<P> Prescribed fires are typically conducted in the spring and fall in the forests adjacent to the canyon to reduce the potential for severe forest fires and resulting smoke conditions . Although prescribed fires also affect air quality, the controlled conditions allow the use of management techniques to minimize their impact . </P> <P> There are approximately 1,737 known species of vascular plants, 167 species of fungi, 64 species of moss and 195 species of lichen found in Grand Canyon National Park . This variety is largely due to the 8,000 foot (2,400 m) elevation change from the Colorado River up to the highest point on the North Rim . Grand Canyon boasts a dozen endemic plants (known only within the Park's boundaries) while only ten percent of the Park's flora is exotic . Sixty - three plants found here have been given special status by the U.S. Fish and Wildlife Service . </P> <P> The Mojave Desert influences the western sections of the canyon, Sonoran Desert vegetation covers the eastern sections, and ponderosa and pinyon pine forests grow on both rims . </P> <P> Natural seeps and springs percolating out of the canyon walls are home to 11% of all the plant species found in the Grand Canyon . The canyon itself can act as a connection between the east and the west by providing corridors of appropriate habitat along its length . The canyon can also be a genetic barrier to some species, like the tassel - eared squirrel . </P>

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