PONDEROSA PINE/WESTERN JUNIPER WOODLAND (58)

Geographic Distribution. Widespread conifer woodland forest type in eastern Oregon. This cover type is usually found in the foothills margin bordering upland conifer types and sagebrush dominant lowlands for most of the regions mountain ranges.

Structure and Appearance. Woodland conifer forest cover type. Two-story canopy with widely spaced overstory ponderosa pine (Pinus ponderosa) over the sub-canopies of western juniper (Juniperus occidentalis). Combined canopy layers generally ranges from 10-50 percent. The shrub layer, interspersed with annual and bunch grasses, typically dominates understory vegetation.

Composition. Ponderosa pine and western juniper dominate the overstory in this cover type. Dominance of the tree layer between Ponderosa and juniper shifts by microsite and elevation. Improved site productivity favors dominance by Ponderosa. In lower elevations with warmer, drier microclimates, or sites with thin soils, dominance shifts to western juniper.

Indicator shrubs in this type include big sagebrush (Artemisia tridentata), low sagebrush (A. arbuscula), rabbitbrush (Chrysothamnus nauseous and C. viscidiflorus), mountain mahogany (Cercocarpus ledifolius), and bitterbrush (Purshia tridentata).

Grasses dominate the herbaceous layer. Overgrazing in the cover type usually leads to the proliferation of cheatgrass (Bromus tectorum), bottlebrush squirreltail (Sitanion hystrix), or bulbous bluegrass (Poa bulbosa). Native bunchgrasses commonly found in this cover type include: Sandberg's bluegrass (Poa secunda), Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Agropyron spicatum), Great Basin wildrye (Elymus cinereus), and ricegrass (Oryzopsis exigua).

Landscape Setting. Similar to the western juniper woodland cover type, the ponderosa/juniper type occupies the transition between upland conifer forests and lowland sagebrush communities.

References. Shiftlet, 1994, Johnson and Clausnitzer 1992, Johnson and Simon, 1987, Dealy et al. 1981.