Vegetation Classification and Mapping Project Report - USGS

Vegetation Classification and Distribution Mapping Report: Petrified Forest National Park
Vegetation hierarchy:
Physiognomic class I Woodland
Physiognomic subclass I.A Evergreen.woodland
Physiognomic group I.A.8 Temperate.or.subpolar.needle-leaved.evergreen.woodland
Physiognomic subgroup I.A.8.N Natural/Semi-natural.temperate.or.subpolar.needle-leaved.
evergreen.woodland
Formation name I.A.8.N.c Rounded-crowned.temperate.or.subpolar.needle-leaved.
evergreen.woodland
Alliance name
Juniperus monosperma Woodland.Alliance.(A.504),.Oneseed.Juniper.Woodland.Alliance
Ecological systems placement:
Ecological system unique ID
CES304.767
Ecological system name
Colorado.Plateau.Pinyon-Juniper.Woodland
NatureServe conservation status:
Global rank. G5 (23-Feb-1994).
Distribution:
Globally. This juniper woodland association occurs in the southern Colorado Plateau,
foothills of the southern Rocky Mountains, and it extends out on limestone and sandstone
breaks in the southwestern Great Plains ranging from northeastern Arizona and northern New
Mexico into southeastern Colorado and possibly extreme southern Utah.
Petrified Forest National Park. Juniperus monosperma - Artemisia bigelovii Woodland was
identified from two relevés on terrace landforms at Petrified Forest National Park. This
association was sampled on top of Chinde Mesa and west of Dry Wash and southwest of
Crystal Forest.
Environmental summary:
Globally. Stands occur in the mesas and hillslopes, piedmonts, canyons, escarpments, and
other geographic breaks in the southern Colorado Plateau to the 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.
Petrified Forest National Park. This association was sampled at 1732 and 1838 m (5680-6030
ft) elevation. Slope is none to minimal (0-3%). Sandstone surface rocks were identified at one
of the relevés.
USFWS wetland system: Not applicable.
Vegetation description:
Globally. 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.
C6