Pinyon/juniper woodlands [Chapter 4]

Pinyon-juniper woodlands occur in 10 states and cover large areas in many of them. These woodlands can be dominated by several species of pinyon pine (Pinus spp. L.) and juniper (Juniperus spp. L.) (Lanner 1975; Mitchell and Roberts 1999; West 1999a). A considerable amount of information is available on the expansion of the woodlands that has occurred over large parts of the geographic ranges of the tree species involved (Miller and Tausch 2001). In southern Utah, the woodlands contain Utah juniper (Juniperus osteosperma), singleleaf pinyon (Pinus monophylla), and two-needled pinyon (Pinus edulis). Singleleaf pinyon is present in the western, and two-needled, or Colorado pinyon, in the eastern portions of the region. Each species can occur alone, or in a mix of one of the pinyon species with Utah juniper. Overall, information on woodland ecology for the southern Utah study area is limited. For this reason, the available literature for the woodlands in general, but particularly for the Great Basin, will be summarized and possible implications for southern Utah indicated.