Print Report

CEGL001202 Salix exigua / Mesic Forbs Wet Shrubland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Narrowleaf Willow / Mesic Forbs Wet Shrubland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This association typically occurs between 1464 and 2562 m (4800-8400 feet) elevation in Utah, western Colorado, central Nevada and eastern Idaho, where it occupies streambanks, terraces, and meadows along a wide variety of low- to moderate-gradient stream types. In contrast, a low-elevation phase of this plant association is found below 1128 m (3700 feet) in south-central and southwestern Idaho on annually flooded banks, islands, and terraces of reservoirs and large rivers (e.g., the Snake River and Boise River). This type usually occurs on well-developed sandy to silty alluvial loam soils, on the wettest (often flooded) but stable sites supporting Salix exigua associations. Both phases are dominated by a tall-shrub overstory of open to dense Salix exigua, although Salix lutea, Ribes spp., and Rosa woodsii are sometimes also present in lesser amounts. In the typical phase, the herbaceous understory is clearly dominated by a lush understory of mixed tall forbs, each with moderate cover, with Aconitum columbianum, Equisetum arvense, Heracleum maximum, Maianthemum stellatum, Mertensia ciliata, Rudbeckia spp., Solidago canadensis, and Urtica dioica being most common. No single forb has consistently high constancy and cover across the association''s range. In the low-elevation phase, flood-disturbed stands in riverine habitats contain abundant native colonizing forbs (e.g., Apocynum cannabinum, Euthamia occidentalis, Glycyrrhiza lepidota, and Polygonum spp.) often mixed with dense exotic forbs (e.g., Dipsacus fullonum, Lythrum salicaria, Melilotus officinalis, and Xanthium strumarium). Total mesic graminoid cover is low in both phases of this association (with each species having only low cover) and composed of both native species (e.g., Carex spp., Elymus glaucus) and/or exotics (e.g., Phalaris arundinacea, Poa pratensis).

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association is quantitatively described from 22 plots: 4 plots in Utah and southeastern Idaho (Padgett et al. 1989) and 4 plots in central Nevada (Manning and Padgett 1995). The low-elevation phase is described from at least 14 plots of Salix exigua / mixed riparian forb plant association sampled along the middle Snake River by Cole (1996), as well as Salix exigua communities with understories dominated by colonizing forbs such as Apocynum cannabinum and Melilotus officinalis (Cole 1995, Holmstead 2001). Euthamia occidentalis has high constancy and sometimes high cover in many of these low-elevation stands. The higher elevation phase is usually a stable, mid- to late-seral association (unless disturbed by excessive grazing), while the low-elevation phase is an early-seral association. The compositional heterogeneity inherent in early-seral, flood-disturbed Salix exigua stands has led some researchers to lump stands into a Salix exigua dominance type (e.g., Hansen et al. (1995) in Montana; Crowe and Clausnitzer (1997) in eastern Oregon; Crawford (2001) in eastern Washington; Hansen and Hall (2002) in southeastern Idaho). Examination of composition data for the Salix exigua dominance type reveals that most stands have greater graminoid cover than forb cover and have no mesic forb species with moderate to high cover and constancy. Some of these stands would better fit with the Salix exigua / Equisetum arvense association described by Youngblood et al. (1985a) but do not (except for rare cases) include stands of Salix exigua / mesic forbs. The Salix exigua / mesic forbs association is probably successionally related to the Salix exigua / bench community type described by Manning and Padgett (1995) from 8 locations in Nevada. Salix exigua ssp. melanopsis is now synonymous with Salix melanopsis. Although recent classifications (i.e., Crowe et al. 2002) have separated Salix exigua and Salix melanopsis associations, most Salix melanopsis stands are considered synonymous with Salix exigua associations by other researchers.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: Both phases are dominated by a tall-shrub overstory of open to dense Salix exigua, although Salix lutea, Ribes spp., and Rosa woodsii are sometimes also present in lesser amounts. Sapling Populus angustifolia or Tamarix ramosissima may also be present. In the typical phase, the herbaceous understory is clearly dominated by a lush understory of mixed tall forbs, each with moderate cover, with Aconitum columbianum, Asclepias speciosa, Equisetum arvense, Heracleum maximum, Maianthemum stellatum, Mertensia ciliata, Rudbeckia spp., Solidago canadensis, and Urtica dioica being most common. No single forb has consistently high constancy and cover across the association''s range. In the low-elevation phase, flood-disturbed stands in riverine habitats contain abundant native colonizing forbs (e.g., Apocynum cannabinum, Euthamia occidentalis, Glycyrrhiza lepidota, Veronica anagallis-aquatica, and Polygonum spp.) often mixed with dense exotic and/or invasive forbs (e.g., Ambrosia trifida, Dipsacus fullonum, Lythrum salicaria, Melilotus officinalis, Tripleurospermum perforatum (= Matricaria perforata), and Xanthium strumarium). Total mesic graminoid cover is low in both phases of this association (with each species having only low cover) and composed of both native species (e.g., Carex spp., Elymus glaucus) and/or exotics (e.g., Phalaris arundinacea, Poa pratensis).

Dynamics:  This association is a mid- to late-seral association that forms on sites wetter and less stable than some Salix exigua / mesic graminoid stands, but on sites more stable and with thicker loam soils than flood-scoured Salix exigua types (Padgett et al. 1989, Manning and Padgett 1995). Unlike some native mesic forb species, Salix exigua is a resilient rhizomatous species that vigorously resprouts after disturbance (Hansen et al. 1995). Although the dense canopy of Salix exigua sometimes minimizes livestock use, overgrazing (and associated soil erosion and compaction), combined with severe fire or flood scouring, may lead to exotic species invasion. The result is sometimes conversion to Salix exigua / Poa pratensis or Salix exigua / Rosa woodsii communities (Manning and Padgett 1995). The low forage value of many native tall forbs and relatively low cover of mesic graminoid species may decrease livestock grazing impacts in this association. The low-elevation phase of the association often has high cover of exotic forbs and aggressive native colonizing species in the understory (Cole 1995, 1996, Holmstead 2001, Jankovsky-Jones et al. 2001). The islands and banks of the lower Snake River are often disturbed by flood scouring, river and reservoir fluctuation, and livestock grazing that leave sandy loam soils highly susceptible to exotic species invasion.
Environmental Description:  This association typically occurs between 1464 and 2562 m (4800-8400 feet) elevation in Utah, western Colorado, central Nevada and eastern Idaho, where it occupies streambanks, terraces, and meadows along a wide variety of low- to moderate-gradient stream types. In contrast, a low-elevation phase of this plant association is found below 1128 m (3700 feet) in south-central and southwestern Idaho on annually flooded banks, islands, and terraces of reservoirs and large rivers (e.g., the Snake River and Boise River). This type usually occurs on well-developed sandy to silty alluvial loam soils, on the wettest (often flooded) but stable sites supporting Salix exigua associations.
Geographic Range: This association has been documented to occur at mid elevations in central Nevada, Utah and western Colorado, north through eastern Idaho. It is expected to occur in similar habitats in Wyoming.

Nations: US

States/Provinces:  CO, ID, NV, OR?, UT, WY


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G2

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.C Shrub & Herb Wetland Subclass S44 2.C
Formation 2.C.4 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland Formation F013 2.C.4
Division 2.C.4.Nb Western North American Temperate Freshwater Marsh, Wet Meadow & Shrubland Division D031 2.C.4.Nb
Macrogroup 2.C.4.Nb.5 Sitka Alder - Booth''s Willow / Northwest Territory Sedge Montane Marsh, Wet Meadow & Shrubland Macrogroup M893 2.C.4.Nb.5
Group 2.C.4.Nb.5.a Narrowleaf Willow - Hawthorn species - Stretchberry Rocky Mountain-Great Basin Riparian Shrubland Group G526 2.C.4.Nb.5.a
Alliance A3800 Narrowleaf Willow - Dewystem Willow Shrubland Alliance A3800 2.C.4.Nb.5.a
Association CEGL001202 Narrowleaf Willow / Mesic Forbs Wet Shrubland CEGL001202 2.C.4.Nb.5.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Salix exigua / Mesic Forb (Jankovsky-Jones et al. 2001)
= Salix exigua / Mesic Forb Community Type (Padgett et al. 1989)
= Salix exigua / Mesic Forb Community Type (Manning and Padgett 1995)
= Salix exigua/mixed riparian forb plant association (Cole 1996)
Concept Author(s): C. Murphy

Author of Description: J. Coles

Acknowledgements: No Data Available

Version Date: 08-29-05
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