Rocky Mountain Subalpine-Montane Riparian Shrublands are found throughout the Rocky Mountain cordillera from New Mexico north into Montana and the Canadian Rockies. In Colorado, these shrublands are found at montane to subalpine elevations from 2,280 to 3,410 m (7,500 to 11,200 ft). This riparian system is a seasonally flooded shrubland that occurs in a variety of geomorphic settings and with variable community structure, often forming a mosaic of shrub- and herb-dominated vegetation types. Occurrences can also be found around seeps, fens, and isolated springs on hillslopes away from valley bottoms. Beaver activity is often associated with the development of these shrubland systems and can profoundly change vegetation structure and alter hydrologic regimes. Vegetation includes short to tall willow, or occasionally birch, alder, or other shrub dominated communities. Above treeline and at subalpine elevations the riparian shrublands typically occupy snowmelt-fed basins, wide glacial valleys and swales, low floodplains adjacent to streams or wet floodplains associated with beaver ponds. These subalpine communities are characterized by low-stature shrublands dominated by planeleaf willow (S. planifolia), barrenground willow (S. brachycarpa), and wolf willow (S. wolfii), or occasionally dwarf birch (Betula nana). With the transition to lower elevations, taller willows including Geyer willow (S. geyeriana), mountain willow (S. monticola), Booth's willow (S. boothii), Drummond willow (S. drummondiana), or other non-willow shrubs such as thinleaf alder (Alnus incana), river birch (B. occidentalis), and red-osier dogwood (Cornus sericea), dominate. Throughout the range of elevations the herbaceous layer may be graminoid or forb dominated, and include many of the species that are also common in adjacent riparian forests and woodlands.

These riparian shrublands support vegetation with a canopy dominated by shrubs with sparse or no tree cover, lying generally adjacent to ephemeral, intermittent or perennial stream channels. Plant communities often form a mosaic of shrub- and herb-dominated vegetation types with species such as thinleaf alder (Alnus incana), dwarf birch (Betula nana), river birch ( B. occidentalis), red-osier dogwood (Cornus sericea), and a number of different willows, including Bebb's willow (S. bebbiana), Booth's willow (S. boothii), barrenground willow ( S. brachycarpa), Drummond willow ( S. drummondiana), Geyer willow (S. geyeriana), mountain willow (S. monticola), planeleaf willow (S. planifolia), and wolf willow (S. wolfii).

This system is found throughout the Rocky Mountain cordillera from New Mexico north into Montana and the Canadian Rockies of Alberta and British Columbia, and also occurs in mountainous areas of the Intermountain West and Colorado Plateau. In Colorado, occurrences are found throughout the central mountainous portion of the state.

Rocky Mountain Subalpine-Montane Riparian Shrublands are linear systems.

In Colorado, Rocky Mountain Subalpine-Montane Riparian Shrublands are found at montane to subalpine elevations between 2,280 to 3,410 meters (7,500 to 11,200 feet). This system can occur as narrow to wide bands of shrub vegetation lining streambanks and alluvial terraces, or as extensive carrs (willow shrublands) of valley bottoms and slopes and typically as a mosaic of shrubland and herbaceous communities. Most precipitation occurs as snowfall (as much as 80% at high elevations) during the winter months. Snowmelt at high elevations contributes a large proportion of water to most wetland types through its influence on groundwater and surface water dynamics. In mountain valleys snowmelt and geomorphology are major factors controlling the extent, depth, and duration of saturation resulting from high groundwater levels and also exert controls on most aspects of the frequency, timing, duration, and depth of flooding along riparian areas.
Flooding in subalpine-montane streams occurs annually in May and June with the volume and duration affected by snowpack levels. Periodic flooding contributes nutrients to riparian areas as it deposits organic material and fine-sediment. Contribution to streamflow also comes from upstream wetlands which make an important input to streamflow during later-summer and periods of drought. Runoff from adjacent hillsides also contribute to the hydrological regime of riparian shrublands by recharging local alluvial aquifers and supporting wetland vegetation that is otherwise disconnected from stream flow.
Alluvial soils within riparian shrublands are of variable thickness and texture and often exhibit redoximorphic features such as mottling and gleying, indicating a fluctuating water table. Organic matter is also of variable thickness and the depth and degree of decomposition varies according to the stability of the water table, quality of detritus, and soil temperatures. However, shrub wetlands with 40 cm or greater organic matter accumulations are indicative of permanent saturation from groundwater input and not fluvial processes and should be classified as Rocky Mountain Subalpine-Montane Fens.

The Rocky Mountain Subalpine-Montane Shrubland system includes short to tall willow and non-willow shrub-dominated communities. These shrublands frequently occur as a mosaic of shrublands and herbaceous meadows. Dominant shrub species vary along elevational, soil, hydrologic and topographic gradients. Above treeline and at subalpine elevations, short willow shrublands occupy snowmelt-fed basins, wide glacial valleys and swales, low floodplains adjacent to streams or wet floodplains associated with beaver ponds. Shrub species include planeleaf willow (Salix planifolia), barrenground willow (Salix brachycarpa), Wolf's willow (Salix wolfii), and bog birch (Betula nana). With the transition to lower, montane zone elevations, medium to tall willows and other non-willow deciduous shrubs become dominant. Drummond willow (Salix drummondiana) is found at low subalpine to upper montane elevations, while Geyer's willow (Salix geyeriana) and mountain willow (Salix monticola) dominate a broad variety of associations ranging from the mid subalpine to lower montane zones. In the lower montane, non-willow tall shrubs such as thinleaf alder (Alnus tenuifolia), water birch (Betula occidentalis), red-osier dogwood (Cornus sericea), and tall-willow species including Bebb willow (Salix bebbiana), strapleaf willow (S. liguifolia), and shining willow (S. lucida) may dominate associations within this system. Occasional scattered trees may occur.
The herbaceous layer may be graminoid or forb dominated. Common graminoids include water sedge (Carex aquatilis), beaked sedge (C. utriculata), smallwing sedge (C. microptera), woolly sedge (C. pellita), fowl mannagrass (Glyceria striata), bluejoint reedgrass (Calamagrostis canadensis), smallflowered woodrush (Luzula parviflora), mountain rush (Juncus balticus var. montanus), slimstem reedgrass (Calamagrostis stricta), tufted hairgrass (Deschampsia cespitosa), American mannagrass (Glyceria grandis), and rough bentgrass (Agrostis scabra). Common forbs include Jacob's ladder (Polemonium sp.), tall fringed bluebells (Mertensia ciliata), willowherb (Epilobium sp.), common cowparsnip (Heracleum maximum), starry false lily of the valley (Maianthemum stellatum), bluntseed sweetroot (Osmorhiza depauperata), angelica (Angelica spp.), monkshood (Aconitum columbianum), Parry's clover (Trifolium parryi), American bistort (Polygonum bistortoides), alpine bistort (P. viviparum), heartleaf bittercress (Cardamine cordifolia), Fendler's meadow-rue (Thalictrum fendleri), marsh marigold (Caltha leptosepala), elephanthead lousewort (Pedicularis groenlandica), Rocky Mountain hemlock parsley (Conioselinum scopulorum), Porter's licorice root (Ligusticum porteri), alpine meadow-rue (Thalictrum alpinum), common yarrow (Achillea millefolium), American vetch (Vicia americana), Richardson's geranium (Geranium richardsonii), arrowleaf ragwort (Senecio triangularis), Fendler's cowbane (Oxypolis fendleri), Virginia strawberry (Fragaria virginiana), largeleaf avens (Geum macrophyllum), Fendler's waterleaf (Hydrophyllum fendleri), brook saxifrage (Saxifraga odontoloma), subalpine larkspur (Delphinium barbeyi), bedstraw (Galium spp.), field horsetail (Equisetum arvense), scouringrush horsetail (Equisetum hyemale), and felwort (Swertia perennis).

American beaver (Castor canadensis) are characteristic of these habitats. Dense willow thickets of high elevation riparian shrublands provide many protected nest sites and an abundance of insects, resulting in a high density of nesting birds. Bird species most commonly found in these areas are Broad-tailed Hummingbird (Selasphorus platycercus), Dusky Flycatcher (Empidonax oberholseri), Yellow Warbler (Setophaga petechia), MacGillivray's Warbler (Geothlypis tolmiei), Wilson's Warbler (Cardellina pusilla), Lincoln's Sparrow (Melospiza lincolnii), Song Sparrow (Melospiza melodia), White-crowned Sparrow (Zonotrichia leucophrys), Fox Sparrow (Passerella iliaca) and American Dipper (Cinclus mexicanus). Boreal toad (Anaxyrus boreas boreas) and northern leopard frogs (Lithobates pipiens) are found in these areas.

Rocky Mountain rivers are characterized by a steep average channel gradient, turbulent flow and sediment movement, and high spatial variability because of elevation differences in rock type, vegetation and sediment supply. The annual flow regime is distinctive with strong seasonal peak flows driven by snowmelt over the course of one to two months that have the potential to move tremendous amounts of sediment. Groundwater-influenced base flow conditions dominate the hydrograph for the remainder of the year.
Key disturbance regimes in this system are annual and episodic flooding and beaver activity. Riparian ecosystems rely on natural disturbance regimes to maintain function and structure. Natural physical disturbance agents include floods, fire, landslides, avalanches, and channel migration. Seasonal and episodic flooding erode and/or deposit sediment resulting in complex patterns of soil development which subsequently have a strong influence on the distribution of riparian vegetation. Beaver have historically been an important hydrogeomorphic driver of Rocky Mountain Subalpine-Montane Riparian Shrublands. Beaver-modified systems have numerous zones of open water and vegetation, large accumulations of detritus and nutrients, more wetland areas, more anaerobic biogeochemical cycles, and in general are more resistance to disturbance. Watersheds with active beaver colonies have increased water storage capacity. Beaver dams modify stream channel form and habitat structure. Beaver ponds resulting from beaver dams elevate local water tables, dissipate energy associated with flood events, reduce stream erosion, enhance nutrient cycling and store fine sediment. Plant establishment and sediment build-up behind beaver ponds raises the channel bed and creates a wetland environment. Beaver in that way create a heterogenous complex of wet meadows, marshes and riparian shrublands that provides valuable habitat for wetland-dependent plants and animals.

Threats to wetland and riparian ecosystems include anthropogenic hydrologic changes associated with flow regulation or alteration of the natural flooding regime, as well as vegetation alteration and the removal of beaver. With the removal of beaver, the gradual loss of beaver dams has had repercussions that include a likely increase in stream gradient, increased stream sediment and nutrients which altered sediment transport and nutrient cycling and loss of riparian habitat and associated biological diversity.
Anthropogenic activities that contribute indirectly to hydrologic alteration include land use in adjacent uplands that affects hillslope runoff and erosion processes, and habitat fragmentation that results in barriers to natural processes or species movements. Direct impacts result from anthropogenic alteration to the floodplain and riparian zone by activities such as ditching, agricultural use, livestock grazing and urbanization or by alteration to the stream channel from dams and diversions, mining especially placer mining, and channelizing activities such as road building or streambank armoring. Water developments by impoundment or diversion significantly alter flow regimes, habitat structure and biological communities of affected rivers.
Livestock grazing can lead to significant changes in vegetation structure and composition which can negatively impact wildlife and fish habitat as well as processes such as precipitation infiltration and soil erosion. Effects of overgrazing include vegetation removal and compacting streambanks, bank erosion, wider and shallower channel cross-sections, finer stream bed substrates, increased nutrient input to rivers, warmer water temperatures, and impaired aquatic and riparian habitat. In sites where there is prolonged disturbance, willow coverage will decrease resulting in a more open canopy. Herbaceous vegetation is likely to include more non-native species such as Kentucky bluegrass (Poa pratensis) and timothy (Phleum pratense) as well as exotics species common to other wetland types such as Canada thistle (Cirsium arvense) and dandelion (Taraxacum officinale).
Climate factors including the amount, form, and seasonality of precipitation, temperature and wind, and the timing of snow-melt influence stream flow regimes, including flow variability and characteristics such as base, mean, and peak flow volumes, and fluvial geomorphic processes such as sediment erosion and deposition. Global climate change is altering the timing and character of processes that maintain riparian systems. Human-induced warming is resulting in the loss of snowpack which is projected to worsen and trends indicate fundamental impacts on streamflow and water supplies across the western United States.