Montana Field Guide

This National Vegetation Classification Group is the dominant grassland type of western and central Montana in the valleys, foothills and lower montane zone. It is typified by cool-season perennial, bunch grasses and forbs with >25% cover, with a sparse shrub cover (generally <10%). It occurs on both sides of the Continental Divide and extends east to all of the island ranges in central and southern MT. These grasslands are found at elevations of about 2,000-5,500 feet. Grasslands above this elevation are generally referrable to G267 - Montane - Subalpine Dry Grassland. At low to mid-montane settings, grasslands may be transitional between the two groups and not easily placed. East of the Continental Divide, this group transitions to G331 - Great Plains Dry Mixedgrass Prairie along the Rocky Mountain Front and in the foothills and lower slopes of the island ranges. In the lower montane zone, these grasslands range from small meadows to large open parks surrounded by conifers; below the lower treeline, they occur as extensive foothill and valley grasslands. Characteristic bunchgrasses include Rough Fescue (Festuca campestris), Idaho Fescue (Festuca idahoensis), Bluebunch Wheatgrass (Elymus spicatus), Sandberg’s Bluegrass (Poa secunda), Needle-and-Thread (Stipa comata) and Prairie Junegrass (Koeleria macrantha). Native, rhizomatous species present at some sites are Western Wheatgrass (Elymus smithii) and Thickspike Wheatgrass (Elymus lanceolatus). Agricultural conversion, invasive species, fire suppression, and overgrazing are major threats to these grasslands and have led to the direct loss of and degradation of habitat.

This group is equivalent to the Rocky Mountain Lower Montane, Foothill, and Valley Grassland Ecological System.

Dominated by Cool Season Bunchgrasses, Occasionally by Rhizomatous Species; Valleys, Foothills and Montane Zones; Rocky Mountain Region; Graminoid Cover >25%; Shrub Cover <10%

Typical Dominants: Bluebunch Wheatgrass (Elymus spicatus), Idaho Fescue (Festuca idahoensis); Rough Fescue (Festuca campestris), Needle-and-Thread (Stipa comata), Sandberg’s Bluegrass (Poa secunda), Western Wheatgrass (Elymus smithii), Thickspike Wheatgrass (Elymus lanceolatus)

In Montana, this group is found in and near the mountainous regions of the state from valleys, foothills and lower montane settings. It occurs on both sides of the Continental Divide and extends east to all of the island ranges in central and southern MT. This group includes all the major, native grasslands west of the divide at lower elevations.

In MT, G273 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies), 41 (Canadian Rockies) and western portions of 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).

In Montana, G273 occurs within these Major Land Resource Areas: 43A - Northern Rocky Mountains, 43B - Central Rocky Mountains, 44A - Northern Rocky Mountain Valleys, 44B - Central Rocky Mountain Valleys, and 46 - Northern and Central Rocky Mountain Foothills.

Large Patch-Matrix

These drier, low-elevation grasslands are transitional between the dry mixedgrass prairie and the montane/subalpine grasslands occurring adjacent to or within forested habitats. To the west, this group grades into Palouse prairie in northern Idaho and contains many of the same species. Average precipitation ranges from 11.5 to 16.5 inches. Where it occurs within glaciated landscapes, numerous pothole wetlands and other wetland types are found.

In western Montana, these grasslands form in openings of Douglas-fir (Pseudotsuga menziesii) and Ponderosa Pine (Pinus ponderosa) forests, below the lower treeline in western valleys and within big sagebrush (Artemisia tridentata) shrublands. East of the Continental Divide, this group is found along valley bottoms and lower slopes along the Rocky Mountain Front and along the island mountain ranges. Rolling uplands and undulating plains are typical topography east of the Continental Divide, from the Alberta border south along the Rocky Mountain Front and east where this group merges with mixed prairie grassland. Soils are generally deep, fine-textured, often with coarse fragments, and are mostly non-saline. Mollisols with shallow to moderately deep A-horizons are dominant, reflecting the incorporation of relatively high amounts of organic matter.

This group is characterized by short to mid-stature, perennial, cool-season grasses and forbs with >25% cover. A sparse shrub cover, generally <10% is present at some sites. Bunchgrasses dominate these communities though rhizomatous grasses are present or may dominate or co-dominate certain sites. Characteristic bunchgrasses include Rough Fescue (Festuca campestris), Idaho Fescue (Festuca idahoensis), Bluebunch Wheatgrass (Elymus spicatus), Sandberg’s Bluegrass (Poa secunda), Needle-and-Thread (Stipa comata) and Prairie Junegrass (Koeleria macrantha). Native, rhizomatous species present at some sites are Western Wheatgrass (Elymus smithii) and Thickspike Wheatgrass (Elymus lanceolatus). Rough fescue (Festuca campestris) and Idaho fescue (Festuca idahoensis) are dominant or co-dominant throughout the range of the group. Bluebunch wheatgrass (Pseudoroegneria spicata) occurs as a co-dominant throughout the range as well, especially on xeric sites. Species diversity ranges from 15 (or fewer) on xeric and disturbed sites to more than 50 mesic sites with most sites having at least 25 vascular species present. The dominant species and plant composition of this group overlaps with G331 Great Plains Dry Mixedgrass Prairie east of the Continental Divide and with G267 Montane - Subalpine Dry Grassland at montane sites on both side of the Divide. To a much more limited extent, it is transitional to G311 Semi-Desert Grassland in some southern areas of the state. These grasslands are also floristically similar to Big Sagebrush Steppe communities, which are part of G302 and G304.

Shrub cover is usually less than 10 percent and includes species such as Shrubby Cinquefoil (Dasiphora fruticosa), Woods’ Rose (Rosa woodsii), Common Snowberry (Symphoricarpos albus), and Common Juniper (Juniperus communis). Serviceberry (Amelanchier alnifolia), Douglas hawthorn (Crataegus douglasii), and Common Chokecherry (Prunus virginiana) often occur as patches on north-facing slopes of foothills or along minor drainages where soil moisture persists longer into the growing season.

Two plant communities dominate this group in Montana: 1) Rough Fescue - Idaho Fescue communities, found on mesic sites such as the north- and east-facing slopes in foothills and swales and valley bottoms with deeper soils; and 2) Bluebunch Wheatgrass - Idaho Fescue communities, found on drier sites such as ridges, hilltops, and south- and west-facing slopes in the foothills and on level sites with sharply drained glacial-till soils. On pristine, mesic sites, Rough Fescue can form a nearly continuous cover, interspersed with Idaho Fescue and other graminoids characteristic of the group as well as Basin Wildrye (Elymus cinereus), and Carex petasata. These mesic sites support a forb- rich community that includes species such as Arrowleaf Balsamroot (Balsamorhiza sagittata), Yarrow (Achillea millefolium), Lupine (Lupinus spp), Sticky Geranium (Geranium viscosissimum), Nine-Leaf Biscuitroot (Lomatium triternatum), Tall Cinquefoil (Drymocallis arguta), Potentilla gracilis, Penstemon spp., Low Larkspur (Delphinium bicolor), Locoweeds (Oxytropis species), Wild Strawberry (Fragaria virginiana), and Paintbrush (Castilleja species).

On drier sites dominated by Idaho Fescue and the Bluebunch Wheatgrass, common forbs include Yarrow, Blanketflower (Gaillardia aristata), Boreal Bedstraw (Galium boreale), Prairie-smoke (Geum triflorum), Arnica (Arnica sororia or A. fulgens), Rosy Pussytoes (Antennaria rosea), Sticky Cinquefoil (Drymocallis glandulosa), Lupine (Lupinus sp.), Biscuitroot (Lomatium spp.), Phlox spp, Gayfeather (Liatris punctata), Stoneseed (Lithospermum ruderale), Buckwheat (Eriogonum species), Fuzzytongue Penstemon (Penstemon eriantherus), Missouri Goldenrod (Solidago missouriensis), Locoweed (Oxytropis species), Pasqueflower (Anemone patens), Brittle Pricklypear (Opuntia fragilis), Western Sagewort (Artemisia ludoviciana), Fringed Sage (Artemisia frigida), and Fleabanes (Erigeron species). Other graminoids present within this drier community include Timber Oatgrass (Danthonia intermedia), Prairie Junegrass (Koeleria macrantha), Sandberg’s Bluegrass (Poa secunda), Indian Ricegrass (Oryzopsis hymenoides), Geyer’s Sedge (Carex geyeri), and Threadleaf Sedge (Carex filifolia). Lesser spikemoss (Selaginella densa) is often present and may have high cover on some sites. Soil crusts and lichens may be present in high-quality occurrences. cover can be high on ungrazed occurrences (Antos et al 1983) or where fire has been suppressed. Moss cover is variable, depending on site conditions.

In Montana, this group is represented by 5 Alliances and 17 Associations within the National Vegetation Classification, which likely covers the diversity of types present in the state.

Shrubs may increase following heavy grazing and/or with fire suppression. Rough Fescue is highly palatable throughout the grazing season and over-grazing during the summer for 2 to 3 years can result in Rough Fescue loss. In one study, a light stocking rate for 32 years did not affect range condition, although a modest increase in stocking rate led to a marked decline in range condition (Willms and Rhode 1998). Oatgrass tends to replace rough fescue under moderate or heavy grazing pressure at some sites. Long-term heavy grazing on mesic sites can result in a shift to a Kentucky Bluegrass (Poa pratensis) – Common Timothy (Phleum pratense) - Smooth Brome (Bromus inermis) dominated community.

In Montana, many exotic species invade these grasslands, and in some cases have completely replaced native species. On disturbed, drier sites, Cheatgrass (Bromus tectorum), Japanese Brome (Bromus japonicus), Sulfur Cinquefoil (Potentilla recta), Leafy Spurge (Euphorbia virgata), Spotted Knapweed (Centaurea stoebe), Saint John’s Wort (Hypericum perforatum), and Whitetop (Cardaria draba) are common. Mesic sites are threatened by Meadow Hawkweed complex species (Hieracium pratense, H. floribundum, H. piloselliodes), Orange Hawkweed (Hieracium aurantiacum), Ox-eye Daisy (Leucanthemum vulgare), Tall Buttercup (Ranunculus acris) and Canada Thistle (Cirsium arvense).

Agricultural conversion, invasive species, fire suppression, and overgrazing are major threats to these grasslands and have led to the direct loss of and degradation of habitat. In the absence of natural fire, periodic prescribed burns can be used to maintain this group, though this should be done in coordination with weed control efforts to mitigate or prevent invasive species from taking over or becoming established at a site. Grazing pressure needs to be actively managed to prevent loss of desirable species and the spread of non-native species.

Restoration strategies will depend largely on the disturbance and severity. Modified grazing practices can allow this group to recover without additional restoration needs. Antos and others (1983) have suggested prescribed fires at intervals of every 5 to 10 years for sites in western Montana. Following burning and depending on fire intensity, Rough Fescue may recover at much slower rates than Idaho Fescue (Antos et al. 1983). Short-term conditions after burning, e.g., precipitation and cold-stress days, appear important in controlling species responses and composition of plant communities (Gross and Romo 2009). On some sites, site preparation will require noxious species eradication and control for at least two seasons before and after restoration. On reclamation sites where soil preparation is required, soil discing techniques that discourage uniform soils and seed beds should be used. Feathering and smoothing topsoil may benefit invasive species such as Kentucky Bluegrass (Poa pratensis) and Smooth Brome (Bromus inermis), while rough conditions may inhibit their growth, allowing Rough Fescue (Festuca campestris) and other native, perennial grasses to establish more readily (Desserud 2006).

M.S. Reid, L. Allen and K.A. Schulz 2015

S. Mincemoyer, L. Vance, T. Luna

12/4/2024