Name:
Andropogon gerardii - (Sorghastrum nutans) Herbaceous Alliance
Reference:
Midwestern Ecology Working Group...
Description:
This alliance is a very widespread mesic tallgrass prairie, which occurs in central North America. Most communities have moderately dense to dense vegetation dominated by graminoids 1-2 m tall. Andropogon gerardii is dominant across this alliance's range. Other abundant species include Bouteloua curtipendula, Pascopyrum smithii (in the western portions of this alliance's range), Schizachyrium scoparium, Sorghastrum nutans (in the center and east), Sporobolus heterolepis (in the Great Plains), and Hesperostipa spartea (= Stipa spartea) (in the northern Great Plains). In Montana, Festuca idahoensis (at its eastern range limits) is codominant in an association in this alliance. Forbs are abundant in stands of this alliance, especially in the more humid East. Among these are Aletris farinosa (in the East), Asteraceae spp., Echinacea pallida, Helianthus grosseserratus, Liatris pycnostachya, Phlox pilosa, Ratibida pinnata, Silphium laciniatum (in the center), and Solidago spp. Galium boreale and Oxalis sp. are more common in northern tallgrass prairies than in southern. Trees and tall shrubs are infrequent in high-quality stands, especially in the Great Plains. Among those that may be found are scattered Symphoricarpos occidentalis (in the northern Great Plains), Rhus spp., and Quercus macrocarpa (in the central and eastern portions of this alliance's range). Stands of this alliance occur on flat to rolling topography. In the West and South, stands are found on lower slopes and valleys that receive extra moisture. On the western plains, the alliance can be found in areas with gravelly soil where water infiltrates below the surface but is held by an impermeable subsurface layer. Floodplain and toeslope soils are deep and fine-textured, whereas the foothills soils are coarse-textured, often with cobble-sized rocks. In the northwestern plains, this alliance in found on lower slopes of hills, creeks and creek terraces. Soils are generally finer-textured (clay loams). In other parts of this alliance's range, stands can be found on many topographic positions. Soils are generally fertile, deep, slightly acidic, and moderately to well-drained. In glacial lakeplains near the Great Lakes, soils tend to be more poorly drained. Soils moisture is generally mesic, although it can vary from dry-mesic to wet-mesic. Soil texture can range from clay loams to sands. In the far western extent, vegetation in this alliance is a relict true prairie found along the eastern foothills and floodplains of the Front Range of the Rocky Mountains. Andropogon gerardii is the major diagnostic species, as well as Sorghastrum nutans, Panicum virgatum, Schizachyrium scoparium, Sporobolus heterolepis, the other common tallgrass prairie species. Bouteloua curtipendula and Pascopyrum smithii are also common grasses. The alliance is found in mesic areas along the Colorado Front Range. Landform position and soil texture dictate potential sites, as precipitation is generally not adequate to support stands of this alliance. In localized areas, hydrological processes of the site enhance the soil moisture. Along the Front Range, 'relict' true prairie is found along the foothills in parks and on slopes below Pinus ponderosa woodlands. Soils are coarse-textured, and runoff and seeps enhance soil moisture. The alliance is also found in floodplains adjacent to streams where the water table is within reach for plant roots.
Accession Code:
VB.CC.17769.ANDROPOGONGERAR
Plot-observations of this Community Concept:
0
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