It’s what we can’t see that can help us

Spring and early summer in the desert are special. They call us to come out and appreciate the glorious environment that surrounds our sprawling city. Breezes are fresh, and plants are full of surprises.

Trees that had been barren through the winter, mesquites and desert willows, show their new leaves and showy flowers. Up on the mountain, evergreens are producing new growth. The floral extravaganza that can happen in the Mojave is delightful. Barrel cactuses display claret cups or golden yellow flowers; almost every arm of the Joshua tree puts on a creamy white cap; and ephemeral wildflowers pop with showy blooms that seem to last only for an instant.

Another whole desert world is considerably less visible. This is not the universe of curmudgeonly burros, nor skittish mustangs, nor even elevated Bighorn sheep, although they are hard to find. No, there is a huge range of life that is “out of sight, out of mind.”

These other life forms are microscopic, yet critical to the survival of the Mojave’s plants and animals. It is rare for us think of this world; not only is it microscopic, it exists beneath the surface of the soil. It has several names, but the term cryptobiotic crust, which means “hidden life,” is wonderfully descriptive.

In this crust are millions upon millions of different kinds of microorganisms, many of which have yet to be identified, despite the efforts of many scientists. Some are known to perform a range of important functions. Who knows what benefits we receive from the unidentified ones? We do know that the microbes work together to form the crust.

The underground life forms are varied — and they all perform different essential activities. Because desert life can be so unforgiving, with infertile soils and limited water supplies, plants require assistance if they are to survive, and microbial life is the source of most of this help.

When people hear the term “bacteria,” many think only of disease. Disease organisms are only a very small segment of this unimaginably enormous group. Most bacteria simply live in hidden spaces, particularly soil particles, having no interaction with humankind.

Certain important bacteria form associations with the roots of many plants growing in the Mojave’s harsh conditions. These specialized bacteria take nitrogen from the air and transform it into compounds that plants use for their very lives. Quite a few desert plants — mesquite, acacia, indigo bush and others — depend on these associations. They would not be able to grow or develop these microbes.

Bacteria are only one part of this subterranean galaxy. People look at fungi either as edible mushrooms, or as molds that cause us many problems. There are in fact thousands of different fungi, some of which play a critical role in the life of the desert.

Trying to find water and nutrients in desert soils is a huge challenge, and left on their own, plants might find it impossible. To deal with this difficulty, most desert plants have associated with certain fungi to create something akin to a secondary root system. With this expanded root system, plants have access to a larger area, thus obtaining more essential nutrients and water.

Among the most critical and plentiful organisms in our desert appears to be a different life form called “cyanobacteria.” These used to be known as the “blue-green algae,” a name that became obsolete years ago. Now researchers have determined that these are the oldest form of life on the planet earth. They are very energetic in our soils. Not only can they fix nitrogen into usable forms, they take carbon dioxide and water and convert into sugar and oxygen.

They also help keep our desert in place. The gale-force winds that we regularly experience in the desert could push the soil into a vast dust cloud, but this happens in construction zones, not in undeveloped areas. One key reason for this is that the interactions among the vast amount of microbial life and the meshwork structures they create actually stabilize the soil, keeping it from blowing away.

All these organisms cooperate. Out in the desert, it is tempting to take all-terrain vehicles, or four-wheel drives, and drive on untouched spots, seeing things others do not. It would be difficult to find an activity more destructive to our delicate desert crust. Even foot traffic is bad.

Air Quality Department advertisements that say breaking the crust raises dust are talking only about part of the devastation. Fracturing the crust causes death in the ecosystem that keeps the desert a living place, and it may take decades for crusts to recuperate.

This season, when going to the beautiful desert, remember, the visible world depends on the invisible one beneath. It is up to us to keep it healthy.

Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.