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Scientific Name: North Pacific Hardwood-Conifer Swamp
Unique Identifier: CES204.090

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Summary: This wetland ecological system occurs from southern coastal British Columbia south into coastal Washington and Oregon, west of the coastal mountain summits (not interior). Treed swamps are common in southeastern Alaska (but are placed into different systems than this one), less so farther south. Forested swamps are mostly small-patch size, occurring sporadically in glacial depressions, in river valleys, around the edges of lakes and marshes, or on slopes with seeps that form subirrigated soils. These are primarily on flat to gently sloping lowlands up to 457 m (1500 feet) elevation but also occur up to near the lower limits of continuous forest (below the subalpine parkland). It can occur on steeper slopes where soils are shallow over unfractured bedrock. This system is indicative of poorly drained, mucky areas, and areas are often a mosaic of moving water and stagnant water. Soils can be woody peat, muck, or mineral. It can be dominated by any one or a number of conifer and hardwood species (Tsuga heterophylla, Picea sitchensis, Tsuga mertensiana, Callitropsis nootkatensis, Pinus contorta var. contorta, Alnus rubra, Fraxinus latifolia, Betula papyrifera) that are capable of growing on saturated or seasonally flooded soils. Overstory is often less than 50% cover, but shrub understory can have high cover. In the southern end of the range of this type, e.g., the Willamette Valley, tends to have more hardwood-dominated stands (especially Fraxinus latifolia) and very little in the way of conifer-dominated stands. While the typical landscape context for the type is extensive upland forests, for the Fraxinus latifolia stands, landscapes were very often formerly dominated by prairies and now by agriculture. Many conifer-dominated stands have been converted to dominance by Alnus rubra due to timber harvest.

Classification Approach: International Terrestrial Ecological Systems Classification (ITESC)

Classification Comments: Shrub swamps are usually not intermixed with the forested swamps and tend to be more wet. Deciduous and conifer forested swamps are often intermixed and more similar to each other in hydrology, and so are combined here in this system.

Similar Ecological Systems
Unique Identifier Name
CES204.315 Alaskan Pacific Poorly Drained Conifer Woodland

Component Associations
Association Unique ID Association Name
CEGL000055 Picea sitchensis / Cornus sericea / Lysichiton americanus Swamp Forest
CEGL000140 Pinus contorta / Carex (aquatilis, angustata) Swamp Woodland
CEGL000147 Pinus contorta / Deschampsia cespitosa Swamp Forest
CEGL000152 Pinus contorta var. contorta / Gaultheria shallon - Rhododendron macrophyllum - Vaccinium ovatum Forest
CEGL000157 Pinus contorta var. murrayana - Populus tremuloides / Spiraea douglasii Swamp Forest
CEGL000158 Pinus contorta - (Populus tremuloides) / Vaccinium uliginosum Forest
CEGL000171 Pinus contorta (var. latifolia, var. murrayana) / Vaccinium uliginosum Forest
CEGL000400 Picea sitchensis / Rubus spectabilis / Carex obnupta - Lysichiton americanus Swamp Forest
CEGL000477 Tsuga heterophylla / Ledum glandulosum / Carex obnupta - Lysichiton americanus Treed Bog
CEGL000640 Fraxinus latifolia / Carex obnupta Riparian Forest
CEGL003202 Pinus contorta / Empetrum nigrum Treed Bog
CEGL003209 Tsuga mertensiana - Callitropsis nootkatensis / Vaccinium parvifolium / Rubus pedatus - Lysichiton americanus Swamp Forest
CEGL003213 Tsuga mertensiana - Callitropsis nootkatensis / Gaultheria shallon / Lysichiton americanus Woodland
CEGL003215 Tsuga mertensiana - Callitropsis nootkatensis / Elliottia pyroliflora / Nephrophyllidium crista-galli Woodland
CEGL003216 Tsuga mertensiana - Callitropsis nootkatensis / Lysichiton americanus - Athyrium filix-femina Swamp Forest
CEGL003235 Tsuga heterophylla / Oplopanax horridus / Lysichiton americanus Swamp Forest
CEGL003240 Tsuga heterophylla - Callitropsis nootkatensis / Vaccinium (alaskaense, ovalifolium) / Lysichiton americanus Swamp Forest
CEGL003257 Picea sitchensis - Tsuga heterophylla / Oplopanax horridus / Lysichiton americanus Swamp Forest
CEGL003265 Picea sitchensis - Tsuga heterophylla / Vaccinium (alaskaense, ovalifolium) / Lysichiton americanus Swamp Forest
CEGL003365 Fraxinus latifolia / Carex deweyana - Urtica dioica Riparian Forest
CEGL003371 Populus tremuloides / Carex obnupta Riparian Forest
CEGL003388 Alnus rubra / Athyrium filix-femina - Lysichiton americanus Swamp Forest
CEGL003389 Alnus rubra / Rubus spectabilis / Carex obnupta - Lysichiton americanus Riparian Forest
CEGL003390 Fraxinus latifolia - (Populus balsamifera ssp. trichocarpa) / Cornus sericea Riparian Forest
CEGL003391 Fraxinus latifolia / Juncus patens Riparian Forest
CEGL003392 Fraxinus latifolia / Spiraea douglasii Riparian Forest
CEGL003393 Fraxinus latifolia / Symphoricarpos albus Riparian Forest


Land Cover Class: Woody Wetland
Spatial Pattern: Large patch
Natural/Seminatural: No
Vegetated ( > 10% vascular cover):
Upland: No
Wetland: Yes
Isolated Wetland: No

Diagnostic Classifiers
Primary Classifier Secondary Classifier
Lowland Lowland
Forest and Woodland (Treed)  
Temperate Temperate Oceanic
Depressional Lakeshore
Needle-Leaved Tree  
Broad-Leaved Deciduous Tree  
Pinus contorta  
Sphagnum spp.  
Eutrophic Water  

At-Risk Species Reported for this Ecological System
Scientific Name
  (Common Name)
NatureServe Global Status U.S. Endangered Species Act Status
Erigeron peregrinus var. thompsonii
  (Thompson's Wandering Daisy)
Hemphillia burringtoni
  (Keeled Jumping-slug)
Pinus contorta var. bolanderi
  (Bolander's Beach Pine)
Pristiloma pilsbryi
  (Crowned Tightcoil)

Vegetation Composition (incomplete)
Species Name Rounded Global Status Growth Form Stratum Char-
Domi-nant Con-stant
Cover Class %
Fraxinus latifolia G5 Broad-leaved deciduous tree Tree canopy  
Populus balsamifera ssp. trichocarpa T5 Broad-leaved deciduous tree Tree canopy    
Chamaecyparis nootkatensis G4 Needle-leaved tree Tree canopy    
Picea sitchensis G5 Needle-leaved tree Tree canopy    
Pinus contorta G5 Needle-leaved tree Tree canopy    
Pinus contorta var. contorta T5 Needle-leaved tree Tree canopy    
Thuja plicata G5 Needle-leaved tree Tree canopy    
Tsuga heterophylla G5 Needle-leaved tree Tree canopy    
Tsuga mertensiana G5 Needle-leaved tree Tree canopy    
Alnus rubra G5 Broad-leaved deciduous tree Shrub/sapling (tall & short)    
Betula papyrifera G5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Erigeron peregrinus var. thompsonii T3 Flowering forb Herb (field)      
Lysichiton americanus G5 Flowering forb Herb (field)    
Carex obnupta G5 Graminoid Herb (field)    

Animal Species Reported for this Ecological System
Scientific Name
  (Common Name)
Global Status U.S. Endangered Species Act Status Charact-
Hemphillia burringtoni
  (Keeled Jumping-slug)
Hyliola regilla
  (Pacific Treefrog)
Microtus oregoni
  (Creeping Vole)
Pristiloma pilsbryi
  (Crowned Tightcoil)
Sorex bendirii
  (Marsh Shrew)
Sorex monticolus
  (Dusky Shrew)
Sorex vagrans
  (Vagrant Shrew)
Taricha granulosa
  (Rough-skinned Newt)
Zapus trinotatus
  (Pacific Jumping Mouse)

Color legend for Distribution Map
Nation: United States
United States Distribution: OR, WA
Nation: Canada
Canadian Province Distribution: BC
Global Range: This system occurs from southern British Columbia south to northwestern Oregon, including the Willamette Valley, west of the Cascade Crest.

Biogeographic Divisions
Division Code and Name Primary Occurrence Status
204-North American Pacific Maritime C: Confident or certain

The Nature Conservancy's Conservation Ecoregions
Code Name Occurrence Status
1 Pacific Northwest Coast Confident or certain
2 Puget Trough - Willamette Valley - Georgia Basin Confident or certain
3 North Cascades Confident or certain
69 S.E. Alaska - B.C. Coastal Forest and Mountains Confident or certain
81 West Cascades Confident or certain

MRLC 2000 Mapzones
Code Name Occurrence Status
1 Northern Cascades Confident or certain
2 Oregon Coastal Range Confident or certain
7 Cascade Mountain Range Confident or certain

National Mapping
ESLF Code (Ecological System Lifeform): 9190

West Landfire Legend: No
East Landfire Legend: No

Element Description Edition Date: 08Dec2008
Element Description Author(s): C. Chappell and M.S. Reid

Ecological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Chappell, C. B. 1999. Ecological classification of low-elevation riparian vegetation on the Olympic Experimental State Forest: A first approximation. Unpublished progress report. Washing Natural Heritage Program, Washington Department of Natural Resources, Olympia. 43 pp.

  • Chappell, C. B., R. C. Crawford, C. Barrett, J. Kagan, D. H. Johnson, M. O'Mealy, G. A. Green, H. L. Ferguson, W. D. Edge, E. L. Greda, and T. A. O'Neil. 2001. Wildlife habitats: Descriptions, status, trends, and system dynamics. Pages 22-114 in: D. H. Johnson and T. A. O'Neil, directors. Wildlife-Habitat Relationships in Oregon and Washington. Oregon State University Press, Corvallis, OR.

  • Chappell, C., and J. Christy. 2004. Willamette Valley-Puget Trough-Georgia Basin Ecoregion Terrestrial Ecological System EO Specs and EO Rank Specs. Appendix 11 in: J. Floberg, M. Goering, G. Wilhere, C. MacDonald, C. Chappell, C. Rumsey, Z. Ferdana, A. Holt, P. Skidmore, T. Horsman, E. Alverson, C. Tanner, M. Bryer, P. Lachetti, A. Harcombe, B. McDonald, T. Cook, M. Summers, and D. Rolph. Willamette Valley-Puget Trough-Georgia Basin Ecoregional Assessment, Volume One: Report prepared by The Nature Conservancy with support from The Nature Conservancy of Canada, Washington Department of Fish and Wildlife, Washington Department of Natural Resources (Natural Heritage and Nearshore Habitat programs), Oregon State Natural Heritage Information Center and the British Columbia Conservation Data Centre.

  • Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, K. Snow, J. Teague, and R. White. 2003-present. Ecological systems of the United States: A working classification of U.S. terrestrial systems. NatureServe, Arlington, VA.

  • Eyre, F. H., editor. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.

  • Green, R. N., and K. Klinka. 1994. A field guide to site interpretation for the Vancouver Forest Region. British Columbia Ministry of Forests. ISSN 0229-1622 Land Management Handbook 28. 285 pp.

  • WNHP [Washington Natural Heritage Program]. 2018. Unpublished data files. Washington Natural Heritage Program, Department of Natural Resources, Olympia, WA.

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Version 7.1 (2 February 2009)
Data last updated: March 2019