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A.114 | EcoArt 2002
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Name: A.114
Reference: EcoArt 2002
Description: This giant forest alliance is found locally in lowland forests within the ~Tsuga heterophylla$ Zone in western Oregon and southwestern Washington. Elevation ranges from 50-200 m. Climate is maritime and wet, with mild winter and summer temperatures. Stands occur in and along the margins of the Willamette Valley, extending north to Olympia, and occasionally can be found in the adjacent Oregon Coast Range and West Cascade regions. These old-growth stands require low-elevation valley bottoms and terraces of medium streams to large rivers, and 500 years without major disturbances. They rarely occur along small or seasonal streams. The terraces are usually well above the river, impacted only by 100+-year floods. The deep alluvial deposits are essential for these highly productive stands, and are derived from volcanic and sedimentary rocks and glacial till. Soil texture ranges from gravelly sandy loam to clay. These forests are characterized by giant (>50 m tall), old-growth ~Pseudotsuga menziesii$ trees, which dominate the closed canopy overstory. ~Abies grandis, Tsuga heterophylla$, and ~Thuja plicata$ are the dominant understory trees, usually with a few individuals in the upper canopy. The small trees ~Corylus cornuta, Oemleria cerasiformis, Taxus brevifolia$, and ~Acer macrophyllum$ may form a subcanopy in moist alluvial soils or rocky areas. The moderately dense undergrowth is dominated by the fern ~Polystichum munitum$ and grows up to 2 m tall. ~Vaccinium parvifolium, Mahonia nervosa (= Berberis nervosa)$, and ~Gaultheria shallon$ are occasional low shrubs, while the forbs ~Oxalis oregana, Trillium ovatum, Maianthemum dilatatum, Rubus ursinus$, and ~Prosartes smithii (= Disporum smithii)$ can be locally important. In seeps and wet areas along streams, ~Adiantum pedatum$ is found. 
Accession Code: VB.CC.912.A114
Plot-observations of this Community Concept: 0
      Party Perspective according to: NatureServe (organization)
Perspective from: 26-Nov-1997 to: 17-Mar-2005
     
  • status: accepted
  • Community's Parent: I.A.8.N.a
  • This Community's Level: Alliance
  • This Community's Children: [none]
Names:   Scientific: ABIES GRANDIS GIANT FOREST ALLIANCE
  Code: A.114
  Common: Grand Fir Giant Forest Alliance
(convergence) and Synonyms:
(undetermined) Abies grandis Giant Forest Alliance