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CEGL000044 Chamaecyparis lawsoniana - Pseudotsuga menziesii / (Rhododendron macrophyllum) / Xerophyllum tenax Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Port Orford-cedar - Douglas-fir / (Pacific Rhododendron) / Common Beargrass Forest
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This coniferous forest association is found in southwestern Oregon and northwestern California between 720-980 m elevation. Stands normally occupy serpentine soils on convex sideslopes or gently rolling ridge positions between drainages. Soils are derived from ultramafic parent material. This association forms large forest patches in a matrix with other terrestrial communities. The mature tree canopy attains 85% cover, and is dominated by Chamaecyparis lawsoniana and Pseudotsuga menziesii, often with some Tsuga heterophylla. More light filters through the canopy than one would expect because the ultramafic parent materials decreases crown vigor. The shrub stratum is highly variable, well developed in some areas and nearly absent in others. The average cover of the shrub layer is 30%, much lower than most other Chamaecyparis associations. The dominant shrubs include Notholithocarpus densiflorus, Rhododendron macrophyllum, Gaultheria shallon and Mahonia nervosa. The moderately dense herbaceous layer is dominated by Xerophyllum tenax which is a clear indicator of ultramafic soils. Xerophyllum tenax occurs in most plots with high cover and density, but decreases when the stand spills onto concave landforms. The herbaceous layer is not very diverse, but may include Polystichum munitum, Goodyera oblongifolia, Iris innominata, Galium ambiguum, Trillium rivale, Erythronium oregonum, and Pyrola picta. Most of these herbs are associated with ultramafic soils. This is the only Chamaecyparis lawsoniana association with clear dominance of Xerophyllum tenax in the herbaceous layer.
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 the tree canopy dominated by evergreen needle-leaved species and the shrub layers dominated by broad-leaved evergreen species. Chamaecyparis lawsoniana and Pseudotsuga menziesii together average 80% cover, but Chamaecyparis lawsoniana is always more abundant and strongly dominates the tree subcanopy with sapling-size regeneration. Several other conifers can occur occasionally. The shrub layers are highly variable, with an average cover of 30%, and include a component of broad-leaved evergreen species that are typically trees, such as Notholithocarpus densiflorus (= Lithocarpus densiflorus) and Quercus chrysolepis. However, in this association they never reach tree stature. Shorter shrubs commonly present include Rhododendron macrophyllum, Gaultheria shallon, Mahonia nervosa (= var. nervosa), and the deciduous Vaccinium parvifolium. The herbaceous layer is relatively sparse (25% cover) and strongly dominated by the perennial forb Xerophyllum tenax, with 18% average cover. Many perennial forb species are found in trace amounts and are indicators of the ultramafic substrate. No graminoids occur. "Rock-loving" bryophytes are abundant; mosses average 45% cover.
Dynamics: No Data Available
Environmental Description: This association occurs in a mountainous region (Klamath Mountains Province) of rugged, deeply dissected terrain. Geologically, the province is very complex and of very old deposits. Rock types include volcanic tuffs and sedimentary rocks which have been metamorphosed into schists, gneisses, marbles, and other metavolcanic and metasedimentary rocks. Sandstones, siltstones and shales have been deposited near the coast. The most notable rock types are granitics and elongated, stringer-like outcrops of serpentine. Elevations of this region vary from sea level to over 1525 m (5000 feet).
The climate of the region is maritime, with wet, mild winters, cool, relatively dry summers, prolonged cloudy periods, and high annual precipitation. Precipitation varies from over 178 cm (70 inches) annually near the coast, to less than 76 cm (30 inches) annually on the eastern slope, where a rainshadow effect is pronounced and summers are very dry.
This association generally occupies moderate to steep, convex sideslopes or gently rolling ridgetops, from 600 to 975 m (1970-3200 feet) elevation. Aspects are predominately westerly, and topography within stands is typically undulating. Parent materials are ultramafic, including peridotite, dunite or serpentinite. Soils are well-drained and shallow, with an average depth to the C horizon of 35 cm. Cobbles and gravels are abundant throughout most soil profiles, and textures without this coarse component vary from sandy loams to silty loams to clay.
The climate of the region is maritime, with wet, mild winters, cool, relatively dry summers, prolonged cloudy periods, and high annual precipitation. Precipitation varies from over 178 cm (70 inches) annually near the coast, to less than 76 cm (30 inches) annually on the eastern slope, where a rainshadow effect is pronounced and summers are very dry.
This association generally occupies moderate to steep, convex sideslopes or gently rolling ridgetops, from 600 to 975 m (1970-3200 feet) elevation. Aspects are predominately westerly, and topography within stands is typically undulating. Parent materials are ultramafic, including peridotite, dunite or serpentinite. Soils are well-drained and shallow, with an average depth to the C horizon of 35 cm. Cobbles and gravels are abundant throughout most soil profiles, and textures without this coarse component vary from sandy loams to silty loams to clay.
Geographic Range: One of the primary dominant species, Port Orford-cedar, is very local, restricted to southwestern Oregon and northwestern California. This association is even more local, found only in the coastal strip at the boundary of southern Coos and northern Curry County, Oregon.
Nations: US
States/Provinces: CA, OR
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.687481
Confidence Level: Low - Poorly Documented
Confidence Level Comments: No Data Available
Grank: G1
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.a Redwood Forest Group | G235 | 1.B.2.Nd.3.a |
| Alliance | A0104 Port Orford-cedar Forest Alliance | A0104 | 1.B.2.Nd.3.a |
| Association | CEGL000044 Port Orford-cedar - Douglas-fir / (Pacific Rhododendron) / Common Beargrass Forest | CEGL000044 | 1.B.2.Nd.3.a |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: No Data Available
- 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.
- Hawk, G. M. 1977. A comparative study of temperate Chamaecyparis forests. Unpublished dissertation, Oregon State University, Corvallis. 194 pp.
- 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.
- Whittaker, R. H. 1960. Vegetation of the Siskiyou Mountains, Oregon and California. Ecological Monographs 30:279-338.