Invalid Unit Specified
CEGL002680 Populus deltoides (ssp. wislizeni, ssp. monilifera) / Pascopyrum smithii Riparian Woodland

The U.S. National
Vegetation Classification
Type Concept Sentence:
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Common (Translated Scientific) Name: (Rio Grande Cottonwood, Plains Cottonwood) / Western Wheatgrass Riparian Woodland
Colloquial Name:
Hierarchy Level: Association
Type Concept: This association represents riparian woodlands on the Great Plains of eastern Wyoming, southeastern Utah and possibly eastern Montana, the western Dakotas and Nebraska. Stands have been documented in Wyoming from 1143 to 1387 m (3750-4550 feet) elevation, primarily along small streams (<50 feet wide), on alluvial soils in a range of textural classes. The vegetation is simple in structure. Populus deltoides dominates a tree overstory that may consist of scattered large trees in old stands or of denser, small or -medium-sized trees in younger stands. Scattered shrubs may be present. The herbaceous undergrowth is composed of short or mid-height grasses and forbs; Pascopyrum smithii contributes as much canopy cover to the undergrowth as does any other native species. As with other Populus deltoides woodlands, stands of this association generally are early- to mid-seral; Populus deltoides seedlings become established on bare sediment bars laid down by flood waters, and trees in the even-aged overstory are not replaced by younger cottonwoods as they age and die. Several different Populus deltoides associations share a number of plant species in the herbaceous undergrowth (including Pascopyrum smithii), and this association contains the woodlands in which Pascopyrum smithii contributes at least as much cover as does any other native graminoid.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: The dominance or codominance of Pascopyrum smithii in the undergrowth sets this association apart from other Populus deltoides ssp. monilifera associations in which Pascopyrum smithii usually is present but other species dominate. In some studies, Populus deltoides vegetation types have been named in which the undergrowth is composed predominantly or entirely of exotic grasses (e.g., Populus deltoides / Poa pratensis community in eastern Wyoming (Jones and Walford 1995), Populus deltoides / Bromus inermis community in eastern Wyoming (Jones and Walford 1995) and eastern Colorado (Carsey et al. 2003a)), and these vegetation types may represent stands of this association (CEGL002680) with highly altered species composition. This association is a broader type containing Populus deltoides - (Salix amygdaloides) / Salix (exigua, interior) Floodplain Woodland (CEGL000659), but the description of that association shows that Populus deltoides (ssp. wislizeni, ssp. monilifera) / Pascopyrum smithii Riparian Woodland (CEGL002680) actually has the narrower range in plant species composition and the smaller geographic range.
Similar NVC Types:
Populus deltoides (ssp. wislizeni, ssp. monilifera) / Distichlis spicata Riparian Woodland, note:
Populus deltoides / Panicum virgatum - Schizachyrium scoparium Floodplain Woodland, note:
Populus deltoides - (Salix amygdaloides) / Salix (exigua, interior) Floodplain Woodland, note:
Physiognomy and Structure: No Data Available
Floristics: The vegetation is simple in structure. Populus deltoides or Populus x acuminata dominate a tree overstory that may consist of scattered large trees in old stands or of denser, small or -medium-sized trees in younger stands. Scattered shrubs may be present. The herbaceous undergrowth is composed of short or mid-height grasses and forbs; Pascopyrum smithii contributes as much canopy cover to the undergrowth as does any other native species. Populus dominates the overstory and often is the only tree, but Salix amygdaloides is present in some stands and may dominate small areas. Pascopyrum smithii is as common as any other native graminoid, but other species may contribute substantial cover, chief among them Distichlis spicata (on fine-textured soils), Sporobolus cryptandrus (on sandy soils), Koeleria macrantha, and Elymus lanceolatus (Jones and Walford 1995). In many stands, the undergrowth is codominated or dominated by exotic grasses, principally Bromus tectorum, Bromus racemosus (= Bromus commutatus), and Poa pratensis. Shrubs generally contribute only trace cover, but Artemisia cana ssp. cana may be present in more than trace amounts. Several different Populus deltoides associations share a number of plant species in the herbaceous undergrowth (including Pascopyrum smithii), and this association contains the woodlands in which Pascopyrum smithii contributes at least as much cover as does any other native graminoid.
Dynamics: As with other Populus deltoides woodlands, stands of this association generally are early to mid seral; Populus deltoides seedlings become established on bare sediment bars laid down by flood waters, and trees in the even-aged overstory are not replaced by younger cottonwoods as they age and die (Friedman et al. 1997).
Environmental Description: Stands have been documented in Wyoming from 1143 to 1387 m (3750-4550 feet) elevation, primarily along small streams (<25 m [50 feet] wide) (Jones 1998a, 1998b, Jones and Walford 1995). One site has been reported from the Colorado Plateau of southeast Utah, on a canyon floor at 1760 m (5777 feet). Soils where stands of this association grow are derived from alluvium and cover a range of textural classes. Plots in eastern Wyoming (Jones and Walford 1995), though, showed that genetic soil horizons beneath stands of this association belong to a broad range of textural classes, and clays are the most common.
Geographic Range: This association has been described from eastern Wyoming, at elevations below about 1829 m (6000 feet). That range encompasses 23,279 square miles. A single stand was described from Natural Bridges National Monument in southeastern Utah. The possible extent of the range in eastern Montana, the western Dakotas and northwestern Nebraska, if any, is not included in this estimate.
Nations: US
States/Provinces: MT?, ND?, NE?, SD?, UT, WY
US Forest Service Ecoregions (1994/1995)
Domain Name:
Division Name:
Province Name: Intermountain Semi-Desert and Desert Province
Province Code: 341    Occurrence Status: Confident or certain
Section Name: Powder River Basin Section
Section Code: 331G     Occurrence Status: Confident or certain
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Intermountain Semi-Desert and Desert Province
Province Code: 341    Occurrence Status: Confident or certain
Section Name: Western Great Plains Section
Section Code: 331F     Occurrence Status: Confident or certain
Omernik Ecoregions:
Confidence Level: Moderate
Confidence Level Comments:
Grank: G3
Greasons: The G3 rank is based on (1) the assumption that this association occurs only in riparian zones on the Great Plains of eastern Wyoming and Montana and, perhaps, the western Dakotas and northwestern Nebraska, (2) the assumption that occurrences larger than a few hundred square meters are uncommon, and (3) the knowledge that occurrences of this association are highly susceptible to changes in flood regime and to invasion by exotics.
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: = Populus deltoides / Elymus smithii Community (Jones and Walford 1995)
= Populus deltoides / Elymus smithii Community (Jones 1998a)
= Populus deltoides / Elymus smithii Community (Jones 1992b)
>< Populus deltoides / Pascopyrum smithii - Panicum obtusum Plant Association (Kittel et al. 1999a)
= Populus deltoides / Pascopyrum smithii - Panicum obtusum Woodland (Carsey et al. 2003a) [has been named from southeastern and northwestern Colorado. It closely resembles the Populus deltoides / Pascopyrum smithii association but contains substantial amounts of central and southern Great Plains grasses (Panicum obtusum, Bothriochloa laguroides ssp. torreyana).]
>< Populus deltoides / Sporobolus cryptandrus Woodland (Carsey et al. 2003a) [named from eastern Colorado, occurs on sandy soils. Pascopyrum smithii may be common in stands of this association, but Sporobolus cryptandrus and other species typical of sandy soils contribute more cover.]
Concept Author(s): Western Ecology Group
Author of Description: G.P. Jones, G. Kittel and J. Coles
Acknowledgements:
Version Date: 07Feb2006
References:
  • Carsey, K., G. Kittel, K. Decker, D. J. Cooper, and D. Culver. 2003a. Field guide to the wetland and riparian plant associations of Colorado. Colorado Natural Heritage Program, Fort Collins, CO.
  • Coles, J., J. Von Loh, A. Evenden, G. Manis, G. Wakefield. and A. Wight. 2008c. Vegetation classification and mapping project report, Natural Bridges National Monument. Natural Resource Technical Report NPS/NCPN/NRTR--2008/077. National Park Service, Fort Collins, CO. 390 pp.
  • Friedman, J. M., M. L. Scott, and G. T. Auble. 1997. Water management and cottonwood dynamics along prairie streams. Pages 49-71 in: F. L. Knopf and F. B. Samson. Ecology and Conservation of Great Plains Vertebrates. Springer-Verlag, New York, NY.
  • Jones, G .P. 1998b. Ecological evaluation of the potential Cheyenne River Research Natural Area within the Thunder Basin National Grassland, Converse County, Wyoming. Prepared for the Nebraska National Forest, USDA Forest Service by the Wyoming Natural Diversity Database. Laramie, WY. 27 pp.
  • Jones, G. 1992b. Wyoming plant community classification (Draft). Wyoming Natural Diversity Database, Laramie, WY. 183 pp.
  • Jones, G. P. 1998a. Ecological evaluation of the potential Antelope Creek Research Natural Area within the Thunder Basin National Grassland, Converse County, Wyoming. Prepared for the Nebraska National Forest, USDA Forest Service by the Wyoming Natural Diversity Database. Laramie, WY. 37 pp.
  • Jones, G. P., and G. M. Walford. 1995. Major riparian vegetation types of eastern Wyoming. Submitted to Wyoming Department of Environmental Quality, Water Quality Division. Wyoming Natural Diversity Database, Laramie, WY. 245 pp.
  • Kittel, G., E. Van Wie, M. Damm, R. Rondeau, S. Kettler, and J. Sanderson. 1999a. A classification of the riparian plant associations of the Rio Grande and Closed Basin watersheds, Colorado. Unpublished report prepared by the Colorado Natural Heritage Program, Colorado State University, Fort Collins.
  • Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.
  • WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.
  • Wyoming CBM Clearinghouse. 2003. University of Wyoming, Ruckleshaus Institute and School of Environment and Natural Resources and Wyoming Geographic Information Science Center. [http://www.cbmclearinghouse.info/] (accessed July 26, 2004).