Print Report

M035 Vancouverian Flooded & Swamp Forest Macrogroup

Type Concept Sentence: This macrogroup covers forested wetlands and riparian areas of coastal lowlands and mountains from Oregon north into southern Alaska. It includes cottonwood- and conifer-dominated riparian forests, conifer swamps, and treed peatlands (fens and bogs). Dominant species in lowland riparian areas include Abies grandis, Acer macrophyllum, Alnus rubra, Fraxinus latifolia, Picea sitchensis, Populus balsamifera ssp. trichocarpa, Salix lucida ssp. lasiandra, and/or Thuja plicata; in montane riparian areas include Abies amabilis, Abies concolor, Abies magnifica, Pinus contorta var. murrayana, Populus tremuloides, and/or Tsuga mertensiana; and in bogs at a variety of elevations, Callitropsis nootkatensis, Picea sitchensis, Pinus contorta var. contorta, Tsuga heterophylla, and Tsuga mertensiana are some of the common characteristic tree species.

Common (Translated Scientific) Name: Vancouverian Flooded & Swamp Forest Macrogroup

Colloquial Name: Vancouverian Flooded & Swamp Forest

Hierarchy Level:  Macrogroup

Type Concept: This macrogroup consists of woodlands and forests of wetland and riparian areas. It includes lowland and montane riparian forests, forested mineral-soil swamps, and treed fens and bogs. In lowland riparian forests, broadleaf dominant species are Acer macrophyllum, Alnus rubra, Populus balsamifera ssp. trichocarpa, Salix lucida ssp. lasiandra, and/or Fraxinus latifolia (in southern part of range), and conifer-dominated types have Abies grandis, Picea sitchensis, or Thuja plicata. Montane riparian areas are more often conifer-dominated by such species as Abies amabilis, Abies concolor, Abies magnifica, Pinus contorta var. murrayana, Populus tremuloides, and/or Tsuga mertensiana. Shrubs include Alnus viridis ssp. sinuata, Oplopanax horridus, Salix spp., Spiraea douglasii, and Vaccinium uliginosum. Along the Gulf of Alaska, glacial-fed rivers (uncommon on the islands) have frequent flooding, shifting channels, and significant sediment deposition, and Picea sitchensis is the dominant tree. Treed swamps are more common in southeastern Alaska, less so farther south. Swamps are small in size and indicative of poorly drained, mostly mineral soil areas often in a mosaic of moving and stagnant water and are dominated by any one or a number of conifer (Callitropsis nootkatensis, Picea sitchensis, Pinus contorta, Tsuga heterophylla, Tsuga mertensiana) and hardwood species (Alnus rubra, Betula papyrifera, Fraxinus latifolia) that are capable of growing on saturated or seasonally flooded soils. Treed peatlands (fens and bogs) are common in southeastern Alaska and central British Columbia, less so farther south, and occur on poorly drained peat soils with little to no influence of groundwater. These can be dominated by any one of a number of conifer species (Callitropsis nootkatensis, Picea sitchensis, Pinus contorta var. contorta, Tsuga heterophylla, Tsuga mertensiana) 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. Common shrubs include Elliottia pyroliflora, Gaultheria shallon (southern portion of the Alaska distribution only), Ledum groenlandicum, and Vaccinium ovalifolium.

Diagnostic Characteristics: Dominance by Alnus rubra, Callitropsis nootkatensis, Fraxinus latifolia, Picea sitchensis, Pinus contorta var. contorta, Populus balsamifera ssp. trichocarpa, Salix lucida ssp. lasiandra, Tsuga heterophylla, Thuja plicata, or Tsuga mertensiana, and herbaceous indicators of the saturated or floodplain soil conditions such as Carex deweyana, Lysichiton americanus, Rubus spectabilis, Trichophorum cespitosum, and/or Sphagnum species.

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: Closed- to open-canopy forests of tall or stunted (but at least 5 m in height) cold-deciduous trees, evergreen trees, or a mix of deciduous and evergreen trees, often with deciduous or evergreen shrub undergrowth and/or an herbaceous undergrowth layer.

Floristics: Riparian and swamp trees occurring throughout most of the range are Alnus rubra, Betula papyrifera, Callitropsis nootkatensis (= Chamaecyparis nootkatensis), Fraxinus latifolia, Picea sitchensis, Populus balsamifera ssp. trichocarpa, Thuja plicata, and Tsuga heterophylla. Additional trees in southern areas include Acer macrophyllum, Salix lucida ssp. lasiandra, and Abies grandis. Populus balsamifera is much less common on the islands of southeastern Alaska and off British Columbia due to a lack of larger floodplains. Dominant species of higher montane riparian areas include Abies amabilis, Abies concolor, Abies magnifica, Picea engelmannii, Pinus contorta var. murrayana, Tsuga mertensiana, and, more rarely, Populus tremuloides. Key understory diagnostics include Cornus sericea, Maianthemum dilatatum, Oplopanax horridus, and Rubus spectabilis. Swamp tree species may include Alnus rubra, Betula papyrifera, Callitropsis nootkatensis, Fraxinus latifolia, Picea sitchensis, Pinus contorta var. contorta, Thuja plicata, Tsuga heterophylla, and/or Tsuga mertensiana. Shrub species include Cornus sericea, Elliottia pyroliflora, Gaultheria shallon (southern portion of the Alaska distribution only), Ledum groenlandicum (= Rhododendron groenlandicum), Oplopanax horridus, Rubus spectabilis, Spiraea douglasii, Vaccinium ovalifolium, and/or Vaccinium uliginosum. Tree species dominant on peatlands (fens and bogs) are mostly Pinus contorta var. contorta or Callitropsis nootkatensis but can include some Tsuga heterophylla, Tsuga mertensiana, or Thuja plicata. Ledum groenlandicum is generally the dominant shrub understory species; other shrubs include Vaccinium uliginosum, Juniperus communis, Myrica gale, or Gaultheria shallon. Low-shrub species include Empetrum nigrum, Kalmia microphylla, and Rubus chamaemorus. Herbaceous species include sedges such as Eriophorum angustifolium, Trichophorum cespitosum, Carex livida, or herbs such as Sanguisorba officinalis, Triantha glutinosa, or Drosera rotundifolia. Dominant bryophytes include Sphagnum spp. and Racomitrium lanuginosum.

Dynamics:  This macrogroup includes highly disturbed broad shifting alluvial glacial run-off river beds and banks, snowmelt or rainfall driven hydrology rivers that have seasonal rise in soil water tables and overbank flooding to very stable wetlands with groundwater or precipitation that causes no change to surface soils. All sites depend on high moisture content of soils during the growing season. Succession can be large scale post-flood regeneration of many tree seedlings or small single tree-fall microsite gap dynamics.
Environmental Description:  All of the communities within this macrogroup occur within a cool temperate climate and are wetlands or riparian areas with permanently saturated soils or seasonal water table fluctuations. They occur at low and high elevations throughout the coastal regions of the Pacific Northwest, as far inward as tributaries to the Columbia River in Idaho and the Sierra Nevada of California, ranging from sea level to as high as 3300 m (10,000 feet). Soils range from thin, to poorly developed and coarse to deep peat. Riparian settings may have frequent flooding, shifting channels, and significant sediment deposition. Swamps and bogs are mostly small-patch size, but can be extensive in size as well, occurring in glacial depressions or river valleys and are poorly-drained with slow-moving groundwater, and on deep organic or gleysolic soils. Other riparian settings are narrow streambanks lining rocky channels with steep gradients. This environmental information was compiled from several sources: for Alaska (DeMeo et al. 1992, Viereck et al. 1992, Martin et al. 1995, Shephard 1995, DeVelice et al. 1999, Boggs 2002, Boggs et al. 2008b), for Washington (Chappell 1999, Chappell et al. 2001), for Oregon and Washington (Franklin and Dyrness 1973), and for British Columbia (Banner et al. 1993, Green and Klinka 1994, MacKenzie and Moran 2004).
Geographic Range: This macrogroup occurs at low and high elevations throughout the coastal regions of the Pacific Northwest from southern Oregon north through British Columbia, Vancouver Island and Haida Gwaii to along the coast of the Gulf of Alaska, including central and southeastern Alaska. It occurs as far inward as the eastern slope of the Cascades and along tributaries of the Columbia River in Idaho, and in the Sierra Nevada of California.

Nations: CA,US

States/Provinces:  AK, BC, CA, ID, OR, WA


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: GNR

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.3 Temperate Flooded & Swamp Forest Formation F026 1.B.3
Division 1.B.3.Ng Vancouverian Flooded & Swamp Forest Division D193 1.B.3.Ng
Macrogroup 1.B.3.Ng.1 Vancouverian Flooded & Swamp Forest Macrogroup M035 1.B.3.Ng.1
Group 1.B.3.Ng.1.b Mountain Hemlock - Fir species / Willow species Montane Riparian Woodland Group G507 1.B.3.Ng.1.b
Group 1.B.3.Ng.1.d Sitka Spruce - Black Cottonwood - Oregon Ash Lowland Riparian Forest Group G851 1.B.3.Ng.1.d
Group 1.B.3.Ng.1.e Western Hemlock - Red Alder / Yellow Skunk-cabbage Swamp Forest Group G853 1.B.3.Ng.1.e
Group 1.B.3.Ng.1.f Sitka Spruce - Black Cottonwood Alaskan Riparian Woodland Group G852 1.B.3.Ng.1.f
Group 1.B.3.Ng.1.g Western Hemlock - Mountain Hemlock / American Skunk-cabbage Swamp Forest Group G854 1.B.3.Ng.1.g
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): G. Kittel, in Faber-Langendoen et al. (2014)

Author of Description: G. Kittel and D. Meidinger

Acknowledgements: With contributions from T. Boucher, C. Chappell, M.S. Reid, and D. Faber-Langendoen.

Version Date: 03-29-17
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