Biotic
Communities of the Colorado Plateau
Alpine Tundra
 |
|
Ancient limber pine in grassland near timberline in the Wellsville Mountains near Logan, Utah. Photo © 1999 Ray Wheeler. |
True alpine tundra communities are found at only the highest elevations on the Colorado Plateau, generally above 12,000 feet. Here only specially-adapted tundra species are able to grow in the harsh climate. Winds are frequently strong, snowfall can be heavy, and the growing season is short, in some areas only thirty days annually. To avoid strong winds and retain precious heat absorbed from the ground or attained through solar radiation, tundra species are commonly small, ground-hugging plants, such as prostrate woody shrubs (commonly willows), herbs, lichens and mosses.
On the western edge of the Plateau, Mount Belknap and Delano Peak, atop the Tushar Plateau east of Beaver, Utah, support alpine tundra. The La Sal Mountains on the eastern fringe of the region are also tall enough at 12,000 feet to support this fragile alpine plant community. Though many of the other high plateaus of Utah, including the Markugunt, Aquarius, and Sevier, rise to over 11,000 feet and treeline, they are not quite high enough to support true tundra communities.
Near the very southern edge of the Colorado Plateau one can find alpine tundra on the uppermost slopes of the San Francisco Peaks just north of Flagstaff, Arizona. At 35° N, these peaks are the southernmost climatic alpine area on the continent north of the high volcanoes of central Mexico. Of over 80 species of plants found in this zone on the Peaks, almost half can be found in polar regions near the Arctic and on high summits north into Canada.
Geographically isolated areas often show endemism as the area serves as an "island" where species develop in a unique environment. Part of the San Francisco Peaks have been closed to travel to protect an endemic groundsel (Senecio franciscanus). The nearest alpine areas in southeastern Utah and southwestern Colorado are too far from the San Francisco Peaks for successful migration of many species.
Most alpine tundra ecosystems on the Colorado Plateau occur within national forests, but threats to these fragile ecosystems include localized recreational use, warming climates, and acid deposition. Changes in species plant composition and soil composition are of concern to alpine ecologists.
References and other resources:
Allen, C. D. 1989. Changes in the landscape of the Jemez Mountains, New Mexico. Ph.D. dissertation, University of California, Berkeley. 346 pp.
Baker, W. L. 1983. Alpine vegetation of Wheeler Peak, New Mexico, USA: gradient analysis, classification, and biogeography. Arctic and Alpine Research 15:223240.
Brown, D. E. 1994. Biotic communities of the Southwestern United States and northwestern Mexico. University of Utah Press, Salt Lake City, 342 pp.
Dick-Peddie, W. A. 1993. New Mexico vegetation: past, present, and future. University of New Mexico Press, Albuquerque. 244 pp.
Moir, W. H. 1993. Alpine tundra and coniferous forest. Pages 4784 in W. A. Dick-Peddie. New Mexico vegetation: past, present, and future. University of New Mexico Press, Albuquerque. 244 pp.
Moir, W. H., and L. S. Huckaby. 1994. Displacement ecology of trees near upper timberline. International Conference for Bear Research and Management 9(1):3542.
Wolters, G. L. 1996. Elk effects on Bandelier National Monument meadows and grasslands. In C. D. Allen, technical editor. Fire effects in southwestern forests: proceedings of the second La Mesa fire symposium. U.S. Forest Service General Technical Report RM-GTR-286. {main}