This
National Vegetation Classification Group (G568) occurs in riparian habitats throughout the Great Plains. These habitats can be found in and along rivers and streams mostly on recently scoured and/or deposited sand, silts and gravels. Sites may occur on deposits within larger streams and rivers or along the banks and edges of all sizes of streams and rivers. Periodic flooding is important for both creating sites where plants typical of the group can establish and for preventing succession to other vegetation types. Sandbar Willow (
Salix exigua) is typically the dominant shrub. Conversely, many different native, herbaceous species may occur in these habitats as either community dominants or with Sandbar Willow. Various, non-native and often invasive grasses and forbs are also common in these areas. Vegetation cover is often low or sparse, especially on more recently deposited alluvium or scoured sites.
This group encompasses a portion of the Great Plains Riparian Ecological System.
In Montana, this group occurs east of the Continental Divide throughout the Great Plains Region potentially along all perennial stream and river drainages.
In Montana, G568 occurs in Level III Ecoregions 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).
In Montana, G568 occurs within these Major Land Resource Areas: 52 - Brown Glaciated Plains, 53A - Northern Dark Brown Glaciated Plains, 53B - Central Dark Brown Glaciated Plains, 58A,B,C,D - Northern Rolling High Plains, and 60A,B - Pierre Shale Plains.
These habitats can be found in and along rivers and streams mostly on recently scoured and/or deposited sand, silts and gravels. Sites may occur on deposits within larger streams and rivers or along the banks and edges of all sizes of streams and rivers. Periodic flooding is important for both creating sites where plants typical of the group can establish and for preventing succession to other vegetation types. In undammed or properly functioning systems, periodic flooding of the fluvial and alluvial soils and channel migration will create alluvial bars, depressions and backwaters supporting zones or mosaics of wetland and riparian vegetation, whose composition and structure is sustained, altered and redistributed by hydrology. This group is more common in the western portions of the Great Plains where the water sources are less consistent and scouring flood events followed by a drop in water levels are more frequent.
Sandbar willow (Salix exigua) is typically the dominant shrub. Other willows such as Diamond Willow (Salix eriocephala) or Bebb’s Willow (Salix bebbiana) may also be present. Seedlings of Eastern Cottonwood (Populus deltoides) may also be present at recently established sites. The herbaceous component may be comprised of various native species with non-native species often present as well. Native species such as Sand Dropseed (Sporobolus cryptandrus), Field Sagewort (Artemisia campestris), Jointed Rush (Juncus articulatus), and Knotweeds and Smartweeds (Polygonum spp.) are often present. Non-natives such as Creeping Bentgrass (Agrostis stolonifera), Reed Canarygrass (Phalaris arundinacea), Quackgrass (Elymus repens), Kentucky Bluegrass (Poa pratensis), Canada Thistle (Cirsium arvense), Leafy Spurge (Euphorbia virgata) and White Clover (Trifolium repens) are some of the many introduced species that may be present at these sites. (Friedman et al. 1996).
This habitat is a disturbance induced and maintained type that requires periodic flooding, scour, and deposition events for establishment and maintenance.
Great Plains riparian habitats have been substantially impacted by damming and the development of both groundwater and surface water for irrigation. Unless water management can restore periodic flooding, floodplains and riparian areas may become dominated by late-seral communities, and nutrient cycles may be disrupted without floodwaters depositing organic material (Decker 2007). In addition, management efforts need to target aggressive non-native shrubs like Salt-cedar (Tamarix spp.) and Russian Olive that can drastically alter ecological processes. Salt-cedar is an early successional species with dispersal strategies and habitat requirements similar to native cottonwoods and willows (Lesica and Miles 2004). It can replace the native vegetation communities where natural flow regimes have been altered. Early detection and rapid response are necessary to prevent its spread. Invasive broadleaf weeds and invasive rhizomatous grasses are also problematic in these habitats and often out-compete native species. For leafy spurge, spring grazing by sheep has been an effective control along some rivers, particularly the upper Powder River (Rinella and Hileman 2009).
Restoration efforts concentrating on the restoration of hydrologic processes or simulating large flood events is neccesary for establishing and maintaining these sites. Removing or limiting grazing can help promote the growth and establishment of desireable, native species while preventing the spread of non-native species.
J. Drake 2015
S. Mincemoyer
