This system occurs in Montana on gentle slopes, rolling plains and badlands in the extreme south-central and south-eastern portions of the state. It also occurs from Glasgow north to the Canadian border. Throughout Montana, it is associated with shale foothills and badlands where soils are saline or alkaline clays and silts with low infiltration rates. It comprises relatively pure stands of Gardner’s saltbush (Atriplex gardneri) or birdfoot sagebrush (Artemisia pedatifida). Other shrubs and sub-shrubs present may include longleaf wormwood (Artemisia longifolia), bud sagebrush (Picrothamnus desertorum), winterfat (Krascheninnikovia lanata), shortspine horsebrush (Tetradymia spinosa), shadscale saltbush (Atriplex confertifolia) or fourwing saltbush (Atriplex canescens). Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis) can occur in patches within this system on substrates that are less saline or alkaline. The herbaceous layer is usually very sparse. Harsh environmental conditions slow down community dynamics. Following disturbance, the same species, or species similar in stature or appearance, often succeed each other. Currently, exotic grass invasions are changing the dynamics of this system.
lowland, alluvial flat, alluvial plain, plains, badland, shrubland, alkaline soil, saline substrate chemistry, calcareous, silt or clay soil texture, dwarf-shrub, Atriplex gardneri, Atriplex species
This system typically supports dwarf-shrublands composed of relatively pure stands of Gardner’s saltbush (Atriplex gardneri), and in south-central Montana, birdfoot sagebrush (Artemisia pedatifida). Other dominant or codominant dwarf-shrubs may include longleaf wormwood (Artemisia longifolia) or bud sagebrush (Picrothamnus desertorum), occasionally with a mix of other low shrubs, such as winterfat (Krascheninnikovia lanata) or shortspine horsebrush (Tetradymia spinosa). Shadscale saltbush (Atriplex confertifolia) or fourwing saltbush (Atriplex canescens) may be present. Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis) can occur in patches within this system on more favorable substrates that are less saline or alkaline. The herbaceous layer is typically sparse. Perennial forbs are infrequent and scattered in the undergrowth. Common species include smooth woody aster (Xylorhiza glabriuscula) and scarlet globe mallow (Sphaeralcea coccinea). Annual species of saltbush (Atriplex), povertyweed (Monolepis), goosefoot (Chenopodium) and seepweed (Suadea) are frequently present. Perennial grasses have the highest herbaceous cover. Indian ricegrass (Achnatherum hymenoides), blue grama (Bouteloua gracilis), squirrel tail (Elymus elymoides), thickspikewheatgrass (Elymus lanceolatus ssp. lanceolatus), western wheatgrass (Pascopyrum smithii), Sandberg’s bluegrass (Poa secunda), or alkali sacaton (Sporobolus airoides) are the most common species found in this system. In less saline areas, there may be inclusions of grasslands dominated by needle and thread (Hesperostipa comata), saline wild rye (Leymus salinus), western wheatgrass, or bluebunch wheatgrass (Pseudoroegneria spicata). There may also be inclusions of non-saline, gravelly barrens or rock outcrops dominated by cushion plants such as Hooker’s sandwort (Arenaria hookeri) and Hood’s phlox (Phlox hoodii) without dwarf-shrubs. Under disturbance, cheatgrass (Bromus tectorum) or other annual bromes can become abundant.
Natural regeneration of saltbush species and associated species occurs where old plants existed in the interspaces, due to accumulated organic matter and nutrients and more favorable moisture (West 1982). Shrub seedlings should be planted in these microsites improve survival rates.
Gardner’s saltbush has an extensive, highly branched root system and tolerates poor site conditions. It has been used to stabilize soils and to reclaim disturbed sites (Clarke and others 1943; Carlson and others 1984). It was one of only two species to establish on coal mine spoils in Wyoming (Frischknecht and Ferguson 1984).
Barbour, Michael G. 2000. North American terrestrial vegetation. Cambridge: Cambridge University Press.
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