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CEGL000483 Thuja plicata - Tsuga heterophylla / Oxalis oregana Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Western Red-cedar - Western Hemlock / Redwood Sorrel Forest
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This association occurs on the western slope of the southern Cascade Range and northern Klamath Mountains of Oregon from roughly 670 to 1300 m (2200-4250 feet) in elevation, on variably moderate to occasionally very steep slopes of northeasterly aspects. Sites are typically cool bottoms, moist, and often occur near watercourses. The influence of maritime air masses from the west is moderated by the presence of the Siskiyou Mountains along the Pacific Coast. Parent materials are basalt or andesite, with a few stands occurring on pumice or ash. Soils are typically deep (over 102 cm [40 inches]) and fertile, with the exception of those formed from pumice or ash. These are usually shallow, sterile and fragile. Over 90% of the forest floor is covered by plant litter, including rotting logs, and moss typically covers over 20% of the floor. This is a structurally diverse forest association, with a thick canopy of Pseudotsuga menziesii (dominates most stands), Thuja plicata, and Tsuga heterophylla. The dense tall-shrub stratum is dominated by Tsuga heterophylla and Thuja plicata regeneration, with some saplings of Abies lowiana and Pseudotsuga menziesii. The deciduous shrub Acer circinatum occurs in patches. There is a shorter shrub layer which is a diverse mix, with only the dwarf Mahonia nervosa present in all stands, while the taller Rhododendron macrophyllum has high cover when present. The herbaceous layer is dominated by perennial forbs, variable in cover and species composition; only the perennial forb Oxalis oregana is present in all stands, with 13% average cover. Few graminoids occur.
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: This is a structurally diverse forest association, with a thick canopy of evergreen needle-leaved trees. Pseudotsuga menziesii dominates most stands (with 46% cover), with Thuja plicata (12% cover) and Tsuga heterophylla (14% cover) also present. The dense tall-shrub stratum is dominated by Tsuga heterophylla and Thuja plicata regeneration (over 50% cover), with some saplings of Abies lowiana (= Abies concolor var. lowiana) and Pseudotsuga menziesii (contributing another 22% cover). The deciduous, broad-leaved shrub Acer circinatum occurs in patches. The short-shrub stratum is a diverse mix of taller (1-2 m height) broad-leaved deciduous shrubs, and lower or creeping broad-leaved deciduous or evergreen species. Only the dwarf Mahonia nervosa is present in all stands, while the taller Rhododendron macrophyllum has high cover when present (typically over 50%). Other common shrubs include Rubus ursinus, Vaccinium parvifolium, Gaultheria shallon, and Cornus nuttallii. The herbaceous layer is dominated by perennial forbs, variable in cover and species composition; only the perennial forb Oxalis oregana is present in all stands, with 13% average cover. Commonly present forbs include Trillium ovatum, Viola orbiculata, Tiarella trifoliata, Clintonia uniflora, Achlys triphylla, and Coptis laciniata. Few graminoids occur.
Dynamics: No Data Available
Environmental Description: This association occurs on the western slope of the southern Cascade Range, a range oriented north-south and with high elevations (alpine) to the east. It occurs from roughly 670 to 1300 m (2200-4250 feet) elevation, on variably moderate to occasionally very steep slopes of northeasterly aspects. Sites are typically cool bottoms, moist, and often occur near watercourses. Parent materials are basalt or andesite, with a few stands occurring on pumice or ash. Soils are typically deep (over 100 cm [40 inches]) and fertile, with the exception of those formed from pumice or ash. These are usually shallow, sterile and fragile. Over 90% of the forest floor is covered by plant litter, including rotting logs, and moss typically covers over 20% of the floor. The climate can be characterized as Mediterranean, with a summer dry season. Influence of maritime air masses from the west is moderated by the presence of the Siskiyou Mountains along the Pacific coast. Average annual precipitation is between 127 and 178 cm (50-70 inches), with only 20 cm (8 inches) falling during the dry season. Average temperatures are mild year-round, but the reduced marine influence results in greater extremes.
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, and the northern end of the Klamath Mountain ecoregion, all in Oregon. It appears to be a slightly drier southern facies of the western hemlock/Oregon oxalis community, more widespread to the north.
Nations: US
States/Provinces: OR
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.683519
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.c Douglas-fir - Western Hemlock / Salal Rainforest Group | G240 | 1.B.2.Nd.3.c |
| Alliance | A3379 Western Hemlock - Douglas-fir / Oceanspray Dry Forest Alliance | A3379 | 1.B.2.Nd.3.c |
| Association | CEGL000483 Western Red-cedar - Western Hemlock / Redwood Sorrel Forest | CEGL000483 | 1.B.2.Nd.3.c |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Thuja plicata - Tsuga heterophylla / Oxalis oregana 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.
- Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.