Abstract for M151

Great Plains Forest & Woodland
Forêts & terres boisées des Grandes Plaines

M151 describes upland North American Great Plains treed vegetation. The Canadian expression includes cold-deciduous broad-leaved woodlands and forest patches in Alberta, Saskatchewan and Manitoba. M151 does not include floodplain forests, which are described by M028 [Great Plains Floodplain Forest]. Most Canadian occurrences of M151 are in the Great Plains Parkland vegetation zone, which occupies the northern edge of the dry North American Great Plains grassland region where it is transitional to boreal forest. Here, the climate is moist enough to support tree growth under certain conditions, and the natural vegetation is a landscape mosaic comprising patches of grassland and groves of forest and woodland (i.e., parkland). M151 describes only the treed portion of the vegetation mosaic. M151 also includes copses of forest and woodland that are found in the prairie grasslands to the south of the parkland on specific sites, including steep north-facing valley slopes, moist depressions and flats within sand dune complexes.

In Canada, the largest proportion of M151 occurrences are pure stands of trembling aspen (Populus tremuloides), sometimes accompanied by balsam poplar (Populus balsamifera), Manitoba maple (Acer negundo) or red ash (Fraxinus pennsylvanica) on moist lower slopes. At the eastern end of the range, bur oak (Quercus macrocarpa) also becomes important, especially on drier sites. Red ash may also occur as an understory associate in upland aspen stands at the eastern end of the range. Understory vegetation in these stands includes a diverse suite of shrubs and herbs adapted to partial shade. Common species include saskatoon (Amelanchier alnifolia), chokecherry (Prunus virginiana), pin cherry (Prunus pensylvanica), hazelnuts (Corylus spp.), western snowberry (Symphoricarpos occidentalis), thin-leaved snowberry (S. albus), Canada gooseberry (Ribes oxyacanthoides), Woods’ rose (Rosa woodsii), vetchlings (Lathyrus spp.), American vetch (Vicia americana), star-flowered false Solomon’s seal (Maianthemum stellatum), wild lily-of-the-valley (M. canadense), meadow-rues (Thalictrum spp.), rough-fruited fairy bells (Prosartes trachycarpa), spreading dogbane (Apocynum androsaemifolium), Maryland sanicle (Sanicula marilandica), wild sarsaparilla (Aralia nudicaulis), slender wildrye (Elymus trachycaulus), purple false melic (Schizachne purpurascens), rough-leaved mountain rice (Oryzopsis asperifolia), dry-spike sedge (Carex siccata) and Sprengel’s sedge (C. sprengelii).

M151 occurs in a subhumid continental temperate climate with cold winters and warm summers. Mean annual temperatures average approximately 2˚C, and precipitation varies from approximately 350 to 540 mm. Elevations are <1000 mASL. Stands of M151 occur on a variety of well-drained, mostly Chernozemic soils. Forest and woodland conditions described here for Canada also occur in North Dakota and Minnesota.