And I see your True Colours Shining Through

My favourite season tends to depend on my mood, but most often, my answer is autumn. It’s refreshing, a cool breeze washing away the heavy haze of summer. Paradoxically, it also feels warm, like shrugging into your favourite coat as you catch a whiff of someone’s wood stove in the crisp morning air.

I think it’s the colours of fall that give the days their warmth. The cool greens slowly fade into yellows, golds, russets and umbers. The forests are suddenly ablaze with a riot of hues.

In the boreal mixedwood forest where I live, the dominant colour is yellow. The poplars and birches sparkle with it against the sapphire September sky. Still, if you look closer to the ground, you can find a little more variety. The dogwoods (Corylus stolonifera) go purple, their leaves a lovely compliment to their reddish branches. The mountain maple (Acer spicatum), like the one pictured above, show quite a bit of variation, ranging from a pale yellow in individuals that are growing in the shade to brilliant orange and deep red for those lucky shrubs that are exposed to full sun.

But, where do these colours come from?

To a certain degree, they’re always there, hiding just below the surface, waiting for their curtain call. New, functioning leaves are full of chlorophyll, a brilliant green pigment that is packed into structures within the cell appropriately known as chloroplasts.Ā  These are the food factories for the tree, working throughout the growing season to transform carbon dioxide and sunlight into nourishing sugars via photosynthesis that are then funnelled into the rest of the tree. During this period, chlorophyll is constantly being degraded and replaced, keeping the leaves a brilliant green, overshadowing any other colours lurking within.

However, as the days become shorter and the sun’s intensity begins to wane, these factories shut down, using up their last stores of chlorophyll until there’s nothing left. Once the green is gone, the veil is pulled back giving other the hues a chance to shine. Carotenoids, a pigment that also plays a role in photosynthesis, remains, painting the trees with bright yellows and oranges. Some leaves also contain pigments known as anthocyanins, a watery dye that stains leaves with intense washes of reds and purples.

Just how bright and varied the fall palette is depends a lot of the weather. Warm, sunny days, followed by cool, but not frosty nights gives the leaves a chance to build up a lot of sugars and trap them within their cells. High sugar levels often results in greater amounts of anthocyanin, yielding more reds and purples, adding to the variety in the forest.

This year’s fall in the north woods has been just the kind we need for a spectacular display and the trees have not disappointed. Every day for the last few weeks, I’ve watched in awe as more and more of the canopy sparkles with colour, filling in the autumn landscape, a spectacular display against the clear blue skies.

Still, all good things must come to an end. Eventually, the nights get too cold and the days too short, signalling to the tree that it’s time to lock down for winter. The veins bringing moisture to the leaves close up and the branches seal over, cutting off the leaf’s lifelife. The late October winds howling off the lake will tear the foliage from their bases, sending them fluttering to the forest floor and returning their nutrients back into the soil to feed next year’s crop. However, those days are a little ways away, and in the meantime I plan enjoy nature’s yearly blaze of glory for as long as I can.

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13 thoughts on “And I see your True Colours Shining Through

  1. Your beautiful image oozes warmth and sunlight, the only chill coming from knowing what the colours portend. The yellow is slowly being stripped from the trees here now and soon the forest will be dark green and brown, the colour remaining only in the crispy carpet. My husband brought an orange currant (I think) leaf home from his walk the other day that had a green stripe through it. A twig had been resting on it, I expect having landed there shortly after the leaf fell from the tree, sheilding that portion that it covered. When Jim removed the twig the stripe was revealed. Do you know how the lack of light (I presume) beneath the twig allowed the leaf to remain greenish beneath? Is it the lack of sunlight or the protection from frost? The leaf is still somewhat flexible and I have placed it in the freezer with the intention of preserving it somehow so that once I get an explanation I will be able to take it to school to display in my library.

    • Hi Cindy!
      I’m glad you liked the image. It’s actually one I made a few years ago. I’ve always been happy with how it turned out. Sounds like your fall is a little ahead of hours. We should have leaves for a few more weeks, assuming the winds down blow them all off.

      As for the current leaf, I can really say for sure, but my guess is that by covering that area, the twig prevented the cholorplasts beneath from sensing the changing day length and they continued to produce chlorophyll as though it was summer. It also likely protected it from the frost too, keeping the cells intact. It’s just a guess, but an educated one šŸ™‚

      You should be able to preserve it just by pressing it between wax paper in a heavy book. I’ve done that will all sorts of leaves to make arrangements and they will keep pretty well. Another way to do it, is to rub the leaf with glycerine. That will keep it supple. It’ll fade eventually (unless you keep in the book all the time), but it should keep for at least a few years.

      Enjoy what’s left of your fall colours!

    • I had one more thought, Cindy. It’s unfortunately possible that by putting the leave in the freezer, it might have destroyed the cells (like a hard frost) and it might not stay the same colour once you take it out. Sorry to be the possible bearer of bad news šŸ˜¦

      • Hello to you both, I winced at your mention of “freezer” and agree, it’s not a good prognosis… But, I do have a (slightly tweaked) suggestion for preserving leaves.
        Every fall, when we were little, my mom would help us wax our most colourful fall treasures. The key to this was having the iron just barely hot enough to melt the wax once you’d sandwiched the leaves between layers of waxed paper. Once waxed, she’d protect our art by sealing between layers of sandwich film. The last of these creations still hangs over the kitchen sink: colour diminished, but still beautiful after all of these years. Alas, this won’t be the year to replace it either, as it’s gone from a rather intense Indian Summer last week with Birch, Walnut and Basswood dropping their finery in drifts at the time you wrote this – to October’s debut with single digit temps, rain and a howling wind that tore all weekend at the remaining, predominantly green leaves.
        Br,rr! Does not bode well…

  2. A wonderful ode to autumn, Heather, from the “shrugging into a favourite coat” to the range of rich colours, “yellows, golds, russetts and umbers.” The trees still haven’t turned but I can feel the shift in the air, that wood-smoke scent and crisp morning chill followed by a burst of brief warmth that signals a new season. Thanks for this wonderful description of these coming days.

    • Thanks, Julian. It’s been an usually warm fall here, so it’s only recently that I’ve had to shrug into my favourite coat, still, you’re right about the shift in the air the season brings. An intense wind took care of over half of our leaves a few days ago, but thanks to the wonder of digital photography, I can enjoy them as much as I want. Enjoy your own changing leaves. From your description of Prespa, I would be interested in knowing how it varies from what I know here in Canada. Happy Canadian Thanksgiving šŸ™‚

      • It varies from year to year but we had the first snows on the highest mountain tops last evening. But strangely, after such a hot and dry summer most of the beech and oak trees are still very much green. By now they’ve usually begun their dance of colours and I’d expected it to be a bit earlier this year. My parents in eastern Ontario were basking in hot sunshine wearing shorts in the garden on the weekend while we were lighting the wood stove and gathering in the ripe tomatoes, eggplants and peppers for fear of frost. I thought I was in Greece and they were in Canada! But the unpredictability of weather is sure to be a common theme in our collective future…

  3. Hi again Heather, Laughing (sort of) at my overreaction to the sudden temperature swing last week as it’s been such incredibly gorgeous weather these past few days!

    But I was wondering if anyone else is feeling just a little nervous about the weather’s “mood swings” besides me? Happy Thanksgiving!

    • Hi Deb,
      We’ve had a few temperature swings here too, from very warm (in the 20’s C) to just above freezing. As much as I loved the warm weather, I do worry about the long-term trends. We’re heading into more seasonable weather this coming week.

      Thanks for sharing your leaf preservation techniques. I’ll have to try that sometime. Happy thanksgiving to you too.

  4. Pingback: Flying Away on a Wing and Prayer « The Naturalist's Miscellany

  5. Heather and Deb, thanks for the advice about preserving the leaf. I will know better next time. I was quite worried when I fished it out of the freezer but found that the pattern left by the stick wasn’t completely lost, just turned from green to yellow. You can see it on my Flickr page if you want.

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