Your own body follows a clock. All of its processes flow in a sweeping daily rhythm, merging into a larger seasonal cycle. Our daily clock is set by our interaction with the natural world around us, especially the movement of the Sun.
Exposure to bright-morning light sends a cascade of wakefulness chemicals through our bloodstream. The bright-blue light of a noonday Sun helps us set our midpoint for the day and the warm-red dying rays of the sunset spiral us down toward sleep.
We are not the only ones with built-in clocks. These internal timepieces are so ancient that this sensitivity to light and dark cycles was set in place far before animal and plants diverged from their common stock.
If you pay close attention, you can watch the effects of these internal clocks play out in nature. As you walk down the trail (or even the street), watch for the subtle signs that a plant is on the daily roller coaster ride of wakefulness.
One of my favorite examples of diurnal (daily) rhythms in plants is the dandelions that adorn the edge of a meadow near my house. Each afternoon as I passed them, I would stop and collect their bright yellow flowers for a nutritious, wild-food snack.
Early one morning, I decided to visit the same patch in hopes of garnering a few tasty morsels to go with breakfast. But, I discovered that I couldn’t find a signle one.
All of the dandelion blossoms had wrapped themselves up tightly in their green buds, asleep until the Sun would come to wake them. You can see this on the trail, as well.
Plants on the northern face of slopes receive less morning light and will often “wake” later in the day. This daily pattern of “sleeping in” leaves them with less time and energy to grow, so you will likely notice they lag behind in their development of leafing out, flowering and setting fruit compared to their neighbors on the sunny, south-facing slope.
Other living things can reveal the culmination effects of rhythms on longer timescales. In most lichens, the brilliance of the color green you see is a good reflection of the average daily amount of sunlight they receive.
Searching for a nice bright rock for future sunbathing? Want a campsite that will stay cool and out of direct sun? Look to the nearby lichens. You can use this to map out areas on and around rocks that should fit your needs through most of the year.
Want to know the age of a pine tree? You don’t have to cut it down and count the rings. Just look to the limbs. Each year, a conifer adds a whirl of branches. Each level or whirl corresponds to a year of growth. If your children (or you) enjoy climbing trees, it’s exciting to realize that you are climbing up through time.
