Common (Translated Scientific) Name: Douglas-fir - Ponderosa Pine Central Rocky Mountain Forest Group

Colloquial Name: Central Rocky Mountain Douglas-fir - Pine Forest

Hierarchy Level:  Group

Type Concept: This group is composed of highly variable montane coniferous forests found in the interior Pacific Northwest, from southernmost interior British Columbia, eastern Washington, eastern Oregon, northern Idaho, western and north-central Montana, and south along the east slope of the Cascades in Washington and Oregon. Most occurrences of this group are dominated by a mix of Pseudotsuga menziesii and Pinus ponderosa (but there can be one without the other) and other typically seral species, including Larix occidentalis (not in central Montana), Pinus contorta, and Pinus monticola (not in central Montana). Picea engelmannii (or Picea glauca or their hybrid) becomes increasingly common towards the eastern edge of the range. In the eastern Cascades, Pinus contorta may be the codominant pine, rather than Pinus ponderosa. The nature of this forest group is a matrix of large patches dominated or codominated by one or combinations of the above species; Abies grandis (a fire-sensitive, shade-tolerant species not occurring in central Montana) has increased on many sites once dominated by Pseudotsuga menziesii and Pinus ponderosa, which were formerly maintained by low-severity wildfire. Understories are typically dominated by graminoids, such as Calamagrostis rubescens, Carex geyeri, Carex rossii, and Pseudoroegneria spicata, and a variety of shrubs, such as Acer glabrum, Juniperus communis, Physocarpus malvaceus, Spiraea betulifolia, Symphoricarpos albus, or Vaccinium membranaceum on mesic sites. Abies concolor and Abies grandis x concolor hybrids in central Idaho (the Salmon Mountains) may occur in some stands, but have very restricted ranges in this area. Abies concolor and Abies grandis in the Blue Mountains of Oregon are probably hybrids of the two and mostly Abies grandis. This group is associated with a submesic climate regime with annual precipitation ranging from 50 to 100 cm, with a maximum in winter or late spring. Winter snowpacks typically melt off in early spring at lower elevations. Elevations range from 460 to 1920 m. These communities rarely form either upper or lower timberline forests. Presettlement fire regimes may have been characterized by frequent, low-intensity surface fires that maintained relatively open stands of a mix of fire-resistant species. Under present conditions the fire regime is mixed-severity and more variable, with stand-replacing fires more common, and the forests are more homogeneous. With vigorous fire suppression, longer fire-return intervals are now prevalent, and multi-layered stands of Pseudotsuga menziesii, Pinus ponderosa, and/or Abies grandis provide fuel "ladders," making these forests more susceptible to high-intensity, stand-replacing fires. They are very productive forests which have been priority areas for timber production.

Diagnostic Characteristics: Montane coniferous forests found in the interior Pacific Northwest; most occurrences of this group are dominated by a mix of Pseudotsuga menziesii and Pinus ponderosa, but Pinus ponderosa can be absent. Other typically seral species, including Pinus contorta, Pinus monticola (not in central Montana), and Larix occidentalis (not in central Montana). Abies grandis (a fire-sensitive, shade-tolerant species) have increased on many sites once dominated by Pseudotsuga menziesii and Pinus ponderosa, which were formerly maintained by low-severity wildfire. Generally, floristic affinities are with areas of maritime-influenced climate of the interior Pacific Northwest.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Need to re-assess the concept of this group in relation to several other groups, including ~Central Rocky Mountain Mesic Grand Fir - Douglas-fir Forest Group (G211)$$, ~East Cascades Mesic Grand Fir - Douglas-fir Forest Group (G212)$$, ~Central Rocky Mountain Ponderosa Pine Open Woodland Group (G213)$$, and ~Middle Rocky Mountain Montane Douglas-fir Forest & Woodland Group (G215)$$. In PNV (PAGs) concept, this is mostly Pseudotsuga menziesii, moist Pinus ponderosa series, dry Abies grandis or warm, dry Abies lasiocarpa series in the Canadian Rockies, northern Middle Rockies, East Cascades and Okanagan ecoregions. Everett et al. (2000) indicate that in the eastern Cascades of Washington, this group forms fire polygons due to abrupt north and south topography with presettlement fire-return intervals of 11-12 years typically covering less than 810 ha. Currently, fires have 40- to 45-year return intervals with thousands of hectares in size. ~East Cascades Mesic Grand Fir - Douglas-fir Forest Group (G212)$$ has a North Pacific floristic composition and is mostly found in the East Cascades ecoregion, peripheral in Okanagan ecoregion, and West Cascades.

For now, the associations attributed to this group do not include any Abies grandis-named types; all of those have been placed in other groups. It may be that some of the drier end of Abies grandis forests should be included in this group, as they may well be mixed with Pinus ponderosa, or Pseudotsuga menziesii.

Similar NVC Types: No Data Available

note: No Data Available