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CEGL000862 Pinus ponderosa / Muhlenbergia montana Woodland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Ponderosa Pine / Mountain Muhly Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This widespread woodland occurs at foothill and lower montane elevations in the southern Rocky Mountains, extending south to the mountains of western Texas, and west to the Mogollon Rim and Colorado Plateau of New Mexico, Arizona and Utah. Elevation ranges from 1890 to 2870 m (6190-9400 feet). Stands occur on bottomlands, elevated plains, cinder cones, piedmont slopes, mesas, foothills, and mountains. Sites include gentle to steep slopes on all aspects, but are more common on southern and western aspects, especially at higher elevations. Substrates are variable but are typically shallow, rocky, coarse-textured soils derived from granitic or cinder parent materials. There is considerable cover of bare soil and exposed bedrock. The vegetation is characterized by an open to moderately dense evergreen, needle-leaved tree canopy to 10-30 m tall that is dominated or codominated by Pinus ponderosa. Associated tree species vary geographically. Pinus edulis, Pinus discolor, and Juniperus spp. may be important in the tree canopy. Pseudotsuga menziesii, Pinus flexilis, and Populus tremuloides may also be present but are considered accidental. Quercus gambelii may be present with low cover (to 5%) in the sparse shrub layer (<10% cover). Other scattered shrubs may include Artemisia tridentata, Ceanothus fendleri, Cercocarpus montanus, Chrysothamnus viscidiflorus, Ericameria nauseosa, Juniperus communis, Purshia tridentata, Rhus trilobata, Ribes cereum, or Yucca baccata. The typically moderately dense herbaceous layer has greater cover than the shrub layer and is dominated by graminoids. Muhlenbergia montana, a warm-season, medium-tall perennial, typically dominates the herbaceous layer and is diagnostic of this association. Common graminoid associates include Aristida spp., Blepharoneuron tricholepis, Bouteloua gracilis, Carex geophila, Carex rossii, Elymus elymoides, Koeleria macrantha, Poa fendleriana, and Schizachyrium scoparium. Festuca arizonica, Muhlenbergia straminea, Muhlenbergia dubia, Muhlenbergia emersleyi, and Hesperostipa spp. are typically absent. Forb cover is typically sparse and highly variable.

Diagnostic Characteristics: Although Muhlenbergia montana is often present to well-represented, it does not have to be present to be called this plant association. Quercus gambelii, if present, is <5% canopy cover. Pseudotsuga menziesii and Populus tremuloides are absent or accidental and then usually in microsites, or if present, may represent an ecotone between this and an adjacent plant association.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This ponderosa pine woodland is a broadly defined plant association. Stuever and Hayden (1997a) suggested the xeric upland and mesic bottomland stands be put into different phases. Fitzhugh et al. (1987) suggested it be divided into regional phases.

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

Floristics: This association is characterized by an open to moderately dense evergreen, needle-leaved tree canopy 10-30 m tall that is dominated or codominated by Pinus ponderosa. Associated tree species vary geographically. Pinus edulis, Pinus discolor, Juniperus monosperma, Juniperus osteosperma, Juniperus deppeana, and Juniperus scopulorum may be important in the tree canopy. Pseudotsuga menziesii, Pinus flexilis, and Populus tremuloides may also be present, but are considered accidental. Quercus gambelii may be present with low cover (to 5%) in the sparse shrub layer (<10% cover). Other scattered shrubs may include Artemisia tridentata, Brickellia californica, Ceanothus fendleri, Cercocarpus montanus, Chrysothamnus viscidiflorus, Ericameria nauseosa, Fallugia paradoxa, Mahonia spp., Purshia tridentata, Quercus grisea, Rhus trilobata, Tetradymia canescens, or Yucca baccata. The typically moderately dense herbaceous layer has greater cover than the shrub layer, and is dominated by graminoids. Muhlenbergia montana, a warm-season, medium-tall perennial, typically dominates the herbaceous layer and is diagnostic of this association. Common graminoid associates include Aristida spp., Blepharoneuron tricholepis, Bouteloua gracilis, Carex geophila, Carex rossii, Elymus elymoides, Koeleria macrantha, Poa fendleriana, and Schizachyrium scoparium. Festuca arizonica, Muhlenbergia straminea (= Muhlenbergia virescens), Muhlenbergia dubia, Muhlenbergia emersleyi, and Hesperostipa spp. are typically absent. Forb cover is typically sparse and may include species such as Antennaria spp., Artemisia ludoviciana, Erigeron spp., Eriogonum racemosum, Chaetopappa ericoides, Lotus wrightii, Oxytropis lambertii, Packera neomexicana, and Penstemon spp.

Dynamics:  Both diagnostic species are tolerant of surface fire. Pinus ponderosa develops thick fire-resistant bark, and Muhlenbergia montana resprouts after burning, although if may take a few years to recover to pre-burn density (Fischer and Bradley 1987, Bradley et al. 1992). This association had frequent fires (every 3-10 years on average) in presettlement times, but fires are less frequent in dry, rocky stands where surface fire is limited by lack of continuous fine fuels (Stuever and Hayden 1997a). Fire-return interval has generally increased because of active fire suppression and historic livestock grazing, which has reduced the fine fuels needed to carry surface fires (Madany and West 1980b, Savage and Swetnam 1990). Absence of fire has led to large accumulations of ground fuel and has likely resulted in denser stands and invasion of less fire-adapted, shade-tolerant species such as Pseudotsuga menziesii. This has likely increased the risk of stand-replacing crown fires.

Improper livestock grazing will favor more grazing-tolerant species, such as Bouteloua gracilis, and over time may eliminate Muhlenbergia montana and convert the stand into ~Pinus ponderosa / Bouteloua gracilis Woodland (CEGL000848)$$.
Environmental Description:  This widespread woodland occurs at foothill and lower montane elevations in the southern Rocky Mountains, extending south to the mountains of western Texas, and west to the Mogollon Rim and Colorado Plateau. Elevation ranges from 1890-2870 m (6190-9400 feet). Stands occur on bottomlands, elevated plains, cinder cones, piedmont slopes, mesas, foothills, and mountains. Sites include gentle to steep slopes on all aspects, but are more common on southern and western aspects, especially at higher elevations. Substrates are variable, but are typically shallow, rocky, coarse-textured soils derived from granitic or cinder parent materials. There is considerable cover of bare soil and exposed bedrock.
Geographic Range: This widespread woodland occurs at foothill and lower montane elevations in the southern Rocky Mountains, extending south to the mountains of western Texas, and west to the Mogollon Rim and Colorado Plateau of New Mexico, Arizona and Utah.

Nations: US

States/Provinces:  AZ, CO, NM, TX, UT


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G4G5

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.Nb Rocky Mountain Forest & Woodland Division D194 1.B.2.Nb
Macrogroup 1.B.2.Nb.1 White Fir - Douglas-fir - Blue Spruce Forest Macrogroup M022 1.B.2.Nb.1
Group 1.B.2.Nb.1.a Ponderosa Pine / Fescue species - Muhly species Southern Rocky Mountain Open Woodland Group G229 1.B.2.Nb.1.a
Alliance A3419 Ponderosa Pine / Grass Understory Southern Rocky Mountain Open Woodland Alliance A3419 1.B.2.Nb.1.a
Association CEGL000862 Ponderosa Pine / Mountain Muhly Woodland CEGL000862 1.B.2.Nb.1.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: ? Pinus ponderosa - Pseudotsuga menziesii / Muhlenbergia montana Plant Association (Johnston 1987)
= Pinus ponderosa / Muhlenbergia montana (Stuever and Hayden 1997a)
? Pinus ponderosa / Muhlenbergia montana Cover Type (Balice et al. 1997)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Wasser and Hess 1982)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Muldavin et al. 1996)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Alexander et al. 1987)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Hess and Alexander 1986)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (DeVelice et al. 1986)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Fitzhugh et al. 1987)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Hess 1981)
= Pinus ponderosa / Muhlenbergia montana Habitat Type (Youngblood and Mauk 1985)
= Pinus ponderosa / Muhlenbergia montana Plant Association (Baker 1984a)
= Pinus ponderosa / Muhlenbergia montana Plant Association (Larson and Moir 1987)
= Pinus ponderosa / Poa longiligula community type (Hanks et al. 1983)
>< Xeric Foothill Woodland (A3) (Peet 1981)
>< Xeric Montane Woodland (A5) (Peet 1981)
Concept Author(s): M.C. Stuever and J.S. Hayden (1997a)

Author of Description: K.A. Schulz

Acknowledgements: No Data Available

Version Date: 10-24-18
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