Ecology of pinon-juniper vegetation in the Southwest and Great Basin

Abstract

Pinon-juniper vegetation is conspicuous in foothills surrounding most mountain ranges in the Great Basin and the Southwest. Utah has the largest percentage of pinon-juniper vegetation, followed by New Mexico, Nevada, Arizona, and Colorado. Although pinon-juniper stands may appear to be similar, the vegetation component varies. The most abundant junipers are Juniperus deppeana, J. monosperma, J. osteosperma, and J. scopulorum. The pinons are Pinus edulis in the Southwest and P. monophylla in the Great Basin. At most locations the tree layer has 1 to 3 species while the understory is also composed of only a few species. Heavy livestock grazing, tree cutting, reduction of fire frequency and intensity, large-scale control programs, and periodic drought have influenced these woodlands over the past 150 years. Generally woodlands have increased at the expense of grasslands, but there is some debate about the nature of the increase-whether it represents encroachment into grasslands or reoccupation of former woodland sites. Several successional models may be applied to the pinon-juniper woodlands, including Clementsian linear succession, state and transition approaches, and cusp models.

Parent Publication

• Ecology, management, and restoration of pinon-juniper and ponderosa pine ecosystems: combined proceedings of the 2005 St. George, Utah and 2006 Albuquerque, New Mexico workshops

Citation

Pieper, Rex D. 2008. Ecology of pinon-juniper vegetation in the Southwest and Great Basin. In: Gottfried, Gerald J.; Shaw, John D.; Ford, Paulette L., compilers. 2008. Ecology, management, and restoration of pinon-juniper and ponderosa pine ecosystems: combined proceedings of the 2005 St. George, Utah and 2006 Albuquerque, New Mexico workshops. Proceedings RMRS-P-51. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 3-10