I’ve been looking at the changing leaves lately and thinking about something I’ve known for years but seldom give much thought to. Why do leaves change color in the fall?
I know the scientific explanation, or at least enough of it to understand what’s happening. But knowing why something happens doesn’t necessarily make it any less interesting to watch.
Every autumn, trees that have spent months looking more or less the same begin doing something different. A maple that hardly attracted a second glance in July suddenly becomes the most noticeable tree in the neighborhood. The leaves turn yellow, orange, and red, sometimes all on the same branch, while the tree next to it seems perfectly content to remain green a little longer.
And then there are those trees that simply turn brown and drop all of its leaves.
What I find particularly interesting is that those autumn colors have been inside the leaves all along.
During spring and summer, chlorophyll gives leaves their familiar green color. It’s also what allows them to capture sunlight and produce the food a tree needs to grow. But chlorophyll is so abundant during the growing season that it hides other pigments already present in the leaves.
When the days grow shorter and the tree begins preparing for winter, chlorophyll production slows and eventually stops. The green fades, and the yellows and oranges that were there all summer become visible.
The reds are a little different. Many trees actually produce red pigments called anthocyanin during autumn. Sunlight, temperature, and the sugars remaining in the leaves all play a part in how those colors develop. This helps explain why one autumn can be spectacular while the next seems rather disappointing.
Apparently, trees have good years and bad years, just like the rest of us.
Of course, the whole business is about survival, not decoration. The trees aren’t changing colors for our benefit. They’re conserving resources, recovering nutrients from their leaves, and preparing for the colder months ahead. The leaves have finished most of the work they were meant to do, and eventually the trees will let them go.
I wonder how many people think about any of this when they’re out admiring the fall foliage.
Probably not many, and there’s no reason they should. A person ought to be able to enjoy a beautiful tree without giving herself a lesson in botany.
Still, I’ve always enjoyed knowing a little about the things I photograph. When you’ve spent years looking at the natural world through a camera, you begin noticing details that might otherwise escape your attention. The shape of a leaf, the way sunlight passes through it, the differences between one tree and another.
I’ve noticed that a single leaf can sometimes be more interesting than an entire tree. One might be almost completely yellow except for a narrow green strip along its veins. Another will be red around the edges and orange in the middle. Occasionally, you’ll find one that seems unable to decide what color it wants to be.
And if you pick up a fallen leaf and examine it closely, you’ll often discover that what appeared to be one color from a distance is actually several.
I suppose that’s one reason I’ve never tired of photographing nature. There’s always something to notice, even in things I’ve seen hundreds of times.
Autumn causes me to think about how differently we experience the seasons depending on where we live. In some parts of the country, entire hillsides turn brilliant red and gold. People travel considerable distances just to see them, and I can understand why.
In Florida, where I’ve spent so much of my life, autumn is a quieter affair. Many trees remain green throughout the year, and the changing colors often appear here and there rather than sweeping across the landscape. Sweetgums, maples, and other deciduous trees provide some color, but you generally have to pay a little more attention to find it. Now, that I am in Tennessee the scenery is so much more bright and colorful.
Perhaps that’s why an especially colorful leaf can catch my attention. When something isn’t everywhere, you tend to notice it more.
There’s another part of this seasonal change that interests me. We tend to think of autumn as the end of something, particularly when the leaves begin falling and the branches are left bare. But the trees aren’t dying. They’re simply going about the business of getting through another winter.
By the time those leaves fall, the buds that will produce next year’s growth may already be waiting on the branches. The tree has been preparing for spring long before we’ve finished admiring autumn.
I find that rather remarkable.
The other day I was considering how much attention we give to the changing leaves and how little we notice them during the rest of the year. Then, just before they fall, we suddenly can’t take our eyes off them.
I suppose that’s human nature.
Anyway, I still find myself stopping to examine a leaf that’s turned an especially beautiful color. Sometimes I’ll photograph it. Other times I’ll just look at it for a moment and go on about my day.
And now that I know a little more about what’s happening inside that leaf, I might look at it a bit longer.
~Deborah