Vegetation Classification and Mapping Project Report - USGS

Appendix C: Global and Local Plant Community Descriptions
NatureServe conservation status:
Distribution:
Global rank. GNR (21-Mar-2005).
Globally. This association occurs in Petrified Forest National Park in northern Arizona
and Capitol Reef National Park in southeastern Utah. It is likely to occur on suitable habitat
throughout the central Colorado Plateau.
Petrified Forest National Park. Ephedra torreyana - Artemisia bigelovii Sparse Vegetation
was sampled from twelve relevés. It occurred throughout the park, mostly on terraces, cliffs
and plateaus, near drainage channels, on rocky slopes, rock piles, and sandy surfaces. Two of
the stands occurred on midslopes. This association occurred throughout the entire project
area, with relevés sampled from north of the Lithodendron Wash at Pilot Rock in the northern
wilderness area, to the central neck of the park, The Flattops, and near Jim Camp Wash in the
southern part of the park.
Environmental summary:
Globally. This Colorado Plateau association has been described from Petrified Forest National
Park in northern Arizona and Capitol Reef National Park in southeastern Utah, where
it is widespread. Stands occur on plateaus, mesas, ridges, hills, cliffs, rocky colluvial slopes,
benches, terraces, and near drainage channels that are gently sloping to steep (3-50%) between
1402 and 1915 m elevation. Aspect is not an important factor in determining the distribution
of this association. The unvegetated surface has moderate to high cover of gravel and
low to moderate cover of large rocks and litter. Cryptogams are typically absent, but one stand
had 75% cover. Parent materials include sandstones and shale of the Summerville, Entrada,
Curtis, Chinle, Carmel, Salt Wash Member and Emery formations. Soils are rapidly drained
and variable in texture, including loams, sands, and clays, but are unified by a coating of fine to
coarse gravels composed of sandstone, shale, basalt, or petrified wood.
Petrified Forest National Park. This association occurred between 1655 and 1880 m (5430-
6170 ft) elevation. Slopes ranged from none to steep (0-43%, average 8%). Several of the relevés
had surface rocks that consisted of sandstone, basalt, various gravel, and petrified wood.
USFWS wetland system: Not applicable.
Vegetation description:
Globally. This vegetation association is typically sparse (