Name:
Picea engelmannii / Senecio triangularis Swamp Forest
Reference:
NatureServe Biotics 2019
Description:
This forest association is known from the northern and central portions of the Blue Mountains ecoregion of Oregon but may also occur in the East Cascades ecoregion. It is found on mid-elevation bars, floodplains, and springs. Sampled sites are in moderate- to moderately high-gradient, very narrow to broad, generally, trough-shaped valleys with gentle to moderately steep sideslopes. This association develops on coarse alluvial deposits of sands, gravels, cobbles, and boulders. Silt loam or sandy loam is usually deposited on top of these coarse layers. Mean depth to the water table is 25 cm in June-July; the spring where sampled was wet the entire growing season. Soil surface cover of rock and gravel approaches 20% in this type. Rosgen stream types of B3 and C3 are associated with sampled areas. Stream widths vary from 1.5 to 5 m. <i>Picea engelmannii</i> is the sole overstory tree with an occasional <i>Pinus contorta, Pseudotsuga menziesii</i>, or <i>Abies grandis</i> in the understory. <i>Picea engelmannii</i> regeneration is scattered in stands but abundant where a light spruce overstory is present. <i>Ribes lacustre</i> is present on all sites. <i>Alnus incana, Ribes hudsonianum, Cornus sericea ssp. sericea</i>, and <i>Rosa gymnocarpa</i> are frequent understory shrubs. The diverse understory is characterized by the wet-site forb <i>Senecio triangularis</i>, with mean canopy coverage of 48%. Other important forbs include <i>Galium triflorum, Saxifraga odontoloma, Streptopus amplexifolius, Aconitum columbianum, Veronica americana, Parnassia fimbriata, Claytonia cordifolia, Heracleum maximum, Angelica arguta</i>, and <i>Thalictrum occidentale</i>. Frequent grass and sedge components include <i>Cinna latifolia, Bromus vulgaris</i>, and <i>Carex disperma</i>. Height of the shrub layer averages 0.9 m. Height of the herbaceous layer averages 102 cm, ranging from 91-122 cm. Average herbaceous biomass is 1878 lbs/acre, ranging from 567-3967 lbs/acre. The frequent occurrence of <i>Alnus incana</i> and <i>Ribes</i> species demonstrates that this association in probably in transition from ~<i>Alnus incana / Ribes (inerme, hudsonianum, lacustre)</i> Wet Shrubland (CEGL001151)$$. As sites receive more fine-textured floodplain materials, the site potential may change to another <i>Picea engelmannii</i> association such as ~<i>Picea engelmannii / Clintonia uniflora</i> Forest (CEGL000360)$$. Severe fires that kill the spruce overstory will leave CEGL001151 as the dominant on the site again. Flood scour that removes fine-textured surface materials, especially following a severe fire, will transition the site back to CEGL001151 until the floodplain starts rebuilding and provides establishment sites for <i>Picea engelmannii</i>.
Accession Code:
urn:lsid:vegbank.org:commConcept:29285-{703339EB-E8DE-4F3E-A4FE-0C87B9980ED5}
Plot-observations of this Community Concept:
0
|
