Name:
Pseudotsuga menziesii / Rosa gymnocarpa - Holodiscus discolor Forest
Reference:
Western Ecology Working Group of...
Description:
This association occurs from sea level to about 1220 m (4000 feet) elevation in the northern portion of the Puget Lowland and the far northeastern Olympic Mountains, Washington (Clallam, Jefferson, San Juan, Skagit, Whatcom counties), and in adjacent British Columbia, especially the Gulf Islands and southeastern Vancouver Island. This is an evergreen needle-leaved forest, or occasionally woodland, dominated by Pseudotsuga menziesii. The broad-leaved deciduous Acer macrophyllum occasionally occurs as a prominent subcanopy. A variable-density tall-shrub layer 2-6 m tall is usually present and dominated by the deciduous broad-leaved Holodiscus discolor, though is absent under heavy browsing pressure on some islands. Shorter shrubs are also variable in their cover and always include the deciduous Rosa gymnocarpa; the evergreen dwarf shrubs Mahonia nervosa and Mahonia aquifolium are usually present, the former sometimes codominant. The herbaceous layer is typically dominated by short grasses, especially Festuca occidentalis, Festuca subuliflora, and Melica subulata. Other frequent species include Bromus vulgaris, Elymus glaucus, Pteridium aquilinum, Rubus ursinus, Galium aparine, Fragaria vesca, and Trientalis borealis ssp. latifolia (= Trientalis latifolia). This association typically occurs on dry to very dry sites, with soils that are shallow to bedrock, in a very dry climatic zone in the rainshadow of the Olympic Mountains (less than 30 inches annual precipitation at sea level). Steep slopes or upper slope positions are typical. This association is distinguished from similar ones by >1% cover of Rosa gymnocarpa or Festuca occidentalis, combined with<10% cover of Symphoricarpos albus, Gaultheria shallon, Tsuga heterophylla, Thuja plicata, and Abies grandis, <20% cover of Arbutus menziesii, and <5% cover of Polystichum munitum.
Accession Code:
VB.CC.20554.PSEUDOTSUGAMENZ
Plot-observations of this Community Concept:
0
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