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D195 Populus angustifolia - Populus balsamifera - Picea engelmannii Rocky Mountain-Great Basin Montane Flooded & Swamp Forest Division

The U.S. National
Vegetation Classification
Type Concept Sentence: Forested riparian and depressional wetlands dominated by broad-leaved deciduous trees or conifers (or both) that occur at mid to high elevations of the Rocky Mountains, ranges of the Intermountain West and the Colorado Plateau, and in the Sierra Nevada and eastern Cascades.
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Common (Translated Scientific) Name: Narrowleaf Cottonwood - Balsam Poplar - Engelmann Spruce Rocky Mountain-Great Basin Montane Flooded & Swamp Forest Division
Colloquial Name: Rocky Mountain-Great Basin Montane Flooded & Swamp Forest
Hierarchy Level: Division
Type Concept: This division is characterized by forests and woodlands dominated either by montane conifers or riparian phreatophyte broad-leaved deciduous trees, or a mix of the two. Populus angustifolia, Populus balsamifera, or Populus tremuloides along with Alnus oblongifolia, Acer grandidentatum or Acer negundo are the characteristic broadleaf dominants. The common montane conifer dominants include species that are somewhat tolerant of wet or saturated soil conditions such as Abies lasiocarpa, Abies grandis, Picea engelmannii, Picea engelmannii x glauca, and Picea pungens, along with somewhat drier site species such as Juniperus scopulorum, Pseudotsuga menziesii, Pinus contorta, and Pinus ponderosa. Stands commonly have subcanopies or tall-shrub layers that can include Alnus incana, Betula occidentalis, Betula papyrifera, Cornus sericea, Crataegus douglasii, Crataegus rivularis, Prunus virginiana, Ribes americanum, Rhus trilobata, Salix amygdaloides, Salix boothii, Salix drummondiana, Salix exigua, Salix lucida ssp. caudata, and Symphoricarpos albus. The herbaceous undergrowth can be lush to depauperate depending on the site. Graminoids typically include obligate or facultative wetland species such as Alopecurus aequalis, Calamagrostis canadensis, Carex aquatilis var. aquatilis, Carex obnupta, Carex pellita, Carex disperma, Carex vesicaria, Deschampsia caespitosa, Eleocharis palustris, and Phalaris arundinacea. Forbs are variable, but wetland indicators are typically present and may include Callitriche heterophylla, Equisetum arvense, Heracleum maximum, Lysichiton americanus, Mentha arvensis, Mitella breweri, Mitella pentandra, Ranunculus alismifolius, Senecio triangularis, and Veratrum californicum. The climate ranges from cool to cold montane or subalpine. Stands typically range between 1500 and 3300 m in elevation to the south and between 900 and 2000 m farther north. They most often occur in mid- to high-montane riparian zones along moderate- to high-gradient (>2%) streams and rivers. The stands become established in seasonally flooded areas along rocky confined channels or on narrow depositional alluvial bars of unconfined mountain valleys. They also can occur on high-elevation, low- gradient (<3%) meandering streams with broad floodplains. Less commonly, they are associated with depressional wetlands, vernal pools, pond and lake margins, or on seeps on gentle slopes (slope wetlands).
Diagnostic Characteristics: Wetland soils supporting forests of broad-leaved deciduous trees and/or conifers along riparian corridors, or surrounding the edges of lakes and marshes or other depressional seeps, at all elevations. Within the context of riparian and forested wetlands, Populus angustifolia and Alnus oblongifolia are strong diagnostic species in the southern portion of the range and Populus tremuloides and Populus balsamifera are moderately diagnostic in the northern portion. Among the subcanopy trees and shrubs, Alnus incana, Betula occidentalis, Crataegus rivularis, Salix boothii, and Salix drummondiana are moderately diagnostic.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Includes both riparian and depressional seep wetlands. And includes riparian forests of Coast Ranges and Sierra Nevada of California but does not include the hot Central Valley riparian forests.
Similar NVC Types:
D016 North American Boreal Flooded & Swamp Forest, note:
D013 Western North American Interior Flooded Forest, note: occurs further south in warmer, desert climates of western North America.
D193 Vancouverian Flooded & Swamp Forest, note:
D194 Rocky Mountain Forest & Woodland, note:
Physiognomy and Structure: This division is characterized by tall broad-leaved deciduous and conifer trees of 30 m or more. The canopies can range from very open to closed. Tall- and short-shrub layers may be present and sometimes high in cover. The herbaceous layer is commonly dominated by graminoids and may be high in cover, and forbs can also be abundant.
Floristics: This division is characterized by forests and woodlands dominated either by montane conifers or riparian phreatophyte broad-leaved deciduous trees, or a mix of the two. Populus angustifolia, Populus balsamifera, or Populus tremuloides along with Alnus oblongifolia, Acer grandidentatum or Acer negundo are the characteristic broadleaf dominants. The common montane conifer dominants include species that are somewhat tolerant of wet or saturated soil conditions such as Abies lasiocarpa, Abies grandis, Picea engelmannii, Picea engelmannii x glauca, and Picea pungens, along with somewhat drier site species such as Juniperus scopulorum, Pseudotsuga menziesii, Pinus contorta, and Pinus ponderosa. Thuja plicata, Tsuga heterophylla, Tsuga mertensiana and Pinus flexilis are also occasional dominants.

Riparian stands commonly have subcanopies or tall-shrub layers that can include Alnus incana, Betula occidentalis, Betula papyrifera, Cornus sericea, Crataegus douglasii, Crataegus rivularis, Prunus virginiana, Ribes americanum, Rhus trilobata, Salix amygdaloides, Salix boothii, Salix drummondiana, Salix exigua, Salix lucida ssp. caudata, and Symphoricarpos albus. The herbaceous undergrowth can be lush to depauperate depending on the site. Graminoids are commonly dominant under marsh conditions where they can form high-cover stands of obligate or facultative wetland species such as Alopecurus aequalis, Calamagrostis canadensis, Carex aquatilis var. aquatilis, Carex obnupta, Carex pellita, Carex disperma, Carex vesicaria, Deschampsia caespitosa, Eleocharis palustris, and Phalaris arundinacea. Forbs are variable, but wetland indicators are typically present such as Callitriche heterophylla, Equisetum arvense, Heracleum maximum, Lysichiton americanus, Mentha arvensis, Mitella breweri, Mitella pentandra, Ranunculus alismifolius, Senecio triangularis, and Veratrum californicum.
Dynamics: Reproduction of the broadleaf species is by a combination of seed germination following flood events or clonal via root suckering. Clonal reproduction can be very successful for Populus spp. and they are capable of quickly establishing on disturbed wet sites.
Environmental Description: The local environments of this division are variable but they are all within a cool to cold montane or subalpine climate. Stands typically range between 1500 and 3300 m in elevation to the south and between 900 and 2000 m farther north. They most often occur in mid- to high-montane riparian zones along moderate- to high-gradient (>2%) streams and rivers. The stands become established in seasonally flooded areas along rocky confined channels or on narrow depositional alluvial bars of unconfined mountain valleys (where the water table is typically at or near the soil surface during the growing season). They also can occur on high-elevation, low-gradient (<3%) meandering streams with broad floodplains mixed with wet meadows and wetlands. More uncommonly, they are associated with depressional wetlands, vernal pools, pond and lake margins, or on seeps on gentle slopes (slope wetlands) with poorly drained soils, which are saturated year-round or may have seasonal flooding in the spring.
Geographic Range: This division occurs throughout the northern Interior West from the foothills of the Sierra Nevada and eastern Cascades, the ranges of the Great Basin and Colorado Plateau, and in the Rocky Mountains from southern British Columbia to New Mexico and Arizona.
Nations: CA, MX, US
States/Provinces: AB, AZ, BC, CA, CO, ID, MT, NM, NV, OR, SD, UT, WA, WY
US Forest Service Ecoregions (2007)
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Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage: D012 (former 1.C.3.Nc) split into 2 new types (D193 & D195).
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > Rocky Mountain Riparian Deciduous Forest (Brown et al. 1979) [This type is a subregional variant of a portion of this division concept.]
> Sierran Cascade Riparian Deciduous Forest (Brown et al. 1979) [This type is a subregional variant of a portion of this division concept.]
Concept Author(s): W.J. Mitsch and J.G. Gosselink (2000)
Author of Description: E. Muldavin and G. Kittel
Acknowledgements:
Version Date: 30Jan2015
References:
  • Brown, D. E., C. H. Lowe, and C. P. Pase. 1979. A digitized classification system for the biotic communities of North America with community (series) and association examples for the Southwest. Journal of the Arizona-Nevada Academy of Science 14:1-16.
  • 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. 2010-2017a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
  • Mitsch, W. J., and J. G. Gosselink. 2000. Wetlands. Third edition. John Wiley & Sons, Inc., New York. 920 pp.
  • Muldavin, E., P. Durkin, M. Bradley, M. Stuever, and P. Mehlhop. 2000a. Handbook of wetland vegetation communities of New Mexico. Volumn I: Classification and community descriptions. Final report to the New Mexico Environment Department and the Environmental Protection Agency prepared by the New Mexico Natural Heritage Program, University of New Mexico, Albuquerque.