What do you think about when you say the word "desert?" Do you think about miles and miles of sand dotted with big, tall cactus? Do you think about high bare sandstone bluffs and tall spires of rock that Wiley Coyote and Roadrunner will jump from behind? Well, that's one type of desert and it's usually found in the Southwestern United States. But, we are talking about a different kind of desert. It's one that's all around us in Southern Idaho. It's called sagebrush steppe.
Sagebrush steppe includes the Great Basin sagebrush desert to the south of us covering much of Nevada and Utah, northeastern California, southeastern Oregon, and western Wyoming. This desert is the largest of four in North America, much of it above 4,000 in elevation. It is a cold desert characterized by cold winters and hot summers. Snow is a common sight in the winter, and moisture is limited to about 4 to 12 inches a year.
As you drive through this area, you are met with mile after mile of low, mounding gray-green shrubs with bunchgrasses, some perennial and annual plants, and a few and cactus mixed in. To some people, it's a boring landscape. For those who understand and appreciate sagebrush ecology, it's fascinating and beautiful.
Southwest Idaho Desert Communities
To say that all the sagebrush steppe country is the same overall would be a very incorrect statement. On the contrary, this country contains a wide variety of plant species. This variety, in large part, is due to different types of soil, elevation, and precipitation levels as well as current and past use patterns of animals (wild and domestic) and humans. An area that supports plant life and has one or more species of plants that dominates an area is called a plant community or vegetation type. These communities are usually named after the most abundant or dominant plant in the community. For example, in southwestern Idaho, commonly observed plant communities are Big Sagebrush, Salt Desert Shrub Mosaic, Green Rabbitbrush, Horsebrush, and Purple Sage. It should also be noted that wildfire has destroyed many remaining traces of the original plant communities over much of southwestern Idaho.
do desert plants save water?
How do plants get water?
One way desert plants, trees, and shrubs suck up as much water as possible is by growing very deep taproots. Sometimes these roots can get to be more than 100 feet long. The above ground plant parts may remain small for years simply because the plant puts most of its energy into developing its taproot system. Desert plants may have a huge, tangled network of shallow roots that spread out from the plant in all directions. The roots can be as long as the plant is tall, and can quickly absorb water from the slightest rainfall.
Why do plants shrink and swell?
Desert plants can soak up water, store it, and prepare to use it during drought. For example, cacti and many other desert plants store water in their fleshy leaves and stems. Desert plants may also have other adaptations for water storage, such as pleats or folds that will allow the plant to swell with added water when it can. The pleats or folds can almost disappear if the plant soaks up a lot of water; then the plant can shrink, and its pleats or folds can become visible again as drought sets in and the plant makes use of water it has stored. Though many desert plants die to the ground during the hottest part of each year, the water they have stored in underground roots, tubers and bulbs will sustain them until the next moist period.
Why do plants grow hairs and spines? The hairs and spines that grow on desert plants help reduce moisture loss by breaking the effects of the wind. They also help to cast minute shadows on desert plants, which can protect them from the sun. The hairs and spines can even serve to reflect the sun's rays away from plants because of their shininess. Lastly, hairs and spines can help protect plants from hungry animal predators.
Why do plants produce special chemicals?
Scientists believe that desert plants may produce and give off chemicals from their leaves or roots that keep other plants from growing nearby. It is thought that plants do this to reduce competition, especially when water is scarce.
Why do seeds of plants sleep?
Some desert plants cope with the desert's dryness by not coping at all. As a result, during drought they are present only as seeds in the soil. For months, years, or even decades these seeds "sleep" to wait out the dry spell in a dormant state. When the right amount of rain falls and soaks into the soil, they sprout and bloom. When this happens the desert's dry brown landscape can quickly change into colorful fields of wildflowers, herbs, and grasses. Most of these fast-growing desert plants do not last very long. So aside from having seeds that are adapted to drought, they have few or no special adaptations to desert conditions. This is why desert plants of this kind sprout, flower, and leave behind a generation of seeds as quickly as possible. Short-lived desert plants like this are called ephemerals. With little water available to help them grow, dormant ephemerals are covered and protected by natural chemicals called inhibitors. The primary function of inhibitors is to keep seeds from germinating until enough moisture and specific temperatures are present. One the inhibitor has been washed off, the seeds can sprout.
Today there are some plants found in the desert that do not belong there. These plants are misfits, and do not benefit the ecosystem in which they were introduced. Idaho is no different. It, too, has its share of misfit plant species. These plants species are referred to as exotic, alien, or non-native species and were introduced from other countries such as Africa, Asia, Australia, Europe, India, Mediterranean area, South America, and Russia.
Why were exotic plant species introduced?
Many exotic plant species were introduced with the idea that they would serve a great purpose and provide excellent benefit to all who used them (e.g. shade trees to control wind and erosion, forage crops for livestock, watershed improvement, beautify landscapes, etc.). In some cases, alien plant species were transported and introduced unintentionally through immigrants and their belongings, or with imported goods. Regardless of how they arrived, as the years have passed since their introduction, we have realized that many of the introduced non-natives are more of a problem and threat than a benefit.
For example, cheatgrass was introduced into the United States form Eurasia with the idea it would be a great food source for livestock and wildlife. That is true in early spring before its seeds emerge, but it is practically worthless throughout the remainder of the year.
Cheatgrass, once dry, is a great fuel for fire. When fire becomes more frequent in a sagebrush-dominated plant community, it kills the shrub, and out-competes other native plants for essential nutrients and moisture. Eventually the cheatgrass takes over and the plant community becomes a monoculture where a varied and productive plant community once stood.