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CEGL000710 Juniperus monosperma / Bouteloua gracilis Open Woodland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: One-seed Juniper / Blue Grama Open Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This southern Rocky Mountains woodland occur on foothills in south-central Colorado and northern New Mexico and extends out into the southwestern Great Plains where it is largely restricted to areas near hills and escarpments. It also extends westward into the southeastern portion of the Colorado Plateau and southward into south-central New Mexico where it is a major association on desert mountains and mesas. Elevation ranges from 1372-2290 m (4500-7500 feet). Sites include gently rolling slopes, including weathered lava plateaus, gentle to steep footslopes and shoulder slopes of low sandstone hills or beneath sandstone bluffs, and steep upper sideslopes of low hills and volcano craters, on a variety of aspects with a tendency of increasing southerly slopes with increasing elevation. Further south it is generally cool (northwest to west), even at higher elevations. Substrates are variable but are frequently finer-textured Mollisols and Aridisols derived from limestone and sandstone, often with piedmont alluvial and slope colluvial deposits. The ground surface is characterized by scattered grass patches and litter amid an equal amount of exposed soil, gravel or rock. Vegetation is characterized by an open to very open tree canopy (10-40% cover) of mature Juniperus monosperma forming a generally open woodland or savanna with the grassy inter-tree spaces dominated by Bouteloua gracilis. Occasionally mature individuals, seedlings or saplings of Pinus edulis can be present. The dwarf-shrub Gutierrezia sarothrae is usually present and scattered throughout sites. Other shrubs are poorly represented or absent; succulents such as Cylindropuntia imbricata and Opuntia phaeacantha are the most frequent. The herbaceous layer is characteristically grassy and dominated by abundant Bouteloua gracilis with ruderal Muhlenbergia torreyi and Aristida purpurea often well-represented along with Pleuraphis jamesii, Sporobolus cryptandrus, and Sporobolus airoides as common subordinate associates. Bouteloua curtipendula may be present but is clearly not dominant. Forbs may be diverse but variable, and cover is generally low and may include Artemisia dracunculus, Astragalus spp., Erigeron divergens, Heterotheca villosa, Ipomopsis longiflora, Ipomopsis multiflora, Penstemon spp., Townsendia spp., and Thelesperma megapotamicum.

Diagnostic Characteristics: A juniper savanna with a rich understory of grasses, usually including Bouteloua gracilis. Juniperus monosperma is the dominant tree, although pinyon pine may be present but is usually confined to microsites. Bouteloua curtipendula is scarce or absent. Pinus edulis is accidental.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: In northern New Mexico, mature Pinus edulis was present in many stands prior to a die-off during the drought of 2002-03, but it is now represented only by seedlings and samplings. Some of these stands may have represented ~Pinus edulis - (Juniperus monosperma, Juniperus deppeana) / Bouteloua gracilis Open Woodland (CEGL002151)$$ before the pinyon die-off. Both associations are established types that have been well-documented elsewhere in New Mexico.

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

Floristics: Vegetation within this open woodland consists of an overstory (10-40% tree cover) dominated by Juniperus monosperma. Pinus edulis may also be present in microsites. The grassy inter-tree spaces are dominated by Bouteloua gracilis. Bouteloua curtipendula is occasionally well-represented, but it is not normally a codominant. Diversity can be high (>150 species). The subshrub Gutierrezia sarothrae is usually present and scattered throughout many sites (Muldavin et al. 2000b). Shrubs species are poorly represented or absent; the ruderal subshrub Gutierrezia sarothrae and succulents such as Cylindropuntia imbricata and Opuntia phaeacantha are the most frequent. The herbaceous layer is characteristically grassy and dominated by abundant Bouteloua gracilis with ruderal Muhlenbergia torreyi and Aristida purpurea often well-represented along with Piptatheropsis micrantha (= Piptatherum micranthum), Pleuraphis jamesii, Sporobolus cryptandrus, and Sporobolus airoides as common subordinate associates. Forbs are diverse but variable. Artemisia dracunculus, Artemisia ludoviciana, Astragalus brandegeei, Cordylanthus wrightii, Erigeron divergens, Eriogonum jamesii, Heterotheca villosa, Hymenopappus filifolius, Ipomopsis longiflora, Ipomopsis multiflora, Menodora scabra, Mirabilis multiflora, Penstemon virgatus, Schoenocrambe linearifolia, Townsendia annua, and Thelesperma megapotamicum are the most frequent species, but cover is generally low.

Dynamics:  Juniperus monosperma is extremely drought-tolerant. It is also non-sprouting and may be killed by fire (Wright et al. 1979). The effect of fire on a stand is largely dependent on the tree height and density, fine fuel load on the ground, weather conditions, and season (Dwyer and Pieper 1967, Wright et al. 1979). Trees are more vulnerable in open stands where fires frequently occur in the spring, the relative humidity is low, wind speeds are over 10-20 mph, and there is adequate fine fuels to carry fire (Wright et al. 1979, Fischer and Bradley 1987). Under other conditions, burns tend to be spotty with low tree mortality. Large trees are generally not killed unless fine fuels, such as tumbleweeds, have accumulated beneath the tree to provide ladder fuels for the fire to reach the crown. Closed-canopy stands rarely burn because they typically do not have enough understory or wind to carry a fire. Altered fire regimes, cutting trees for fencing, and improper grazing by livestock have significant impacts on the quality of sites. Grazing by livestock can modify the fire regime by removing the fine fuels that carry fire. Juniperus monosperma invasion into grasslands has occurred in places. Control efforts by chaining and prescribed burning have mixed results. More study is needed to understand and manage these woodlands ecologically.
Environmental Description:  This widespread open woodland / savanna association occurs on valleys, plains, piedmont alluvial fans, mesas and foothills between 1372 and 2290 m (4500-7500 feet) in elevation. It typically is found on gently rolling slopes, including weathered lava plateaus, gentle to steep footslopes and shoulder slopes of low sandstone hills or beneath sandstone bluffs, and steep upper sideslopes of low hills and volcano craters, on a variety of aspects with a tendency of increasing southerly aspects with increasing elevation. Further south it is generally cool (northwest to west), even at higher elevations. Soils are composed of a variety of substrates including eolian material, alluvium, or colluvium derived from rhyolitic tuff or pumice, sandstones and limestones. The ground surface is characterized by scattered grass patches and litter amid an equal amount of exposed soil, gravel or rock.
Geographic Range: This southern Rocky Mountains woodland occur in foothills in south-central Colorado and northern New Mexico and extends out into the southwestern Great Plains where it is largely restricted to areas near breaks and escarpments. It also extends southward into central New Mexico and westward into the southeastern Colorado Plateau. Specific locations include the San Isabel National Forest in south-central Colorado, Comanche National Grassland in southeastern Colorado, the Upper Rio Puerco watershed in northwestern New Mexico, Bandelier National Monument, Salinas Pueblo Missions National Monument in central New Mexico, and White Sands Missile Range in south-central New Mexico where it is also a major association of the Oscura and San Andres mountains and of the Chupadera Mesa - Red Rio area.

Nations: US

States/Provinces:  AZ, CO, NM


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G5

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.2 Two-needle Pinyon - One-seed Juniper Southern Rocky Mountain Woodland Macrogroup M897 1.B.2.Nc.2
Group 1.B.2.Nc.2.b One-seed Juniper Open Woodland Group G252 1.B.2.Nc.2.b
Alliance A3575 One-seed Juniper Wooded Grassland Alliance A3575 1.B.2.Nc.2.b
Association CEGL000710 One-seed Juniper / Blue Grama Open Woodland CEGL000710 1.B.2.Nc.2.b
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Juniperus monosperma / Bouteloua gracilis (Stuever and Hayden 1997b)
= Juniperus monosperma / Bouteloua gracilis PA (Muldavin and Mehlhop 1992)
= Juniperus monosperma / Bouteloua gracilis Plant Association (Muldavin et al. 1998d)
= Juniperus monosperma / Bouteloua gracilis Plant Association (Larson and Moir 1987)
= Juniperus monosperma / Bouteloua gracilis Plant Association (Larson and Moir 1986)
= Juniperus monosperma / Bouteloua gracilis Plant Association (Johnston 1987)
>< Juniperus monosperma / Bouteloua gracilis Plant Community (Shaw et al. 1989)
> Juniperus monosperma / Bouteloua gracilis Plant Community (Francis 1986)
= Juniperus monosperma / Bouteloua gracilis Range (Pieper et al. 1971)
< Juniperus monosperma / Bouteloua spp. Vegetation Type (Dick-Peddie 1993)
= Oneseed Juniper/Blue Grama PA (Muldavin et al. 2000b) [(Juniperus monosperma/Bouteloua gracilis: JUNMON/BOUGRA)]
Concept Author(s): M.C. Stuever and J.S. Hayden (1997b)

Author of Description: K.S. King and K.A. Schulz

Acknowledgements: No Data Available

Version Date: 10-17-18
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