There are a number of major ecological zones in the Grand Canyon. Each is broken down into specific plant communities.
Lower Sonoran Zone
Riparian Habitat and River Corridor
Riparian areas are the thin, green lines o f water-dependent vegetation found along rivers, streams, springs, and seeps. Smaller plants like willow, cattail, and maidenhair fern, as well as trees like salt cedar (tamarisk) and cottonwood, are generally associated with riparian habitat. In the arid West, riparian habitat is rare but biologically critical. In the Grand Canyon, most riparian habitat is found along the Colorado River.
Immediately beyond the riparian habitat of the Colorado River, between 1,200 and 4,00 feet elevation, lies a zone of plants adapted to hot desert conditions, including barrel cacti, creosote bush, ocotillo, Joshua tree, white bursage, four-winged saltbush, and cholla.
Upper Sonoran Zone
The upper Sonoran zone lies between the Tonto Plateau around 4,00 feet and therims at 7,000 feet. There are a number of plant communities in this zone, including pinyon-juniper woodland, mountain shrub and chaparral, sagebrush desert, blackbrush desert, and desert grasslands.
Desert grasslands are relatively rare in the Grand Canyon region. Native grasses include Indian rice grass, three-awn, and big galleta. The best examples of grasslands are found in the Toroweap Valley and on top of the Grand Wash Cliffs between 3,800 and 5,200 feet.
Blackbrush Desert Shrub
The blackbrush desert shrub community lies in the transition zone desert to cold desert dominated by sagebrush. Blackbrush is the most common plant on the Tonto Plateau within the canyon. Other plants found in limited quantities include prickly pear cactus, cliffrose, rabbit-brush, and acacia.
At slightly higher, colder elevation is the sagebrush desert. Growing between 4,000 and 7,000 feet, particularly on limestone soils, this plant community is found on the South Rim. It is also common on the Kaibab Plateau and in the Toroweap Valley. Other plants found with sagebrush include four-winged saltbush, snakeweed, banana yucca, and cliffrose.
Mountain Shrub and Chaparral
This plant community is often mixed in among the pinyon-juniper woodlands just below the rims. It consists of deciduous species like serviceberry, Gambel oak, skunkbush, snowberry, and fernbush, plus chaparral species like shrub oak, manzanita, and mountain mahogany.
Utah juniper and pinyon pine are the dominant species of this community. This woodland type is common between 4,000 and 7,500 feet elevation. Mixed with these species are others from the mountain shrub and chaparral community like shrub oak, Gambel oak, and mountain mahogany.
Upper-Elevation Forest Zone
The upper-elevation forest zone has two major components: a transition zone dominated by ponderosa forest, and the higher zone of spruce-fir-aspen, sometimes called the boreal zone.
Transition Ponderosa Pine Forest
Ponderosa grows in open parklands between 7,000 and 8,000 feet on large areas of the Kaibab Plateau as well as some of the higher elevations of the South Rim. Other species sometimes found with the pine are Gambel's oak and aspen. On the Kaibab Plateau, white fir is often mixed with ponderosa above 8,000 feet.
Boreal Spruce-Fir-Aspen Forest
The spruce-fir-aspen forest is only found on the Kaibab Plateau above 8,500 feet. This zone i s dominated be snowy winters and cool summers. The dominant tree species are Engelmann spruce, subalpine fir, white fir, Douglas fir, and aspen. Lush meadows are interspersed with the trees, providing forest openings.
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