Common (Translated Scientific) Name: Ponderosa Pine / Rough Fescue Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This association is most prevalent throughout northwestern Montana and the isolated ranges of central Montana, but it also occurs farther west in northern Idaho, eastern Washington, and possibly in interior British Columbia. It occurs primarily as small (to large) stands on south- and west-facing slopes at elevations of less than 1525 m (5000 feet). It is also found on moderate north slopes and benchlands near lower timberline where it transitions to fescue grasslands or ~Pinus ponderosa / Pseudoroegneria spicata Woodland (CEGL000865)$$ on drier exposures. It occurs on a broad spectrum of parent materials, including calcareous substrates. Surface soils are generally gravelly, ranging from silts to fine sandy loams. Bare soil is minimal, and there are only moderate amounts of exposed rock. Soils average about 4 cm of duff depth and have a darkened A1 surface horizon, indicative of the strong influence of abundant graminoids and forbs on soil development. Stands are open to approaching a savanna-like condition and uniquely dominated by Pinus ponderosa with negligible amounts of Pinus flexilis and/or Juniperus scopulorum; Pseudotsuga menziesii is considered to be an "accidental." The shrub component is depauperate in species and cover, with only Amelanchier alnifolia and Symphoricarpos albus exhibiting constancy approaching 50%. Bunchgrasses dominate the undergrowth (highest coverages approaching 70%, averaging about 55%) with dominance shifting between Festuca campestris, Festuca idahoensis, Pseudoroegneria spicata, Koeleria macrantha, Elymus trachycaulus, Achnatherum occidentale, and Achnatherum nelsonii, depending on disturbance regime (livestock grazing primarily). Forbs of highest constancy include Achillea millefolium, Anemone multifida, Balsamorhiza sagittata, Lithospermum ruderale, Galium boreale, Geum triflorum, and Potentilla gracilis; total forb cover seldom exceeds 20%.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: As described and documented by Pfister et al. (1977), this is a climax plant association (habitat type) at the dry end of the moisture gradient of sites capable of supporting tree-dominated vegetation. As originally conceived, Pinus ponderosa (and to a limited degree Pinus flexilis and Juniperus scopulorum) should be the only trees capable of establishing on such xeric sites. However, the International Vegetation Classification (IVC) recognizes no distinction between types defined by potential versus those representing existing vegetation, which means stands with other conifer species in the subcanopy or reproductive layers (most likely Pseudotsuga) will classify to this type until the more shade-tolerant species assume dominance.

Similar NVC Types: No Data Available

note: No Data Available