Photosynthesis: Don’t take plants for granted

Gaze across any late winter landscape as February winds down, and you’ll soon notice small patches of fresh greenery.

Longer days, warmer temperatures, and frequent rainfall promote lush plant growth. Because plants — grass, wildflowers, shrubs and trees — are such ubiquitous parts of our lives, it is easy to take them for granted.

Worse, we curse them for the work they foist upon us during the growing season.

Growth

But it won’t be too long before summer heat and drought slow plant growth, and we’ll long for the lush days of spring.

The sheer biomass (plant material) that grows each spring always impresses me. Thickets that were manageable just six weeks earlier form impenetrable barriers.

Grass seems to grow an inch a day.

And the naked trees of winter, which made birding so easy, leaf out.

Just where does all this new plant biomass — the leaves, stems and blossoms — originate?

Many people, including some who should know better, believe plant matter comes from the ground — from the soil. That’s certainly the message we get from fertilizer ads.

Spend lots of money to enrich the soil with miracle chemicals to make trees, shrubs, flowers, and garden vegetables grow bigger and faster.

But if plants build their biomass from the soil, why doesn’t soil disappear? Because about 94 percent of plant matter comes from either air or water.

Plants consist primarily of organic (carbon-containing) material. Most organic molecules consist of some combination of carbon, oxygen and hydrogen.

The concentration of these elements in plants, as a percentage of dry weight, is typically 44 percent carbon, 44 percent oxygen and 6 percent hydrogen.

Photosynthesis

Plants extract these three major building blocks from air and water by means of a biochemical process called photosynthesis.

Longer days and warmer temperatures stimulate plants to produce the green chemical pigment, chlorophyll. And it is chlorophyll that makes photosynthesis, plant life and ultimately animal life (including humans) possible.

Chlorophyll captures solar energy and uses it to convert atmospheric carbon dioxide (CO2) and water (H2O) from the soil into organic molecules composed of carbon, hydrogen and oxygen.

Oxygen and reassembled water molecules are by-products of the reaction.

Not only does photosynthesis make plant material literally out of thin air, it also produces the oxygen we and all other animals need to breathe.

In return, we (animals) exhale carbon dioxide, which plants then recycle.

Photosynthesis is not simply a wondrous biochemical reaction that builds plants, it’s also the engine that drives the planet’s oxygen cycle.

All life on earth has been powered by the sun for billions of years. That’s why science and industry have come to understand that converting from fossil fuels to solar power is the planet’s saving grace.

The sun has powered all life on earth since life began, so it is now time to free humanity from the yoke of fossil fuels.

This is ultimately why conservationists want to save the world’s plant life. Without the oxygen plants produce, life on the planet would suffocate. And bigger plants make more oxygen than smaller ones, hence the critical importance of tropical rain forests and the plant life that grows in the waters that cover three-quarters of the planet’s surface.

If we destroy the plants that produce the world’s supply of oxygen, all life on the planet would eventually die.

If photosynthesis accounts for the three elements that comprise 94 percent of plant material, what is the source of the rest?

In nature, these other elements come from the soil. On cropland, lawns and gardens, we supplement natural supplies with fertilizer.

Nitrogen, potassium, calcium, phosphorus, magnesium and sulfur are the major nutrients that account for most of the remaining 6 percent.

These elements are the building blocks of genes, enzymes and energy-rich compounds that plants cannot live without.

A handful of other micronutrients or “trace elements” occur in minute amounts (just a few parts per million), but each is necessary for certain essential biochemical reactions.

These micronutrients include iron, chlorine, copper, manganese, zinc, molybdenum, boron, cobalt and sodium.

It’s easy to take plant life for granted. But it’s also important to acknowledge the absolute interdependence of the plant and animal kingdoms.