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

 

Introduction

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




 

 

 

Conclusion

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.

 

Photo3
 

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 https://bit.ly/2L434Ln