Print Report

CEGL000782 Pinus edulis - Juniperus osteosperma / Purshia stansburiana Woodland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Two-needle Pinyon - Utah Juniper / Stansbury''s Cliffrose Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This woodland association is known from the Colorado Plateau of southern Utah and Colorado south to central Arizona. The vegetation is characterized by an open to moderately dense tree canopy (10-60% cover) codominated by Pinus edulis and Juniperus osteosperma. Purshia stansburiana dominates or codominates the sparse to moderately dense short-shrub layer, often with Artemisia tridentata in the northern part of its range. Other shrubs may be present, including Amelanchier utahensis, Arctostaphylos patula, Chamaebatiaria millefolium, Ephedra viridis, Gutierrezia sarothrae, Quercus gambelii (<5% cover), or species of Yucca and Opuntia. Cercocarpus montanus and Purshia tridentata are scarce or absent. Herbaceous cover is variable, ranging from sparse to moderately dense, but generally dominated by graminoids (<5% cover) with scattered perennial forbs. It occurs on dry sites on canyon rims, ridges and slopes. Elevations range from 1400 to 2165 m. Stands typically occur on gentle to moderately steep slopes on all aspects. The soils are generally shallow and rocky, ranging from sand to clay loam in texture. Rock outcrop and bare soil are common. Parent materials include sandstone and shale.

Diagnostic Characteristics: The overstory consists of Pinus edulis and Juniperus osteosperma and occasionally Quercus gambelii. The shrubby understory includes Purshia stansburiana; Purshia tridentata and usually Cercocarpus montanus are scarce or absent. Oaks are poorly represented.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association is largely known and described from National Park Service inventory efforts in the Colorado Plateau. The global name of this association was changed on 2001-09-04 because of a taxonomic change of the nominal species. Purshia mexicana var. stansburiana (Torr.) Welsh is now recognized as Purshia stansburiana (Torr.) Henrickson (Kartesz 1999). Purshia mexicana (D. Don) Henrickson, a closely related species, occurs in Chihuahua, Durango and Zacatecas, Mexico, and possibly extreme southern Arizona, and is not known to be present in this association (Cronquist et al. 1997).

This association appears to be part of a continuum of Colorado Plateau woodland communities growing on fractured sandstone. Stands where Purshia stansburiana is the dominant understory shrub are less common than those in which it is a component of a mixed shrub understory that includes Cercocarpus montanus, Amelanchier utahensis, and Cercocarpus intricatus in mesic stands, or Coleogyne ramosissima and Yucca spp. in xeric stands. An analysis of the woodland data from four parks (Colorado, Arches, Natural Bridges, Canyonlands) confirmed that ~Pinus edulis - Juniperus osteosperma / Purshia stansburiana Woodland (CEGL000782)$$ is a valid association but not always easy to distinguish from more mixed-shrub woodlands in the field.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This woodland association is characterized by an open to moderately dense tree canopy (10-60% cover) codominated by Pinus edulis and Juniperus osteosperma. Purshia stansburiana dominates or codominates the sparse to moderately dense short-shrub layer, often with Artemisia tridentata in the northern part of its range. Other shrubs may be present, including Amelanchier utahensis, Arctostaphylos patula, Artemisia bigelovii, Artemisia nova, Artemisia tridentata, Brickellia microphylla, Chamaebatiaria millefolium, Ephedra viridis, Ericameria nauseosa, Eriogonum corymbosum, Eriogonum microthecum, Fraxinus anomala, Gutierrezia microcephala, Gutierrezia sarothrae, Mahonia fremontii, Quercus gambelii (<5% cover), Rhus trilobata, Shepherdia rotundifolia, Symphoricarpos longiflorus, Yucca angustissima, or other species of Yucca and Opuntia spp. Cercocarpus montanus and Purshia tridentata are generally absent or with scarce cover. Herbaceous cover is variable, ranging from sparse to moderately dense, but generally dominated by graminoids (>5% cover) with scattered forbs. Associated graminoids include Achnatherum hymenoides (= Oryzopsis hymenoides), Aristida purpurea, Bouteloua curtipendula, Bouteloua gracilis, Bouteloua hirsuta, Elymus elymoides, Hesperostipa comata, Hesperostipa neomexicana, Koeleria macrantha, Poa fendleriana, Pleuraphis jamesii, and Schizachyrium scoparium. Forbs may include Artemisia ludoviciana, Artemisia frigida, Calliandra humilis, Cordylanthus wrightii, Descurainia pinnata, Eriogonum ovalifolium, Lappula occidentalis, Oenothera pallida, Penstemon linarioides, and Tetraneuris acaulis (= Hymenoxys acaulis). Total vegetation cover can vary from 12% to more than 65%, with tree canopy sometimes falling below 10% cover in very open stands. Biological soils crusts or dark cyanobacteria may have high cover in some stands, acting to stabilize the soil pockets within the sandstone mosaic.

Dynamics:  Stuever and Hayden (1997) described two phases of this plant community, an Artemisia tridentata phase and a Purshia stansburiana phase. Both are restricted geographically, with the Artemisia tridentata phase common in northern Arizona, southern Utah, northern New Mexico, and southwestern Colorado, where winter precipitation is higher than summer. The Purshia stansburiana phase, which lacks Artemisia tridentata, occurs in central Arizona, where summer monsoon precipitation is higher than winter (Stuever and Hayden 1997). Fires in this association are thought to be infrequent because Pinus edulis, Juniperus osteosperma, and Juniperus monosperma are killed or severely damaged by burns and do not resprout (Wright et al. 1979). Purshia stansburiana is also generally killed by fire; however, it is known to resprout after cool burns (Wright et al. 1979, Britton and Wright 1983). This association is little affected by regional drought due to the fact that the woody vegetation roots in bedrock cracks where moisture collects.
Environmental Description:  This woodland occurs on dry canyon rims, ridges, plateaus, canyon sides, hills, benches, mesas and occasionally in intermittent drainages. Elevations range from 1400 to 2210 m (4600-7250 feet). Stands typically occur on gentle to moderately steep slopes on all aspects, but range from flat to steep slopes (0-30%). Soils are generally shallow and rocky, ranging in texture from sand in most stands to clay loam or sandy clay. Exposed sandstone or limestone bedrock and bare soil have high cover, and woody plants are generally rooted in cracks and joints in bedrock. A minority of stands may also occur on shale slopes covered by sandstone colluvium. Parent materials are variable and include sandstones and shale of the Moab Tongue of the Curtis Formation, Kayenta Formation, Navajo sandstone, Moenkopi Formation, Morrison Formation, Shinarump conglomerate, Cedar Mesa sandstone and eolian silt deposits.
Geographic Range: This woodland association occurs in the Colorado Plateau region of central Arizona, western New Mexico, southwestern Colorado, and southern Utah.

Nations: US

States/Provinces:  AZ, CO, NM, UT


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G4?

Greasons: No Data Available
Type Name Database Code Classification Code
Class 1 Forest & Woodland Class C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland Subclass S15 1.B
Formation 1.B.2 Cool Temperate Forest & Woodland Formation F008 1.B.2
Division 1.B.2.Nc Western North American Pinyon - Juniper Woodland & Scrub Division D010 1.B.2.Nc
Macrogroup 1.B.2.Nc.1 Singleleaf Pinyon - Utah Juniper - Western Juniper Intermountain Woodland Macrogroup M896 1.B.2.Nc.1
Group 1.B.2.Nc.1.a Two-needle Pinyon - Utah Juniper Woodland Group G900 1.B.2.Nc.1.a
Alliance A3573 Two-needle Pinyon - Utah Juniper Colorado Plateau Shrubby Open Woodland Alliance A3573 1.B.2.Nc.1.a
Association CEGL000782 Two-needle Pinyon - Utah Juniper / Stansbury''s Cliffrose Woodland CEGL000782 1.B.2.Nc.1.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Juniperus osteosperma - Pinus edulis / Cowania mexicana Plant Association (Baker 1984a)
= Pinus edulis / Cowania mexicana Plant Association (Larson and Moir 1987)
= Pinus edulis / Purshia stansburiana (Stuever and Hayden 1997b)
< Coronado Province Pinyon - Juniper Woodlands (Isaacson 1967)
< Juniper-Pinyon Stand-Type (Northcutt 1978)
< La Sal Province Pinyon - Juniper Woodlands (Isaacson 1967)
Concept Author(s): M.C. Stuever and J.S. Hayden (1997b)

Author of Description: K.A. Schulz, J. Coles and G. Kittel

Acknowledgements: No Data Available

Version Date: 04-06-16
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