Physiognomy and Structure: No Data Available

Floristics: The vegetation is characterized by an open to moderately dense tree canopy (10-40% cover) typically codominated by Pinus monophylla and Juniperus osteosperma. Juniperus osteosperma is often more abundant at lower elevation. The short-shrub layer is typically sparse (10-15% cover) and is dominated by Artemisia tridentata. Chrysothamnus viscidiflorus or Purshia tridentata are frequent associates. Other associated shrubs may include low cover of Amelanchier spp., Ephedra nevadensis, Ephedra viridis, Ericameria nauseosa, Grayia spinosa, and species of Gutierrezia, Opuntia, Tetradymia and Yucca. The sparse to moderately dense herbaceous layer is dominated by graminoids with scattered forbs. Frequent graminoids are Elymus elymoides and Poa secunda. Other associated graminoids may include Achnatherum hymenoides (= Oryzopsis hymenoides), Achnatherum thurberianum (= Stipa thurberiana), Koeleria macrantha, Pleuraphis jamesii, or Pseudoroegneria spicata. Although forb cover is generally sparse, it may be very diverse. Common forbs include Astragalus spp., Balsamorhiza sagittata, Cryptantha cinerea var. jamesii (= Cryptantha jamesii), Lomatium spp., Machaeranthera canescens, Eriogonum spp., Gayophytum ramosissimum, and Phlox spp. Disturbed stands may have high cover of the introduced annual grass Bromus tectorum.

Dynamics:  Pinus monophylla and Juniperus osteosperma trees and Artemisia tridentata are highly susceptible to fire because of highly flammable foliage, and they do not self-prune their dead branches. When burned they are killed or severely damaged and do not resprout. Artemisia tridentata will re-establish relatively quickly (about 10-20 years), if a seed source is nearby (Barney and Frischknecht 1974, Wright et al. 1979, Bunting 1987). However, Pinus monophylla and Juniperus osteosperma are relatively slow to recover following fire, and sagebrush may dominate the burned sites for decades (Jameson et al. 1962). If fire-return intervals are more frequent than 10 years, then Artemisia tridentata has difficulty recovering (Bunting 1987, Everett 1987).

This community may be increasing in extent by invading adjacent grasslands and steppe because of reduction of fire frequency due to fire suppression and fine fuels removal by grazing livestock that would allow fires to spread (Blackburn 1967, Johnson and Payne 1968). Fire, drought and competition with grasses are thought to have kept Juniperus spp. communities restricted to rocky areas that do not burn frequently (Wright et al. 1979). When understory is more continuous, fires will be more frequent. The invasion of Bromus tectorum across the western U.S. is changing fire frequencies by providing a continuous layer of fine fuel. However, these woodlands often have low tree density, and if they lack fine fuel needed to spread surface fire, fire frequency is relatively low, needing extreme conditions to carry a crown fire (Wright et al. 1979, Bradley et al. 1992).