Name:
Betula occidentalis Shrubland
Reference:
Western Ecology Working Group of...
Description:
This shrubland occurs on stream benches and floodplains in narrow to moderately wide valleys and hillside seeps in mountains, canyons, foothills, and sheltered alcoves across much of the western U.S. Surface water is present for extended periods during the growing season. The water table, after flooding ceases, is variable, extending from saturated to well below the ground surface, but the roots of <i>Betula occidentalis</i> are always in saturated soil. Substrates are typically alluvial and range from fairly shallow, finer-textured soils to gravel and boulders. Soils usually have signs of saturation (mottles). The vegetation is characterized by a nearly continuous tall-shrub to small-tree canopy dominated by <i>Betula occidentalis</i> along the streambank. Other shrub species include <i>Alnus incana, Cornus sericea, Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda), Salix</i> spp., <i>Amelanchier utahensis, Rhus trilobata, Shepherdia argentea</i>, and <i>Prunus virginiana</i>. Along narrow valleys at higher elevations, conifers may overhang the stream edge. Herbaceous undergrowth can be limited because of the dense shrub canopy. However, if the shrub canopy is open and the stand is on relatively well-drained yet mesic site (for example, elevated river benches), the herbaceous layer can be abundant. It is often a diverse mixture of grasses and forbs that is dominated by disturbance-induced species, including most commonly <i>Agrostis stolonifera, </i><i>Cirsium arvense</i><i>, </i><i>Phleum pratense</i>, and <i>Poa pratensis</i>. Forb species include <i>Maianthemum stellatum, </i><i>Heracleum sphondylium</i><i>, Thalictrum fendleri</i>, and <i>Rudbeckia laciniata</i>. Graminoid cover is highly variable and can include <i>Carex utriculata, Carex pellita (= Carex lanuginosa), Carex microptera, Carex nebrascensis, Glyceria</i> spp., <i>Juncus balticus</i>, and introduced hay grasses. Diagnostic of this association is the <i>Betula occidentalis</i>-dominated tall-shrub layer and a variable, weedy, mixed herbaceous undergrowth that occurs on sites that are flooded for extended periods during the growing season.
Accession Code:
VB.CC.33938.CEGL001080
Plot-observations of this Community Concept:
0
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