Montana Field Guide

This riparian shrubland group occurs at low elevations in the valleys of western and central Montana and into the foothills and lower montane zones. It occurs on both sides of the Continental Divide. East of the Divide it is found near the island ranges extending into areas of southeastern Montana. Sites are usually below the lower treeline extending slightly into areas within the forested, montane zone. It also extends onto the plains. These communities are dominated by short to tall shrubs (up to 15ft tall) of one or more of the following species; Water Birch (Betula occidentalis), Red-osier Dogwood (Cornus sericea), Chokecherry (Prunus virginiana), American Plum (Prunus americana), Skunkbush Sumac (Rhus trilobata), Hawthorns (Crataegus spp), Sandbar Willow (Salix exigua), Pacific Willow (Salix lasiandra), Silverberry (Elaeagnus commutata), Alderleaf Buckthorn (Rhamnus alnifolia), Silver Buffaloberry (Shepherdia argentea), and/or Silver Sagebrush (Artemisia cana). These communities occur along permanent, intermittent and ephemeral streams and along major floodplains. Stands may occur along floodplains in broad, flat valleys to zones along small streams in steep-sided drainages. They can be relatively large, wide occurrences on islands in larger rivers or occur as narrow bands along small streams and on well-drained benches. They are also found in backwater channels and in other perennially wet but less scoured sites, such as floodplain swales and irrigation ditches, and they can also occur along depressional wetlands. Stands may also occur on upper benches away from active channel movement.

This Group is similar to the Rocky Mountain Lower Montane-Foothill Riparian Woodland and Shrubland Ecological System.

Riparian Shrubland; Rocky Mountain and Great Plains Region; Valleys, Foothills and Lower Montane Zones; Medium to Tall Shrubs; Floodplains and Streambanks.

Typical Dominants: Water Birch (Betula occidentalis), Red-osier Dogwood (Cornus sericea), Chokecherry (Prunus virginiana), American Plum (Prunus americana), Skunkbush Sumac (Rhus trilobata), Hawthorns (Crataegus spp), Sandbar Willow (Salix exigua), Pacific Willow (Salix lasiandra), Silverberry (Elaeagnus commutata), Alderleaf Buckthorn (Rhamnus alnifolia), Silver Buffaloberry (Shepherdia argentea), Silver Sagebrush (Artemisia cana)

This group occurs on both sides of the Continental Divide from valleys bottoms to the lower montane zone. East of the Divide it occurs in or adjacent to the island mountain ranges and it extends along the foothills of the mountains including into the hills and lower mountains of southeastern MT.

In MT, G526 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies), 41 (Canadian Rockies) and 43 (Northwestern Great Plains).

In Montana, G526 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, 46 - Northern and Central Rocky Mountain Foothills, 52 - Brown Glaciated Plains, 58A,B,D - Northern Rolling High Plains, and 60B Pierre Shale Plains.

Small Patch

These communities occur along permanent, intermittent and ephemeral streams and along major floodplains. They often occur in a mosaic of shrub and tree dominated communities. Stands may occur along floodplains in broad, flat valleys to zones along small streams in steep-sided drainages. They can be relatively large, wide occurrences on islands in larger rivers or occur as narrow bands along small streams and on well-drained benches. They are also found in backwater channels and in other perennially wet but less scoured sites, such as floodplain swales and irrigation ditches, and they can also occur along depressional wetlands. Stands may also occur on upper benches away from active channel movement. Many sites occur in environments that are subject to annual or periodic flooding and scouring events. Sites dominated by Water Birch occur up to 6,000ft in elevation (Hansen etal 1995).

These riparian communities are dominated by short to tall shrubs (up to 15ft tall) of one or more of the following species; Water Birch (Betula occidentalis), Red-osier Dogwood (Cornus sericea), Chokecherry (Prunus virginiana), American Plum (Prunus americana), Skunkbush Sumac (Rhus trilobata), Hawthorns (Crataegus spp), Sandbar Willow (Salix exigua), Pacific Willow (Salix lasiandra), Silverberry (Elaeagnus commutata), Alderleaf Buckthorn (Rhamnus alnifolia), Silver Buffaloberry (Shepherdia argentea), and/or Silver Sagebrush (Artemisia cana). Herbaceous vegetation is often abundant and diverse and varies widely by individual communities, topographic setting and geographic area. Individual plant associations should be consulted for species commonly associated with particular communities. Non-native, herbaceous species are often common in lower elevation communities of this group. Communities dominated by several of the shrubby species, including Chokecherry, Skunkbush Sumac, Silverberry or Silver Sagebrush may also be found in upland vegetation types and NVC Groups and their presence alone cannot be used to identify this group.

This group is represented in Montana by 4 Alliances and 11 Associations within the National Vegetation Classification. These likely represent the vast majority of the variation in this group though some communities may not be represented by these types.

Willow-dominated shrublands, require flooding and bare gravels for reestablishment. Stands are maintained by annual flooding and hydric soils throughout the growing season. Sites are subject to temporary flooding during spring runoff. The water table is often just below the ground surface. Occurrences are found within the flood zone of rivers, on islands, sand or cobble bars, and immediate streambanks and upper benches, and occasionally on hillslope springs.

Exotic trees of Russian olive (Elaeagnus angustifolia) and Saltcedar (Tamarix species) may invade some stands, particularly east of the Continental Divide.

Information on restoration considerations for these communities is lacking at this time.

G. Kittel (2015)

S. Mincemoyer, L. Vance, C. McIntyre, T. Luna

12/6/2024