Name:
Populus balsamifera ssp. trichocarpa / Cornus sericea Riparian Forest
Reference:
NatureServe Biotics 2019
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 2135 m (2000-7000 feet) where <i>Populus balsamifera ssp. trichocarpa</i> 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. <i>Populus balsamifera ssp. trichocarpa</i> dominates the overstory with average cover values ranging from approximately 30-90%. <i>Populus angustifolia, Populus tremuloides, Betula papyrifera</i>, and <i>Salix amygdaloides</i> 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 <i>Tsuga heterophylla, Pseudotsuga menziesii, Abies lasiocarpa</i>, and <i>Picea engelmannii</i>. The shrub layer comprises at least 25% cover, with <i>Cornus sericea</i> diagnostic for the type and having anywhere from 1-90% cover; other shrub taxa with high constancy include <i>Symphoricarpos</i> spp., <i>Rosa</i> spp., <i>Salix</i> spp., <i>Crataegus</i> spp., <i>Amelanchier alnifolia, Salix lutea, Acer glabrum</i>, and <i>Alnus incana</i>. 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 <i>Calamagrostis canadensis, Glyceria striata</i>, and <i>Deschampsia cespitosa</i> can be abundant in undisturbed stands, but this is increasingly less common. <i>Maianthemum stellatum, Galium triflorum, Solidago canadensis</i>, and <i>Equisetum</i> spp. are the only forbs that exhibit even relatively high constancy across the range of the type.
Accession Code:
urn:lsid:vegbank.org:commConcept:29581-{47B3A4CD-C384-4DFA-A18E-23F5B51A449B}
Plot-observations of this Community Concept:
22
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