Vegetation Classification and Mapping Project Report - USGS

Vegetation Classification and Distribution Mapping Report: Petrified Forest National Park
Distribution:
Globally. This broadly defined shrubland association occurs in saline overlow areas in bottomlands
in the Great Basin, Mojave, Colorado, and Sonoran deserts, and in the southern part
of the Great Central Valley of California. The species occurs throughout the western U.S., so
this type may be more widespread.
Petrified Forest National Park. Suaeda moquinii Shrubland was identified from one relevé
along the flats adjacent to the Puerco River in Petrified Forest National Park.
Environmental summary:
Globally. These shrublands occur in desert basins or playas in Nevada, Arizona, and southern
and eastern California. Sites are generally flat to gently sloping saline valley bottoms, floodplains
and playas, saline seeps, and along intermittent washes at elevations ranging from sea
level to 1640 m (5381 ft). Soils are deep, saline, alkaline clay loams derived from alluvium.
Petrified Forest National Park. This association occurred at an elevation of 1640 m (5381 ft).
The site was a flat, intermittently flooded area adjacent to the Puerco River.
USFWS wetland system: Lacustrine.
Vegetation description:
Globally. This association is characterized by a sparse to open shrub layer less than 1.5 m tall
that is strongly dominated by Suaeda moquinii sometimes with scattered Atriplex polycarpa,
Atriplex canescens, Allenrolfea occidentalis, or Sarcobatus vermiculatus. The sparse herbaceous
layer may include the forbs Bassia hyssopifolia and Salicornia maritima (= Salicornia europaea).
Graminoids are not abundant except for Distichlis spicata and occasional Sporobolus
airoides or Sporobolus cryptandrus.
Petrified Forest National Park. Only one relevé was classified as Suaeda moquinii Shrubland,
with total vegetation cover of 17%. This vegetation cover consisted of 2% cover in the shrub
stratum and 15% cover in the herbaceous stratum. The species diversity was low with only
four species. The shrub layer was dominated by Suaeda moquinii with 6% cover, and the herbaceous
layer was dominated by Distichlis spicata with 8% cover.
Most abundant species:
Stratum Global species PEFO species
Short.shrub/ Suaeda moquinii Suaeda moquinii
sapling
Herb.(field) Distichlis spicata Distichlis spicata
Other noteworthy species:
Global species
Data are not available.
PEFO species
Data are not available.
References:
Bourgeron and Engelking 1994, Donnelly et al. 2006, Driscoll et al. 1984, Faden 1977, NVNHP 2003,
Western Ecology Working Group n.d.
C60