Name:
Alnus viridis ssp. sinuata / Athyrium filix-femina - Cinna latifolia Shrubland
Reference:
Western Ecology Working Group of...
Description:
This association is found in cool and moist mountainous regions between about 1022-1837 m (3350-6012 feet) elevation, ranging from northern California, along the eastern slope of the Cascades to southern British Columbia, through northeastern Oregon, Washington and Montana and north into the Canadian Rockies. It usually occurs as narrow stringers in moderate to steep, V-shaped valleys in areas of deep or long-lasting snowpacks. Such habitats include floodplains and streambanks of small streams (orders 1 and 2), avalanche chutes, and occasionally springs. These areas often flood during snowmelt and remain wet throughout the summer. Soils vary, but are typically thin silt or sandy loams over alluvial cobble and gravel. <i>Alnus viridis ssp. sinuata</i> forms dense, 3- to 5-m tall thickets with 60 to nearly 100% cover, but less dense stands are also known. Conifers, especially <i>Abies grandis</i> and <i>Picea engelmannii</i>, are sometimes present and may indicate a successional trend toward conifer-dominated associations. Periodic severe flood or avalanche disturbance may be necessary for maintaining the long-term dominance of <i>Alnus viridis ssp. sinuata</i>. The only understory shrubs with greater than 50% constancy (but usually low cover), are <i>Ribes</i> spp. (<i>Ribes hudsonianum</i> or <i>Ribes lacustre</i>), <i>Salix drummondiana</i>, and <i>Rubus parviflorus</i>. <i>Athyrium filix-femina</i>, 30-90 cm tall, is always present in the understory, typically with 20-80% cover, while another fern, <i>Gymnocarpium dryopteris</i>, is sometimes subdominant. <i>Cinna latifolia</i> is often present, but averages only 5% cover (and less than <i>Athyrium filix-femina</i>). Tall forbs, most commonly <i>Maianthemum stellatum, Senecio triangularis, Chamerion angustifolium, Prosartes</i> spp. (= <i>Disporum</i> spp.), and <i>Streptopus amplexifolius</i>, have high constancy but usually have less than 10% cover, although they can occasionally be quite abundant, with as much as 50% canopy cover. A lush ground layer composed of species including, but not limited to, <i>Boykinia major, Circaea alpina, Claytonia cordifolia, Galium triflorum</i>, and <i>Mitella</i> spp., is often present beneath the taller <i>Athyrium filix-femina</i> canopy.
Accession Code:
VB.CC.34260.CEGL001156
Plot-observations of this Community Concept:
0
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