Name:
Populus balsamifera ssp. trichocarpa / Cornus sericea Forest
Reference:
Western Ecology Working Group of...
Description:
This association has been documented from Washington south to northern California and eastward to Idaho and Montana west of the Continental Divide, as well as central Montana. It occurs over a broad elevation range of 610 to 2010 m (2000-7000 feet) where Populus balsamifera ssp. trichocarpa is the dominant cottonwood at elevations considered relatively low to mid gradient. This forest type occupies alluvial terraces of major rivers and streams, point bars, side bars, mid-channel bars, delta bars, an occasional lake or pond margin, and even creeps onto footslopes and lower subirrigated slopes of hilly or mountainous terrain. Stands occasionally occur on upper positions of moderate to steep toeslopes and colluvial fans at the base of avalanche chutes. Many of these sites are flooded in the spring and dry deeply by summer's end; capillary action keeps upper portions of the soil profile moist. Other sites are merely subirrigated. Populus balsamifera ssp. trichocarpa dominates the overstory with average cover values ranging from approximately 30-90%. Populus angustifolia, Populus tremuloides, Betula papyrifera, and Salix amygdaloides are common subordinates. Several conifer species can be present with low cover (2-10%) in the upper canopy or as young saplings and are never consistently present. Conifers include Tsuga heterophylla, Pseudotsuga menziesii, Abies lasiocarpa, and Picea engelmannii. The shrub layer comprises at least 25% cover, with Cornus sericea diagnostic for the type and having anywhere from 1-90% cover; other shrub taxa with high constancy include Symphoricarpos spp., Rosa spp., Salix spp., Crataegus spp., Amelanchier alnifolia, Salix lutea, Acer glabrum, and Alnus incana. There are no graminoids exhibiting high constancy, though any one of a number of disturbance-associated exotics can manifest high coverages. Native grasses such as Calamagrostis canadensis, Glyceria striata, and Deschampsia caespitosa can be abundant in undisturbed stands, but this is increasingly less common. Maianthemum stellatum, Galium triflorum, Solidago canadensis, and Equisetum spp. are the only forbs that exhibit even relatively high constancy across the range of the type.
Accession Code:
VB.CC.26738.POPULUSBALSAMIF
Plot-observations of this Community Concept:
0
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