Environmental Engineering Reference
In-Depth Information
FIGURE 7.3
Creosote bush (
L. tridentata
) is the most common species across the hot deserts of North America. Note the abun-
dance of ruderal species around the shrub including the invasive grass red brome (
Bromus rubens
). (Courtesy
of WW Brady.)
cirio (
Fouquieria columnaris
) whose English name, the boojum tree, was taken from Lewis
Carroll's poem “The Hunting of the Snark.”
Across all of its subdivisions, the Sonoran Desert is drained by a series of streams and
rivers that ultimately empty into the Gulf of California. Along these watercourses, arboreal
species dominate, particularly along perennial streams where well-developed riparian
forests occur that are dominated by such species as the Fremont cottonwood (
Populus
fremontii
), Goodding willow (
Salix gooddingii
), and velvet ash (
Fraxinus velutina
). Salt cedar
(
Tamarix ramosissima
), an invasive species from southern Eurasia,
16
is now a dominant
species in many riparian areas. The riparian corridors that cross the Sonoran Desert form
critical elements of the wildlife habitat of the region. A distinctive habitat type found
primarily in the Sonoran Desert but also in adjacent portions of the Mojave Desert is a
fan
palm oasis
(Figure 7.6) dominated by native California fan palm (
Washingtonia filifera).
). Like
riparian areas, the fan palm oases are critical habitats for wildlife.
The Sonoran Desert is among the most studied deserts of the world. The Carnegie
Institute established the Desert Laboratory in Tucson in 1903 for the study of desert
ecosystems.
17
The world's oldest and most regularly monitored vegetation plots are located
on this facility and have been instrumental in shaping our understanding of the structure
and function of desert species and ecosystems.
18
7.3.2 The Chihuahuan Desert
The Chihuahuan Desert lies to the east and south of the Sonoran Desert. This large desert,
which lies primarily in the Mexican state of Chihuahua, extends further to the south than
any other North American desert. It lies on the large intermountain plateau of northern
Mexico and thus much of the area is at a fairly high elevation compared to the Sonoran
Desert. Because of its location and elevation, the climate is one of hot summers with spo-
radic rains and cold, dry winters, often with hard frosts. While the Sonoran Desert is
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