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CEGL000089 Thuja plicata / Linnaea borealis Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Western Red-cedar / Twinflower Forest
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This evergreen forest association is found on the west slope of the Oregon Cascades, on the east slope of the Cascades near Mount Hood, and possibly extending into Washington. Stands generally occur along stream margins between 1100-1400 m elevation on all aspects. Upland stands are usually indicative of a perched water table. Soils are fine, sandy clay loams with weak subangular, blocky structure. The tree canopy is dominated by Thuja plicata, averaging between 30-50% cover. Abies grandis and Picea engelmannii are common tree associates. Occasionally Populus balsamifera ssp. trichocarpa and/or Populus tremuloides may be conspicuous associates. Linnaea borealis is always present though cover values rarely exceed 5%. Other shrubs may include Acer circinatum, Ribes lacustre, Mahonia nervosa, and Athyrium filix-femina. The most common forb is Maianthemum stellatum. A rich and varied assortment of other shrubs and forbs is usually present.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: No Data Available
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: The evergreen needle-leaved tree Thuja plicata dominates both the canopy and understory of this forest association. Mature trees of this species are very large, form a dense canopy, and reach heights over 50 m. The somewhat shorter (40-50 m tall) conifers Picea engelmannii and Abies grandis form a subcanopy, but are not particularly abundant. Several other trees may occur, including the conifers Pseudotsuga menziesii and Larix occidentalis, and the deciduous, broad-leaved Populus balsamifera ssp. trichocarpa (= Populus trichocarpa). The understory is somewhat depauperate and dominated by regeneration of Thuja. Several shrubs are always present with low cover, including the low broad-leaved evergreen Chimaphila menziesii and the taller deciduous Rosa woodsii. The herbaceous layer is sparse but diverse, and dominated by perennial forbs, the most important and characteristic being the creeping evergreen Linnaea borealis (which is considered by some workers to be a shrub), and Maianthemum stellatum, which average over 5% cover. Other constant forbs include Anemone oregana and Trillium ovatum. The ground surface has a thick litter layer of branches and needles.
Dynamics: No Data Available
Environmental Description: This association is found on the eastern side of the Cascade Range crest in a region with a steep precipitation gradient created by topographic rainshadow effects. Despite moderate to high annual precipitation (140-200 cm/year), there is a distinct summer drought. Temperatures are relatively warm, but snow packs often persist into spring. This association is found along streams, in areas where the water table is high; if it is found on upland sites it indicates a perched water table. Elevations range from 1220 to 1315 m. Sites are typically lower slopes and valley bottoms, with gentle slopes (6-9%) and flat to concave microrelief. The surrounding topography can be undulating to steep and rugged. Parent materials of the soils are not described, but are likely to be colluvium or alluvium derived from volcanic deposits, with a mantle of volcanic ash or loess. The soils are 50 cm or more in depth, with a mid-summer water table at roughly 38 cm. Textures are fine sandy clay loams with iron stains throughout the profile. Stoniness is highly variable, from very little to nearly half the soil volume.
Geographic Range: The only description of this community (Atzet and McCrimmon 1990) is from the central to southern portion of the West Slope Cascade ecoregion. It appears to be a slightly drier southern phase of the western hemlock/rhododendron/ Oregon oxalis community, more widespread to the north.
Nations: US
States/Provinces: OR, WA
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.685170
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: G2
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.B Temperate & Boreal Forest & Woodland Subclass | S15 | 1.B |
| Formation | 1.B.2 Cool Temperate Forest & Woodland Formation | F008 | 1.B.2 |
| Division | 1.B.2.Nd Vancouverian Forest & Woodland Division | D192 | 1.B.2.Nd |
| Macrogroup | 1.B.2.Nd.3 Western Hemlock - Sitka Spruce - Redwood Rainforest Macrogroup | M024 | 1.B.2.Nd.3 |
| Group | 1.B.2.Nd.3.f Western Hemlock - Sitka Spruce North-Central Pacific Rainforest Group | G751 | 1.B.2.Nd.3.f |
| Alliance | A3609 Grand Fir - Sitka Spruce - Western Red-cedar Forest Alliance | A3609 | 1.B.2.Nd.3.f |
| Association | CEGL000089 Western Red-cedar / Twinflower Forest | CEGL000089 | 1.B.2.Nd.3.f |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Thuja plicata / Linnaea borealis Forest (Atzet and McCrimmon 1990)
- Atzet, T., and L. A. McCrimmon. 1990. Preliminary plant associations of the southern Oregon Cascade Mountain Province. USDA Forest Service, Pacific Northwest Region, Siskiyou National Forest, Grants Pass, OR. 330 pp.
- Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
- Kagan, J. S., J. A. Christy, M. P. Murray, and J. A. Titus. 2004. Classification of native vegetation of Oregon. January 2004. Oregon Natural Heritage Information Center, Portland. 52 pp.
- WNHP [Washington Natural Heritage Program]. 2018. Unpublished data files. Washington Natural Heritage Program, Department of Natural Resources, Olympia, WA.
- Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.
- Williams, C. K. 1978. Vegetation classification for the Badger Allotment, Mt. Hood National Forest. Unpublished dissertation, Oregon State University, Corvallis. 117 pp.
- Williams, C. K., and A. H. Winward. 1976. Plant community types of the Badger Allotment, Barlow Ranger District, Mt. Hood National Forest. USDA Forest Service and Oregon State University Rangeland Resources Program. 68 pp.