On Brightness

Bouleau. This is the French word for birch. I learned it from Bernard and Francine, whom you saw a couple posts back, in New Brunswick…

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This is my favorite tree, up north. We don’t really have them where I grew up, in the woods of north central Texas, which are filled with scraggly oaks and thorny underbrush. Because I cook over a wood fire, when I take the time to make a hot dinner, I always carry dry tinder with me. Down south, I’d often use loosely twisted dry grass… but up here, where the birches grow richly, I never finish a day’s hike without picking up the discarded pieces of birch bark that litter the ground* along my trail, waiting for me to turn their wee carbon bits into a firestarter for my pot.

*peeling birch bark off a live tree is taking off its protective outer layers. Sometimes shreds are falling off already; but if something’s holding on tight, I’d probably look for my tinder from a tree that has already let go. Besides, you can always find enough on the trail over the course of any day’s walk… and if you keep it in your pocket, even if it’s covered in ice, it dries out and warms up for you.

White (or “paper”) birch gets its bright color from a compound called betulin, which is arranged in the cells of the outer bark to reflect the sunlight. Rapid freezing and thawing in winter climates can severely damage a tree; and while some trees compensate with craggy outer layers of dead cells that can crack without damaging anything alive, birch and its smooth-skinned cousin beech have adapted with a surface water can’t seep into, and a light color that reflects away the sun’s heat to help stave off rapid heating on one side of the tree, during the day. (It doesn’t always work; you’ll find quite a few trees with deep, vertical “frost cracks”. Over the course of ensuing winters, water will continue to work its way into these crevices, then freeze, making them even wider and contributing to a gaping wound that can foster rot, and if it becomes too deep, eventually lead to the tree’s tragic demise. Alas.)

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In addition to being a well-colored defence mechanism, betulin is a waterphobic (water-hating) particle, and incredibly flammable, which means that birch bark is waterproof, and particularly fine for starting everyone’s fires.

In December, when I had my wood stove, I’d hike until I found a fallen birch tree, then set up camp nearby and make my fire with its broken branches. This also means I never have to carry a saw; because dry wood snaps easily. Anything I can’t break with my hands, or by leveraging between two trees, probably doesn’t need to be in my tiny cookfire anyways. (Even if the fire involves heating up steak bits, like this one did. This was a very, very good day.)

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Now that I’ve ditched my wood tent stove, for weight in steeper terrain, I mostly go without making hot dinners; or occasionally, I’ll make a campfire in the snow, but the process of keeping a lookout for dead birch trees is still the same. Dead standing birch trees, or loose limbs that have spent the winter on the ground, will often have water trapped inside their hydrophobic bark and be soggy, rotten wood. Whole fallen trees tend to have limbs that are dried out perfectly, and are what I look for when I’m looking to have fire at my campsite.

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To the left, live birch. Nice, cute. In the middle, standing dead birch. Good for harvesting bark, but soggy wood inside. Will scrape apart in your hands. Bad for my fire, good for birds to live in. See the hole in the top of it?

Trees deal with cold differently than us humans. They are made of plant cells, which are mostly water, and get their structure from a stiff cell wall. If the water in the cell freezes, it will often make sharp edges, which will break this cell wall and destroy the cell’s ability to hold a structure. (This is why your soft plants get all wilty and sad if you freeze them. You’re breaking down their cell walls with stabby ice bits.)

Since they are stuck in one place, have no hands, and have had thousands and thousands more years to evolve… When winter is imminent, cold-tolerant trees have mastered the ability of moving water out of each individual plant cell, and into the spaces between the cells. This leaves a sort of thick, sugary gloop inside their cells, which does not freeze nearly as easily as good ole pure H2O.

The water between the cells, in the meantime, is ultra-pure. Although there are no additives in this bit, water needs something to start freezing into ice on. Usually, dust does the trick, or even small vibrations in the water. However, in the intercellular spaces in a tree, there is usually nothing to start this process.

**You can observe this lack of freezing, sometimes, with distilled water that will remain unfrozen in the cold until you start shaking it. With liquid that has no condensation points (no dust, very still) you, too, can be like a tree, and cool water to well below freezing point and have it remain liquid. Google “supercooled water.”

Good thing trees are so smart and highly evolved, amirite.

Ok. But the only reason I know the word bouleau is because sometimes these birches do something odd. Trees droop when they’ve got snow on them. Young birches in particular are very flexible. But every now and then, as I’m walking through a stretch of forest, I’ll pass a birch tree or two that looks like a limp spaghetti noodle. Its entire head will be embedded in the snow. If it is just snow weight, the entire trunk should not look like a wet rag, and some of the trees next to you should be this sad, too. What the heck, tree? Aren’t you all lignified and stuff; why are you acting like grass; are you really dead, or is this some trick to deter the tree-eating creatures that stalk the woods in the winter. Why.

So after Bernard told me he had been a logger, back when logging involved a horse, chains, and a single tree… I learned from him many things, and then asked about the droopy trees. You can see them on the IAT in New Brunswick, all chopped up where they’ve arched down into the snowmobile tracks and frozen to the ground there; and then they are in the way, and people come and cut them away so they can ride their snowmobiles, not into tree branches.

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He took me outside, and pointed to a mature birch tree standing straight and tall in his yard. “See that?”

A huge ice storm had come, one winter, and he and Francine had noticed the tree was drooping over, with its head on the ground. Aha, it is broken, they said. We will cut it down in the spring. (This is what has happened with most of the droopy birches I’ve passed on the trail.) But then spring came… and the snow holding its crown melted, and the tree popped back up.

Like daisies.

I don’t know why. Maybe it has something to do with the supercooled water actually freezing, by accident, and forcing the tree over… Except since birches are flexible, or deal with water differently, they can survive? This is a mystery. Someone knows. It’s like the exploding trees in the winter in Virginia and Maryland. Perhaps this also has to do with water expansion, and unluckily placed condensation nuclei.

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There were splinters everywhere! And a tree, flung across the trail!!

Anyways,

Word on the google is that, in English, the words “birch” and “bright” come from the same linguistic indo-european base.

Keep being flexible, kids. And remember, if you’re scared of tree-eating snow monsters

or got hit by a massive storm of freezing cold, and then something went terribly wrong

so now you are upside-down with your head in the snow…

You don’t actually need to destroy the things with your chainsaw. Just wait. Spring is coming. It’s ok. You’re flexible.

Sometimes, all you need is time.

-sail

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2 thoughts on “On Brightness

  1. Interesting to know what is going on with the trees in winter. I had no idea and actually never thought about it.Thanks for the insights!
    PS: In German the tree is called ‘Birke’.

    Like

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