Scrubs
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Sagebrush scrub is the dominant community of the Great
Basin, and is characterized by the dominant plant, Great Basin sagebrush, Artemisia
tridentata. Bitterbrush, perennial bunchgrasses, and rabbitbrush are also common
species. This habitat has cold winters, often with snow, and very hot, dry summers.
The plants are often widely spaced due to competition for nutrients and water. Most of
the growth goes into the roots of these plants, and they have extensive, shallow root
systems.
Shadscale scrub grows in the same areas as sagebrush scrub, but in more alkaline soils. The plants here are more salt-tolerant, and are more tolerant of dry conditions. Typical plants include two members of the saltbush family, shadscale and winter fat, as well as bud sagebrush, and desert holly. The Great Basin kangaroo rat, with its chisel-like teeth, eats the saltbush leaves in the dry season, stripping off the outer salty layer and eating the soft green interior of the leaf.
Creosote bush scrub extends over large areas of the Mojave and Colorado deserts. It covers more area than any other habitat in California – over 21 million acres. Creosote bush, Larrea tridentata, is most common on well-drained soils, and is the desert shrub that can best tolerate very dry conditions. It is allelopathic to the bur-sage, another common species, but not to itself. Creosote bushes are evenly spaced in the desert, probably because it is difficult for another creosote bush to germinate in the area of the root system of a mature bush, since the mature bushes are so good at removing water and nutrients from the soil. Creosote bushes clone themselves, and clones may form rings of bushes in older plants. The oldest clone discovered has been estimated to be over 18,000 years old, by far the oldest living things on earth.