A warm October sun bathes my face as I sit in a seasoned wicker chair on my patio, sipping hot apple cider, admiring Montana’s brilliant fall colors, displayed by the maple, willow, mountain ash and cottonwood trees in my backyard. The crispness of distant, snow-capped Tobacco Root mountains adds to the splendor. A brisk westerly wind drifts in and strips some of the cottonwoods’ brilliant, mustard-yellow leaves from the trees. As they whisk skyward in half-playful swirls, I cock an eye and say, “There’s a story waiting for me here.” Windy waves continue to surge across the back acre, beating against the willows, limbs waving, shedding a slew of leaves, adding to the golden blanket below. Every autumn, it amazes me to see the magic of the bright greens of spring and summer subtly transition to fiery goldens, oranges, reds and burgundies – lavish bouquets of “flowers” displayed for sparkling viewing.

Act One of the story of fall colors opens with our ability to perceive both quality and beauty while viewing one of Mother Nature’s colorful presentations. With repeated viewings, it expands through successive stages of appreciation to values yet uncaptured, values beyond the reach of words – values that evoke something precious and deep within. French author, Albert Camus, reminds us that “Autumn is a second spring, when every leaf is a flower.”

The Second Act involves an understanding of the biological sequence of why leaves change color in the fall, and how the process occurs. Each leaf is a specialized nutritive organ, whose function is to carry on photosynthesis, the process of synthesizing carbohydrates (sugars and starches) from carbon dioxide and water, utilizing the radiant energy of light captured by the chlorophyll molecules in plant cells. This process slows and eventually stops as summer fades due to several factors including: genetics, decreasing temperatures and precipitation, lower soil moisture levels, and geographic locations. But the main reason is due to declining daylight hours. Leaves can sense the loss of light, due to the chemical light receptors, phytochrome and cryptochrome, which can register day-length changes of as little as thirty minutes. The change in color of the leaves that we see occurs due to the fading and eventual death of the masking green chlorophyll, exposing the hidden xanthophyll (yellow), carotene (orange), anthocyanin (red, purple, burgundy), and tannin (brown) pigments, resulting in seasonal changes from luscious greens to bright hues, showing a fiery display of leaf colors.

Soil moisture levels have an impact on the ability to produce good fall colors. A prolonged drought can delay color change for a few weeks. Freezing temperatures and an early hard frost can trigger an early shutdown, leading to poor fall colors. Ideal conditions for providing the best fall colors are favorable summer temperatures, timely rainfall and sunny days, combined with cool, frostless night temperatures. Achieving a display of peak colors depends on a delicate balance — one currently jeopardized by climate change. Warmer temperatures and drier summers lead to environmental stress than can accelerate leaf pigment deterioration, and earlier leaf drop. Severe climate /environmental changes essentially mean that a tree can’t properly function, thereby preventing a normal display of vibrant fall colors.

Act Three focuses on leaf departure from the tree. As autumn days grow shorter and colder, a hormone in deciduous trees is triggered to send a chemical message to every leaf that says, in essence, “Time for departure.” At the location where the petiole (stalk) of the leaf is attached to the stem is a special layer of thin-walled cells, the abscission layer (separation layer), extending across the base of the petiole. This abscission layer functions in weakening the base of the leaf. Abscission cells have the same root as the word scissors, meaning they function like scissors when activated, to make a cut. The cellular part next to the stem becomes cork-like and forms a protective layer which remains when the leaf falls off, sealing off the vessels that supplied the leaf with nutrients and water. The combination of reduced light, colder temperatures, chlorophyll death, activation of the abscission layer, and a little push of the wind and pull of gravity act as catalysts for leaf departure. The broad, thin leaves of deciduous trees are in reality an Achilles’ heel when these latter forces of wind and gravity are activated.

A spectator might conclude that, with leaf departure, the story of fall colors ends. Since Mother Nature seems to abhor waste, it’s not surprising to know that for the final curtain call,  fallen leaves still have not exhausted their ecological calling. As they decompose and decay, their bloodstream  nutrients seep into the soil, providing and releasing a flow of energy that feed future generations of plant and animal life. The soil’s intricate and dynamic digestive apparatus, bacteria and fungi, break down the complex compounds of dead organic matter, and in doing so, release simpler inorganic compounds back into the ecosystem. Food chains are the living channels which conduct energy upward; death and decay return it to the soil. Soil, then, is not only soil, it is a fountain of energy flowing through a circuit of soils, plants, and animals. This is the yin and yang of biotic continuance. Together, they provide for the breakdown of organic matter, recycling it and making it available for new organisms to utilize — a complete energy circuit that reminds us that there is no life without death.

Although many would agree that New England’s northern tier landscapes rank best in the nation for viewing a beautiful tapestry of vivid fall colors, many Montanans would argue that the Treasure State also provides a good sampling of fall colors to viewers in all reaches of Big Sky Country, from the high plains of eastern Montana to the Rocky Mountain west. So, when fall colors start to show, put on your walking shoes, fill the car’s gas tank for a drive to a favorite viewing area, or hop on your bike for a day’s outing. Whatever your preference of travel may be, unlimited opportunities await for you to verify the ancient doctrine that the best things in life are free. That includes the opportunity to view Montana’s tapestry of vivid reds, oranges, yellows, golds, purples, and other varying shades of leaf colors during fall days.