Print Report

G548 Populus balsamifera / Salix spp. - Alnus viridis Flooded & Rich Swamp Forest Group

Type Concept Sentence: This group represents well-drained, active and inactive floodplains of boreal and sub- boreal areas of Alaska with variable-height vegetation dominated by Populus balsamifera and Picea glauca.

Common (Translated Scientific) Name: Balsam Poplar / Willow species - Green Alder Flooded & Rich Swamp Forest Group

Colloquial Name: Alaskan-Yukon Boreal Flooded & Rich Swamp

Hierarchy Level:  Group

Type Concept: This group includes glacially-fed and non-glacially-fed, low- and high-volume rivers and streams throughout the boreal and subboreal regions of Alaska. It occurs on active and inactive portions of the floodplain. The substrate is typically well-drained sand or cobble, although silts are found on higher terraces, distal floodplains, and in lower-energy systems. Frequent river channel migration, flooding, scour and other fluvial processes constitute the major disturbances in this type. Vegetation is variable, and may be dominated by short- or tall-statured Populus balsamifera ssp. balsamifera, Populus balsamifera ssp. trichocarpa, Picea glauca, Salix species, or Alnus viridis with mesic herbaceous species. Stands of full-statured Populus balsamifera often have an understory of tall willow, Calamagrostis canadensis, ferns and scattered forbs.

Diagnostic Characteristics: This group is defined by deciduous or coniferous forest with Populus balsamifera ssp. balsamifera (continental boreal), Populus balsamifera ssp. trichocarpa (subboreal), and Picea glauca. The shrub canopy is typically dominated by Alnus or Salix species, especially Alnus viridis ssp. fruticosa, Alnus viridis ssp. sinuata, Alnus incana ssp. tenuifolia, and Salix alaxensis. Calamagrostis canadensis and Equisetum arvense are often abundant in the understory.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The concept for this group was developed in coordination with the CNVC Technical Committee (Ken Baldwin, chair). Species composition is somewhat different between the subboreal and boreal, but they are treated here as one group. Several of the species shifts occur at the subspecies level. The Circumboreal Vegetation Map splits subboreal from boreal floodplains (Jorgenson and Meidinger 2015).

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This group is represented by a mixed mosaic of forest and woodland vegetation composed of needle-leaved evergreen trees and broad-leaved deciduous trees.

Floristics: Populus balsamifera ssp. balsamifera is the dominant deciduous tree in floodplains in the continental boreal region, while Populus balsamifera ssp. trichocarpa is dominant in the subboreal region. Picea glauca may be codominant in mid-seral stages and becomes dominant in late-seral stages. Picea x lutzii replaces Picea glauca in the transitional region between the subboreal and temperate biomes. The shrub canopy is often dominated by Alnus or Salix species. Alnus viridis ssp. sinuata occurs more commonly in the subboreal, while Alnus viridis ssp. fruticosa is more common to the north in the continental boreal. Alnus incana ssp. tenuifolia occurs on poorly-drained floodplain terraces in both boreal regions. Salix alaxensis is the most common willow across both the subboreal and boreal regions. Other common willows include Salix pulchra and Salix barclayi (subboreal only). Other common shrubs include Rosa acicularis, Viburnum edule, or Oplopanax horridus (subboreal only). Shrub composition on very well-drained, coarse deposits includes Shepherdia canadensis, Elaeagnus commutata, and Dryas drummondii. The composition of the herbaceous layer is diverse and varies by substrate type. Common herbaceous species may include Calamagrostis canadensis, Equisetum arvense, Chamerion angustifolium, Aconitum delphiniifolium, Hedysarum alpinum, and Rubus arcticus. Hylocomium splendens is the dominant moss in late-seral stands.

Dynamics:  Flooding is the dominant process for this group and can be caused by snowmelt, precipitation, ice jams, and glacial runoff. Different rivers or portions of rivers may be more prone to certain types of flooding. Frequent flooding and channel migration create a pattern of gravel bars and early-successional stages across the valley bottom. Sediment deposition raises the surface of the floodplain over time. As the terrace becomes farther removed from the channel, flooding becomes less frequent. Water availability on terraces plays a major role in community structure and composition. Water inputs are from overbank flow (flooding), groundwater, and precipitation. Fine sediments are trapped when the floodwaters recede; this ongoing sediment input maintains high productivity.
Environmental Description:  This group includes large floodplains associated with high- and low-volume rivers. Flooding regime is characterized by large spring floods at breakup. The active flooding zone is often several kilometers wide. Ice-scour and ice dams are important dynamics that may cause regeneration of early-seral willow stands where scoured by ice. Wetland development in abandoned channels is intermixed with succession on more mesic sites. The substrate is typically well-drained sand, gravel, or cobble, although finer silts and clays can be found on higher terraces, in ponds, on distal floodplains, and in lower-energy systems. Permafrost is usually absent.
Geographic Range: This group occurs along glacially-fed and non-glacially-fed rivers and streams throughout the boreal and boreal transition regions of Alaska.

Nations: CA,US

States/Provinces:  AK, YT


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.5 Boreal Flooded & Swamp Forest Formation F036 1.B.5
Division 1.B.5.Na North American Boreal Flooded & Swamp Forest Division D016 1.B.5.Na
Macrogroup 1.B.5.Na.2 North American Boreal Flooded & Rich Swamp Forest Macrogroup M300 1.B.5.Na.2
Group 1.B.5.Na.2.d Balsam Poplar / Willow species - Green Alder Flooded & Rich Swamp Forest Group G548 1.B.5.Na.2.d
Alliance A4265 White Spruce - Balsam Poplar / Mountain Alder Central Floodplain Forest Alliance A4265 1.B.5.Na.2.d
Alliance A4266 Paper Birch - Spruce species Central Floodplain Forest Alliance A4266 1.B.5.Na.2.d
Alliance A4267 White Spruce - Balsam Poplar / Feltleaf Willow Northern Floodplain Forest Alliance A4267 1.B.5.Na.2.d
Alliance A4268 White Spruce - Black Cottonwood / Squashberry Southwest Floodplain Forest Alliance A4268 1.B.5.Na.2.d
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< I.B.1.c - Balsam poplar (Viereck et al. 1992)
Concept Author(s): Western Ecology Group and Alaska Natural Heritage Program

Author of Description: T. Boucher

Acknowledgements: M.E. Hall

Version Date: 01-19-16
  • Boggs, K. 2000. Classification of community types, successional sequences and landscapes of the Copper River Delta, Alaska. General Technical Report PNW-GTR-469. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. March 2000. 244 pp.
  • Boggs, K. W., S. C. Klein, J. E. Grunblatt, and B. Koltun. 2003. Landcover classes, ecoregions and plant associations of Katmai National Park and Preserve. Natural Resource Technical Report NPS/KATM/NRTR--2003/001. National Park Service, Fort Collins, CO. 274 pp.
  • Boggs, K., T. Boucher, et al. 2011. List of plant associations for Alaska. 2011 draft. Alaska Natural Heritage Program, Environment and Natural Resources Institute, University of Alaska Anchorage, Anchorage.
  • Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
  • Jorgenson, T., and D. Meidinger. 2015. The Alaska-Yukon Region of the Circumboreal Vegetation Map (CBVM). Draft June 26, 2015. Conservation of Arctic Flora and Fauna.
  • Scott, R. W. 1974. Successional patterns on moraines and outwash of the Frederika Glacier, Alaska. Pages 319-329 in: V. C. Bushnell and M. G. Marcus, editors. Icefield ranges research project scientific results. Volume 4. American Geographical Society, New York.
  • Shephard, M. E. 1995. Plant community ecology and classification of the Yakutat Foreland, Alaska. R10-TP-56. USDA Forest Service, Alaska Region. 213 pp. plus appendices.
  • Thilenius, J. F. 1990. Woody plant succession on earthquake-uplifted coastal wetlands of the Copper River Delta, Alaska. Forest Ecology and Management 33/34:439-462
  • Viereck, L. A. 1966. Plant succession and soil development on gravel outwash on the Muldrow Glacier, Alaska. Ecological Monographs 36(3):181-199.
  • Viereck, L. A. K. Van Cleve, and C. T. Dyrness. 1986. Forest ecosystems in the Alaska Taiga. Pages 22-43 in: K. Van Cleve, F. S. Chapin, III, and P. W. Flanagan, et al., editors. Forest Ecosystems in the Alaskan taiga: A synthesis of structure and function. Springer-Verlag, New York.
  • Viereck, L. A., C. T. Dyrness, A. R. Batten, and K. J. Wenzlick. 1992. The Alaska vegetation classification. General Technical Report PNW-GTR286. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. 278 pp.
  • Walker, D. A., P. J. Webber, E. F. Binnian, K. R. Everett, N. D. Lederer, E. A. Nordstrand, and M. D. Walker. 1987. Cumulative impacts of oil fields on northern Alaskan landscapes. Science 238(4828):757-761.
  • Witten, E. 2004. Potential natural vegetation descriptions. LANDFIRE. [http://www.frcc.gov/pnvgSummaries.html]