Vegetation Classification and Mapping Project Report - USGS
Vegetation Classification and Mapping Project Report - USGS
Vegetation Classification and Mapping Project Report - USGS
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<strong>Vegetation</strong> <strong>Classification</strong> <strong>and</strong> Distribution <strong>Mapping</strong> <strong>Report</strong>: Petrified Forest National Park<br />
C.4 Herbaceous<br />
C.4.6. Ericameria nauseosa / Bouteloua gracilis Shrub Herbaceous <strong>Vegetation</strong><br />
Base map class<br />
NatureServe common name<br />
NatureServe code<br />
Rubber.Rabbitbrush./.Blue.Grama.Shrub.Herbaceous.<br />
<strong>Vegetation</strong><br />
Rubber.Rabbitbrush./.Blue.Grama.Shrub.Herbaceous.<br />
<strong>Vegetation</strong><br />
CEGL003495<br />
Summary:<br />
This shrub herbaceous association occurs on valley floors, swales, <strong>and</strong> alluvial flats in the southern<br />
<strong>and</strong> central part of the Colorado Plateau. Its presence generally indicates disturbance, <strong>and</strong> it may<br />
represent degraded forms of other grassl<strong>and</strong>, shrubl<strong>and</strong>, or woodl<strong>and</strong> communities. St<strong>and</strong>s occupy<br />
gentle to moderate slopes (2-13%) between 1635 <strong>and</strong> 2010 m (5360-6600 ft) elevation. Aspect<br />
does not affect the distribution of this association. Litter <strong>and</strong> bare soil cover most of the unvegetated<br />
surface. Parent materials are variable <strong>and</strong> include s<strong>and</strong>stones <strong>and</strong> shale that have eroded <strong>and</strong> been redeposited<br />
as alluvium or windblown sediments (loess). Soils are well-drained <strong>and</strong> fine-s<strong>and</strong>y or silty<br />
in texture. Total vegetation cover ranges from 10 to 65%, roughly equally divided between the shrub<br />
<strong>and</strong> herbaceous layers. The vegetation is characterized by an open short-shrub canopy of Ericameria<br />
nauseosa that ranges in cover from 5 to 25% <strong>and</strong> an understory dominated by Bouteloua gracilis that<br />
ranges in cover from 5 to 35%. Other shrubs may be present with very low cover, including Tetradymia<br />
canescens, Atriplex spp., Gutierrezia sarothrae, <strong>and</strong> Opuntia polyacantha. Associated graminoids<br />
present include the bunch grasses Achnatherum hymenoides, Aristida purpurea, Pascopyrum smithii,<br />
Pleuraphis jamesii, Sporobolus airoides, Sporobolus crypt<strong>and</strong>rus, <strong>and</strong> Muhlenbergia pungens. Only scattered<br />
forbs are present.<br />
<strong>Classification</strong> confidence: 2 - Moderate.<br />
<strong>Classification</strong> comments:<br />
Globally. Former CEGL001738 <strong>and</strong> CEGL001739 were lumped into this new association;<br />
separation of these two types by subspecies of Ericameria nauseosa was not supported by the<br />
data in Francis (1986).<br />
Petrified Forest National Park. This map class was distinguished from Ericameria nauseosa<br />
Desert Wash Shrubl<strong>and</strong> (CEGL002261) by its restriction to upl<strong>and</strong> areas. This association also<br />
tended to have a proportionally higher herbaceous cover, as well as no codominance by other<br />
shrub species.<br />
<strong>Vegetation</strong> hierarchy:<br />
Physiognomic class V Herbaceous.<strong>Vegetation</strong><br />
Physiognomic subclass V.A. Perennial.graminoid.vegetation<br />
Physiognomic group V.A.7. Temperate.or.subpolar.grassl<strong>and</strong>.with.a.sparse.shrub.<br />
layer<br />
Physiognomic subgroup V.A.7.N. Natural/Semi-natural.temperate.or.subpolar.grassl<strong>and</strong>.<br />
with.a.sparse.shrub.layer<br />
Formation name V.A.7.N.j. Short.temperate.or.subpolar.grassl<strong>and</strong>.with.a.sparse.<br />
microphyllous.evergreen.shrub.layer<br />
Alliance name<br />
Ericameria nauseosa.Shrub.Short.Herbaceous.Alliance.<br />
(A.1546),.Rubber.Rabbitbrush.Shrub.Short.Herbaceous.<br />
Alliance<br />
C78