Print Report

CEGL000442 Pseudotsuga menziesii / Mahonia repens Forest

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Douglas-fir / Creeping Barberry Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This forest association occurs on dry, often nutrient-poor sites in the southern and central Rocky Mountains and high plateaus of the Colorado Plateau from northern Arizona and New Mexico north through Colorado and Utah into central Idaho, Wyoming and Montana, and extends to the eastern Cascades in Oregon. Stands occur on lower mountain slopes and upper canyon slopes. Elevations range from 1740 to 2930 m (5700-9600 feet) in northern New Mexico, Arizona and Colorado, and 1375 to 2595 m (4500-8500 feet) in Utah, Wyoming and southern Idaho. Soils are variable in texture and parent material but are usually deep and often rocky. The vegetation is representative of closed-canopy stands of Pseudotsuga menziesii where most species other than Mahonia repens have been shaded out. In some stands, a few individual Pinus ponderosa, Pinus contorta, Pinus flexilis, Pinus strobiformis, Populus tremuloides, or Juniperus scopulorum may persist in the canopy or subcanopy. The understory may be sparse, with 10% or less total cover, but sometimes will have up to 30% total herbaceous and shrub cover. Mahonia repens is the dominant species with at least 1% cover, but other species are usually present with at least trace cover, including Juniperus communis, Symphoricarpos oreophilus, Paxistima myrsinites, and Prunus virginiana. The herbaceous layer is generally sparse but may include small amounts of graminoids such as Poa fendleriana, Festuca arizonica, Carex geyeri, Carex rossii, and scattered forbs such as Arnica cordifolia, Galium boreale, and Thalictrum fendleri. The mature, older canopy trees in some stands are fire-scarred, indicating that ground-fire activity may be important in stands of this type. Some stands appear to be ponderosa pine woodlands that have filled in within the last 150 years with a closed canopy of Douglas-fir.

Diagnostic Characteristics: This type is distinguished by a sparse understory. Mahonia repens does not need to be in the understory. Quercus spp. are poorly represented and Holodiscus dumosus is also scarce. Abies concolor is absent or accidental. Populus tremuloides may occur on moist microsites.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association describes a dry, mature to old-growth, closed-canopy Pseudotsuga menziesii forest of the interior western U.S.; earlier seral stages have a more open, mixed canopy and more diversity and cover by shrubs and herbaceous species. Mahonia repens is a common understory species in all seral stages of these dry Douglas-fir forests, but usually is mixed with varying amounts of species that are also indicators in other associations. It is not necessarily clear what degree of dominance by Mahonia repens versus other diagnostic species (such as Carex geyeri, Paxistima myrsinites, Symphoricarpos oreophilus, or Juniperus communis) constitutes a stand of this association. This association is similar to Pseudotsuga menziesii / Arnica cordifolia Habitat Type of Pfister et al. (1977) in Montana.

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

Floristics: This association represents closed-canopy stands of Pseudotsuga menziesii where most species other than Mahonia repens have been shaded out. In some stands, a few individual Pinus ponderosa, Pinus contorta, Pinus flexilis, Pinus strobiformis, Populus tremuloides, or Juniperus scopulorum may persist in the canopy or subcanopy. The understory may be sparse, with 10% or less total cover, but sometimes will have up to 30% total herbaceous and shrub cover. Mahonia repens is the dominant species with at least 1% cover, but other species are usually present with at least trace cover, including Juniperus communis, Symphoricarpos oreophilus, Paxistima myrsinites, and Prunus virginiana. The herbaceous layer is generally sparse but may include small amounts of Poa fendleriana, Festuca arizonica, Carex geyeri, Carex rossii, Arnica cordifolia, Maianthemum racemosum (= Smilacina racemosa), Galium boreale, Bromus ciliatus, Clematis columbiana, and Thalictrum fendleri.

Dynamics:  The mature, older canopy trees in some stands are fire-scarred, indicating that ground-fire activity may be important in stands of this type. Some stands appear to be Pinus ponderosa woodlands that have filled in within the last 150 years with a closed canopy of Pseudotsuga menziesii. In older stands, the Pseudotsuga can develop a dense canopy that suppresses the taller shrubs and leaves Mahonia repens or Paxistima to dominate the undergrowth. Mahonia repens generally survives all but severe fires. This understory plant, often found in shady locations, can also tolerate full sunlight. The plant regenerates following fire from rhizomes in the top soil layer or by seed. Recovery of Mahonia repens may take several years (Walkup 1991b).
Environmental Description:  This forest occurs on dry, often nutrient-poor sites in northern Arizona and New Mexico north through Colorado and Utah into Idaho, Wyoming and Montana, and extends to the eastern Cascades in Oregon (Cole 1982, Atzet and Wheeler 1984, Mauk and Henderson 1984, Stuever and Hayden 1997a). Stands occur on lower mountain slopes and upper canyon slopes. Elevations range from 2135 to 2595 m (7000-8500 feet) in northern Arizona and New Mexico, 1740 to 2930 m (5700-9600 feet) in Colorado, and 1375 to 2595 m (4500-8500 feet) in Utah, Wyoming and southern Idaho. Soils are variable in texture and parent material but are usually deep and often rocky. Litter and downed wood cover nearly all the unvegetated surface.
Geographic Range: This association occurs in dry mountain and canyon sites in northern Arizona and New Mexico, north through central Utah into Oregon and southern Idaho, and east into Wyoming and Colorado.

Nations: US

States/Provinces:  AZ, CO, ID, MT, NM, OR, UT, WY


Confidence Level: Moderate

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.Nb Rocky Mountain Forest & Woodland Division D194 1.B.2.Nb
Macrogroup 1.B.2.Nb.2 Ponderosa Pine - Douglas-fir - Limber Pine Central Rocky Mountain Dry Forest Macrogroup M501 1.B.2.Nb.2
Group 1.B.2.Nb.2.c Douglas-fir Middle Rocky Mountain Montane Forest & Woodland Group G215 1.B.2.Nb.2.c
Alliance A3462 Douglas-fir Middle Rocky Mountain Dry-Mesic Forest & Woodland Alliance A3462 1.B.2.Nb.2.c
Association CEGL000442 Douglas-fir / Creeping Barberry Forest CEGL000442 1.B.2.Nb.2.c
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Pseudotsuga menziesii / Arnica cordifolia Habitat Type (Pfister et al. 1977)
= Pseudotsuga menziesii / Berberis repens Community Type (Cole 1982)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Hoffman and Alexander 1976)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Larson and Moir 1987)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Mauk and Henderson 1984)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Steele et al. 1981)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Steele et al. 1983)
= Pseudotsuga menziesii / Berberis repens Habitat Type (Youngblood and Mauk 1985)
= Pseudotsuga menziesii / Mahonia repens (Stuever and Hayden 1997a)
= Pseudotsuga menziesii / Mahonia repens Plant Association (Johnston 1987)
= Pseudotsuga menziesii / Mahonia repens Plant Association (Johnston 1984)
< Pseudotsuga menziesii / Sparse Undergrowth Habitat Type (Alexander et al. 1984b)
Concept Author(s): M.C. Stuever and J.S. Hayden (1997a)

Author of Description: J. Coles and K.A. Schulz

Acknowledgements: No Data Available

Version Date: 11-06-18
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