Print Report
A3570 Cercocarpus ledifolius Grassy Woodland Alliance
Type Concept Sentence: This woodland alliance is characterized by an open tree canopy of Cercocarpus ledifolius with the understory characterized by an open to moderate herbaceous layer typically dominated by bunchgrasses. It occurs in semi-arid steppe and temperate mountainous habitats of the interior western United States.
Common (Translated Scientific) Name: Curl-leaf Mountain-mahogany Grassy Woodland Alliance
Colloquial Name: Curl-leaf Mountain-mahogany Grassy Woodland
Hierarchy Level: Alliance
Type Concept: The vegetation in this alliance is characterized by an open canopy of Cercocarpus ledifolius. Steppe woodlands typically have only Cercocarpus ledifolius in the overstory canopy, but Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, Pinus edulis, or Pinus monophylla occur in local areas. The understory is characterized by an open to moderate herbaceous layer typically dominated by bunchgrasses. Characteristic species include Achnatherum spp., Calamagrostis rubescens, Elymus elymoides, Festuca idahoensis, Leymus ambiguus, Leymus salinus, and Pseudoroegneria spicata. Diverse forbs may be present, usually with low cover. Scattered short shrubs may be present, but they do not form a layer (<10% cover) and have less total cover than the herbaceous layer. Plant associations in this alliance occur in semi-arid steppe and cool temperate mountainous habitats of the interior western United States. These woodlands often form small patchy stands in forested areas or may form the only tree cover in steppe regions. Elevation ranges from1730-2745 m (5675-9000 feet). Lower elevation stands in steppe regions have rolling topography, whereas mountain stands occur on moderate to very steep slopes and ridges. Aspect is variable depending on elevation. Annual precipitation is variable in amount (18-56 cm) and season depending on location with mostly snow in mountains and spring convective showers in steppe region. Soils are moderately shallow, rocky, well-drained gravelly loams over cracked bedrock or colluvium.
Diagnostic Characteristics: The vegetation in this woodland alliance is characterized by an open tree canopy dominated by Cercocarpus ledifolius, sometimes with low cover of Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, Pinus edulis, or Pinus monophylla. The understory is characterized by an open to dense herbaceous layer. Diagnostic species include Achnatherum spp., Calamagrostis rubescens, Elymus elymoides, Festuca idahoensis, Leymus ambiguus, Leymus salinus, and Pseudoroegneria spicata. If shrubs are present, then cover is low (<10%) and the herbaceous layer significantly exceeds shrub cover forming a layer.
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 stands 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 about 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 as 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.
The woodland stands 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 about 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 as 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: Plant associations in this alliance are woodlands dominated by a spreading broad-leaved evergreen small tree (5-15 m tall) of open cover (10-30%). Scattered evergreen or cold-deciduous shrubs may be present with low cover (<10%). A ground layer of cespitose or rhizomatous perennial graminoids is present and characterizes the understory.
Floristics: The vegetation in this alliance is characterized by an open canopy of Cercocarpus ledifolius. Steppe woodlands typically have only Cercocarpus ledifolius in the overstory canopy, but Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, Pinus edulis, or Pinus monophylla occur in local areas. The understory is characterized by an open to moderate herbaceous layer typically dominated by bunchgrasses. Characteristic species include Achnatherum spp., Calamagrostis rubescens, Elymus elymoides, Festuca idahoensis, Leymus ambiguus, Leymus salinus, and Pseudoroegneria spicata. Diverse forbs may be present, usually with low cover, and include such perennials as Geum triflorum, Hieracium cynoglossoides, Senecio integerrimus, and Viola nuttallii; the annual Agoseris heterophylla is often present. Other abundant and constant species include Achnatherum lemmonii, Hesperostipa comata, Poa fendleriana, and Poa secunda, and the perennial sedge Carex rossii. Scattered short shrubs may be present, including Amelanchier alnifolia, Artemisia tridentata ssp. vaseyana, Ericameria nauseosa (= Chrysothamnus nauseosus), Holodiscus dumosus, Purshia tridentata, Prunus virginiana, Ribes spp., and Symphoricarpos spp., but they do not form a layer (<10% cover) and have less total cover than the herbaceous layer.
Dynamics: Cercocarpus ledifolius is a slow-growing, drought-tolerant species that can inhabit very poor sites, such as cliffs 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 or elk.
Environmental Description: Plant associations in this woodland alliance occur in semi-arid steppe and foothills, and cool temperate mountainous habitats of the interior western United States. These woodlands often form small patchy stands in forested areas or may form the only tree cover in steppe regions. Elevations range from 1730 m to over 2745 m (5675-9000 feet). Climate ranges from semi-arid at lower elevations in southern Idaho to cool temperate in mountains of Montana. Precipitation is variable in amount and season depending on locations, with annual precipitation ranging from 18-56 cm with much of the precipitation falling during the winter months as snow in mountains or as convective showers in May and June in steppe and foothills. Lower elevation sites in steppe regions have rolling topography with low relief. Stands found in foothills and mountains occur on moderate to very steep slopes and ridges. Aspect is variable depending on elevation, with cooler east to north slopes more typical of lower elevation sites. Soils are moderately shallow (30-48 cm deep), rocky, well-drained gravelly loams over cracked bedrock or colluvium. Stones make up 30-60% of the soil volume. Cercocarpus roots extend into cracks within the bedrock. Parent materials include andesite, granite, rhyolite, tuffs and metamorphic (schist).
Geographic Range: This alliance occurs in the Great Basin extending west into the foothills of the Sierra Nevada and north into the Columbia Plateau, from northeastern California north across Nevada, into southeastern Oregon, southern Idaho, western Utah and western Montana.
Nations: US
States/Provinces: CA, ID, MT, NV, OR, UT
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899628
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: This alliance includes 4 herbaceous understory associations from Old Alliance II.A.5.N.a. Cercocarpus ledifolius Woodland Alliance (A.586). A.586 (in part).
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]
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