Montana Field Guide

This Group is composed of barren, rocky and sparsely vegetated landscapes from the foothills to the subalpine zone throughout the mountains of western and central MT, including the island mountain ranges. It includes steep cliff faces, rock outcrops, scree and talus slopes and areas of exposed bedrock on igneous, sedimentary, and metamorphic bedrock types. It is characteristically dry and sparsely vegetated, typically having less than 10% plant cover. There may be small patches of dense vegetation, or scattered plants within these communities. Because the elevation range is so broad, species composition may vary widely. Near timberline, this type may transition seamlessly into G571 Alpine Bedrock & Scree, especially along large scree and talus slopes that extend along a large elevational gradient.

This Group is equivalent to the Rocky Mountain Cliff, Canyon and Massive Bedrock Ecological System.

Cliffs, Scree, Talus, Rock Outcrops, Canyons, Bedrock, Sparsely-Vegetated; Shallow and/or Poorly Developed Soils; Less than 10% Vascular Plant Cover; Rocky Mountain Region.

This group is located throughout the Rocky Mountains, including the mountainous areas of western Montana and the isolated island ranges of central Montana.

In Montana, G565 occurs throughout Level III Ecoregions 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies) and 41 (Canadian Rockies)

In Montana, G565 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains and 43B-Central Rocky Mountains

Large Patch

The Rocky Mountain Cliff, Scree & Rock Outcrop Group occurs on steep cliff faces, in narrow canyons, on smaller rock outcrops, on scree and talus slopes and in areas of exposed bedrock. These systems are shaped by the parent material, climate, aspect, and physical weathering patterns making them distinct from neighboring vegetated communities (Larson et al 2000). 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.

This type is characteristically dry and sparsely vegetated, typically having less than 10% plant cover. Species composition includes individuals present in adjacent systems (unless exposed parent material is radically different) and shrubby or herbaceous species adapted to these stable or shifting, rocky habitats. Soil development is limited and often patchy, as is the herbaceous cover. There may be small patches of dense vegetation, or scattered plants within these communities, especially within cracks and crevices. Particular species present at a site are determined largely by rock type and its physical and chemical properties, formation and position on the landscape, elevation, aspect, and overall geographic location. As such, the potential list of species present within this group is quite large and may include various trees, shrubs, forbs and graminoids.

Shrubs adapted to xeric growing conditions and rocky soils are often present, including Oceanspray (Holodiscus discolor), Currants and Gooseberries (Ribes species), Ninebark (Physocarpus malvaceus), Rose (Rosa species), Common Juniper (Juniperus communis), Lewis’ Mock Orange (Philadelphus lewisii), Oregon-grape (Berberis repens), Skunkbush Sumac (Rhus trilobata), American Red Raspberry (Rubus idaeus) or Serviceberry (Amelanchier alnifolia).

Herbaceous plants inhabit both the talus and scree slides and fractures in the cliff faces. Potential forbs are many, but commonly include Penstemon (Penstemon species), Buckwheat (Eriogonum species), Silver Sagewort (Artemisia ludoviciana), Michaux’s Sagewort (Artemisia michauxiana), and Spotted Saxifrage (Saxifraga bronchialis). Potential graminoids vary significantly among sites. Xeric-adapted ferns such as Cliff Fern (Woodsia species), Brittle Bladder Fern (Cystopteris fragilis) and Rockbrake (Cryptogramma acrostichoides) often occur in fractures of the bedrock, cliff faces or on toeslopes of talus slides. Lichen cover can be high on larger size talus and rock faces.

In Montana, this barren and sparsely-vegetated group is currently represented by 2 Alliances and 3 Associations within the National Vegetation Classification. Additional plant communities certainly occur within this Group in MT, either undocumented, undescribed, or not attributed to MT as of yet.

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.

G. Kittel and M.S. Reid 2010

S. Mincemoyer, E. Luther, L. Vance and T. Luna

12/5/2024