Vegetation Classification and Mapping Project Report - USGS

Appendix C: Global and local plant community descriptions
USFWS wetland system: Not applicable.
Vegetation description:
Globally. This broadly defined shrubland association is characterized by a sparse to moderately
dense canopy (10-40% cover) of shrubs dominated by Atriplex canescens, with a sparse
to moderate graminoid layer that is dominated by Pleuraphis jamesii. Many stands have the
appearance of a shrubby grassland and may form a mosaic with rabbitbrush, greasewood or
shadscale shrublands. Associated shrubs may include Ericameria nauseosa, Ephedra torreyana,
Ericameria nauseosa, Grayia spinosa, several species of Opuntia, Chrysothamnus
viscidiflorus, Krascheninnikovia lanata, Gutierrezia sarothrae, and Artemisia bigelovii. Other
graminoids include Achnatherum hymenoides and Sporobolus cryptandrus on sandy sites, and
Bouteloua gracilis and Sporobolus airoides on fine-textured soils of lowland sites. Forbs generally
have low cover and may include Astragalus nuttallianus, Cryptantha crassisepala, Descurainia
pinnata, Mentzelia albicaulis, Phacelia crenulata, Sphaeralcea grossulariifolia, and Chenopodium
spp. Introduced species such as Bromus tectorum, Erodium cicutarium, and Salsola kali
are common on some sites. In many sites, the herbaceous layer is sparse because of a history of
grazing or other disturbance.
Petrified Forest National Park. Four relevés were classified as Atriplex canescens / Pleuraphis
jamesii Shrubland. The total vegetation cover of these relevés varied between 25 and 30%
(average 28%) with a shrub stratum of 4-8% cover (average 6%) and an herbaceous stratum
of 18-26% cover (average 22%). Each relevé varied in species diversity between 21 and 30
species (average 26 species). The shrub layer was relatively patchy, was dominated or codominated
by Atriplex canescens, and varied between 1 and 6% cover (average 3%). In some of the
relevés, other shrubs may codominate the association. Pleuraphis jamesii either dominated
the herbaceous layer or occurred as an indicator species for this association, ranging from 1to
12% cover (average 6%). Two of these relevés had a high cover of annuals and notable drought
impacts. Phacelia crenulata covered 9% of one relevé, and Phacelia sp. had a high cover in two
of the relevés (6 and 10%).
Most abundant species:
Stratum Global species PEFO species
Short.shrub/ Chrysothamnus viscidiflorus, Atriplex canescens
sapling
Ericameria nauseosa, Atriplex
canescens, Gutierrezia sarothrae,
Krascheninnikovia lanata
Herb.(field) Achnatherum hymenoides, Pleuraphis jamesii
Bouteloua gracilis, Pleuraphis jamesii,
Sporobolus airoides, Sporobolus
cryptandrus
Other noteworthy species:
Global species
Bromus tectorum, Salsola kali
PEFO species
Data are not available.
References:
BLM 1979a, BLM 1979b, Bourgeron and Engelking 1994, CONHP unpubl. data 2003, Diamond 1993,
Driscoll et al. 1984, Francis 1986, Miller et al. 1977, Shute and West 1978, Soil Conservation Service
1978, U.S. Bureau of Reclamation 1976, Von Loh 2000, Western Ecology Working Group n.d.
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