Interzonal Wet Fresh Streambank (willow)

Description

The Reference State is a description of this ecological site prior to Euro-American settlement but long after the arrival of Native Americans. The description of the Reference State was determined by NRCS Soil Survey Type Site Location information and familiarity with rangeland relict areas where they exist. The least modified plant community (1.1) within the Reference State would have been a carr (i.e. tall shrub-dominated wetland) dominated by willows (Booth's willow (Salix boothii), shortfruit willow (Salix brachycarpa), Drummond's willow (Salix drummondiana), Geyer willow (Salix geyeriana), grayleaf willow (Salix glauca), Bebb willow (Salix bebbiana), Pacific willow (Salix lucida ssp. lasiandra), yellow willow (Salix lutea), and/or Scouler’s willow (Salix scouleriana)), species depending on geographic region. This list of willow species may be different than those listed in the “Plant Community Composition by Weight and Percentage” section of this document because these species are identified in higher elevations (Montane and Sub-alpine zones) only.

Dominant grasses would have included tufted hairgrass (Deschampsia cespitosa), blue wildrye (Elymus glaucus), and mountain brome (Bromus marginatus), and the grass-like water sedge (Carex aquatilis). Associated forbs would have included common cowparsnip (Heracleum maximum), field horsetail (Equisetum arvense), and feathery false lily of the valley (Maianthemum racemosum). Englemann spruce (Picea engelmannii) and blue spruce (Picea pungens) would have also occurred sparingly as small trees. Tree species present indicated where this phase was located topographically.

Submodel

Description

State 2 is very similar to State 1 in form and function, with the exception of the presence of non-native plants and animals, possible extinctions of native species, and a different climate.
State 2 is a description of the ecological site shortly following Euro-American settlement. This state can be regarded as the current potential. State 2 can fluctuate between two willow-dominated phases: one that is relatively undisturbed with a rich and productive understory (2.2), and another where the understory is reduced due to the heavy livestock grazing (2.1). Phase 2.1 is a willow (Salix spp.) stand with a reduced understory due to the heavy livestock grazing. This Phase was also produced by horses and mules belonging to early European settlers and travelers (2.2a). These areas usually have surface water available, an attractant to most animals in the vicinity, which tend to pass through these stands at least once daily to feed, get water, and find shade. Heavy use of this part of the landscape was common until the creation of the Forest Reserves and U.S. Forest Service, when forest managers began to require users to be more sensitive of these areas. When the U.S. Forest Service began regulating use of their lands, including areas occupied by this ESD (circa 1910), the number of livestock and their season of use was reduced drastically, salt was placed only on upland locations, and sheep camps were required to be moved often. Because of the high resilience of these sub-irrigated habitats, partial recovery of the understory was attained in many instances and accelerated soil erosion arrested. Sustainable use was approached in such instances (2.1a).

Submodel

Description

Where control of grazing intensity isn’t been achieved earlier and excessive use by livestock prevails, the vegetation takes on more of the character of that of drier sites at low elevations. As the water table is lowered, the stature of the willows and other riparian shrubs declines, allowing upland species such as rubber rabbitbrush (Ericameria nauseosus), mountain big sagebrush (Artemisia tridentata ssp. vaseyana), and snowfield sagebrush (Artemisia spiciformis) to fill in these sites (3.2). Wildfire followed by continued heavy livestock grazing (3.2a) will temporarily remove the shrub and palatable herbaceous component, leaving annuals and biennials such as lesser burdock (Arctium minus), rough cocklebur (Xanthium strumarium), horehound (Marrubium vulgare), houndstongue (Cynoglossum officinale), stickseed (Hackelia spp.), Canada thistle (Cirsium arvense), and Scotch cottonthistle (Onopordum acanthium) to flourish (3.1). The recovery of moose and beaver puts more pressure on the remaining willows. However, if enough willow and other deciduous shrubs survive previous herbivory to allow beaver dam building, and thus re-ponding of these sites (R3a), it may be possible for the original mesic species to re-establish and for the site to return to State 2. A return to heavy livestock grazing will negatively impact the resiliency of this State.

Submodel

Description

A seeded grassland state is possible if the site is tilled and re-seeded to increase forage for livestock and to stabilize the streambanks. Species such as meadow foxtail (Alopecurus pratensis), tall oatgrass (Arrhenatherum elatius), meadow brome (Bromus biebersteinii), mountain brome (Bromus marginatus), orchardgrass (Dactylis glomerata), tufted hairgrass, sheep fescue (Festuca ovina), meadow barley (Hordeum brachyantherum), and timothy (Phleum pratense) may be used. Levels of grazing will have to be controlled (4.2a) or the initially pure grassland (4.1) will quickly be re-invaded by rabbitbrush, sagebrush, willow, or other mesic shrubs (4.2), along with the noxious understory forbs such as burdock, cocklebur, horehound, houndstongue, stickseed, and a variety of thistles. Heavy continuous season long grazing would deplete the seeded grasses, giving an advantage to shrubs and other invasive species (4.1a).

Submodel