Name:
A.107
Reference:
EcoArt 2002
Description:
This coniferous forest alliance occurs at low elevations (0-1500 m) within the maritime-influenced region of the Pacific Northwest, generally west of the Cascade Mountains. Stands are best represented on lower mountain slopes of the coastal ranges with high precipitation, long frost-free periods, and low fire frequencies. Sites include upper slope and ridgetop positions, moist, rich sites such as ravines or north-facing slopes, or in depressions, swales and east- or west-facing slopes. Slopes are gentle to moderately steep. Soil types are variable, but growth is decreased on heavy soils or soils with poor drainage. These forests are characterized by a mixed canopy of ~Tsuga heterophylla$ and ~Pseudotsuga menziesii$, often with trees exceeding 50 m in height and a complex, multi-tiered structure of multiple age classes. ~Thuja plicata$ may codominate on valley bottom sites with poorly drained soils, and ~Tsuga heterophylla$ is generally the dominant regenerating tree species. However, young stands may lack ~Tsuga heterophylla$ or ~Thuja plicata$. Other common tree associates include ~Abies grandis, Picea sitchensis, Pinus monticola$, and in southwestern Oregon ~Pinus lambertiana, Chamaecyparis lawsoniana, Calocedrus decurrens$, and occasionally ~Pinus ponderosa$. A subcanopy of ~Acer macrophyllum, Chrysolepis chrysophylla (= Castanopsis chrysophylla), Lithocarpus densiflorus, Umbellularia californica$, and/or ~Taxus brevifolia$ may also be present. The moderately dense shrub layer is commonly composed of ~Acer circinatum, Mahonia nervosa, Rhododendron macrophyllum, Gaultheria shallon, Holodiscus discolor, Vaccinium ovatum$, and ~Oplopanax horridus$. The herbaceous layer is dominated by shade-tolerant forbs and ferns, including ~Pteridium aquilinum, Polystichum munitum, Trientalis borealis ssp. latifolia (= Trientalis latifolia), Oxalis oregana, Achlys triphylla, Chimaphila umbellata, Linnaea borealis$, and many others. Diagnostic of this alliance is an upper tree canopy dominated by ~Tsuga heterophylla$ and ~Pseudotsuga menziesii$.
Accession Code:
VB.CC.839.A107
Plot-observations of this Community Concept:
0
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