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A3420 Abies concolor Dry Forest & Woodland Alliance

Type Concept Sentence: Forests and woodlands of the southern Rocky Mountains characterized by canopies dominated by Abies concolor in association with other conifers.

Common (Translated Scientific) Name: White Fir Dry Forest & Woodland Alliance

Colloquial Name: Dry White Fir Forest & Woodland

Hierarchy Level:  Alliance

Type Concept: Forests and woodlands of this alliance occur primarily in the southern Rocky Mountains and extend west into the intermountain ranges of the Great Basin. These mixed conifer forests and woodlands have an open to closed canopy with Abies concolor successfully reproducing and typically codominant in the tree canopy. The composition of other species in the tree canopy varies across the range of the alliance with Pinus ponderosa or Pseudotsuga menziesii being most consistent. Populus tremuloides may codominate in early-seral stands. Other canopy associates that may be present include Abies lasiocarpa, Picea engelmannii, Pinus flexilis, and Pinus strobiformis. The density of the understory varies with the amount of tree canopy shading. Shrub and dwarf-shrub layers may be present and vary in structure and composition. Ericaceous or cold-deciduous shrubs are most common. Common shrub species include Acer glabrum, Amelanchier alnifolia, Arctostaphylos patula, Arctostaphylos uva-ursi, Jamesia americana, Juniperus communis, Mahonia repens, Paxistima myrsinites, Purshia tridentata, Quercus gambelii, Ribes cereum, Rosa woodsii, Rubus parviflorus, Symphoricarpos oreophilus, and Vaccinium myrtillus. The herbaceous layer may be dominated by shade-tolerant forbs, ferns or graminoids. The most common dominant herbaceous species include Carex rossii, Carex siccata, Danthonia parryi, Festuca arizonica, Galium triflorum, Leymus triticoides, and Muhlenbergia straminea. These forests occur at middle to high elevations (1200-3150 m) and occupy a variety of topo-edaphic positions, such as lower and middle slopes of ravines, upper slopes at higher elevations, along stream terraces, ridgetops, and north- and east-facing slopes that burn somewhat infrequently. Parent materials and soils are highly variable and nondefinitive for these forests. Temperature and moisture regimes appear to be the key factors in their distribution.

Diagnostic Characteristics: Forests and woodlands of the southern Rocky Mountains where Abies concolor is the dominant canopy species and is successfully reproducing. It is distinguished from other Abies concolor forests and woodlands in having an understory composed of species that have affinities to drier conditions.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The name of the alliance needs to include better diagnostic species, as this alliance has a name very similar to ~Abies concolor Southern Rocky Mountain Mesic Forest & Woodland Alliance (A3369)$$ (G225). For now, a soil moisture modifier is used to distinguish it. This alliance does not occur in California, according to T. Keeler-Wolf (pers. comm. 2018). Although Sawyer et al. (2009) call the California alliance "Abies concolor," it''s really Abies concolor ssp. lowiana (or Abies lowiana sensu USDA PLANTS). For that reason, we recommend keeping "Abies concolor" out of California for the treatment. This is one potential exception, but it needs more investigation. Populations of Abies concolor ssp. concolor within the Clark, Kingston, and New York mountains of the eastern Mojave Desert are mostly intermixed with Pinus monophylla and are largely part of the Pinus monophylla alliance stands. However, there was at least one plot sampled in the NPS Mojave Network dataset which has been called out as an "Abies concolor" alliance stand (plot_ID MOJA0262 on Clark Mountain). There are definitely stands of Abies concolor ssp. concolor alliance on the Spring Mountains of western Nevada about 25 miles to the northeast of this site, so it is possible that this stand could be considered the only outlier California representative of the otherwise non-Californian alliance. For a recent discussion of the taxonomy of Abies concolor, see Ott et al. (2015).

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These are open to closed, medium-statured to tall (20-50 m in height), multi-storied forests and woodlands of needle-leaved evergreen trees. Occasionally, a subcanopy (10-20 m tall) of broad-leaved evergreen or cold-deciduous trees may be present. Many densely stocked stands may have a somewhat depauperate understory, but more open stands often have a well-developed ericaceous or cold-deciduous shrub layer. The herbaceous layer is usually dominated by shade-tolerant forbs or cespitose graminoids.

Floristics: The successful reproduction of Abies concolor is always diagnostic in these stands and often it is one of the codominant species in the canopy. Common conifer associates include Abies lasiocarpa var. arizonica, Abies lasiocarpa var. lasiocarpa, Juniperus scopulorum, Picea engelmannii, Picea pungens, Pinus flexilis, Pinus ponderosa, Pinus strobiformis, and Pseudotsuga menziesii. Populus tremuloides is occasionally codominant in early-seral stands. The composition and proportions of these species are dependent upon the temperature and moisture relationships of the site and the successional status of the stand (DeVelice et al. 1986, Muldavin et al. 1996). A tall-shrub or low-tree layer composed of cold-deciduous species may also be present, including Acer glabrum, Acer grandidentatum, Quercus gambelii, or Robinia neomexicana. Locally abundant low to mid-statured shrubs include Arctostaphylos patula, Arctostaphylos uva-ursi, Holodiscus dumosus, Jamesia americana, Juniperus communis, Mahonia repens, Paxistima myrsinites, Ribes cereum, Rubus parviflorus, Symphoricarpos oreophilus, and Vaccinium myrtillus. The herbaceous layer can either be graminoid- or forb-dominated. The most common dominant herbaceous species include Carex rossii, Carex siccata, Danthonia parryi, Festuca arizonica, Galium triflorum, Leymus triticoides, and Muhlenbergia straminea (= Muhlenbergia virescens). Important forbs include Erigeron eximius, Geranium richardsonii, Lathyrus lanszwertii, Maianthemum spp. (= Smilacina spp.), Pseudocymopterus montanus, Pteridium aquilinum, Thalictrum fendleri, Thermopsis rhombifolia, and Valeriana arizonica. Important graminoids include Bromus ciliatus var. ciliatus (= Bromus canadensis), Carex rossii, Carex siccata (= Carex foenea), Festuca arizonica, Koeleria macrantha, and Poa fendleriana.

Dynamics:  With fire suppression, Abies concolor tends to replace many of the important conifers at lower elevation sites (Chappell et al. 1997). At higher elevations, the stands are naturally more closed and burn less frequently. Forb, shrub, and wildlife diversity varies greatly with the substrate (Chappell et al. 1997). In the Southern Rockies, frequent surface fires restricted these forests to rather moist or less fire-prone areas. With fire suppression, Abies concolor has vigorously colonized many sites which were formerly occupied by open Pinus ponderosa woodlands. These invasions have dramatically changed the fuel load and potential behavior of fire in these forests. In particular, the potential for high-intensity crown fires has increased.
Environmental Description:  These forests and woodlands occur at middle to high elevations (1200-3150 m) of major mountain ranges of the southern Rocky Mountains where annual precipitation is 75 cm or less. Summer "monsoonal" rainfall contributes substantial moisture. These forests and woodlands occupy a variety of topo-edaphic positions, such as lower and middle slopes of ravines, upper slopes at higher elevations, canyon sideslopes, along stream terraces, ridgetops, and north- and east-facing slopes that burn somewhat infrequently. All slopes and aspects are represented within this alliance. Parent materials and soils are highly variable and nondefinitive for these forests. Temperature and moisture regimes appear to be the key factors in their distribution.
Geographic Range: This alliance is known from western Arizona east to the Colorado Plateau and southern Rocky Mountains of Utah, Colorado, New Mexico and Wyoming.

Nations: US

States/Provinces:  AZ, CO, NM, NV, 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.1 White Fir - Douglas-fir - Blue Spruce Forest Macrogroup M022 1.B.2.Nb.1
Group 1.B.2.Nb.1.c White Fir - Douglas-fir Southern Rocky Mountain Dry Forest Group G226 1.B.2.Nb.1.c
Alliance A3420 White Fir Dry Forest & Woodland Alliance A3420 1.B.2.Nb.1.c
Association CEGL000242 White Fir / Greenleaf Manzanita Forest CEGL000242 1.B.2.Nb.1.c
Association CEGL000243 White Fir / Kinnikinnick Forest CEGL000243 1.B.2.Nb.1.c
Association CEGL000244 White Fir - Douglas-fir / Dry-spike Sedge Forest CEGL000244 1.B.2.Nb.1.c
Association CEGL000249 White Fir / Common Juniper Forest CEGL000249 1.B.2.Nb.1.c
Association CEGL000251 White Fir / Creeping Barberry Forest CEGL000251 1.B.2.Nb.1.c
Association CEGL000252 White Fir / Screwleaf Muhly Forest CEGL000252 1.B.2.Nb.1.c
Association CEGL000261 White Fir / Gambel Oak Forest CEGL000261 1.B.2.Nb.1.c
Association CEGL000265 White Fir - Douglas-fir / Whortleberry Forest CEGL000265 1.B.2.Nb.1.c
Association CEGL000431 White Fir - Douglas-fir / Ross'' Sedge Forest CEGL000431 1.B.2.Nb.1.c
Association CEGL000522 Quaking Aspen - White Fir / Greenleaf Manzanita Forest CEGL000522 1.B.2.Nb.1.c
Association CEGL000885 White Fir / Curl-leaf Mountain-mahogany Woodland CEGL000885 1.B.2.Nb.1.c
Association CEGL000886 White Fir / Beardless Wildrye Woodland CEGL000886 1.B.2.Nb.1.c
Association CEGL000887 White Fir / Arizona Fescue Woodland CEGL000887 1.B.2.Nb.1.c
Association CEGL000891 White Fir - Douglas-fir / New Mexico Locust Woodland CEGL000891 1.B.2.Nb.1.c
Association CEGL002732 White Fir - Ponderosa Pine - Curl-leaf Mountain-mahogany Forest CEGL002732 1.B.2.Nb.1.c
Association CEGL005350 White Fir - Douglas-fir / Thurber''s Fescue - Parry''s Oatgrass Woodland CEGL005350 1.B.2.Nb.1.c
Association CEGL005351 White Fir - (Douglas-fir) / Gambel Oak / Ross'' Sedge Forest CEGL005351 1.B.2.Nb.1.c
Association CEGL005357 White Fir / Mixed Grasses Forest CEGL005357 1.B.2.Nb.1.c
Concept Lineage: This alliance is the combination of the former Abies concolor Forest Alliance (A.152) and Abies concolor Woodland Alliance (A.553).

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Abies concolor Series (Johnston 1987)
>< Western Needleleaf Forests: 20: Spruce-Fir-Douglas fir Forest (Picea-Abies-Pseudotsuga) (Küchler 1964)
>< Western Needleleaf Forests: 5: Mixed Conifer Forest (Abies-Pinus-Pseudotsuga) (Küchler 1964)
Concept Author(s): D. Sarr, in Faber-Langendoen et al. (2013)

Author of Description: M.E. Hall

Acknowledgements: No Data Available

Version Date: 03-14-14
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