Name:
Pseudotsuga menziesii - Pinus ponderosa Central Rocky Mountain Forest Group
Reference:
NatureServe Biotics 2019
Description:
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 <i>Pseudotsuga menziesii</i> and <i>Pinus ponderosa</i> (but there can be one without the other) and other typically seral species, including <i>Larix occidentalis</i> (not in central Montana), <i>Pinus contorta</i>, and <i>Pinus monticola</i> (not in central Montana). <i>Picea engelmannii</i> (or <i>Picea glauca</i> or their hybrid) becomes increasingly common towards the eastern edge of the range. In the eastern Cascades, <i>Pinus contorta</i> may be the codominant pine, rather than <i>Pinus ponderosa</i>. The nature of this forest group is a matrix of large patches dominated or codominated by one or combinations of the above species; <i>Abies grandis</i> (a fire-sensitive, shade-tolerant species not occurring in central Montana) has increased on many sites once dominated by <i>Pseudotsuga menziesii</i> and <i>Pinus ponderosa</i>, which were formerly maintained by low-severity wildfire. Understories are typically dominated by graminoids, such as <i>Calamagrostis rubescens, Carex geyeri, Carex rossii</i>, and <i>Pseudoroegneria spicata</i>, and a variety of shrubs, such as <i>Acer glabrum, Juniperus communis, Physocarpus malvaceus, Spiraea betulifolia, Symphoricarpos albus</i>, or <i>Vaccinium membranaceum</i> on mesic sites. <i>Abies concolor</i> and <i>Abies grandis x concolor</i> hybrids in central Idaho (the Salmon Mountains) may occur in some stands, but have very restricted ranges in this area. <i>Abies concolor</i> and <i>Abies grandis</i> in the Blue Mountains of Oregon are probably hybrids of the two and mostly <i>Abies grandis</i>. 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 <i>Pseudotsuga menziesii, Pinus ponderosa</i>, and/or <i>Abies grandis</i> 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.
Accession Code:
urn:lsid:vegbank.org:commConcept:40006-{5B485476-72ED-43D1-8E0A-EB55061F11E8}
Plot-observations of this Community Concept:
0
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