Search the CP-LUHNA Web pages


Agents of Change

Forest Management
Power Generation
Population Growth
Reintroduction of Fire
Reintroduction of Native Species
Uranium Mining
Water Development

Special Topics

Arroyo Cutting
Native Use of Fire

biotaCattle and Sheep Grazing

old sheep grazing (21a).jpg (28133 bytes)
Sheep grazing in ponderosa pine forests and grasslands near Flagstaff, AZ, ca. 1899. Image 21a by F.H. Maude courtesy of Cline Library Special Collections, Northern Arizona University.


One of the most significant human-induced changes affecting the biota of the Colorado Plateau has been the widespread introduction of domestic livestock.  Brought to the Southwest by the Spanish in the late 1500s, cattle and sheep only began to have a significant impact on the region's biota with their large scale transportation into the region with the arrival of the railroads in the late 1800s. By 1890, hundreds of thousands of cattle and large numbers of sheep were grazing on the Plateau—in pine forests, on grasslands, and along riparian corridors.

Cattle Drive

Cattle Drive in Grand Staircase Escalante National Monument. Photo 1998 Ray Wheeler.

By the time federal forest reserves were proclaimed in the 1890s, ranchers on the Colorado Plateau had become accustomed to unregulated use of public lands as range for livestock. As a result of these excessive stocking numbers, once rich grasslands were seriously degraded even before the turn of the century, after less than a human generation of use. By the early 1900s, overstocking of sheep on many middle-elevation mesas and in the area's highlands had brought forest regeneration to a halt. The forest floor in some places was "as bare and compact as a roadbed." The fire ecology of the region's forests, particularly the once grass-rich ponderosa pine forests, was drastically altered, causing significant long-term changes to their structure and composition.

By 1912, livestock pressures had penetrated the most remote, timbered and mountainous areas. Theodore Rixon, one of the first foresters in the Southwest, described the situation:

"At the beginning the mountains and heavily timbered areas were used but little, but as the situation grew more acute in the more accessible regions the use of these areas became more general and in course of time conditions within them were more grave than elsewhere... The mountains were denuded of their vegetative cover, forest reproduction was damaged or destroyed, the slopes were seamed with deep erosion gullies, and the water-conserving power of the drainage basins became seriously impaired. Flocks passed each other on the trails, one rushing in to secure what the other had just abandoned as worthless, feed was deliberately wasted to prevent its utilization by others, the ranges were occupied before the snow had left them. Transient sheepmen roamed the country robbing the resident stockmen of forage that was justly theirs." (Source: Roberts, P.H. 1963. Hoof prints on forest ranges. San Antonio, TX: Naylor. 151 p.)

Over one hundred years later, the effects of intense grazing in the latter part of the 19th century can still be readily seen in many parts of the Colorado Plateau.

Impact on Riparian Areas

Ungrazed riparian area
Grazed riparian area

Photographs of ungrazed (top) and grazed (bottom) sections of the Rio de Las Vacas, New Mexico. Photographs courtesy of Forest Guardians.

Although riparian habitats represent less than 1 percent of the total acreage of public lands in the 11 western states, they are among the most biologically diverse and important fish and wildlife habitats. In Arizona and New Mexico, approximately 80 percent of all vertebrate wildlife use riparian habitat during part of their lives.

The abundance of food, water, and shade which attracts wildlife to these areas also attracts livestock. Despite widespread recognition of the problem and attempts to remove or restrict livestock from riparian areas, riparian degradation due to overgrazing is a serious problem on the Colorado Plateau. Destruction of streamside vegetation, shallowing of channels or its opposite, arroyo formation, are some of the effects of poor grazing practices.

Livestock and Water Use

One common misconception of water use in the Colorado River basin and in the West in general is that rapidly growing urban areas are the main users of the region's limited water. In the upper Colorado River basin states, Wyoming, Colorado, Utah, and New Mexico, 90% of the water used is spread on land irrigated for crops, leaving 10% for urban and other uses. Of the 1.6 million acres irrigated in the upper basin, feed for livestock is raised on 88% of the irrigated land. In the lower basin states, California, Arizona, and Nevada, 85% of water goes to agricultural purposes, with a significant but slightly less percentage going to grow feed for livestock. Of the 99 million acres in the lower basin, 82 million acres are rangeland or pasture, while only 500,000 acres are classified as urban.

Studies have shown that nearly all Colorado River water is used for the irrigation agriculture, and most of the crops produced, including heavily water-consumptive crops such as alfalfa, are grown to provide feed for cattle. Despite the enormous public cost of the region's elaborate water damming and diversion projects, the seven Colorado River basin states, including those portions of the states lying outside the basin and not receiving any Colorado River water, produced only 13% of the total value of the nation's livestock. Though urban use, flood control, and recreation are commonly cited as major uses of the region's water supply, these uses are negligible when compared to that of agricultural interests associated with the livestock industry.

Grazing on the Navajo Reservation

Livestock raising on the Colorado Plateau has always been a marginal business subject to the climate irregularities typical of semi-arid areas. The primary climate component is precipitation, usually only sufficient to support a scant forage but capable, during the summer rainy period, of dropping over two inches of moisture in a few hours. Many of the ranchers who have struggled with the semi-arid conditions of the area consider much of the Plateau to be '60-40 range.' This is a range where a cow must have a mouth sixty feet wide and move at forty miles-per-hour to be able to find enough to eat. The Navajo Reservation is no exception to this rule and, if anything, conditions there are worse than in other locations on the Plateau.

Just prior to the Navajo War their sheep numbered between 250,000 and 500,000. Upon their return to the Reservation in 1868 following the Navajo War and the Long Walk, their livestock assets were 940 sheep, 1,025 goats, 1,550 horses and 20 mules. Rapid growth of the herds was the trend for the 1870s followed by a leveling off during the 1880s. By 1892 sheep and goats totaled almost 1.72 million with horses at 250,000 and cattle just under 10,000 head and overgrazing was becoming a recognized problem on the Reservation range lands. Between 1893 and 1900 there was a precipitous decline in stock numbers followed by an equally rapid recovery between 1900 and 1915 that brought total stock numbers to their highest level since the Navajo were placed on the reservation. From 1915 to 1922 there was another rapid descent when Navajo horse herds were greatly reduced along with more modest declines in sheep, goats and cattle. During the period 1923 through 1931, herds and flocks again increased but at a much slower pace although overstocking was still very much of a problem. In 1933, the Bureau of Indian Affairs, judging two-thirds of the Navajo range to have been destroyed by overgrazing, unilaterally instituted a stock reduction program on the Reservation which was greeted with little enthusiasm on the part of the Navajo. As a result of this program, stock numbers declined until well into the 1940s. From 1950 through 1975, there was a steady, gradual increase in animals which led again to calls for a new reduction program, a pattern which has been repeated regularly to the present day.


The Social and Ecological Consequences of Early Cattle Ranching in the Little Colorado River Basin. Examines the early development of cattle ranching in the Little Colorado River Basin, the various factors which contributed to overgrazing in the region, and the pervasive effects that early commercial cattle ranching had on the local environment. Adapted from a published journal article by William S. Abruzzi.

Where have all the grasslands gone? Numerous ecological studies across the Southwest have documented the decline in herbaceous vegetation (grasses and non-woody flowering plants) while forests thicken and brush invades. Documenting the changes in the Jemez Mountains of northern New Mexico, ecologist Craig Allen considers the evidence that these patterns are tied to changes in land use history, primarily livestock grazing and fire suppression.

Native Americans and the Environment. A comprehensive survey of twentieth century environmental issues facing Native Americans on the Colorado Plateau and throughout the Southwest, including discussions of agriculture, logging, mining, grazing, water rights, and tourism. Adapted from a published journal article by David Rich Lewis.

References and Resources:

Abert, J. W. 1848. Report of his examination of New Mexico in the years 1846-47. U.S. Senate Executive Document No. 23. U.S. Government Printing Office, Washington, D.C., 132 pp.

Abruzzi, W. S. 1995. The social and ecological consequences of early cattle ranching in the Little Colorado River Basin. Human Ecology 23: 75-98.

Ames, C. R. 1977. Wildlife conflicts in riparian management: Grazing. Pp. 49-58 In: Johnson, R. R. and Jones, D. A., editors. The importance, preservation and management of the riparian habitat. General Technical Report RM-43. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Anderson, B. 1993. Grazing management plan: Wupatki National Monument and Flagstaff areas, Arizona. National Park Service, Flagstaff, AZ.

Anderson, G. W., Hawke, H. and Moore, R. W. 1985. Pine needle consumption and bark stripping by sheep grazing annual pastures in young stands of widely spaced Pinus radiata and P. pinaster. Agroforestry Systems 3: 37-45.

Archer, S. 1994. Woody plant encroachment into southwestern grasslands and savannas: Rates, patterns and proximate causes. Pp. 13-68 In: Vavra, M., Laycock, W. A. and Pieper, R. D., editors. Ecological implications of livestock herbivory in the west. Society for Range Management, Denver, CO.

Armour, C., Duff, D. and Elmore, W. 1991. The effects of livestock grazing on riparian and stream ecosystems. Fisheries 16: 7-11.

Arnold, J. F. 1950. Changes in ponderosa pine bunchgrass ranges in northern Arizona resulting from pine regeneration and grazing. Journal of Forestry 48: 118-26.

Arnold, J. F., Jameson, D. A. and Reid, E. H. 1964. The pinyon-juniper type of Arizona -- Effects of grazing, fire and tree control. Production Research Report 84. USDA Forest Service, 28 pp.

Baars, D. L. 1995. Navajo country: A geology and natural history of the Four Corners region. University of New Mexico Press, Albuquerque.

Bailey, G. and Bailey, R. G. 1986. A History of the Navajos: The reservation years. School of American Research Press, Santa Fe, NM, 360 pp.

Bailey, L. R. 1980. If you take my sheep: the evolution and conflicts of Navajo pastoralism, 1630-1868. Westernlore Publishing, Pasadena, CA.

Baker, R. D., Maxwell, R. S., Treat, V. H. and Dethloff, H. C. 1988. Timeless heritage: A history of the Forest Service in the Southwest.Report FS–409. USDA Forest Service, Washington, D.C., 208 pp.

Barnes, W. C. 1913. Western grazing grounds and forest ranges: A history of the livestock industry as conducted on the open ranges of the arid west, with particular reference to the use now being made of the ranges in the National Forests. Breeder's Gazette, Chicago.

Barth, R. C. and McCullough, E. J. 1988. Livestock grazing impacts on riparian areas within Capitol Reef National Park. Capitol Reef National Park, Torrey, UT.

Belnap, J. 1995. Potential role of cryptobiotic soil crusts in semiarid rangelands. Pp. 179-185 In: Ecology, management and restoration of Intermountain annual rangelands. Report INT-GTR-313. USDA Forest Service.

Belsky, A. J. and Blumenthal, D. M. 1996. Effects of livestock grazing on stand dynamics and soils in upland forests of the interior west. Conservation Biology 11: 315-327.

Berry, K. H. 1978. Livestock grazing and the desert tortoise. Transactions of the North American Wildlife and Natural Resources Conference 43: 505-519.

Bich, B. S. 1992. The response of vegetation, birds, and rodents to grazing by domestic livestock within selected blackbrush/Indian ricegrass communities of Glen Canyon National Recreation Area. M.S. Thesis. University of South Dakota, Vermillion.

Bock, C. E., Saab, V. A., Rich, T. D. and Dobkins, D. S. 1993. Effects of livestock grazing on neotropical migratory landbirds in western North America. Pp. 296-309 In: Finch, D. M. and Stangell, P. W., editors. Status and management of neotropical migratory birds. General Technical Report RM-229. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Brady, W., Stromberg, M., Aldon, E. F., Bonham, C. D. and Henry, S. H. 1989. Response of a semidesert grassland to 16 years of rest from grazing. Journal of Range Management 42: 284-288.

Branson, F. A. 1985. Vegetation changes on western rangelands. Range Monograph No. 2. Society for Range Management, Denver, CO.

Brown, D. E., Lowe, C. H. and Hausler, J. F. 1977. Southwestern riparian communities: Their biotic importance and management in Arizona. Pp. 201-211 In: Johnson, R. R. and Jones, D. A., editors. Importance, preservation, and management of riparian habitat. General Technical Report RM-43. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Brown, J. H. 1995. Livestock grazing and conservation on southwestern rangelands. Conservation Biology 9: 1644-1647.

Buffington, L. C. and Herbel, C. H. 1965. Vegetational changes on a semidesert grassland range from 1858 to 1963. Ecological Monographs 35: 139-164.

Calef, W. 1960. Private grazing and public land: Studies of the local management of the Taylor Grazing Act. University of Chicago, Chicago, IL.

Calkins, H. G. 1941. Man and gullies. New Mexico Quarterly Review 11: 69-78.

Cline, P. 1976. They came to the mountain: The story of Flagstaff's beginnings. Northern Arizona University with Northland Press, Flagstaff, 364 pp.

Cole, K. L. 1997. Impacts of nineteenth century grazing at Capitol Reef National Park as determined through packrat midden analysis. 2/25/99.

Cole, K. L., Henderson, N. and Shafer, D. 1997. Holocene vegetation and historic grazing impacts at Capitol Reef National Park reconstructed using packrat middens. Great Basin Naturalist 57: 315-326.

Colton, H. S. 1937. Some notes on the original condition of the Little Colorado River: A side light on the problem of erosion. Museum Notes of the Museum of Northern Arizona 10: 17-20.

Cook, C. W. and Stubbendick, J., editors. 1986. Range research:Basic problems and techniques. Society for Range Management, Denver, CO.

Cottam, W. P. 1947. Is Utah Sahara bound? University of Utah Bulletin 37: 40.

Cottam, W. P. and Stewart, G. 1940. Plant succession as a result of grazing and meadow desiccation by erosion since settlement in 1862. Journal of Forestry 38: 613-626.

Dahms, C. W. and Geils, B. W., editors. 1997. An assessment of forest ecosystem health in the Southwest. General Technical Report RM-GTR-295. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO, 97 pp.

Davenport, D. W., Breashears, D. D., Wilcox, B. P. and Allen, C. D. 1998. Viewpoint: Sustainability of pinyon-juniper ecosystems -- A unifying perspective of soil erosion thresholds. Journal of Range Management 51: 229-238.

Denevan, W. M. 1967. Livestock numbers in nineteenth-century New Mexico and the problem of gullying in the Southwest. Annals of the Association of American Geography 57: 691-703.

Dennis , P., Young, M. R. and Gordon, I. J. 1998. Distribution and abundance of small insects and arachnids in relation to structural heterogeneity of grazed, indigenous grasslands. Ecological Entomology 23: 253-264.

Duce, J. T. 1918. The effect of cattle on the erosion of canyon bottoms. Science 47: 450-452.

Dwyer, D. D. and Pieper, R. D. 1967. Fire effects on blue grama-pinyon-juniper rangeland in New Mexico. Journal of Range Management 20: 359-362.

Evans, R. D. and Belnap, J. 1999. Long-term consequences of disturbance on nitrogen dynamics in an arid grassland ecosystem. Ecology 80: 150-160.

Finch, D. M., Ganey, J. L., Yong, W., Kimbal, R. and Sallabanks, R. 1997. Effects and interactions of fire, logging and grazing. In: Ecology and management of songbirds in Southwestern ponderosa pine forests. General Technical Report. USDA Forest Service, Rocky Mountain Forest and Range Experimental Station.

Fleischner, T. L. 1994. Ecological costs of livestock grazing in western North America. Conservation Biology 8: 629-644.

Fradkin, P. 1994. A river no more: The Colorado River and the west. Second Edition. University of California Press, Berkeley.

Frischknecht, N. C. and Harris, L. E. 1968. Grazing intensities and systems on crested wheatgrass in central Utah: Response of vegetation and cattle. Technical Bulletin 1388. USDA Forest Service, Washington, D.C., 47 pp.

GAO. 1992. Wilderness: Effects of designation on economy and grazing in Utah. GAO/RCED-93-11. General Accounting Office, Washington, D.C., 51 pp.

Gary, H. L. 1960. Utilization of five-stamen tamarisk [Tamarix pentandra] by cattle. Research Note No. 51. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Ft. Collins, CO.

Gordon, C. 1883. Report of cattle, sheep, and swine supplementary to enumeration of livestock on farms in 1880. In: Report on the production of agriculture as returned at the tenth census (June 1, 1880) embracing general statistics and monographs. U.S. Department of the Interior, Census Office, Tenth Census. Government Printing Office, Washington, D.C.

Graf, W. L. 1986. Fluvial erosion and federal public policy in the Navajo Nation. Physical Geography 7: 97-115.

Grand Canyon Trust. 1997. Beyond the boundaries: The human and natural communities of the greater Grand Canyon. Grand Canyon Trust, Flagstaff, AZ, 69 pp.

Haskett, B. 1935. Early history of the cattle industry in Arizona. Arizona Historical Review 6: 3-42.

Haskett, B. 1936. History of the sheep industry in Arizona. Arizona Historical Review 7: 3-49.

Herbel, C. H. 1986. Vegetation changes on arid rangeland of the southwestern United States. Cambridge University Press, New York, NY.

Hill, R. R. 1917. Effects of grazing upon western yellow pine reproduction in the National Forests of Arizona and New Mexico.Bulletin 580. U.S. Department of Agriculture, Washington, D.C.

Horton, J. S. and Campbell, C. J. 1974. Management of phreatophyte and riparian vegetation for maximum multiple use values. Research Paper RM-117. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Hughes, L. E. 1990. Twenty years of rest-rotation grazing on the Arizona strip--an observation. Rangelands 12: 173-176.

Hull, A. C., Jr. 1976. Rangeland use and management in the Mormon West. Symposium on agriculture, food and man--a century of progress. Brigham Young University, Provo, UT.

Jacobs, B. F. and Gatewod, R. G. 1999. Restoration studies in degraded pinon-juniper woodlands of north-central New Mexico. Pp. 294-298 In:  Monsen, S. B., Stevens, R., Tausch, R. J., Miller, R. and Goodrich, S., editors. Proceedings: Ecology and management of pinyon-juniper communities within the Interior West. Proc. RMRS-P-9. USDA Forest Service, Ogden, UT.

Kelley, K. B. 1986. Navajo land use: An ethnoarchaeological study. Academic Press, Orlando, FL.

Kleiner, E. F. 1983. Successional trends in an ungrazed, arid grassland over a decade. Journal of Range Management 36: 114-118.

Leiberg, J. B., Rixon, T. F. and Dodwell, A. 1904. Forest conditions in the San Francisco Mountains Forest Reserve, Arizona.Professional Paper 22. U.S. Geological Survey, Washington, D.C., 95 pp.

Love, C. M. 1916. History of the cattle industry in the southwest. Southwest Historical Quarterly 19: 370-399.

Madany, M. H. and West, N. E. 1983. Livestock grazing - fire regime interactions within montane forests of Zion National Park, Utah. Ecology 64: 661-667.

Mast, J. N., Veblen, T. T. and Linhart, Y. B. 1998. Disturbance and climatic influences on age structure of ponderosa pine at the pine/grassland ecotone, Colorado Front Range. Journal of Biogeography 25: 743-755.

McCarthy, M. M. 1981. The past and future of southwest grasslands: Changing issues in land planning. Pp. 99-113 In: Southwest grasslands: Past, present and future. Bureau of Land Management, Washington, D.C.

McClaran, M. P. 1991. Forest Service and livestock permittee behavior in relation to wilderness designation. Journal of Range Management 44: 483-486.

Mecham, E. H. 1925. The history of the sheep industry in Utah. M.S. Thesis. University of Utah, Salt Lake City.

Milchunas, D. G. and Lauenroth, W. K. 1989. Plant communities in relation to grazing, topography, and precipitation in a semiarid grassland. Vegetatio 80: 11-23.

Miller, F. H. 1921. Reclamation of grass lands by Utah juniper on the Tusayan National Forest, Arizona. Journal of Forestry 19: 647-651.

Mitchell, J. E. and Freeman, D. R. 1993. Wildlife–livestock–fire interactions on the North Kaibab: An historical review. General Technical Report RM–222. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO, 12 pp.

Moir, W. H. and Mowrer, H. T. 1995. Unsustainability. Forest Ecology and Management 73: 239-248.

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. 1994. Displacement ecology of trees near upper timberline. International Conference for Bear Research and Management 9: 35-42.

Neary, D. G. and Medina, A. L. 1995. Geomorphic responses of a montane riparian habitat to interactions of ungulates, vegetation, and hydrology. In: Shaw, D. W. and Finch, D. M., editors. Desired future conditions for Southwestern riparian ecosystems: Bringing interests and concerns together. General Technical Report RM–272. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Office, G. A. 1988. Public rangelands: some riparian areas restored but widespread improvement will be slow. General Accounting Office, Washington, D.C., 85 pp.

Ohmart, R. D. 1994. The effects of human-induced changes on the avifauna of western riparian habitats. Studies in Avian Biology 15: 273-285.

Ohmart, R. D. 1995. Historical and present impacts of livestock grazing on fish and wildlife resources in western riparian habitats.Unpublished manuscript Arizona State University, Center for Environmental Studies, Tempe, AZ.

Orodho, A. B., Trlica, M. J. and Bonham, C. D. 1990. Long-term heavy grazing effects on soil and vegetation in the Four Corners Region. Southwestern Naturalist 35: 9-14.

Painter, E. L. and Belsky, A. J. 1993. Application of herbivore optimization theory to rangelands of the western United States. Ecological Applications 3: 2-9.

Pfister, J. A. and Adams, D. C. 1993. Factors influencing pine needle consumption by grazing cattle during winter. Journal of Range Management 46: 394-398.

Pieper, R. D. 1994. Ecological implications of livestock grazing. Pp. 177-211 In: Vavra, M., Laycock, W. A. and Pieper, R. D., editors. Ecological implications of livestock herbivory in the West. Society for Range Management, Denver, CO.

Platts, W. S. 1990. Managing fisheries and wildlife on rangelands grazed by livestock: A guidance and reference document for biologists. Nevada Department of Wildlife, Reno, NV, 448 pp.

Potter, L. D. and Krenetsky, J. C. 1967. Plant succession with released grazing on New Mexico range lands. Journal of Range Management 20: 145-51.

Reid, K. D., Wilcox, B. P., Breashears, D. D. and McDonald, L. in press. Runoff and erosion in a pinyon-juniper woodland: Influence of vegetation patches. Soil Science Society of America Journal.

Reneau, S. L. and McDonald, E. V. 1996. Landscape history and processes on the Pajarito Plateau, Northern New Mexico.Report LA-UR-96-3035. Los Alamos National Laboratory, Los Alamos, NM, 195 pp.

Reynolds, R. V. R. 1911. Grazing and floods: A study of conditions in the Manti National Forest, Utah.Bulletin 91. U.S. Forest Service, Washington, D.C., 16 pp.

Rice, B. and Westoby, M. 1978. Vegetation responses of some Great Basin shrub communities protected from jackrabbits or domestic stock. Journal of Range Management 31: 28-33.

Richmond, A. J. and Baron, W. R. 1989. Precipitation, range carrying capacity and Navajo livestock raising, 1870-1975. Agricultural History 63: 217-230.

Rinne, J. N. 1999. Fish and grazing relationships: The facts and some pleas. Fisheries 24: 12-21.

Roberts, P. H. 1963. Hoof prints on forest ranges: The early years of National Forest Range administration. The Naylor Company, San Antonio, TX, 151 pp.

Roessel, R. and Johnson, B. H. 1974. Navajo livestock reduction: A national disgrace. Navajo Community College Press, Tsaile.

Rothman, H. 1989. Cultural and environmental change on the Parjarito Plateau. New Mexico Historical Review 64: 185.

Savage, M. and Swetnam, T. W. 1990. Early 19th-century fire decline following sheep pasturing in a Navajo ponderosa pine forest. Ecology 71: 2374-2378.

Schmatz, E. M. 1968. Livestock-poisoning plants of Arizona. University of Arizona Press, Tucson.

Schmutz, E. M., Michaels, C. C. and Judd, B. I. 1967. Boysag Point: A relict area on the North Rim of Grand Canyon in Arizona. Journal of Range Management 20: 363-369.

Schultz, T. T. and Leininger, W. C. 1990. Differences in riparian vegetation structure between grazed areas and exclosures. Journal of Range Management 43: 295-299.

Schultz, T. T. and Leininger, W. C. 1991. Nongame wildlife communities in grazed and ungrazed riparian sites. Great Basin Naturalist 51: 286-292.

Shurig, R. G. 1971. Soil survey and range site and condition inventory of Wupatki National Monument, Arizona. U.S. Department of Agriculture, Soil Conservation Service/National Park Service, Washington, D.C.

Southwest Center for Biological Diversity. 2000. Grazing Bibliography. <> 9/11/00.

Stoddard, L. A. 1946. Some physical and chemical responses of Agropyron spicatum to herbage removal at various seasons. Utah State Agricultural College, Agricultural Experiment Station Bulleti 324: 24.

Sypolt, C. M. 1974. Keepers of the Rocky Mountain flocks: a history of the sheep industry in Colorado, New Mexico, Utah and Wyoming to 1900. Ph.D. Dissertation. University of Wyoming, Laramie, 336 pp.

Taylor, D. M. 1986. Effects of cattle grazing on passerine birds nesting in riparian habitat. Journal of Range Management 39: 254-258.

Touchan, R., Swetnam, T. W. and Grissino-Mayer, H. D. 1995. Effects of livestock grazing on presettlement fire regimes in New Mexico. In: Symposium on fire in wilderness and park management. General Technical Report INT-320. USDA Forest Service, Intermountain Research Station, Ogden, UT.

Trimble, S. 1993. How many sheep is too many sheep? Pp. 155-160 In: The People: Indians of the American Southwest. School of American Research Press, Santa Fe, NM.

U.S. Department of the Interior, B.L.M., Arizona Strip District. 1992. Arizona Strip District Rangeland Program summary update. USDI/BLM, St. George, UT.

Underwood, A. H. 1970. A study of ranch management practices in Navajo County, Arizona. M.A. Thesis. University of Arizona, Tucson.

United States Bureau of Land Management. 1983. Henry Mountain grazing: Final environmental impact statement. Bureau of Land Management, Richfield District, Richfield, UT, 334 pp.

United States Bureau of Land Management. 1988. Henry Mountain coordinated resource management proposals: Final environmental assessment. Bureau of Land Management, Richfield, UT, 166 pp.

Vavra, M., Laycock, W. A. and Pieper, R. D., editors. 1994. Ecological implications of livestock herbivory in the West. Society for Range Management, Denver, CO.

West, N. E., Provenza, F. D., Johnson, P. S. and Owens, M. K. 1984. Vegetation change after 13 years of livestock grazing exclusion on sagebrush semidesert in west central Utah. Journal of Range Management 37: 262-264.

Wilcox, B. P., Newman, B. D., Allen, C. D., Reid, K. D., Brandes, D., Pitlick, J. and Davenport, D. W. 1996. Runoff and erosion on the Pajarito Plateau: Observations from the field. Pp. 433-439 In: New Mexico Geological Society Guidebook, 47th Field Conference, Jemez Mountains Region. New Mexico Geological Society, Albuquerque, NM.

Wilcox, B. P., Pitlick, J., Allen, C. D. and Davenport, D. W. 1996. Runoff and erosion from a rapidly eroding pinyon-juniper hillslope. Pp. 61-77 In: Anderson, M. G. and Brooks, S. M., editors. Advances in hillslope processes. Vol. 1. John Wiley & Sons Ltd., New York, NY.

Willey, D. W. 1994. Effects of livestock grazing on grassland birds in Capitol Reef National Park, Utah. Technical Report NPS/NAUCARE/NRTR-94/05. National Park Service, Flagstaff, AZ.

Wilson, A. K. 1941. History of the Arizona Strip to 1913. M.S. Thesis. Arizona State Teacher's College (Northern Arizona University), Flagstaff.

Wilson, R. E. 1944. Tree planting and soil erosion control in the southwest. Journal of Forestry 42: 668-673.

Wolters, G. L. 1996. Elk effects on Bandelier National Monument meadows and grasslands. Pp. 196-205 In: Allen, C. D., editor. Fire effects in southwestern forests: proceedings of the second La Mesa fire symposium. U.S. Forest Service General Technical Report RM-GTR-286, Fort Collins, CO.

Wooton, E. O. 1908. The range problem in New Mexico. Agriculture Experiment Station Bulletin 66. New Mexico College of Agriculture and Mechanic Arts, Las Cruces, NM, 46 pp.

Workman, J. P. 1994. Higher federal grazing fees: Impacts on Utah ranches. Rangelands 16: 7-8.

Workman, J. P. 1996. Optimum cattle management on Utah ranches. Rangelands 18.

Workman, J. P. and Evans, S. G. 1993. Utah ranches: An economic snapshot. Rangelands 15: 253-255.

Wright, H. E., Jr., Bent, A. M., Hensen, B. S. and Maher, L. H., Jr. 1973. Present and past vegetation of the Chuska Mountains, northwestern New Mexico. Geological Society of America Bulletin 84: 1155-1180.