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A4371 Juniperus osteosperma Colorado Plateau Shrubby Woodland Alliance
Type Concept Sentence: This juniper woodland alliance is characterized by an open to moderately dense, short (<15 m) tree canopy that is strongly dominated by Juniperus osteosperma or Juniperus scopulorum (at higher elevations) with an understory characterized by an open dense layer of shrubs (<10% cover). If understory is sparse then shrubs exceed herbaceous cover. It occurs in the Colorado Plateau, but it extends out into adjacent ecoregions primarily west into the Great Basin and north and east into the foothills of the central and southern Rocky Mountains.
Common (Translated Scientific) Name: Utah Juniper Colorado Plateau Shrubby Woodland Alliance
Colloquial Name: Colorado Plateau Utah Juniper Shrubby Woodland
Hierarchy Level: Alliance
Type Concept: Stands have a short, typically open to moderately dense tree canopy with an understory characterized by shrubs. Tree canopy is dominated by Juniperus osteosperma with Juniperus scopulorum becoming important and sometimes dominant at higher elevations and on relatively mesic sites such as along drainages. Pinus species are absent or accidental with very low cover. Shrubs typically dominate the understory and form an open to moderately dense layer. Scattered shrubs frequently characterize the sparse and rocky understory. Characteristic shrubs are many, including Artemisia arbuscula, Artemisia nova, Artemisia tridentata, Cercocarpus intricatus, Cercocarpus montanus, Coleogyne ramosissima, Mahonia fremontii, Quercus gambelii, and Symphoricarpos oreophilus. The herbaceous layer is sparse to moderate and composed of grasses and often diverse forbs. Common species may include Achnatherum hymenoides, Bouteloua gracilis, Hesperostipa comata, Hesperostipa neomexicana, Leymus salinus, Pleuraphis jamesii, and Pseudoroegneria spicata. The non-native, invasive annual grass Bromus tectorum may be abundant and dominate the herbaceous layer of highly disturbed stands. This alliance also includes sparse understory stands often with scattered shrubs and grasses. The core distribution of this juniper alliance is semi-arid canyons, foothills, plateaus and low mountains in the Colorado Plateau, but it extends out into adjacent ecoregions primarily west into the Great Basin and north and east into the foothills of the central and southern Rocky Mountains. Stands have been observed on north-facing steep slopes along bluffs of the Snake River in southeastern Idaho. Stands occur on a variety of sites, including alluvial fans and stream terraces, colluvial slopes, benches, ledges, hills, ridges, mesas, and badlands. Sites range from level to steep terrain that may be oriented to any aspect. Elevation of most stands ranges from 1220 to 2260 m (4000-7400 feet). Soils are often calcareous, shallow, poorly developed, rapidly to well-drained sands, sandy clays, or clay loams derived from shales, sandstones, or a mix of the two.
Diagnostic Characteristics: Stands have an open to moderately dense tree canopy dominated by Juniperus osteosperma with Juniperus scopulorum present to dominant at higher elevations. Understory is characterized by dominant and diagnostic shrub species such as Artemisia arbuscula, Artemisia bigelovii, Artemisia nova, Artemisia tridentata, Atriplex confertifolia, Atriplex confertifolia, Cercocarpus intricatus, Cercocarpus montanus, Chrysothamnus viscidiflorus, Coleogyne ramosissima, Ephedra nevadensis, Ephedra viridis, Ericameria teretifolia, Eriogonum fasciculatum, Fendlera rupicola, Fraxinus anomala, Grayia spinosa, Gutierrezia sarothrae, Mahonia fremontii, Purshia glandulosa, Purshia tridentata, Quercus gambelii, Rhus trilobata, Salvia dorrii, Symphoricarpos oreophilus, Tetradymia axillaris, and Yucca spp.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance may include stands with Juniperus monosperma present to codominant in northeastern Arizona. There is a transition zone between the ranges of the two species of Juniperus in the southern Colorado Plateau. Scattered shrubs frequently characterize the sparse and rocky understory of stands and so are included in this alliance.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These are sparsely to densely (5-80% cover) wooded communities dominated by scale-leaved evergreen trees of low stature (<15 m). Evergreen or cold-deciduous shrubs occupy the interstices between trees, interspersed with cespitose graminoids. In total, the shrub layer is usually open to moderate (10-50% cover), but may also be sparse (<10% cover) or when shrubs exceeds herbaceous cover.
Floristics: Stands have a short (<15 m tall), open to moderately dense tree canopy with an understory characterized by shrubs. Tree canopy is dominated by Juniperus osteosperma with Juniperus scopulorum becoming important and sometimes dominant at higher elevations and on relatively mesic sites such as along drainages. Pinus species, such as Pinus monophylla, Pinus edulis, Pinus flexilis, Pinus ponderosa, or Pseudotsuga menziesii are absent or accidental. Shrubs typically dominate the understory and form an open to moderately dense layer. Characteristic shrubs are many, including Artemisia arbuscula, Artemisia bigelovii, Artemisia nova, Artemisia tridentata, Atriplex confertifolia, Atriplex confertifolia, Cercocarpus intricatus, Cercocarpus montanus, Chrysothamnus viscidiflorus, Coleogyne ramosissima, Ephedra nevadensis, Ephedra viridis, Ericameria teretifolia, Eriogonum fasciculatum, Fendlera rupicola, Fraxinus anomala, Grayia spinosa, Gutierrezia sarothrae, Mahonia fremontii, Purshia glandulosa, Purshia tridentata, Quercus gambelii, Rhus trilobata, Salvia dorrii, Symphoricarpos oreophilus, Tetradymia axillaris, and Yucca spp. The herbaceous layer is typically sparse to low in terms of cover but high in species diversity. Common graminoids provide sparse to moderate cover and include Achnatherum hymenoides, Aristida purpurea, Bouteloua gracilis, Bouteloua curtipendula, Bromus tectorum, Elymus elymoides, Hesperostipa comata, Hesperostipa neomexicana, Leymus salinus, Pleuraphis jamesii, Poa fendleriana, Poa secunda, and Pseudoroegneria spicata. Associated forbs may include Chamaesyce fendleri, Cryptantha spp., Eriogonum inflatum, Eriogonum alatum, Gayophytum racemosum, Hymenoxys richardsonii, Hymenopappus filifolius, Lepidium montanum, Linanthus pungens (= Leptodactylon pungens), Machaeranthera canescens, Mirabilis multiflora, Packera multilobata (= Senecio multilobatus), Phlox hoodii, Plantago patagonica, Stenotus acaulis (= Haplopappus acaulis), and Tetraneuris acaulis (= Hymenoxys acaulis). The non-native, invasive annual grass Bromus tectorum may be abundant and dominate the herbaceous layer of highly disturbed stands. This alliance also includes sparse understory stands often with scattered shrubs and grasses. The lack of understory can be caused by harsh substrate (rockland, shale badland) or dense tree canopy resulting from lack of fire that shades out understory.
Dynamics: Within the distribution of Pinus edulis, this alliance typically occurs at lower elevation and on more xeric sites than Pinus edulis - (Juniperus spp.) woodlands. There is elevational overlap between this alliance and Pinus monophylla woodlands as this pinyon can occur on more xeric sites than Pinus edulis. Juniperus osteosperma also occurs on sites outside the ranges of Pinus edulis and Pinus monophylla. There has been significant expansion of this alliance over the last century into sagebrush-dominated shrublands. An altered fire regime (such as fire suppression, thus longer return intervals) is considered a primary cause of this expansion.
Fires in this alliance are thought to be infrequent because Juniperus osteosperma and many shrubs such as Artemisia tridentata are easily killed by burns and do not resprout (Barney and Frischknecht 1974, Everett 1986). In addition, many stands have an open canopy with insufficient understory to carry fire. Shrubs will often re-establish relatively quickly (about 10-20 years) if a seed source is nearby (Barney and Frischknecht 1974, Bunting 1987). However, Juniperus osteosperma is relatively slow to recover following fire, and shrubs such as sagebrush may dominate the sites for decades (Jameson et al. 1962). Fire, drought and competition with grasses are thought to have kept Juniperus spp. communities restricted to rocky areas that do not burn frequently (Wright et al. 1979).
Fires in this alliance are thought to be infrequent because Juniperus osteosperma and many shrubs such as Artemisia tridentata are easily killed by burns and do not resprout (Barney and Frischknecht 1974, Everett 1986). In addition, many stands have an open canopy with insufficient understory to carry fire. Shrubs will often re-establish relatively quickly (about 10-20 years) if a seed source is nearby (Barney and Frischknecht 1974, Bunting 1987). However, Juniperus osteosperma is relatively slow to recover following fire, and shrubs such as sagebrush may dominate the sites for decades (Jameson et al. 1962). Fire, drought and competition with grasses are thought to have kept Juniperus spp. communities restricted to rocky areas that do not burn frequently (Wright et al. 1979).
Environmental Description: This open to dense woodland alliance occurs in semi-arid canyons, foothills, plateaus and low mountains across the Intermountain West from the eastern Sierra Nevada to the central and southern Rocky Mountains. Climate is temperate with freezing temperatures during winter. Distribution of the alliance is often correlated with "thermal belts" which occur above the areas of cold-air drainage in high intermountain basins. Average annual precipitation is between 25 and 50 cm; however, seasonal distribution is variable across the range of the alliance. Stands occur on a variety of sites, including alluvial fans and stream terraces, colluvial slopes, benches, ledges, hills, ridges, mesas, and badlands. Sites range from level to steep terrain that may be oriented to any aspect, and most sites are on cooler north and east aspects at lower elevations and warmer/drier south and west aspects at higher elevations. Elevation of most stands ranges from 1220 to 2260 m (4000-7400 feet). Soils are often calcareous, shallow, poorly developed, rapidly to well-drained sands, sandy clays, or clay loams derived from shales, sandstones, or a mix of the two. Less frequently substrates are derived sandy loams from eolian sands. Parent materials are sandstones, shale, and Precambrian gneiss. The unvegetated ground surface often has a high percentage of rock, exposed bedrock or bare ground, but in undisturbed stands, the cover of cryptobiotic crusts may be high.
Geographic Range: The core distribution of this juniper alliance is the Colorado Plateau, but it extends out into adjacent ecoregions primarily west into the Great Basin and north and east into the foothills of the central and southern Rocky Mountains. Stands have been observed on north-facing steep slopes along bluffs of the Snake River in southeastern Idaho.
Nations: US
States/Provinces: AZ, CA, CO, ID, NM, NV, UT, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.1085089
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Juniperus osteosperma (Utah juniper woodland) Alliance (Sawyer et al. 2009) [89.300.00]
= Juniperus osteosperma Woodland Alliance (Evens et al. 2014)
= Juniperus osteosperma Woodland Alliance (Evens et al. 2014)
- Evens, J. M., K. Sikes, D. Hastings, and J. Ratchford. 2014. Vegetation alliance descriptions for Lake Mead National Recreation Area, Death Valley National Park and Mojave National Preserve. Unpublished report submitted to USDI National Park Service, Mojave Desert Network Inventory and Monitoring Program. California Native Plant Society, Sacramento, CA.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Keeler-Wolf, T., and K. Thomas. 2000. Draft descriptions of vegetation alliances for the Mojave Ecosystem Mapping project. California Natural Diversity Database, California Department of Fish and Game, Sacramento.
- Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.