March 2020.
It is the last day of February, albeit a leap year, as I write this. Now is time to watch for signs of spring if you haven’t already begun. Tree silhouettes show expanding buds and some maples are already in flower. The mild winter has encouraged early bud expansion.
As you walk take time to look at tree bark. I’ve been drawn to sycamore bark on many occasions, remarking to students that the colors and textures would make lovely tapestries. About five years ago, I photographed a tree at the Bordentown Beach. When I examined the photograph at home, I noted how bark patches detached revealing other colors and textures. This was an ‘A Ha’ moment for me, and began an exploration of bark, further stimulated by a collaboration with Patricia Bender, a photographer, that led to ‘The Wisdom of Trees: The Art and Science of Trees, an Exhibit‘, at the Tulpehaking Nature Center until July 19th.
The bark of trees is amazingly varied between species, with age, and even from top to bottom of the same tree.
As I endeavored to learn about tree and bark growth, I discovered several books about trees, but one by Michael Wojtech* provides interesting insights about bark, the layer external to the wood and vascular cambium. For example, there are six distinct pattern types. He illustrates how each originates. Tree bark is complex and there are a dozen terms just for bark layers.
I’m not completely there yet, but it is intriguing to understand how, as a tree lays down wood layers and expands in diameter and circumference, the resulting stresses cause the outer bark layers to create species- and age- specific patterns and textures. How this happens is amazing to me.
However, bark is more than a layer that serves to protect the living / functional cells of a tree. Take a close look; the black locust trees (Robinia pseudoacacia) near the Tulpehaking Nature Center are a good place to begin. Notice the varied colors. Bark is habitat for many other organisms, some of which are visible. These include lichens, mosses, liverworts, fungi, protists such as slime molds (mostly invisible), and even animals. Of the last, some may be obvious such as spiders and ants, but if the bark is loose, a bat may find the space a suitable daytime roost. In some bark, you might find rows of holes made by sapsuckers. These holes cause sap to flow, and insects attracted to the sap and the sap itself are food for this woodpecker.
There are myriad connections. A forester who visited the exhibit noted that recent data suggests that the bark biome is analogous to the human gut micro biome. This doesn’t even address the root connections between trees and those with fungi, called mychorrhizae.
While much of a tree’s bark and wood is composed of nonliving cells, the living cells in the sap wood (e.g., storage cells in rays), vascular cambium and cork cambium, and the active phloem all require oxygen and to get rid of carbon dioxide, the waste product of respiration. Exchange of oxygen and carbon dioxide occurs through areas of porous tissue with large spaces between cells, called lenticels. These may be horizontal in birches and cherries, or vertical in young pin oaks; in other species or as trees age, they’re at the base of cracks in the bark. There are exceptions. Beech bark is thin and does not peel, crack, or become furrowed. In this and other similar species, the dead bark cells that slough off are replaced and the bark maintains a similar thickness, presumably allowing gas exchange. Interestingly, some barks such as that of beech, permit photosynthesis and, if the outer layer is scrapped away, the tissue beneath is green.
Elegy to Trees
In my short lifetime, geologically speaking, there have been marked changes in our forests. I was at the tail end of the loss of American Chestnut. The chestnut blight was discovered in New York City in 1904; by 1950 billions of trees had died and the species was virtually eliminated. I recall my dad finding a few burrs on a small tree in western Massachusetts. On the forested hillsides of the Abbott Marshlands there are a few remnants, growing as root sprouts. The one shown is about 6 inches in diameter, and is the largest I’ve found.
Other tree species that are nearly gone from our local woodlands, lost during my lifetime, include American Elm (Ulmus americanus, due to Dutch Elm Disease), Canadian Hemlock (Tsuga canadensis, due to the Wooly Adelgid), and white and green ashes (Fraxinus americana, F. pennsylavanica, due to the Emerald Ash Borer). Our forests are less diverse without these species. Another looming threat is the Spotted Lantern Fly. One can only speculate as to what ecosystem elements have been lost.
Other threats to our woodlands include invasive species, including Garlic Mustard and Japanese stilt grass that affect the establishment of woody seedlings. There is also climate change that can affect the timing of spring bud growth, tree flowering, and emergence of pollinators.
Regardless of these and other changes in our woodlands, there is much in the Abbott Marshlands to enjoy (and to learn) about trees. Spring and fall foliage color displays are uplifting. There are some species, such as Chestnut Oak (Quercus prinus) and Canadian Hemlock, that are found primarily in one location (Bordentown Bluffs), while others, such as Tulip Tree and Red Maple (Acer rubrum) are much more wide spread. I can only wonder at a species range of tolerances – red maples, for example, can be found in swamps or on the Bordentown Buffs.
As for me personally: I am now more challenged to identify trees by their bark (leaves are often easier). I also look more closely at bark patterns and textures and am awed by the beauty, complexity, and evolutionary history of what I see. I am reminded, too, to photograph tree silhouettes before they are obscured by leaves!
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All photographs are the property of the photographer, MA Leck; please address questions to: [email protected].
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*Bark book: Wojtech, M. 2011. Bark: A Field Guide to Trees of the Northeast. University Press of New England. Lebanon, NH.
Tree identification:
Martine, C.T. 1998. Trees of New Jersey and the Mid-Atlantic States. New jersey Department of Environmental Protection, Division of Parks and Forestry, Forest Resource Education Center, 370 East Veterans Highway, Jackson, NJ 08527 (732 928 0029). Available as a free pdf file: https://rucore.libraries.rutgers.edu/rutgers-lib/54233/.
Sibley, D.A. 2009. The Sibley Guide to Trees. Alfred Knopf, New York.
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Some Quotes:
David Allenl Sibley (From a Parade interview). “You’ve long been known as a bird man. What moved you to explore trees? “I’ve always noticed them, but most of the time they were just what was holding up the birds. Still, as a birder, you eventually develop a sort of sixth sense about trees: recognizing the patterns in the vegetation and associating it with certain species. “)
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Never say there is nothing beautiful in the world anymore. There is always something to make you wonder in the shape of a tree, the trembling of a leaf. Albert Schweitzer
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For in the true nature of things, if we rightly consider, every green tree is far more glorious than if it were made of gold and silver. Martin Luther
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A few minutes ago every tree was excited, bowing to the roaring storm, waving, swirling, tossing their branches in glorious enthusiasm like worship. But though to the outer ear these trees are now silent, their songs never cease. John Muir
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No traveler, whether a tree lover or not, will ever forget his first walk in a sugar-pine forest. The majestic crowns approaching one another make a glorious canopy, through the feathery arches of which the sunbeams pour, silvering the needles and gilding the stately columns and the ground into a scene of enchantment. John Muir
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Give fools their gold, and knaves their power; let fortune’s bubbles rise and fall; who sows a field, or trains a flower, or plants a tree, is more than all. John Greenleaf Whittier
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The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. Thomas Jefferson
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The vegetable life does not content itself with casting from the flower or the tree a single seed, but it fills the air and earth with a prodigality of seeds, that, if thousands perish, thousands may plant themselves, that hundreds may come up, that tens may live to maturity; that, at least one may replace the parent. Ralph Waldo Emerson
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The tree I had in the garden as a child, my beech tree, I used to climb up there and spend hours. I took my homework up there, my books, I went up there if I was sad, and it just felt very good to be up there among the green leaves and the birds and the sky. Jane Goodall
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I often lay on that bench looking up into the tree, past the trunk and up into the branches. It was particularly fine at night with the stars above the tree. Georgia O’Keeffe
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As soon as a redwood is cut down or burned, it sends up a crowd of eager, hopeful shoots, which, if allowed to grow, would in a few decades attain a height of a hundred feet, and the strongest of them would finally become giants as great as the original tree. John Muir
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You can’t be suspicious of a tree, or accuse a bird or a squirrel of subversion or challenge the ideology of a violet. Hal Borland
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One of the best ways to see tree flowers is to climb one of the tallest trees and to get into close, tingling touch with them, and then look broad. John Muir
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Every crag and gnarled tree and lonely valley has its own strange and graceful legend attached to it. Douglas Hyde
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What is the purpose of the giant sequoia tree? The purpose of the giant sequoia tree is to provide shade for the tiny titmouse. Edward Abbey
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Just touching that old tree was truly moving to me because when you touch these trees, you have such a sense of the passage of time, of history. It’s like you’re touching the essence, the very substance of life. Kim Novak
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I had actually finished the manuscript of ‘The Wild Trees’ and turned it in to Random House when all of a sudden word came. Michael Taylor and his colleague, Chris Atkins, another explorer, have just knocked one out of the park. They found the world’s tallest tree. The tree is named Hyperion, 379.1 feet tall. Richard Preston
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A tree’s wood is also its memoir. Hope Jahren
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As the poet said, ‘Only God can make a tree,’ probably because it’s so hard to figure out how to get the bark on. Woody Allen
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Until you dig a hole, you plant a tree, you water it and make it survive, you haven’t done a thing. You are just talking. Wangari Maathai
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