Rain, rain

Middle Tennessee is a verdant wet, a palate of green dripping with spring and sugar. The season has helped wrestle plants from their wintering repose, and the plants are hard at work producing sugars called glucose from carbon dioxide and water—a process that releases the oxygen we breathe. They'll use this glucose in part to build cell walls (by arranging glucose molecules to create cellulose), and they'll also store plenty as starch for use during the cold of next year’s winter.

The sunlight is their catalyst and guide. On rainy days like today, when clouds hang hazy on a horizon of Tennessee hills, photosynthesis slows. The plants enjoy a college weekend: a time to imbibe. But excess water can prove just as destructive as excess booze. Waterlogged soil can deplete the soil of oxygen, which plants use alongside glucose in a process called respiration that yields energy (ATP) as well as byproducts carbon dioxide and water. This energy is used to carry out all important cellular functions. Too much rain, therefore, can suffocate and damage root structures and plant cells. A plant's unique makeup and geographic adaptations gained through evolution ultimately determine the effect of binge drinking. Native Tennessee trees like sassafras and shortleaf pine considered "hardy" in their abilities to withstand drought are also the lightweights of the Tennessee arboral community. Longer-term rain events can damage these trees, causing a cutoff of integral nutrients from oxygen depletion in the soil. Excess rain can also cause a rising of the underground water table so that toxins like agricultural runoff can flow into wells and water sources.

Such a simple reminder is rain of nature’s vulnerabilities, adaptions and needs. The ceaseless drum of water on rooftops and rocks is no dispirited song; it is both a celebration of life and its mourning, a ballad of balance that simultaneously sustains and destroys.

#rain #photosynthesis #sassafras