Print Report

M151 Quercus macrocarpa - Populus tremuloides / Pascopyrum smithii Forest & Woodland Macrogroup

Type Concept Sentence: This macrogroup contains aspen, oak, and mixed hardwood woodlands dominated by Quercus macrocarpa, Populus tremuloides, or Betula papyrifera, often with an understory dominated by prairie shrubs, grasses and forbs that are more tolerant of shade. It is found throughout northern Great Plains, from central Kansas to the Canadian aspen parkland region.


Common (Translated Scientific) Name: Bur Oak - Quaking Aspen / Western Wheatgrass Forest Woodland Macrogroup

Colloquial Name: Great Plains Forest & Woodland

Hierarchy Level:  Macrogroup

Type Concept: This macrogroup consists of aspen, oak and mixed hardwood woodlands found throughout much of the Great Plains, from central Kansas to the Canadian aspen parkland region. Deciduous trees dominate most stands. Trees are typically short to medium in height, and the canopy can vary from open to closed (10-100%). Quercus macrocarpa is common across much of eastern part of the range; Populus tremuloides and Betula papyrifera are most abundant northward, and scattered in the southern parts. Fraxinus pennsylvanica and Ulmus americana are abundant in ravines and draws in the central and southern parts of the range. The shrub stratum can be nearly absent but is typically moderate to dense. Amelanchier alnifolia, Corylus spp., Elaeagnus commutata, Prunus americana, Prunus virginiana, Ribes spp. (including Ribes oxyacanthoides), Rosa spp. (including Rosa arkansana, Rosa woodsii), Salix spp., Shepherdia argentea, Symphoricarpos albus, Symphoricarpos occidentalis, and small trees are common. The understory is typically dominated by shrubs, grasses and sedges more tolerant of shade, but may also be common in the surrounding prairies. Among these are Andropogon gerardii, Calamagrostis canadensis, Festuca spp., Pascopyrum smithii, Sorghastrum nutans, and Sporobolus heterolepis. Most stands occur on the landscape where water accumulates and where there is some protection from fire, i.e., in ravines, near rivers or ponds, or on mesic slopes. Northward, where the woodlands approach the boreal forests, trees are more common and this type is more widespread on the landscape. Stands occur on a variety of soils, though fine-textured soils are more common. Fire, drought, and grazing are important drivers of the system.

Diagnostic Characteristics: This macrogroup is distinguished from the grasslands adjacent to it across much of its range by having >10% tree cover. Trees are almost entirely broadleaf deciduous, dominated by Quercus macrocarpa, Populus tremuloides, and Betula papyrifera, rarely any other species. Absence of almost any other tree species is a diagnostic feature of this division. Ground layer varies from grass-dominated (mixed or tallgrass species) in more open and fire-maintained sites to shrub- and forb-dominated in more closely canopy sites.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Where the northwestern Great Plains transition to mountains, this macrogroup may appear similar to early-successional stands of Rocky Mountain macrogroups at the lowest montane elevations where those occur. See classification comments at the division level (1.B.2.Ne ~North American Great Plains Forest & Woodland Division (D326)$$), many of which apply to this macrogroup. It''s possible that Great Plains Pinus ponderosa types could be added to this macrogroup.

Similar NVC Types: No Data Available
note: No Data Available

Physiognomy and Structure: This macrogroup is dominated by deciduous trees, though the tree cover can vary from 10-100%. Trees are short to medium-tall (5-10 m tall). The shrub layer is usually moderate to dense with most shrubs 0.5-2 m tall. The herbaceous layer is also typically moderate to dense and dominated by a mix of graminoids, forbs and shrubs.

Floristics: Quercus macrocarpa is dominant in the eastern part of the range; Populus tremuloides and Betula papyrifera are abundant northward, especially in the aspen parkland regions, and more scattered in the southern parts. Fraxinus pennsylvanica and Ulmus americana are abundant in ravines and draws. Trees that can be locally common or abundant include Juniperus scopulorum in the western Great Plains, Populus balsamifera in the far northern Great Plains, and Tilia americana and Juniperus virginiana in the eastern Great Plains. The shrub stratum can be nearly absent but is typically moderate to dense. Amelanchier alnifolia, Corylus spp., Elaeagnus commutata, Prunus americana, Prunus virginiana, Rosa spp. (including Rosa acicularis, Rosa arkansana, Rosa blanda, Rosa woodsii), Salix spp., Shepherdia argentea, Symphoricarpos albus, Symphoricarpos occidentalis, and small trees are common. Crataegus spp., Juniperus horizontalis, and Cornus sericea can be locally common. The understory is typically dominated by low shrubs, grasses, sedges or forbs, some of which may be common in the surrounding prairies, particularly if woodlands are allowed to burn under natural fire regimes. Common grasses found in more open, fire-maintained stands include Andropogon gerardii, Calamagrostis canadensis, Festuca spp. (including Festuca altaica), Pascopyrum smithii, Sorghastrum nutans, and Sporobolus heterolepis.

Dynamics:  This type occurs in a landscape where fire was historically common, in combination with periodic droughts. Fire restricts this type within much of its range, limiting the trees to protected places on the landscape. Fire was used by aboriginal peoples for maintaining open grassland. A reduction in fire frequency typically allows this woodland type to spread into surrounding prairies, though it also allows the tree canopy of established stands to close with a reduction in the prairie flora in the understory. In the northeastern Great Plains, conditions are more favorable for tree growth and fire is necessary to maintain this type. A significant reduction in fire frequency allows the woodlands to succeed to forests and the prairie plants are replaced by a forest understory.

Periodic drought and grazing also help maintain the open canopy of this type with intense grazing by bison, elk, and other grazers to limit woody regeneration. The combination of natural fire regimes and grazing pressures, especially in the northern part of the range, contributed to a dynamic natural landscape tension between parkland and prairie, with trees advancing in times of greater moisture and/or less grazing. Native wildlife (e.g., buffalo wallows) also created areas of exposed mineral soil that acted as seed beds for aspen, willow, etc. seedling establishment (Bird 1961).

Environmental Description:  Across much of its range, stands occur on landscape positions that receive more water than the surrounding landscape, i.e., in ravines or canyons, near rivers and lakes, and on mesic, typically north-facing slopes. In the aspen parklands of the southern Canadian provinces, Montana, North Dakota and northwestern Minnesota, this type is common on flat or rolling topography. In these areas, the evapotranspiration rate and precipitation are more favorable to tree growth and trees are not as restricted to protected landscape positions. See Zoltai (1975) and Hogg (1994) regarding climatic balance between parkland and boreal forest in Canada. Stands can occur on a variety of soil textures but fine-textured soils are more common. The aspen woodlands in the parkland region are more mesic than stands found in the rest of the Great Plains and wet-mesic or even wet pockets are common.

Geographic Range: This type is found throughout the central and northern Great Plains from Kansas and Colorado north to southeastern Alberta, southern Saskatchewan, southwestern Manitoba, northern North Dakota and northwestern Minnesota. It may occur in Oklahoma.

Nations: CA,US

States/Provinces:  AB, CO, IA, KS, MB, MN, MO, MT, ND, NE, OK?, SD, SK, WY




Confidence Level: Moderate

Confidence Level Comments: No Data Available

Grank: GNR

Greasons: No Data Available


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): Faber-Langendoen et al. (2014)

Author of Description: J. Drake, D. Faber-Langendoen and K. Baldwin

Acknowledgements: Jeff Thorpe, Ken Baldwin, and Lorna Allen

Version Date: 01-08-16

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  • Bird, R. D. 1961. Ecology of the aspen parkland of western Canada in relation to land use. Canada Department of Agriculture Publication 1066, Ottawa, ON. 155 pp.
  • 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]
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