Print Report
A0828 Cercocarpus ledifolius Scrub Alliance
Type Concept Sentence: This shrubland is characterized by an open to moderately dense shrub layer dominated or codominated by Cercocarpus ledifolius with a sparse to moderately dense herbaceous layer. It occurs in semi-arid, mountainous habitats of the interior western United States.
Common (Translated Scientific) Name: Curl-leaf Mountain-mahogany Scrub Alliance
Colloquial Name: Curl-leaf Mountain-mahogany Scrub
Hierarchy Level: Alliance
Type Concept: The vegetation in this alliance is characterized by an open shrub canopy of Cercocarpus ledifolius. The vegetation may occur as scattered small- and large-patch communities in arid steppe or on rocky outcrops or steep escarpments within forests. Other shrubs often occur in the stands and include Amelanchier alnifolia, Artemisia arbuscula, Artemisia frigida, Artemisia nova, Artemisia tridentata, Ericameria nauseosa, Mahonia repens, Prunus virginiana, Ribes spp., and Symphoricarpos spp. The herbaceous layer is usually composed of xeric graminoids, including Achnatherum hymenoides, Achnatherum occidentale, Calamagrostis rubescens, Elymus glaucus, Festuca idahoensis, Hesperostipa comata, Koeleria macrantha, Poa fendleriana, Poa secunda, and Pseudoroegneria spicata. Diverse forbs may be present, usually with low cover. Outcrop communities usually include many of the species above, but may also include occasional forest trees, such as Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, Pinus flexilis, Pinus jeffreyi, Pinus ponderosa, or Pseudotsuga menziesii. The plant associations in this alliance occur in semi-arid, mountainous habitats of the interior western United States. These shrublands are often located on rocky outcrops or escarpments in forested areas. Most stands occur on steep rimrock slopes, usually in areas of shallow soils or protected slopes. Soils are typically rocky and immature, and are always rockier than found in surrounding sites. In Wyoming, stands of this alliance primarily grow on carbonate sediments (limestone or dolomite) or on sandstones rich in calcium carbonate. Other rock types include quartz, gneiss, and basalt.
Diagnostic Characteristics: This alliance is composed of shrub-form Cercocarpus ledifolius dominating or codominating the shrub layer with other shrubs and dwarf-shrubs such as Amelanchier alnifolia, Artemisia arbuscula, Artemisia frigida, Artemisia nova, Artemisia tridentata, Ericameria nauseosa, Mahonia repens, Prunus virginiana, Ribes spp., and Symphoricarpos spp. An open to moderately dense herbaceous layer is usually present and composed of xeric graminoids, including Achnatherum hymenoides, Achnatherum occidentale, Calamagrostis rubescens, Elymus glaucus, Festuca idahoensis, Hesperostipa comata, Koeleria macrantha, Poa secunda, and Pseudoroegneria spicata.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: The Cercocarpus ledifolius woodland and shrubland alliances are poorly distinguished in the literature, as most authors describe the species as having either a tall-shrub or small-tree growth form within a single association. Some associations may have shrub-dominated stands in one area and also have a woodland physiognomy in another. The woodland physiognomy appears to be more typical, based on available literature. Near the northern edge of its range in Montana and Idaho, Cercocarpus ledifolius is described as occurring primarily in the shrub-form (Mueggler and Stewart 1980, Tisdale 1986). These northern variants are the only described stands which appear to be clearly distinct from the woodland alliance. The woodland alliance may have a different subspecies (or variety) as a dominant than the shrubland. In Wyoming, the heritage program is proposing to recognize two Cercocarpus ledifolius alliances, based upon varieties of Cercocarpus ledifolius. The most widespread proposed alliance there is dominated by Cercocarpus ledifolius var. ledifolius, which grows up to ca. 1.5 m tall. The other proposed alliance, dominated by Cercocarpus ledifolius var. intercedens, is found only along the western border of the state, and the growth form is small trees 4-5 m tall. The two taxa are obviously different in Wyoming, in stature and leaf characteristics, and are easily separated. Further review of the two current Cercocarpus ledifolius alliances may warrant treatment as proposed for Wyoming.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: The vegetation in this alliance is dominated by a spreading broad-leaved evergreen shrub layer of open to moderate cover. If present, the herbaceous layer is composed of open to moderate cover of perennial bunch grasses.
Floristics: The vegetation in this alliance is characterized by an open shrub canopy of Cercocarpus ledifolius. The vegetation may occur as scattered small- and large-patch communities in arid steppe or on rocky outcrops or steep escarpments within forests. Other shrubs often occur in the stands and include Amelanchier alnifolia, Artemisia arbuscula, Artemisia frigida, Artemisia nova, Artemisia tridentata, Ericameria nauseosa (= Chrysothamnus nauseosus), Mahonia repens, Prunus virginiana, Ribes spp., and Symphoricarpos spp. The herbaceous layer is usually composed of xeric graminoids, including Achnatherum hymenoides (= Oryzopsis hymenoides), Achnatherum occidentale (= Stipa occidentalis), Calamagrostis rubescens, Elymus glaucus, Festuca idahoensis, Hesperostipa comata, Koeleria macrantha, Poa fendleriana, Poa secunda, and Pseudoroegneria spicata. Diverse forbs may be present, usually with low cover. Outcrop communities usually include many of the species above, but may also include occasional forest trees, such as Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, Pinus flexilis, Pinus jeffreyi, Pinus ponderosa, or Pseudotsuga menziesii. These shrublands are often located on rocky outcrops or escarpments in forested areas.
Dynamics: Cercocarpus ledifolius is a slow-growing, drought-tolerant species which can inhabit very poor sites, such as cliffs, stony slopes, and outcrops. Stands are often small and clumped near ridgetops. These sites may also afford the species some protection from fire. The species is highly susceptible to fire damage and generally does not resprout. Cercocarpus ledifolius is highly favored by native ungulates for winter range and many individual shrubs show evidence of highlining by deer and elk.
Environmental Description: The plant associations in this alliance occur in semi-arid, mountainous habitats of the interior west. Annual precipitation averages 25-45 cm, with a significant proportion falling as winter snow. These shrublands are often located on rocky outcrops or escarpments in forested areas. Most stands occur on steep rimrock slopes, usually in areas of shallow soils or protected slopes. In Wyoming, stands of this alliance primarily grow on carbonate sediments (limestone or dolomite) or on sandstones rich in calcium carbonate. Other rock types include quartz, gneiss, and basalt. Soils are typically rocky and immature, and are always rockier than found in surrounding sites. Adjacent vegetation is usually Pinus ponderosa or Pseudotsuga menziesii forests or woodlands, pinyon and/or juniper woodlands, or Artemisia shrubland.
Geographic Range: This alliance occurs in mountain ranges throughout the Great Basin and into the northern Mojave Desert, from eastern California and Oregon to Colorado and north to Wyoming and western Montana.
Nations: US
States/Provinces: CA, CO, ID, MT, NM, NV, OR, UT, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.866461
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: This alliance is the same as Old Alliance III.A.4.N.a. Cercocarpus ledifolius Shrubland Alliance (A.828).
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Cercocarpus ledifolius (Curl leaf mountain mahogany scrub) Alliance (Sawyer et al. 2009) [76.200.00]
>< Curlleaf Mountain-Mahogany Series (Sawyer and Keeler-Wolf 1995)
>< Curlleaf Mountain-Mahogany Series (Sawyer and Keeler-Wolf 1995)
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