Common (Translated Scientific) Name: Short-bristle Needle-and-Thread - Thick-spike Wheatgrass Grassland

Colloquial Name: Short-bristle Needle-and-Thread - Thick-spike Wheatgrass Mixedgrass Prairie

Hierarchy Level:  Association

Type Concept: This association is a highly productive prairie type of sheltered hillslopes in prairie pothole and prairie parkland regions and also occurs as the matrix community of rolling prairie landscapes of the provinces and adjoining northern Great Plains states. It is quite likely that it occupied some of the richest agricultural land in the northern Great Plains (typified by deep Mollisols) and that virtually all of it has been put under the plow. A few remnant areas in northern Valley County, Montana, show that given the proper soils it can occur on gently rolling to flat terrain; the same environment, termed the dark-brown soil zone, is occupied by this association. Generally, it is rich in species numbers, particularly forbs, and incudes grasses and forbs that are restricted to or reach their peak frequency in this association, compared to surroundings. This association occurs primarily on glacial till on which deep loamy soils have developed on cool, moist north-facing slopes or in swales that probably receive in excess of normal precipitation through snow deposition. There are also examples where this association occurs on gently rolling to flat terrain associated with silty loam Mollisols, also a till- and drift-mantled landscape. These occurrences probably represent how the majority of this association was distributed as a matrix type prior to settlement. Soils are well-drained and mantled by a deep and continuous litter layer with little or no soil or rock exposed. Combined graminoid canopy cover frequently exceeds 80% and Hesperostipa curtiseta, the diagnostic graminoid, is also usually the herbaceous dominant. Occurrences with both Elymus lanceolatus and Nassella viridula dominant also have been reported. Koeleria macrantha, Carex duriuscula, Carex filifolia, Carex inops, and Bouteloua gracilis all have constancy values in excess of 40%. The forb cover is diverse and varies by locality with Pediomelum argophyllum, Achillea millefolium, Geum triflorum, and Pulsatilla patens being particularly constant. Shrub cover may include scattered Rosa arkansana and Symphoricarpos occidentalis and very limited amounts of Artemisia frigida, ostensibly where grazing has been intensive.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: At the Manitoba CDC meeting on Nov. 3, 1994, this type was thought not to occur in Manitoba (J. Greenall pers. comm. 1994). Type concept needs be verified with information from Saskatchewan. In the U.S. Hesperostipa curtiseta has been documented from northwestern North Dakota (Great Plains Flora Association 1986), but it is unclear whether the species is dominant enough to warrant a separate type. Stands would otherwise probably fit with ~Hesperostipa comata - Bouteloua gracilis - Carex filifolia Grassland (CEGL002037)$$.

Similar NVC Types: No Data Available

note: No Data Available