Vegetation Classification and Mapping Project Report - USGS

Appendix C: Global and local plant community descriptions
C.2 Woodland
C.2.1. Juniperus monosperma / Artemisia bigelovii Woodland
Base map class
NatureServe common name
NatureServe code
One-seed.Juniper./.Bigelow’s.Sagebrush.Shrubland
One-seed.Juniper./.Bigelow’s.Sagebrush.Woodland
CEGL000705
Summary:
This woodland association ranges from southern Colorado to northern New Mexico and Arizona,
and possibly extreme southern Utah. Stands occur in the mesas and hillslopes, piedmonts, canyons,
escarpments, and other geographic breaks in the southern Colorado Plateau to foothills of
the southern Rocky Mountains and breaks in the southwestern Great Plains. Elevation ranges from
1520-2130 m (5000-7000 ft). Sites are on nearly level surfaces to steep, rocky slopes in canyons and
on hillsides. Stands occur on all aspects except in elevational extremes where low-elevation stands
are restricted to the more mesic north slopes; whereas high-elevation stands occur on southern
aspects. Sites are typically dry with shallow, rocky, calcareous, alkaline soils. Soil textures range
from sandy loam to clay soils typically derived from limestone, sandstone, or shale. The vegetation
is characterized by a typically open (5-15% cover) to occasionally moderately dense evergreen,
scale-leaved tree canopy 2-7 m tall composed of Juniperus monosperma. Sparse canopy stands
have trees distributed in patches, resembling a savanna; whereas, in the moderately dense stands,
the tree crowns touch. Occasional Pinus edulis trees may also be present. At higher elevations,
Juniperus scopulorum may be present, and in the southern extent, Madrean evergreen woodland
elements such as Juniperus deppeana and Juniperus coahuilensis (= Juniperus erythrocarpa) may
be present but not codominant. The understory is typically a sparse and patchy dwarf-shrub layer
dominated by Artemisia bigelovii. Other shrubs and dwarf-shrubs may be present, such as Atriplex
canescens, Ephedra spp., Gutierrezia sarothrae, Krascheninnikovia lanata, Opuntia spp., Parryella
filifolia, Purshia stansburiana, Yucca spp., and Mahonia fremontii, depending on geography. A
sparse to moderately dense herbaceous layer dominated by perennial grasses may be present. The
most abundant species are Bouteloua eriopoda, Bouteloua gracilis, Aristida spp., Pleuraphis jamesii
(= Hilaria jamesii), Achnatherum hymenoides (= Oryzopsis hymenoides), Piptatherum micranthum
(= Oryzopsis micrantha), Sporobolus spp., Hesperostipa comata, Hesperostipa neomexicana, and
introduced annual grass Bromus tectorum. Many forb species can occur, but few have much cover.
Classification confidence: 2-Moderate
Classification comments:
Globally. Stuever and Hayden (1997a) suggest that this association may occur in southern
Utah; however, Welsh et al. (1993) states that all identifications of Juniperus monosperma in
Utah are tentative.
Petrified Forest National Park. The sparse total vegetation cover of these two relevés and
the existence of a tree layer makes it diffcult to classify this association as a woodland community.
However, the dominant species in both relevés was Juniperus monosperma, which
had a distinct structural component not present in the adjacent vegetation communities.
C5