Fall has always been my favorite season. The time when everything bursts with its last beauty, as if nature had been saving up all year for the grand finale. ~Wither
Shades of perspectives
People have all kinds of reasons to love autumn. Some love the cool crisp air and the smell of the fallen leaves, especially blended with wood fires. Others love pumpkin spice coffee and apple cider. I enjoy all those things, but even without most of them, fall is a sentimental time for me.
As a child, our family camped when Mother and Daddy had a long weekend or took some weekdays off. There were likely multiple reasons we camped instead of staying in a hotel, but here’s one. My parents owned a business in a small town and about the only way to get relief from constant phone calls for appliance repair was to leave town. They simply needed to get away from our landline. It was our only line, so leaving town worked magic. We stayed in state parks, Chickasaw, Natchez Trace, and Fall Creek Falls, as well as the Great Smoky Mountains National Park. Daddy’s favorite time to camp was in the fall when the leaves were turning, and it was always a challenge to catch them at their peak.
Daddy usually guessed pretty well, as I recall. The trees were beautiful and the weather normally cooperated. That is, I don’t remember it being rainy, and the temperatures in October wouldn’t have yet dropped to the point I couldn’t tolerate the cold. And, yes, that’s a low bar. There was always a campfire to watch, wrapped in a blanket, mesmerized. Mother usually brought homemade chili for at least one of our meals. Fall camping trips were almost always packed with good memories. There’s a connection to leaves here. Hang with me.
I’ve heard a number of theories about why unusually colorful displays might manifest themselves at certain times, but I never researched it before. I’m remedying that oversight now.
Variables abound
According to the Forest Service, there are two critical factors that determine timing. That is, there are two other than the weather, which is the one everyone seems to put their money on. You might want to focus instead on leaf pigments and the length of night. The latter is more of a change agent than most other factors. It isn’t the temps. Nor the amount of rainfall. The steadily increasing exposure to nighttime air triggers the process. All that from the USDA Forest Service, but along those lines, a fellow volunteer mentioned to me last week that he thought it was the reduction to sunlight that was the culprit (or maybe hero?). Six of one and half a dozen of the other, but let’s move on.
Color requires pigmentation. Just like humans don’t control their natural hair color, different kinds of trees produce and ultimately drop different colored leaves. Here are the types:
- Carotenoids: all things yellow and orange. Think carrots and corn and rutabagas.
- Anthocyanin: Think reds and blues and purples in strawberries and blueberries and plums.
- Chlorophyll: Ah. Finally one I’ve heard of. This the green, of course, and enables photosynthesis, the magic that happens when a plant converts sunlight into sugar food.
Both chlorophyll and carotenoids are in the leaf cells chloroplasts* during the entire growing season. However, anthocyanin is produced only in the autumn. When the growing season fades away, chlorophyll is no longer produced and the colors from the other pigmentation manifest themselves. If you aren’t familiar with the term chloroplast, you can look it up here.
And then there are the differences among trees. They don’t all have the same pigmentation. Of those we see a lot of in Tennessee, here’s what you can expect:
- Oaks: red, brown, or russet. One of the easiest trees to spot by leaf shape, and they are plentiful in the Southeast.
- Hickories: golden bronze. I haven’t noticed these before, but I’ll be on the lookout for them this year.
- Yellow-poplar: golden yellow. Unlike ginkos, which are brilliantly yellow, poplars will likely have some orange/brown mixed in.
- Dogwood: purplish red. To me they look like they’re dead sometime before the last gasp actually occurs.
No, I’m not leaving without mentioning the scarlet/red maples. Those are the ones that punctuate the scenery and make people like me think about the 1950s. I used to rake leaves back then, only to jump into them and start all over again. Now I just take another sip of my pumpkin spice and enjoy the view. But back to the reason behind the color.
Every tree’s color is a function of its species plus the cocktail it blends during the season. This is where the weather factors in. The brilliance of colors is at least partially sealed by:
- A wet spring
- A summer with typical heat and enough rain
- Warm autumn days with cool, but not freezing, nights.
A factoid about the smell of fall you love
I hardly know how to tell you this, but that smell that makes you pause and sniff again? It’s rot. Not literally, I guess, but certainly the onset of decay. WHYY, a PBS article, suggests that it isn’t the actual smell in the air that gives us the overwhelming “I love life” vibe, but it is instead nostalgia. We are associating past activities and foods and good times with the autumnal season.
Soooo, we are converting a fragrance, or odor, into a memory. Our brains, while obviously useful, do have a sense of humor. This makes me wonder if I’d eat–and enjoy–beef tongue if I didn’t know what I was eating. Or snake. I understand it tastes like chicken. It’s illegal to kill them here anyway, so I’ll never know.
This fall season as I enjoy the sights and sounds, I will also be wondering how many things on this planet I love to eat or look at only because I am ignorant of their sources. Or chemical changes. Or perhaps I’ll accept that some scents and sights are especially close to my heart because of the people and places they call to mind.
You?
Good research on leaf colors. Definitely would not have stumbled across that in my motorcycle publications. I recall many of the camping trips though as soon as I could, I stayed back to work in the grocery store and that was fine with me. I was home with my motor scooter and freedom to roam!
In this case, our memories align. 😉