Grand Canyon, Arizona (Page 3 of 3)

Land Use Issues

The creation of Glen Canyon Dam in 1963, upriver from the canyon, has had dramatic effects on the ecology and stream dynamics of the Colorado River within the canyon. Before the river was impounded, it carried a tremendous load of sand and silt through the canyon, especially during spring floods. These sediments scoured the canyon bottom and both eroded and deposited material along the river shores. Now, water discharge by the dam is controlled, virtually sediment-free and of a much colder temperature, leading to many changes in the ecology of the river corridor. Beaches are eroded, but not resupplied with sand; native plants and fish have been largely displaced by exotics; and other wildlife have been negatively impacted. In 1994, an attempt was made to simulate flood conditions by a large release of water from the base of the dam, but the results received mixed responses from the scientific community as the effects were not long-term.

Click on table for a larger image

Grand Canyon National Park is perhaps the country's most famous park, and it is among the most visited. As visitation has grown (see figure), the park's major visitor area along the South Rim has suffered from overcrowding, particularly by automobiles. As a result, the National Park Service is attempting to implement a plan to allow only pedestrian and bus and/or light rail traffic past the Tusayan south entrance. Attempts are also being made to restore the area's quiet by reducing the number and further restricting the routes of helicopter and fixed-wing aircraft tours over the park.

New park superintendent Joe Allston has observed that the clarity of the air that he remembers from his early days as a park ranger in Grand Canyon is no longer the norm. Studies have shown that much of the decrease in air quality and visibility that leaves the canyon blanketed in a haze many days of the year comes from large coal-fired power plants which have been built in the region. Expensive scrubbers have been installed at the Navajo Power Plant in Page, Arizona, and agreement was recently reached to do the same at the Mohave Power Plant in Laughlin, Nevada.

A large portion of the Grand Canyon is managed by the National Park Service, with the adjacent Coconino and Kaibab Plateaus predominantly managed by the U. S. Forest Service. Grazing and logging are major uses of the land just outside the park boundaries, while recreation is the most important land use within the park. An extensive ponderosa pine ecosystem restoration project is now underway in the Bureau of Land Management's Mt. Trumbull Resource Conservation Area in the Arizona Strip country north of the Grand Canyon. A controversial plan by National Park Service management to allow similar restoration treatments in Grand Canyon National Park, which would call for logging within a national park, is being challenged by environmental groups. Research in the canyon is extensive and varied, ranging from geomorphology and hydrogeology studies to ecological assessment of periodic flood releases and changes in local biotic communities.

Map of the Biotic Communities of the Greater Grand Canyon Region.

Map of Grand Canyon area road network.

Diary page from Henry F. Louzon's 1912 Grand Canyon river trip with the Kolb Brothers' Expedition.

Previous Page     References

--Researched and written by Shannon Kelly

Packrat Midden Research in the Grand Canyon. On the Colorado Plateau the ice age (Pleistocene) vegetation of the Grand Canyon has been determined through the analysis of plant fossils preserved in caves and fossil packrat middens. Significant changes occurred as the most recent ice age ended and the Holocene era began.

Restoring Ecosystem Health in Ponderosa Pine Forests of the Southwest. Previous research has established that forests of ponderosa pine in the Southwest were much more open before Euro-American settlement. Restoration of ecosystem structure and reintroduction of fire are necessary for restoring rates of decomposition, nutrient cycling, and net primary production to natural, presettlement levels. The rates of these processes will be higher in an ecosystem that approximates the natural structure and disturbance regime.

Changed Southwestern Forests: Resource effects and management remedies. Over 150 years of occupancy by northern Europeans has markedly changed vegetative conditions in the Southwest. Less fire due to grazing and fire suppression triggered a shift to forests with very high tree densities, which in turn contributed to destructive forest fires. Options to deal with these changes include prescribed fire, thinning and timber harvest to mimic natural disturbances and conditions. However, there are barriers to implementing these activities on a scale large enough to have a significant benefit. Adapted from a published journal article by Marlin Johnson.

Anderson, M.F. 1998. Living at the edge: Explorers, exploiters and settlers of the Grand Canyon region. Grand Canyon Association, Grand Canyon, AZ, 184 pp.

Cole, K. L. 1990. Late Quaternary vegetation gradients through the Grand Canyon. Pp. 240-258 In: Betancourt, J. L., Martin, P. S. and Devender, T. R. V., editors. Packrat middens: The last 40,000 years of biotic change. University of Arizona Press, Tucson.

Cole, K. L. The Holocene and Pleistocene vegetation history of the Grand Canyon. <http://ecosys.usgs/~kcole/grdcany.html> 2/25/99.

Dolan, R., Howard, A. and Gallenson, A. 1974. Man's impact on the Colorado River in the Grand Canyon. American Scientist 62: 392-401.

Elias, S.A. 1997. The Ice-Age history of southwestern National Parks. Smithsonian Institution Press, Washington D.C., 200 pp.

Hughes, D. J. 1967. The story of man at the Grand Canyon. Bulletin #14. Grand Canyon Natural History Association, Grand Canyon, AZ, 93 pp.

Mead, J. I. 1981. The last 30,000 years of faunal history within the Grand Canyon, Arizona. Quaternary Research 15: 311-326.

Schwartz, D. W. 1958. Prehistoric man in the Grand Canyon. Scientific American 198: 97-102.

Smithson, C. L. and Euler, R. C. 1994. Havasupai legends: Religion and mythology of the Havasupai Indians of the Grand Canyon. University of Utah Press, Salt Lake City.

Stockwell, C. A., Bateman, G. C. and Berger, J. 1991. Conflicts in National Parks: a case study of helicopters and bighorn sheep time budgets at the Grand Canyon. Biological Conservation 56: 317-328.

Verkamp, M.M. 1940. History of Grand Canyon National Park. M.S. Thesis. University of Arizona, Tucson. Published in 1993 by Grand Canyon Pioneers Society as "Collectors Series Volume 1."