Name:
Populus balsamifera ssp. trichocarpa - (Populus tremuloides) / Heracleum maximum Riparian Forest
Reference:
NatureServe Biotics 2019
Description:
This association has been described from the foothills of the eastern slope of the Rocky Mountains in northwestern Montana. It is found on the bottoms of narrow mountain valleys, intra- and inter-morainal depressions, areas possibly underlain by clay lenses, and fringing kettle lakes, from 1372-1678 m (4500-5500 feet) elevation. These sites have gentle slopes and occur on all aspects. Sites on southerly aspects are typically moist mountain slopes where soil moisture is probably augmented by subsurface flow. Soils are derived from alluvium (some deposited by slopewash), colluvium, or eolian materials derived from sedimentary rock types and layered over morainal drift. Soils are seasonally saturated and have relatively high organic matter. This forest association is dominated by the broad-leaved deciduous tree <i>Populus balsamifera ssp. trichocarpa</i>, with <i>Populus tremuloides</i> usually present. Where both species are present, <i>Populus balsamifera ssp. trichocarpa</i> has at least 1-5% cover, and is the indicator species for this association. Occasional individuals of <i>Picea engelmannii</i> and <i>Pseudotsuga menziesii</i> occur, but seedlings of these species are rare. The understory is characterized by a low-shrub layer composed of patches of <i>Symphoricarpos albus</i>. <i>Amelanchier alnifolia</i> and <i>Mahonia repens</i> occur in most stands, but are typically not abundant. The herbaceous layer is diverse, well-developed and composed of species indicative of mesic conditions. Important perennial forbs include <i>Osmorhiza occidentalis, Heracleum maximum, Actaea rubra, Galium triflorum, Viola canadensis</i>, and <i>Angelica arguta</i>. Other forbs of high constancy are <i>Thalictrum occidentale, Fragaria virginiana, Maianthemum stellatum, Geranium viscosissimum, Geranium richardsonii</i>, and <i>Packera pseudaurea</i>. On sites that are transitional to those with permanently saturated soils, <i>Equisetum arvense, Streptopus amplexifolius</i>, and <i>Calamagrostis canadensis</i> become more important.
Accession Code:
urn:lsid:vegbank.org:commConcept:29451-{2E3D7043-47EF-4E13-9A69-ADC3E6AD2BEC}
Plot-observations of this Community Concept:
7
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