Vegetation Transition Model

Barren

      Description.--This cover type is characterized by a paucity or absence of vegetation cover. The substrate may be bedrock or unstable colluvium or highly erosive bedrock at any elevation, salt-rich shale at low elevations ("salt-desert shrublands" sensu West 1983), or may be persistent snow or ice. Often a few plants can be found, e.g., scattered Utah Juniper (Juniperus osteosperma) or shadscale saltbush (Atriplex confertifolia) or cushion-forming herbs at low elevations, or low shrubs and cushion-forming herbs at high elevations. Soil fertility and decomposition rates generally are greatest in the immediate vicinity of the shrubs (West 1983).

      Distribution.–Barren cover is scattered throughout the area on all aspects at all elevations, but is especially common at lower elevations, especially on “slickrock” or outcrops of marine shales, and at higher elevations on talus slopes and persistent snow and ice fields (Figure-distribution map; Figure-elevation chart; Table-areal coverage). Similar communities are found throughout the Colorado Plateau region (West 1983, 1988; Heil et al. 1993, Romme et al. 1993).

      Stand conditions.–Barren was treated as a static cover type (i.e., no succession) and therefore did not have separate stand conditions.

    No Conditions (NC) – we did not recognize separate stand conditions in this cover type.

      Succession Transitions.–Barren areas do not appear to undergo any obvious pattern of succession - at least over the spatial scales and time frames considered in this modeling application; therefore, we treated barren areas as static.

      Disturbance Transitions.–Disturbances do not appear to have an important impact on the few plants and animals that live in this environment. In particular, wildfire probably is extremely infrequent because of lack of fuels. Thus, barren areas were treated as ineligible for disturbances in RMLANDS.