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CEGL000494 Tsuga heterophylla / Gymnocarpium dryopteris Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Western Hemlock / Western Oakfern Forest
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This association occurs as small, usually linear patches from Coeur d''Alene National Forest northward to northeastern Washington and northwestern Montana, west of the Continental Divide. This association is generally restricted to conditions of moisture accumulation and low insolation, i.e., sheltered slopes and toeslopes, alluvial bottoms and benches forming part of the meso-riparian zone. It shows no affinity for particular aspects due to sheltered positions and is perhaps subirrigated, at least until early summer. The elevation range is from 555 to 1370 m (1820-4500 feet). In northeastern Washington and northern Idaho, soils generally have an ash component overlying a mixed alluvium or colluvium derived from metasediments and glacial till. In Montana soils are derived from a variety of parent materials, though alluvium from sedimentary rock is common. Textures are silt, silt loam, loams and sandy loams. This mesic forest type varies widely in degree of canopy closure from nearly 100% in younger stands to open (less than 60% canopy cover) in stands that have experienced wind-throw, root-rot or underburns. This type can include all successional stages. Early seral stands can be dominated by other than Tsuga heterophylla or Thuja plicata; however, in late seral to climax stands these two conifers invariably dominate the canopy with specimens approaching 50 m (160 feet) in height. Long-persisting seral tree species include Abies grandis, Picea engelmannii, Pinus monticola (particularly in northern Idaho), Larix occidentalis, Pseudotsuga menziesii, and Betula papyrifera. The shrub layer is often relatively species-rich but not abundant and clearly subordinate to the herbaceous cover. Tall and mid-shrubs with the highest constancy and cover include Acer glabrum, Lonicera utahensis, Paxistima myrsinites, Rosa gymnocarpa, Rubus parviflorus, Taxus brevifolia, and Vaccinium membranaceum. Linnaea borealis is the only subshrub of note. Bromus vulgaris is consistently present in trace amounts. In addition to being 100% constant the herbaceous indicator Gymnocarpium dryopteris ranges in cover from 10 to 90% and averages around 25%. Other forbs of high constancy (>60%) and indicative of mesic or moister moisture levels include Adenocaulon bicolor, Asarum caudatum, Aralia nudicaulis, Clintonia uniflora, Tiarella trifoliata, Galium triflorum, Prosartes hookeri, Maianthemum stellatum, Trillium ovatum, and Viola orbiculata.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This association is defined as a PNV vegetation type. If it were renamed as a dominance type the species would include Thuja plicata, Tsuga heterophylla, Betula papyrifera, and Abies grandis.
Regarding subcanopy and undergrowth composition, the defining abiotic parameters and geographic distribution of this community is virtually indistinguishable from ~Thuja plicata / Gymnocarpium dryopteris Forest (CEGL000476)$$. The difference between Tsuga and Thuja dominance of the upper canopy is quite probably related to historical accident, past disturbance events and subsequent successional patterns. Despite the very long fire-return intervals (200-500 years for stand-replacing fire), the longevity of both species, especially Thuja, argues for considering the dual designation (Thuja plicata - Tsuga heterophylla) as appropriate (i.e., combining these two associations into one); if one or the other species responds to disturbance by attaining canopy dominance, it is unlikely the non-dominant species will become dominant in the average fire-free interval. Others have recognized that quite probably a dominance continuum exists between these two species by naming at least 8 plant associations with the dual designation (Tsuga heterophylla - Thuja plicata /_).
Arguing against this approach is the approach being taken by the USNVC placing emphasis on existing vegetation composition, and it is indisputable that either climax tree species can be strongly dominant with the other species only occurring in the reproductive layers, if at all. In northern Idaho, where these species are sympatric over an extensive range, there are drainages where one or the other species is present and its complement is not (Daubenmire and Daubenmire 1968); this phenomenon has never been satisfactorily explained and again argues for recognizing separate Thuja plicata and Tsuga heterophylla types.
Regarding subcanopy and undergrowth composition, the defining abiotic parameters and geographic distribution of this community is virtually indistinguishable from ~Thuja plicata / Gymnocarpium dryopteris Forest (CEGL000476)$$. The difference between Tsuga and Thuja dominance of the upper canopy is quite probably related to historical accident, past disturbance events and subsequent successional patterns. Despite the very long fire-return intervals (200-500 years for stand-replacing fire), the longevity of both species, especially Thuja, argues for considering the dual designation (Thuja plicata - Tsuga heterophylla) as appropriate (i.e., combining these two associations into one); if one or the other species responds to disturbance by attaining canopy dominance, it is unlikely the non-dominant species will become dominant in the average fire-free interval. Others have recognized that quite probably a dominance continuum exists between these two species by naming at least 8 plant associations with the dual designation (Tsuga heterophylla - Thuja plicata /_).
Arguing against this approach is the approach being taken by the USNVC placing emphasis on existing vegetation composition, and it is indisputable that either climax tree species can be strongly dominant with the other species only occurring in the reproductive layers, if at all. In northern Idaho, where these species are sympatric over an extensive range, there are drainages where one or the other species is present and its complement is not (Daubenmire and Daubenmire 1968); this phenomenon has never been satisfactorily explained and again argues for recognizing separate Thuja plicata and Tsuga heterophylla types.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: This small-patch (usually linear in form), mesic forest type varies widely in degree of canopy closure from nearly 100% in younger stands to open (less than 60% canopy cover) in stands that have experienced wind-throw, root-rot or underburns. This type, as defined here, can include early seral as well as late seral to climax stands, though the latter condition is by far the one that has been most thoroughly sampled (documented by plots). Early seral stands can be dominated by other than Tsuga heterophylla or Thuja plicata; however, these two conifers invariably dominate the canopy with specimens approaching 50 m (160 feet) in height in late seral to climax stands. Long-persisting seral tree species include Abies grandis, Picea engelmannii, Pinus monticola (particularly in northern Idaho), Larix occidentalis, Pseudotsuga menziesii, and Betula papyrifera. Though Larix occidentalis has been cited as an early seral dominant, the more usual condition is that the climax dominants (Tsuga heterophylla and Thuja plicata) are the early seral dominants on these especially mesic sites that do not require post-disturbance amelioration to make them habitable by climax species. The shrub layer is often relatively species-rich but not abundant and clearly subordinate to the herbaceous cover. Tall and mid-shrubs with the highest constancy and cover include Acer glabrum, Lonicera utahensis, Paxistima myrsinites, Rosa gymnocarpa, Rubus parviflorus, Taxus brevifolia, and Vaccinium membranaceum. Linnaea borealis is the only subshrub of note. Bromus vulgaris is consistently present in trace amounts. In addition to being 100% constant the herbaceous indicator Gymnocarpium dryopteris ranges in cover from 10 to 90% and averages around 25%. Other forbs of high constancy (>60%) and indicative moisture levels rated mesic and moister include Adenocaulon bicolor, Asarum caudatum, Aralia nudicaulis, Clintonia uniflora, Tiarella trifoliata, Galium triflorum, Prosartes hookeri (= Disporum hookeri), Maianthemum stellatum, Trillium ovatum, and Viola orbiculata. Among the forbs with at least sub-hydric affinities are Athyrium filix-femina (low cover and stature), Circaea alpina, Streptopus amplexifolius, Trautvetteria caroliniensis, and Viola glabella; the foregoing species have low to moderate constancy (20-50%).
Dynamics: Fire-return intervals for this and related mesic to hygric associations are estimated to be on the order of 200 to 400 years. The moisture regime of these sites is such that the climax species (Thuja plicata and Tsuga heterophylla) are able to rapidly recolonize disturbed sites, even those experiencing stand-replacing fire. Thus these sites may be occupied by early-seral forest as well as late-successional and climax stages. Though highly reduced in abundance and occurring only in microsite positions, mesophytic forbs consistently survive fire (stand-replacing and surface fires) and logging; once a shrub/tree canopy is re-established they flourish to characterize the undergrowth with their lushness and diversity. At the canopy closure stage of succession the undergrowth may be reduced to scattered forbs; often Gymnocarpium dryopteris is the most conspicuous, though its stature may be reduced in microsite positions.
Environmental Description: This association occurs as small, usually linear patches extending from Coeur d''Alene National Forest northward to northeastern Washington and northwestern Montana, west of the Continental Divide. This association is generally restricted to conditions of moisture accumulation and low insolation, i.e., sheltered slopes and toeslopes, alluvial bottoms and benches forming part of the meso-riparian zone. Overall it shows no affinity for particular aspects due to sheltered positions and is perhaps subirrigated, at least until early summer; however, with certain drainages it is not found on southerly exposures. The documented elevation range is from 555 to 1370 m (1820-4500 feet). In general these are nutrient-rich soils with a relatively thick (3-6 inches) organic layer in older stands. In northeastern Washington and northern Idaho soils generally have an ash component overlying a mixed alluvium or colluvium derived from metasediments and glacial till; loams, silt loams and sandy loams predominate, with gravel content ranging from 30 to 50%. In Montana soils are derived from a variety of parent materials, though alluvium from sedimentary rock is often predominant, and textural range is similar to that of Idaho and Washington occurrences. There is no mottling or gleying to indicate other-than-seasonal saturation at most.
Geographic Range: This association is strongly associated with an Inland Maritime climatic regime and is thus confined to that portion of eastern Washington, northern Idaho and western Montana receiving in excess of 30 inches annual precipitation and not experiencing severe Arctic cold fronts.
Nations: US
States/Provinces: ID, MT, WA
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.687287
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G3G4
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.Nb Rocky Mountain Forest & Woodland Division | D194 | 1.B.2.Nb |
| Macrogroup | 1.B.2.Nb.3 Western Hemlock - Grand Fir - Western Larch Mesic Lower Montane Forest Macrogroup | M500 | 1.B.2.Nb.3 |
| Group | 1.B.2.Nb.3.b Western Red-cedar - Western Hemlock Central Rocky Mountain Forest Group | G217 | 1.B.2.Nb.3.b |
| Alliance | A3613 Western Hemlock - Western Red-cedar Warm-Mesic Central Rocky Mountain Forest & Woodland Alliance | A3613 | 1.B.2.Nb.3.b |
| Association | CEGL000494 Western Hemlock / Western Oakfern Forest | CEGL000494 | 1.B.2.Nb.3.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Tsuga heterophylla / Gymnocarpium dryopteris Association (Kovalchik 1993) [(p.40)]
= Tsuga heterophylla / Gymnocarpium dryopteris Habitat Type (Hansen et al. 1995)
= Tsuga heterophylla / Gymnocarpium dryopteris Habitat Type (Cooper et al. 1987)
>< Tsuga heterophylla / Gymnocarpium dryopteris Plant Association (Williams et al. 1995)
= Tsuga heterophylla / Gymnocarpium dryopteris Habitat Type (Hansen et al. 1995)
= Tsuga heterophylla / Gymnocarpium dryopteris Habitat Type (Cooper et al. 1987)
>< Tsuga heterophylla / Gymnocarpium dryopteris Plant Association (Williams et al. 1995)
- 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.
- Cooper, S. V., K. E. Neiman, R. Steele, and D. W. Roberts. 1987. Forest habitat types of northern Idaho: A second approximation. General Technical Report INT-236.USDA Forest Service, Intermountain Research Station, Ogden, UT. 135 pp. [reprinted in 1991]
- Daubenmire, R. F., and J. B. Daubenmire. 1968. Forest vegetation of eastern Washington and northern Idaho. Washington State University Agricultural Experiment Station Technical Bulletin No. 60. 104 pp.
- Hansen, P. L., R. D. Pfister, K. Boggs, B. J. Cook, J. Joy, and D. K. Hinckley. 1995. Classification and management of Montana''s riparian and wetland sites. Miscellaneous Publication No. 54. Montana Forest and Conservation Experiment Station, School of Forestry, University of Montana. 646 pp. plus posters.
- Hansen, P., K. Boggs, and R. Pfister. 1991. Classification and management of riparian and wetland sites in Montana. Unpublished draft version prepared for Montana Riparian Association, Montana Forest and Conservation Experiment Station, School of Forestry, University of Montana, Missoula. 478 pp.
- Hop, K., M. Reid, J. Dieck, S. Lubinski, and S. Cooper. 2007. U.S. Geological Survey-National Park Service Vegetation Mapping Program: Waterton-Glacier International Peace Park. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI. 131 pp. plus Appendices A-L.
- IDCDC [Idaho Conservation Data Center]. 2005. Wetland and riparian plant associations in Idaho. Idaho Conservation Data Center, Idaho Department of Fish and Game, Boise. [http://fishandgame.idaho.gov/tech/CDC/ecology/wetland_riparian_assoc.cfm] (accessed 14 June 2005).
- Kovalchik, B. L. 1993. Riparian plant associations on the national forests of eastern Washington - Draft version 1. USDA Forest Service, Colville National Forest, Colville, WA. 203 pp.
- MTNHP [Montana Natural Heritage Program]. 2002b. List of ecological communities for Montana. Montana Natural Heritage Program, Montana State Library, Helena, MT.
- Reid, M. S., S. V. Cooper, and G. Kittel. 2004. Vegetation classification of Waterton-Glacier International Peace Park. Final report for USGS-NPS Vegetation Mapping Program, International Peace Park Mapping Project. NatureServe, Arlington VA.
- 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., B. F. Kelly, B. G. Smith, and T. R. Lillybridge. 1995. Forest plant associations of the Colville National Forest. General Technical Report PNW-GTR-360. USDA Forest Service, Pacific Northwest Region, Portland, OR. 140 pp.
- Williams, C. K., T. R. Lillybridge, and B. G. Smith. 1990b. Forested plant associations of the Colville National Forest. Report prepared for USDA Forest Service, Colville National Forest, Colville, WA. 133 pp.
- Williams, C. K., and T. R. Lillybridge. 1985. Forested plant associations of the Colville National Forest. Draft. Unpublished field guide prepared for USDA Forest Service.