Physiognomy and Structure: No Data Available

Floristics: This association is characterized by a sparse to moderately dense (10-35% cover) short-shrub layer (1-2 m tall) that is codominated by Atriplex canescens and Artemisia tridentata. On some sites, Pinus edulis and/or Juniperus osteosperma canopy trees provide sparse cover. Associated shrubs include Chrysothamnus viscidiflorus, Ephedra viridis, Ephedra nevadensis, Eriogonum corymbosum, Ericameria nauseosa, Gutierrezia sarothrae, Gutierrezia microcephala, Krascheninnikovia lanata, Lycium spp., Opuntia spp., and Salix gooddingii (Warren et al. 1982, Roberts et al. 1992). Sarcobatus vermiculatus and Suaeda moquinii may be present with low cover on more saline sites. The sparse to moderately dense (10-20% cover) herbaceous layer is dominated by graminoids with scattered forbs. Achnatherum hymenoides, Bouteloua gracilis, Elymus elymoides, Leymus salinus, Muhlenbergia asperifolia, Pleuraphis jamesii, Pascopyrum smithii, and Sporobolus cryptandrus are common grasses. Forbs may include Abronia fragrans, Cirsium neomexicanum, Eriogonum inflatum, Eriogonum racemosum, Heliomeris longifolia (= Viguiera longifolia), Lappula occidentalis, Machaeranthera canescens, Mentzelia multiflora, Oenothera caespitosa, Penstemon spp., Rumex hymenosepalus, or Sphaeralcea coccinea. Introduced species such as Agropyron cristatum, Arctium minus, Bromus rubens, Bromus tectorum, Carduus nutans, Chenopodium album, Cirsium arvense, Convolvulus arvensis, Descurainia sophia, Erodium cicutarium, Lactuca serriola, Lappula occidentalis, Medicago sativa, Salsola tragus, and Tragopogon dubius are common in disturbed stands. Cryptogams are generally sparse but one sampled plot had 25% cover.

Dynamics:  Atriplex canescens is tolerant of fire and generally sprouts vigorously from the rootcrown after burning (Wright 1980). It often recovers fully within 2 or 3 years after a burn (Wright 1980). However, Artemisia tridentata shrubs are readily killed by fire and do not resprout (Wright et al. 1979). Artemisia tridentata will re-establish relatively quickly (about 10-20 years) if a seed source is nearby (Bunting 1987). If fire-return intervals are more frequent than 10 years, then Artemisia tridentata has difficulty recovering (Bunting 1987, Everett 1987). This community is an interesting combination of a species with different tolerances to soil alkalinity and salinity. Although Artemisia tridentata occurs on a variety of substrates, it is intolerant of strongly alkaline and saline soils (Howard 1999, 2003), whereas Atriplex canescens, which also occurs on a wide variety of substrates, can tolerates saline, alkaline, boron, and gypsum soils (Howard 2003). This frequently results in relatively sharp boundaries between fourwing saltbush and big sagebrush communities, although each species may occur as associates for the other. More research is needed to understand the dynamics of this mixed shrub community.