Montana Field Guide

This group occurs in MT in the Bighorn Basin in Carbon and Big Horn Counties, where it reaches its northern extent. It also occurs in southwest Montana but no specific sites or vegetation communities have been described or attributed to this area as of yet though it does occur in adjacent ID. It can be found from foothill to montane elevations on landforms that contain steep cliff faces, canyon walls and rocky outcrops derived from a variety of parent materials. It includes talus and scree fields immediately below cliff and outcrop faces as well as other, harsh, sparsely-vegetated sites. Vegetation inhabiting this ecological system is typically sparse and may include conifers and shrubs adapted to limited soil moisture and soil development. Herbaceous cover is typically very sparse and limited to species adapted to inhabiting cliff faces, unstable rock and shallow soils. In Montana, this group is very similar to G565 Rocky Mountain Cliff, Scree & Rock Outcrops and is differentiated by geographic location and the specific sparse-vegetation communities occupying the site.

This group is equivalent to the Wyoming Basin Cliff and Canyon Ecological System.

Cliffs, Scree, Talus, Rock Outcrops, Canyons, Bedrock, Sparsely-Vegetated; Shallow and/or Poorly Developed Soils; <10% Vascular Plant Cover; Intermountain, Wyoming, and Bighorn Basins.

This group occurs in MT in the Bighorn or Wyoming Basin in Carbon and Big Horn Counties, where it reaches its northern extent. It also occurs in southwest Montana, but no specific sites or vegetation communities have been described or attributed to this area as of yet, though it does occur in adjacent ID.

In Montana, G570 occurs within or immediately adjacent to Level III Ecoregion 18 (Wyoming Basin), specifically in Level IV 18b (Bighorn Basin) and portions of Level III Ecoregion 17, primarily in the sw corner of the state.

In Montana, G570 occurs within Major Land Resource Areas: 32-Northern Intermountain Desertic Basins and into surrounding portions of 43B-Central Rocky Mountains, 44B - Central Rocky Mountain Valleys, and 46-Northern and Central Rocky Mountain Foothills.

Large Patch

This group consists of barren and sparsely vegetated substrates in an arid climate on steep cliff faces, in narrow canyons, on smaller rock outcrops, on scree and talus slopes, in areas of exposed bedrock and adjacent badlands topography. This group occurs in the lowest area of precipitation within MT. These communities are shaped by the parent material, climate, aspect, and physical weathering patterns making them distinct from neighboring vegetated communities (Larson et al 2000). Some substrates, such as marine shales, are strongly alkaline and/or saline which chemically limits plant growth. Soils are patchy, thin and/or poorly developed, and moisture for plant growth is primarily retained in crevices in the rock substrate. Limited soil availability, harsh microclimates, and water stress impose physiological constraints on plant establishment and growth and plant community development. Within this type, a mosaic of microhabitats may be present within cliff habitats, small ledges, overhangs, and cracks and crevices (Graham and Knight 2004). These microhabitats may provide critical habitat for endemic or rare plant species.

Vegetation is very sparse or patchy within this Group and includes areas where soil and moisture have accumulated such as in cracks and crevices and at the base of cliff faces and rock outcrops. Vegetation communities and plant species specific to this group and occurring in MT are poorly documented and in need of additional research. Currently, only the Pseudoroegneria spicata - Eriogonum brevicaule Plant Association is attributed to MT. Plant species frequently occurring may include scattered shrubs, such as Rubber Rabbitbrush (Ericameria nauseosa), Broom Snakeweed (Gutierrezia sarothrae), Shadscale (Atriplex confertifolia), and grasses such as Indian Ricegrass (Oryzopsis hymenoides) and Sandberg Bluegrass (Poa secunda), and the forbs Hooker's Sandwort (Arenaria hookeri), Cryptantha spp. and Rayless Tansy-aster (Xanthisma grindelioides).

In Montana, this sparsely-vegetated, cliff and badlands group includes 2 Alliances with only 1 Alliance having a described Association within the National Vegetation Classification. Additional review of Alliances and Associations is needed.

These rock-dominated and sparsely-vegetated communities are influenced by the type of parent rock, elevation, aspect, climate, and both physical and chemical weathering patterns. Erosional and depositional processes are locally important. All of these processes and characteristics can have a strong influence over which species occur within these habitats (Larson et al 2000).

This type is generally not a focus for management or restoration activities. Avoiding or preventing impacts to areas within this type, particularly those that support rare taxa or Species of Concern is the primary means of management.

See Management Section.

K.A. Schulz, M.S. Reid and G. Kittel (2015)

S. Mincemoyer

12/5/2024