134.5 feet tall ... a very impressive hemlock! Also present are a handful of old northern red oaks, black birch, and others. One of the hilltop red oaks appears to be at least 200 years old, based on its bark characteristics.

For those who long to experience what it felt like to wander among ancient eastern white pines, a trail walk through the remnant Cathedral Pines can be quite rewarding. Take your time; walk slowly; look at and feel the rugged bark; breathe in the pine scent; gaze skyward at the lofty green needles; let troubled thoughts drift away on the breeze. 

And then, take a very short drive down the road to the Ballyhack Preserve, also in Cornwall. Walk the loop trail there to see another stand of very respectable large, old pines. On the far side of the property where the trail passes along the deep ravine, look for a number of white pines with distinctly older looking bark; these are well over 200 years old, perhaps as much as 250.

New Cathedral Pines Film

Before you visit, watch our new 14-minute film, The Cathedral Pines Forest of Cornwall, CT - 2020.

You'll see pre-tornado images of the Cathedral Pines taken by Jack Sobon as much as 42 years ago, and what the forest looks like today. See Jack's reaction upon his first return to the forest after 30 years. Plus, old-growth forest guru Bob Leverett offers his insights on his favorite tree species.

View from top of 145' pine

Wednesday, August 12, 2020

Black Birch: Setting the Record Straight

Bob Leverett, co-founder of the Native Tree Society, co-author of The Sierra Club Guide to the Ancient Forests of the Northeast, and co-author of American Forests' champion tree measuring guidelines, has been leading the charge to give the black birch tree proper recognition for the height stature it achieves. The following is an essay penned by Bob.

The Birch Quintet

Lessons in Natural History, Tree-Measuring,

and Ecology with Aesthetic Overtone

by Robert T. Leverett



How is the tree species black birch (Betula lenta) related to classical music? This is a question to which I gave little thought until Monica and I got married and I moved in to share her beautiful home in the woods of Florence, MA, and I do mean in the woods. Monica has a cantilevered music room that is nestled beneath the canopy of a cluster of eastern hemlocks (Tsuga canadensis) and black birches that are located downhill behind the house. The crowns of the birch form a canopy that shades the music room from strong sun. In return, these trees are daily bathed in the mellifluous sounds coming from Monica’s pianos. As a classical pianist and retired professor of music from Smith College, Monica has spent countless hours at her instruments. The non-human beneficiaries of her playing have been the chipmunks, squirrels, songbirds, and an occasional barred owl (perched on a hemlock branch watching for scrumptious little rodents); but most importantly, her trees. I don’t know if trees, and plants in general, actually respond to different musical sounds, but if they do, Monica’s trees get their leaves bathed daily in Mozart, Beethoven, Schubert, Bach, and dozens of other distinguished composers.

How does black birch compare to other species in terms of height? As a dendromorphometrist and co-founder of the Native Tree Society (NTS), I spend my time not only measuring trees, but developing better methods, and testing high-tech instruments. The trees behind our house provide me with a superb outdoor laboratory. The canopy is dominated by exceptionally tall trees, including a white pine (Pinus strobus) now just topping 141 feet. Three tuliptrees (Liriondendron tulipifera) and a second white pine all top 130 feet in height. Northern red oaks (Quercus rubra) make it almost to 120 feet. A lone white ash (Fraxinus americana) touches 113 feet. This, then, is an exceptionally tall private forest for our geographical region. 

But where does a species like black birch, which is usually described as a medium-sized tree reaching from 60 to 80 feet at most in height, fit in? Presumably, the birches fit snugly under the super canopy created by the other species. The prestigious Silvics of North America, the U.S. Forest Service’s bible, states a maximum height of 70 to 80 feet for the black birch, and then, only on the best sites. The U.S. Plant Database lists 60 feet as the species’ mature height. Other sources, often university arboretums, frequently list the maximum height of the species to be 50 to 60 feet. I can tell you reliably that all these sources are wrong, and wrong by a lot. Perhaps this species just isn’t paying attention to the scholarly sources.

I acknowledge that initially I didn’t pay much attention to the cluster of slender birches shading the music room. As we descend the hill behind the house, we must pass between them, as a gateway to the robust pines, tuliptrees, and oaks just beyond. However, at some point, I started noticing these dutiful gate keepers, offering us a pathway into the forest green. Much later I named the cluster of five the “Birch Quintet.” 

The story could have ended there, except from the time I joined Monica in 2006 to the present, those five trees continued to rapidly gain stature, despite their slender trunks (the largest is a mere 4.7 feet around). But despite our seeming indifference, Monica’s “Birch Quintet” refused to be ignored. In addition, I had begun a database on the species. My NTS companions and I proceeded to measure black birch from New Hampshire to Georgia and west to Ohio. I was determined to correct the record on the species, as alluded to above. But surely outstanding members of the species would not be growing just outside Monica’s music room, preferring some distant woodland--or would they?

The Quintet has quietly and gradually crept up into the upper height category for the species, and I am now pleased to announce that one of the five ("Monica's Birch") has just reached a height of 99.0 feet! Please remember, you heard it from me first. But is my claim accurate? Confirming the measurement is a story unto itself and is the focus of the appendix following this essay. 

99-ft Monica's Birch

Notice how Monica's Birch bends eastward to reach the light – and toward the music room. Two other members of the group are also in the photo.

This essay will now look more generally at the dimensions of the black birch being achieved throughout its range and speculate on why it has been so under-measured.

The Black Birch Along Broad Brook and Elsewhere

Of the five members of the “Birch Quintet,” three for certain, and maybe four, reach skyward over 90 feet in height, and the remainder are close behind. However, it turns out that the quintet is in good company. In the swath of forest along the Broad Brook corridor that extends about a mile and a half upstream and a quarter mile downstream behind our house, there are at least a dozen black birches over 90 feet tall. I expect that if we did an intensive search, we’d find 18 to 20. One tree, a half-mile upstream, is named “Schubirch,” after Monica’s favorite composer, Franz Schubert. This outstanding birch is a very impressive 107.5 feet tall as last measured by NTS member Jared Lockwood.

In fact, the birches are so impressive that I hardly pay attention to any growing along the stream corridor just reaching to the 80-foot threshold maximum cited by Silvics. So, given what these outside sources say about the black birch’s stature, is Broad Brook’s contribution exceptional for the species? No, not in the least. We have measured black birch to over 100 feet on more than 25 sites in Massachusetts alone. I expect that number could double. Elsewhere within the range of the species, 100-footers have been confirmed from New York all the way to Georgia and South Carolina. One tree on Long Island reaches a remarkable 121 feet, as measured by NTS member Erik Danielsen. Erik’s measurement is the best we’ve done. The second best is 117 feet, measured by Will Blozan of NTS. That tree grows in the Great Smoky Mountains National Park.

In Massachusetts, Jared Lockwood recently measured a black birch to 111.5 feet in Mohawk Trail State Forest, breaking John Eichholz’s old record of 110.5 feet. In fact, 111.5 is the best we’ve done in New England. This said, I expect that Connecticut, to the south, can easily match Massachusetts with respect to tall black birches. We have spent almost no time measuring the species in the Constitution State.

In Pennsylvania and Ohio, we’ve measured black birch to between 113 and 115 feet tall. And on good growing sites, the species has little trouble reaching heights of from 90 to 105 feet over much, if not most, of its range. We can authoritatively state that the maximum for the species on good sites exceeds 100 feet, though usually not by much.

In the bigger picture, black birch is our 74th tallest eastern species based on our NTS database. So, the species can’t be promoted as a super performer, but one-hundred-foot tall black birches are widely spread and 80–90 feet is quite common in mature forests where that species is present and reasonably abundant.

Still, the “Birch Quintet” remains a small cluster of slender trunks growing outside of Monica’s music room. Most people visiting us hardly notice those trees. At best, they serve as part of a pleasant forested backdrop, visible from our back windows, deck, and patio. They create a kind of soothing natural woodland wallpaper, but without distinction. However, Monica’s Birch, now standing a proud 99 feet tall, reminds us that it and its Quintet members should not be taken lightly.

The next photo shows the largest member of the Quintet, which measures 4.7 feet in circumference at breast height, or 18 inches in diameter. By comparison, Schubirch measures 7.0 feet in girth, and another named Archie is 7.1 feet around. The straight trunk to the left is Monica’s Birch. 

Largest Quintet member



Birch Quintet

Photo "Birch Quintet" shows the trees from above. The rightmost birch has two stems, but is one tree. The big tree with the orange ribbon is Monica’s Pine - the 141-footer mentioned above. A hemlock trunk is in the right foreground; its lower dead branches were trimmed to enhance its aesthetic appeal. 


 Ecology and Beyond

The black birch has simple, serrated leaves that turn a pleasing golden yellow in the fall – arguably the prettiest of the birch family. Branching is upright and alternate. Bark is smooth and gray-black when young, with rows of lenticels plainly visible. 

Young black birch


~130-year-old black birch

Bark on older trees is broken up, first into an irregular vertical pattern, and later into numerous platelets, the sign of advanced age. The species has a number of common names, with black, cherry, sweet, and mahogany birch being the principal ones. The name mahogany probably has several origins. One comes out of the southern Appalachians, where old timers thought they had a species of mahogany growing in the coves. They called it mountain mahogany.


Our New England woodlands are well suited to grow members of the birch family, including white (or canoe) (Betula papyrifera), black, yellow (or silver) (Betula alleghaniensis), gray (Betula populifolia), and river birch (Betula nigra). By the way, river birch is also referred to by some as black birch.

The seeds of the birches are very small and light; they don’t penetrate the leaf layer on the forest floor easily. As a consequence, we commonly find birch seedlings sprouting where the litter layer is thin and mineral soil is exposed, and prolifically on the trunks and tip-up mounds of fallen trees. For the more botanically inclined, black birch is classified as monoecious, meaning that both sexes occur on the same tree. Birch roots can also wrap themselves around rocks in an octopus-like embrace. The effect can create a kind of Tolkienesque woodland.

Black birch is a heavy wood. Its green weight of 65 lbs per cubic foot (ft3), exceeds that of yellow and white birch, and is about the same as N. red oak and most of the hickories. Its oven-dried weight is 41 lbs/ft3. It literally is no lightweight.

Black birch has a distinguished cultural past. From its sap, birch beer has been brewed. With age, the wood of the species looks like mahogany. It burns well as firewood. In recent years it fell out of favor with lumbermen, but I think it is now rebounding. In the past, I heard some lumbermen refer to black birch as a “trash tree,” a regrettably insensitive and utterly uninformed way of thinking about a naturally occurring and ecologically important species. 

Black Birch Burl lamp





Our birch trees are around 100 years old, maybe a little older, which means they likely started growing during World War I. In human terms, they would be very old, but in birch terms, they still have lots of life left. Black birches can easily live past 200 years, and have been dated to as old as 368 years. The oldest birch we know of in Massachusetts is now approaching 350 years, and Ray Asselin and I have dated many to over 200 years, with one almost 300 years old.

Those tackling the following appendix will recognize that confirming the height of Monica’s Birch was a lot of work for me-- fun work-- but work, nonetheless. Still, it’s what I do in retirement. Such fussiness over decimal places isn’t necessary for the vast majority of forest workers. In fact, the amount of work that accurately measuring a tree like Monica’s Birch requires, eliminates the method in the appendix as a useful technique for forestry professionals who live off of quick results. Timber cruisers can’t afford the time that members of the Native Tree Society devote to achieving the highest degree of accuracy that their instruments allow. But there is a price for the loss of accuracy. The public cannot trust traditional sources like Silvics of North America and the USDA Plant Database to provide accurate species maximums.

I will now close the main essay by suggesting an experiment for the imagination. As you look at the photos, imagine for a moment Monica sitting at her piano playing the New England composer Amy Beach’s composition Young Birches. True, the Beach piece is most likely about young white birches, or if not, then yellow - Thoreau’s favorite of the three. However, the Quintet is composed of older black birches. All three birch species, black, yellow, and white, grow together along the Broad Brook corridor, and do so coexisting peaceably. Black, yellow, and white living in harmony - a lesson for us humans …… Shhh, everyone, Monica has begun to play. 


For a delightful film on birches, see New England Forests' "Birch, Sweet Birch: New England’s Forest Birches".

Appendix - Measuring Monica’s Birch (an engineering nerd’s favorite retirement pastime)

The traditional forestry technique for measuring tree height uses a tape commonly either 66 or 100 feet long, and a device called a clinometer, of which there are several kinds, but one has a scale that reads height of an object as a percent of a level baseline. This is a convenient tool because if the baseline is exactly 100 feet, then the percentage read directly from the scale is the height. For example, if the baseline is 100 feet and the percentage display reads 70, then there is 70 feet of the tree’s height above eye level. Were the baseline, say, 75 feet, then the height would be 75 x 0.75 = 56.3 feet.

After getting height above eye level, turning the instrument toward the base of the tree and taking a reading gives the part of the tree’s height that is below eye level. Then adding the two results gives the full height of the tree – supposedly. However, this method carries the assumption that the base of the tree, the end of the base line, and the top being measured are all in vertical alignment. This is often close for young conifers growing in a stand on level ground, but for older trees, especially hardwoods grown in a stand and on uneven ground, the verticality requirement is frequently not met. If the measurer is too close to the trunk, the top is often not visible and what is mistaken for the top is the end of an upturned branch that is closer horizontally to the measurer than the baseline. This leads to an estimate that is too high.

More could be said here, but suffice it to say that clinometer measurements are seldom satisfactory in a closed canopy forest. This applies equally to the automated hypsometer equivalent that often is labeled as a tree-height routine. However, with modern laser rangefinders and their hypsometer equivalents, the distance to the top of a tree can be measured directly. This distance represents the hypotenuse of a right triangle, and, along with the angle taken to the top, allows the measurer to calculate the vertical separation between top and eye using the trigonometric sine function. The trunk and a level baseline to it at eye level is not required. Taking the distance and angle from the same location to the base gives the vertical separation between eye and base. Adding these two components of height together gives total tree height. This is called the Sine Method. The tape and clinometer technique is called the Tangent Method. With the Sine Method, the measurer can measure tree height to within the accuracy limits of the equipment, avoiding the pitfalls of the Tangent Method. Both these measuring techniques are built into most laser hypsometers.

The top and base of what I call Monica’s Birch cannot be seen from a single location. This is frequently the case for trees growing in close proximity to one another. What happens if the top and base of the tree being measured are not concurrently visible from any location? We must turn to a surveying method to measure height in stages. This is how Monica’ Birch was measured.

I first located a spot where I could see the top of the birch. From there I could see downhill to the trunk of a honey locust. From a chosen spot on the trunk at near eye level when standing next to the trunk, I could see the base of the tree and a marker that I had put on it. I had to work my way around part of the house to get from top to base.

From my first spot, I shot the top of the birch with an LTI TruPoint 200h laser rangefinder. The TruPoint has both class 1 and class 2 lasers. Each shot returns the most accurate reading it can obtain. If the shot is from the class 2 laser, the answer is to three decimal places. If from the class 1 infrared laser, the return is to two decimal places. As can be seen in photo 1, the direct slope distance from instrument to target was 120.81 feet. The vertical distance was 73.81 feet.

Photo 1

 So, from where I took that measurement, I had accounted for 73.81 feet of the vertical separation between top and base. Note that the distances are to two decimal places meaning that the infrared laser had to be used. 


 I swiveled my tripod and aimed at the target downhill on the honey locust, and measured the additional vertical separation down to that point. Photo 2 shows the result. 


Photo 2

 The center of the target on the honey locust tree was 6.024 feet below instrument level. The minus sign indicates below instrument level. Therefore, from the top of the birch down to the level of the target on the honey locust was a vertical separation of 73.81 + 6.024 = 79.834 feet.

Next, I moved down to the honey locust target, placed my TruPoint against the center of the target, pointed it down to the target on the base of the birch, and shot that target. Photo 3 shows the TruPoint’s display.



As can be seen, the vertical distance to the center of the base target was -18.875 feet. This gave a total of 79.834 + 18.875 = 98.709 feet of vertical separation between top and the center of the base target. I then went to the base with a yard stick. I had placed the base target at a visible point from the honey locust target. The center of the base target was 3.5 inches above ground level at the mid-point of the base. So, adding another 0.292 inches gave a total tree height of 99.001 feet. An even 99 is close enough. On Aug 8, 2020, I performed the measurements again and came out with 98.985 feet. I’ll stay with an even 99 feet.

The above measurements were all done using my LTI TruPoint 200h, which I affectionately named Mini-Me. However, I have other instruments and decided to use my Impulse 200LR (named Sasquatch) as a check. The result came out to 98.75 feet. So, we have now three results: 99.001, 98.985, and 98.75. Not wanting to leave any instrument out, next, I used my TruPulse 200X (named Sparky), and got a height of 99.05 feet. So, now that we have four independent measurements of Monica’s Birch averaging 98.94
feet, I suppose it becomes an honorary 99. 

Ah, but I still wasn’t satisfied. I had my Nikon Forestry Pro. Using it, I got 74.5 + 7.0 + 19.5 = 101.0 feet. Alas, the Forestry Pro is not as reliable as the LTI instruments, because for the crown shot, I got numbers ranging from 73.5 to 75.5. The 74.5 was, conveniently, the average of the extremes. The average of the 4 instruments yields 99.4 feet. Still, how tempting it is for me to conclude that Monica’s Birch is 100 feet. However, averaging a mix of measurements from more accurate instruments with those of less accuracy is not the best strategy. So, I had to have at least one more set of measurements from a more accurate instrument. So, on August 12th, I headed out again with the Impulse laser. My measurements came to 73.52 + 6.66 + 18.53 + 0.29 = 99.0. Going once. Going twice. Going three times. SOLD!

Tuesday, March 17, 2020

Winter is Leaving the Beaver Pond

As this is being written, Americans, and many others around the world, are keeping their distance from each other, fearful of contracting the new Corona virus COVID-19. We're staying out of work, school, restaurants, sports events, and other places where people gather. This is likely to go on for many weeks.

Many are probably wondering what they can do to pass the time and forget about viruses. Well, for me, there's no better way to escape the saturated media Covid coverage than to head for the nearest forest and beaver pond.

It's late winter. Actually, spring begins in a couple days on March 19, the earliest first-of-spring since 1896. Just a few weeks ago, local beaver ponds here in Massachusetts were still capped with ice. Beavers, mostly locked under a frozen crystal roof, were rarely seen on "our side" of the ice during the winter, unless they kept plunge holes open. They've relied on the brushy food cache they anchored in the muddy pond bottom near their lodges last fall; this they could access under the ice, after exiting the lodge via its underwater passageway.

Muskrats don't have the foresight beavers do, and don't establish a winter food cache. They must forage for food (plants, roots, etc) under the ice. They too typically maintain open plunge holes though, so, in winter, you might spot them above the ice if you're lucky, and/or patient.

Beaver lodge in ice

Beaver at plunge hole, with ice on its head

Muskrat at plunge hole. Note acorns it was eating.
But those few weeks have made all the difference. Although we still have cool days and cold nights, the ice has pretty much flown the coop. Warming days coax beavers and muskrats out of their nocturnal habits to enjoy some sunshine.

A beaver at the last of its winter food cache of submerged branches

Muskrat enjoying spring and a marsh meal

And now that warm spring breezes are sweeping last year's tenacious leaves out of the oaks, migrant birds are heading north. Some will stay with us, others will just pass through on their way to higher latitudes. Either way, spring is the time of great awakening in our region, when the solitude of winter woods is broken by the chirping, peeping, quacking, trilling, honking, and warbling of birds in the trees and on the water. Redwing blackbirds. Belted kingfishers. Tree swallows. Ducks of many persuasions... mallards, ring-necks, blacks, pintails, teal, mergansers, wood ducks, and more.

Redwing blackbird
Female kingfisher

Ring-necks, Canada geese, green-winged teal
Male wood duck

I've been visiting and enjoying beaver ponds all winter, and have never been disappointed. But there's so much more action now that energetic creatures are returning, eager to bring new generations of life into the world. Competition for territory, food, and mates brings an energy to the pond that is unmatched at any other time of year. It's exciting. The hours evaporate.

So, here's a suggestion. If you're stuck at home with rambunctious kids, or you just need some time away from the tube to reclaim your sanity, take a romp around a swamp and let nature soothe your spirit. Take time to look closely at the little things. You'll wonder where the time went.

Beaver-chewed American Elm

Sunday, March 8, 2020

“Lost Forests” film at CT Conservation Conference

The 36th Annual Connecticut Land Conservation Conference takes place at Wesleyan University on Saturday March 21, 2020. Among the many other scheduled speakers and presentations, we will be showing our film “Lost Forests of New England”. As usual, the screening will be followed by a Q&A session with old-growth forest expert Bob Leverett, botanist and big-tree hunter Jared Lockwood, and filmmaker Ray Asselin.

Pre-registration will ensure you a seat for the sessions of your choice, and can be done online here.

If your organization would like to host a screening of one of our films in central New England, email me (see Contact page).

3/10/20 Update: Due to the Corona virus scare, the convention has been postponed.

Friday, February 7, 2020

High Class Sassafras

Forester and ox-team logger Tom Jenkins of Blue Dog Forestry in Westhampton, MA, recently sent photos of some incredible sassafras trees (Sassafras albidum). They're beautiful; arrow straight, and taller than any I've ever seen. I suspect it was a slow day for Tom; probably for his own amusement he wanted to find out just how quickly I'd jump to come see these giants.
Sassafras   (Tom Jenkins photo)

I immediately contacted my expert tree-measuring cohorts from the Native Tree Society, Bob Leverett and Jared Lockwood, to have them accurately determine the trees' height using laser instruments. Bob was not feeling well and was unable to make it, but Jared and I were on site the very next day.

After meeting Tom at the home of the landowner, a short walk put us in a small gully with a running stream flanked by grand old sugar maples, black locusts, ashes, bigtooth aspens, elms, basswood, and twenty-four to thirty super sassafras. This early February day was chilly and mostly overcast, and devoid of green foliage. But there was an unobstructed view of the trees, from the ground to the treetops; that would make Jared's task of measuring the heights a fairly simple one.
Streamside Sassafras Stand

So, just how tall are these new Massachusetts state champions-to-be? Well, hold on just a minute. Let's first review some sassa-facts.

Sassafras in History

Before Europeans settled here, 16th century explorers scoured the coastal forests for highly valuable sassafras, which Nicholas Monardes, a doctor in Seville, had declared to be a cure for all manner of ills: pain, colds, rheumatism, even syphilis, which was a problem for folks across the big pond (we won't elaborate further). During the colonial era, tons of sassafras were shipped to Europe. Tobacco was a leading export, but sassafras was right up there too. Unfortunately, it was the tree's roots that were needed, so a given tree's medicine could only be harvested once, leading to a great reduction in the number of trees to be found. Eventually, the curative powers of sassafras were found to be lacking, and demand for it fell.

Sassafras was also a spicy flavoring agent for root beer, candy, and other foods, as well as fragrance for soaps and perfumes. Southerners were fond of chewing on its tasty roots. In one of its famous southern culinary roles, its dried, crushed leaves make "filé" powder, used in filé gumbo. The safrole contained in the tree's root bark has been found to possibly be carcinogenic, however, so its use in foods is not recommended.

The wood of sassafras is quite durable in contact with the ground, so it was used for fenceposts, as well as in furniture and shipbuilding applications.

Sassafras Today

Sassafras occurs sporadically throughout the eastern forest, offering a fragrant treat to all who pass by. Scratch a green twig with your thumbnail, crush a leaf, or even crumble a bit of the bark; you'll likely be delighted with the spicy, fresh aroma.

You can recognize the sassafras by its light green twigs, and its three leaf shapes... some are elliptical (1-lobed), some mitten-shaped (2-lobed), and some "ghost"-shaped (3-lobed). Many people find the mitten leaf particularly charming. Curiously, the three leaf shapes are not found randomly distributed on more mature trees. The 1-lobed, elliptical leaf tends to occur at the near and far ends and upper side of a shoot, while the mitten and ghost are most often found more centrally along the shoot, and more often on its undersides, and primarily on younger, vigorous shoots.
1- and 3-lobed leaves
2-lobe mitten
Mature sassafras bark

Generally (certainly at least here in New England), sassafras trees are relatively short, reaching maybe 50 feet to 60 feet or so, often less. Mature trees require ample light, so they tend to be found in forest locations where a canopy disturbance allows sunlight to penetrate below the taller competitor species. The typical sassafras trunk is somewhat contorted, due to the tree's growth response to shifting light conditions. Usually, where you find a larger specimen, you'll find a number of shorter and younger clones nearby, which have arisen from root sprouts.

Come autumn, sassafras foliage can be a spectacular show of fluorescent orange, yellow, and red.

Autumn sassafras
Sassafras Meadow (Jared Lockwood photo)

 Champion Sassafras

Ok, back to our Westhampton superstars. Jared went to work measuring the tallest and largest of the more than two dozen sassafras trees in this grove of beauties. Tom and I assumed supervisory roles, and discussed heady topics of great importance to humanity (well, at least to two of its members). Within minutes we received a shouted report... "they're all over 100 feet tall !". This was incredible. We just don't see straight-boled sassafras trees anywhere near 100 feet tall in these parts. "Wait... this one's 110 feet !".

Then my cell phone rang. It was Bob Leverett. Despite illness, he couldn't stand the suspense any longer... "what's the report??", he queried. When we responded with "they're over 100 feet", I'm pretty sure I heard Bob's head hit the ceiling. "Holy cow! That's incredible!". If you happen to know Bob, you can imagine his excited state.

Wow !!   (Jared Lockwood photo)

Super Sassafras (Jared Lockwood photo)

A few hours later, Jared had finished measuring seven of the very tallest of the bunch. The king rises to 112.0 feet! The greatest diameter-at-breast-height (DBH; diameter at the standard of 4.5' above ground) Jared found is 23.6 inches.

Jared at sassafras blowdown

Sassafras has been found to reach 120 feet in New York state, and top 130 feet in the southern Appalachians, but even in those forests 110 or more feet is super. In New England, it's tremendous.

Jared's careful measurement results so far are as follows:

18.6”   DBH x 111.58’ tall
18.87” DBH x 105.67’ tall
19.17” DBH x 110.75’ tall
19.33” DBH x 112’ tall
20.66” DBH x 109.67’ tall
22.96” DBH x 109.5’ tall x 31.9’ average crown spread (188.6 big tree points)
23.6”   DBH x 106.92’ tall x 26.5’ average crown spread (187.1 big tree points)
"Big tree points" refers to the method of determining champion trees. Points are computed by adding the height of a tree (in feet), its circumference at breast height (CBH) (in inches), and one quarter of its average crown spread (in feet).

The last two trees above will be submitted to the Massachusetts state register of champion trees, and will surely be new state co-champions (sassafras is not currently represented on the list).

Some of New England's forests are slowly recovering from the heavy deforestation of past centuries; where allowed to, they're gaining age, size, structure, biodiversity, carbon storage, solitude, and beauty. But sometimes, even in younger stands there are unexpected gems to be discovered by those with a keen eye. Thanks Tom!

Yours Truly (L), Tom Jenkins (R)
(Jared Lockwood photo)

Tuesday, January 28, 2020

Lost Forests of New England Film Screening in Keene, NH

The Harris Center for Conservation Education, the Monadnock Conservancy, and the Keene State College Film Society will host a screening of our film Lost Forests of New England on Thursday, January 30, 2020, in Keene, NH. The event will be held in the Putnam Theater, at the Redfern Arts Center of Keene State College at 7pm, and is free and open to the public.

After the film, old-growth forest expert Bob Leverett of the Native Tree Society, ecologist Tom Wessels, botanist Jared Lockwood, and filmmaker Ray Asselin will conduct a Q&A session to further help attendees understand the complexities and importance of the remnant old growth forests of the region.

More info here .

Monday, January 20, 2020

The Value of Large Trees in Carbon Sequestration

The topic of climate change is a hot-button issue today. Carbon sequestration has been identified as the tool of choice to reverse the negative effects of a warming climate. The following article by old-growth forest expert and author Bob Leverett, and Ray Asselin, discusses the best tool in the toolbox.

What is Carbon Sequestration, and Why Do We Need It?

Earth's atmosphere contains gases, primarily oxygen and nitrogen. But there are small amounts of other gases, including carbon dioxide (CO2), which is designated as a “greenhouse” gas. Why “greenhouse”? Because it acts like the glass of a greenhouse, in that it allows solar radiation to penetrate through the atmosphere to heat Earth, but does not allow heat to radiate back into space. This causes a rise in surface temperatures on the planet, resulting in climate change. 

The gradual rise in temperatures causes a cascade of ecological and environmental problems, such as polar ice cap and glacial melting (and therefore rising sea levels), desiccation of forests, changing forest species composition and distribution, etc. With the rise of industrialization and burning of fossil fuels, carbon dioxide concentrations have increased substantially in the atmosphere.

We must find ways to reduce the level of CO2 in the atmosphere in order to reverse negative climate change effects. That's what “carbon sequestration” is all about. The carbon in carbon dioxide must be recaptured, or sequestered, from the atmosphere and stored long-term on Earth. How on earth (pardon the pun) can this be done?

Trees Sequester Carbon

Carbon is a major constituent of plants on land and in the oceans, because their process of photosynthesis uses carbon dioxide, water, and solar radiation to grow their tissues. In particular, woody plants such as trees contain relatively large amounts of carbon. 

So, if we grow more trees, and let trees grow larger, they will sequester greater amounts of carbon in their wood, drawing CO2 out of the atmosphere. In theory, it's a very simple solution, and requires virtually no effort or great cost... just let more forests grow, and grow to old age! In reality though, we regularly harvest trees to satisfy our demand for wood and paper products. As long as wood products remain intact, the carbon they contain is still stored, although there is a significant loss of carbon in the harvesting process. But as they decompose (or are burned), their carbon re-enters the atmosphere. To reduce atmospheric CO2, we have to sequester much more carbon (principally, in the form of trees) than we allow to enter the atmosphere. There is no method more effective, less expensive, and quicker than letting trees already growing get progressively larger. Planting lots more trees is also helpful, but not nearly as effective in the short-term. It is becoming clear that large trees play the major role in sequestering carbon; here, we will look at carbon storage in large trees by focusing on big eastern white pines (Pinus strobus). But first, it is worthwhile to briefly pay a visit to New England past.

Primeval Eastern White Pines


Our New England woodlands are not associated with exceptionally large trees like those in California and the Pacific Northwest. But it wasn’t always this way. In the 1600s and 1700s, chroniclers described a landscape that featured giant eastern white pines, some claimed to be well over 200 feet in height, and up to seven or more feet in diameter. Romantic accounts exist of pines in Maine and New Hampshire reaching astounding sizes and achieving great ages, and of course, the species was famous as a resource for British ship masts.

The great whites became the replacement for the exhausted European Riga Fir (actually Scots Pine, Pinus sylvestris L.) used by the King’s Navy to hold up the sails of its warships. Trees of a certain size and shape were reserved exclusively for the Royal Navy. They were often marked by three slashes with an ax, called the broad arrow mark. In fact, the white pine was the foremost symbol of the region’s original virgin wilderness, but the time of those legendary pines came and went. 
Ancient Eastern White Pine

The intense lumbering of the region, especially in the 1700s and 1800s, depleted the rich old growth forests. By the early to mid-1900s, New England’s recovering woodlands consisted of younger trees, and it is safe to conclude that, based on what they saw, people’s perception of what the white pine (or any species for that matter) could achieve in size was greatly scaled down.

Today’s forest historians largely relegate chronicler accounts of giant pines to the pages of history. This is evidenced by descriptions of the species in popular 20th century field guides, which often listed the white pine as a tree capable of surpassing 100 feet in height, but commonly reaching only 75 to 100. More descriptive authors like Donald Culross Peattie reminded us of the historic heights, but most of these authors made it clear that such giants no longer grow. In fact, the stature of the species had been so diminished in the public eye that one hiking guide to trails in New Hampshire described a white pine, stated to be 125 feet tall, as exceptional. The guide was written in the mid-1980s, even though many pines then were already above that height, with specimens reaching to 150 feet and more in iconic places like Cook Forest and Hearts Content in western Pennsylvania, Hartwick Pines in Michigan, Pack Forest in the Adirondacks, and the Cathedral Pines in Cornwall, CT.

Further diminishing the growth potential of the species in our eyes today, forest managers keep woodlands artificially young, largely for short-term economic reasons. Yet despite this reigning management paradigm, the eastern white pine is re-emerging to reclaim some of its former glory as our tallest eastern species.

The Return of Large White Pines in the Landscape


In some Massachusetts conservation areas, parks, state forests, and private lands, white pines are starting to once again reach impressive stature (often on recovering old fields). As of 2019, Mohawk Trail State Forest is home to at least 146 white pines reaching to over 150 feet in height as confirmed by the Native Tree Society; 25 of these surpass 160 feet, and two of those exceed 170.
Saheda (center)

One of the most impressive pines is a 180- to 200-year-old tree growing in western Massachusetts. It is presently 172.4 feet tall and has a circumference (at breast height) of 12.2 feet. It is an example of a class of emerging modern-day super pines that offers us an opportunity to better understand the long-term carbon storage capacity of very big trees and their rates of sequestration from youth to maturity and beyond. Our huge pine, which we named “Saheda”, is neither a young tree nor what we would classify as old growth. Based on the longevity of the species, it may have another 100 years or more of life.

How does a pine in Saheda’s size and age class perform in terms of its rate of carbon sequestration from youth until the present? Many may think that the growth performance of trees like Saheda is well understood, but white pines of its age and stature are rare today, since the species is typically harvested (at least in the Northeast) at 60 years or less. The prevailing belief in forest management has been that trees much over 100 years in age have plateaued in their annual growth, and are stagnant or senescent. This belief has led to a gap in our understanding of the growth performance of large dominant trees in the Northeast.

The calculated trunk volume of Saheda is 864 cubic feet (ft3). Its limbs add approximately 15.4% of the trunk’s volume, giving a trunk and limb total of 997 ft3 (the 15.4% is from a US Forest Service biomass model that we use). In today’s management paradigm, pines one third to one half this size are considered large. In fact, pines with diameters over 18 inches typically fall into the large category. By contrast, Saheda’s diameter is 46.6 inches, making it a super-pine. 
Beyond the simple dimensions of diameter and height, there is volume. Determining the trunk, limb, and root volume of a tree is important because, from it, we can calculate the amount of carbon sequestered in the tree (and from that, the equivalent amount of CO2 removed from the atmosphere).

Those who favor using forests as the climate solution are divided on strategy. Some advocate concentrating on young forests, believing that they grow fastest and can sequester the most carbon in the near future. Many in this camp also believe that forests hit growth plateaus at 70 or 80 years. This faction is prone to making statements like: younger forests have a higher rate of carbon sequestration than older ones do. They seldom specify the dividing point between young and old.

A second group believes that older forests should be left to grow. Some believe this primarily because of the great carbon stores the old forests presently hold. Releasing large amounts of carbon by harvesting would work against the sequestration objective. Some of the second group believe that annual growth in the older forests exceeds that of their younger counterparts. With due respect to both groups, the truth lies somewhere in the middle, but favors the arguments of the older-forest champions over those of young-forest advocates, and substantially so (if "young" forests are those in the age range of 0 to 50 years, a not untypical age for stand rotation).

What follows is a discussion of the role large dominant eastern white pines can play in productively sequestering carbon for beyond a century and a half.

The Efficiency of Large Trees in Sequestering and Storing Carbon 

A stand of white pines on a good growing site will gain carbon most rapidly between 40 and 80 years. However, growth from 80 to 120 years will outpace growth from 0 to 40 years. Growth from 120 to 140 years will outpace growth from 0 to 20. Beyond 160 years, annual sequestration in the living pines drops more quickly, partly due to continued self-thinning of the stand. However, other species progressively fill the gaps left by dying larger pines. Additionally, after logging, the soil releases carbon from the root systems for 10 to 30 years, partially offsetting gains from new growth. Consequently, for between 140 and 160 years, annual sequestration likely outpaces that of the first 40 years. So, how does this information impact the arguments given for young versus old forests?

Young White Pine Stand
One reason the older forest group’s position has gained ground among the scientific community is the high performance of the dominant trees. They continue to add carbon at accelerated rates for decades longer than commonly realized. Ordinary stand rotations of 50 years or less do not allow managers to assess the performance of really big trees. 

It is often stated that young, vigorously growing forests are the most effective at sequestering carbon. That seems intuitive, doesn't it? One can rather easily witness the rapid growth taking place in a sapling from year to year. Young trees seem like they’re on steroids. Surely, they can outperform an old, hulking, grandfather of a tree. Or can they? An 8-foot tall pine sapling might put on another foot of height in the next year; as a percentage, that's an impressive 12.5% growth in height. But in terms of actual volume, that doesn't amount to very much wood. The growth looks impressively fast, but there's still not a lot of wood in a 9-foot tall pine sapling. A larger tree can add much more volume of wood in a year (and therefore sequester more carbon), but we don't tend to notice it because most of the growth is occurring aloft, and is spread over a large trunk diameter. A 1/8-inch increase in the radius of a 3-foot diameter tree represents far more wood than a 1/8-inch increase in the radius of a 1-inch diameter sapling.

So, just how effective is a huge pine like Saheda (mentioned above) in sequestering carbon compared to younger/smaller pines? We have performed considerable, accurate measurements of white pines, and careful calculations of their trunk volumes. Here, we will offer generalized results for the class of largest pines.

Imagine the space on the ground under Saheda's crown. If we were to replace Saheda with 20-year-old pines, approximately 27 would fit in the same space; but it would require about 402 of those young pines to equal Saheda's volume and carbon content! This would require ground space equal to 73% of an acre. It is apparent that large trees are efficient utilizers of ground space, since most of their bulk is aloft. In addition, young trees can grow beneath their crowns. That is a win-win situation. 

Grand White Pines

A tree does not add a fixed volume of wood to its trunk and limbs each year. As it grows larger, its greater foliage area carries on more photosynthesis, thereby creating a greater volume of new wood. So, for a period of many years, as it grows larger, it increases its volume faster, and consequently outperforms young trees in sequestering carbon. Eventually, an older tree's growth will slow down. But its total carbon content is still there, stored in its trunk, limbs, and roots. What's more, when that huge tree comes crashing down in the wind and is lying on the forest floor, its large carcass will take much longer to decompose than a small log would, so its carbon remains stored longer, not released to the atmosphere.

So, how might a Saheda-sized pine gain trunk volume across a span of 180 years? A new stand development model we are employing gives the following cubic-foot gains at 20-year periods for this largest size class pine. Between 20 and 40 years, the largest class pines gain 56.5 ft3 of trunk volume on the model. Between 140 and 160 years, the amount is 97.9 ft3. Trunk growth stays above the first 35 to 40 years up to an age of 180. It is abundantly clear that most of the fast volume growth for this size class pine occurs after 40 years. If that were not the case, the tree would not have achieved such a huge size.

What's the Lesson Here?

There is great concern about climate change these days. Increased atmospheric CO2 has been identified as one of the main culprits, so we must take steps to reduce it. Harvesting trees on short rotations (e.g. 50 years) is counterproductive for climate change resolution. Managing for large tree size is an excellent strategy, as is retaining as much carbon on the forest floor as possible. Removing all downed coarse woody material from the forest floor during harvest operations, or chipping it up on site, releases stored carbon more rapidly. It also invites drying of the forest floor and introduction of non-native invasive plants, and compromises wildlife habitat. 

Carbon-rich Coarse Woody Debris

And, certainly, burning trees as a biomass fuel is counterproductive, by not only removing still-growing carbon-storing plants, but putting their carbon directly back into the air. Some argue that those removed trees will be replaced by vigorous young trees that will quickly store carbon... yes, they will; but it has now been shown that those vigorous young trees can't come close to matching the carbon content of the large trees they're replacing, at least for many, many decades. And in the meantime, the carbon of the burned trees is making the problem worse.

Since we don’t have much time to make headway in getting CO2 emissions under control, the most straightforward and easiest solution, especially in our public forests, is allowing the trees to grow to their maximum sizes. Nothing else will be as effective, less costly, more ecologically beneficial, or easier. One approach to doing this is explained in the concept of “Proforestation”, which basically advocates letting as many of our forests as practicable grow without interference. 

More information can be found at