Vegetation Zones of the Southwest - Design with the Desert: Conservation and Sustainable Development - page 144

FIGURE 7.9
Big sagebrush ( A. tridentata ) dominates large areas of the Great Basin Desert.
FIGURE 7.10
Shadscale saltbush ( Atriplex confertifolia ) is one of the signature species of the Great Basin Desert.
and thus is found in the higher portions of the basins (Figure 7.9). In the lower portions of
the basins where salts have accumulated, chenopods ( Atriplex , Grayia , and Ceratoides spp.)
become dominant (Figure 7.10). Limited amounts of perennial grass species such as blue-
bunch wheatgrass ( Pseudoroegneria spicata ) and sheep fescue ( Festuca ovina ) occur in sagebrush
stands. Ephemeral species also occur. Two annual invasive species of importance are cheat-
grass ( Bromus tectorum ) and halogeton ( Halogeton glomeratus ). Because of the dominance of the
low-shrub life form and the uniform gray-green color of these species, the landscape across
the Great Basin Desert is also rather visually monotonous. Close inspection, however, reveals
a complex mosaic of ecosystems with a surprising richness of plant and animal species.
7.3.5 Correlation of Vegetation and Climate above the Desert Background
There is, of course, more to the relationship between vegetation and climate than a simple
measure of water availability. Gleason and Cronquist 3 discuss correlation of climate and