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A3621 Pinus contorta var. murrayana Subalpine Forest & Woodland Alliance
Type Concept Sentence: This alliance consists of forests and woodlands dominated by Pinus contorta var. murrayana with shrub, grass or barren understories. This alliance is widespread in glacial basins at upper montane to subalpine elevations of the central and northern Sierra Nevada and Transverse and Peninsular ranges where cold-dry conditions exist. It also occurs on extensive broad ridges and pumice plateaus of the southern Cascades in Oregon.
Common (Translated Scientific) Name: Sierra Lodgepole Pine Subalpine Forest & Woodland Alliance
Colloquial Name: Subalpine Sierra Lodgepole Pine Forest & Woodland
Hierarchy Level: Alliance
Type Concept: This alliance consists of forests and woodlands dominated by Pinus contorta var. murrayana with shrub, grass or barren understories. Understories are open, with scattered shrubs and herbaceous species, which do provide a continuous fuel bed for fire. Trees can be old and can attain diameters of 1.2 m (4 feet). Associated plant species include Arctostaphylos nevadensis, Artemisia tridentata, Ceanothus cordulatus, Cercocarpus ledifolius (although not that common, just occasional in drier sites), Chrysolepis sempervirens, Phyllodoce breweri, and Ribes montigenum. Common graminoids include Carex exserta, Carex filifolia, Carex rossii, and Poa wheeleri. This alliance is widespread in glacial basins at upper montane to subalpine elevations of the central and northern Sierra Nevada and Transverse and Peninsular ranges where cold-dry conditions exist (1800-2450 m [6000-8000 feet] in the north and 2450-3600 m [8000-11,800 feet] in the south). It also occurs on extensive broad ridges and pumice plateaus of the southern Cascades in Oregon (the broad ridges that form the Cascade Crest in southern Oregon tend to be dominated by extensive stands of lodgepole pine). Soils are often shallow and coarse-textured.
Diagnostic Characteristics: Dominance by Pinus contorta var. murrayana at high elevations. Typically without other conifers present.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance is based upon the concept of ecological system ~Sierra Nevada Subalpine Lodgepole Pine Forest and Woodland (CES206.912)$$. Low-elevation stands of Pinus contorta in the pumice zone of Oregon are included in ~Rocky Mountain Lodgepole Pine Forest & Woodland Group (G220)$$. This alliance occurs in less severe settings than ~Juniperus grandis - Pinus albicaulis Woodland Alliance (A3622)$$.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These are closed-canopy (>60% cover) to open (<60% cover) stands of needle-leaved evergreen trees from 10-30 m in height. Scattered ericaceous shrubs dominate a sparse ground layer, which may include a sparse cover of cespitose graminoids.
Floristics: These forests and woodlands are dominated by Pinus contorta var. murrayana with shrub, grass or barren understories. Understories are open, with scattered shrubs and herbaceous species, which do provide a continuous fuel bed for fire. Trees can be old and can attain diameters of 1.2 m (4 feet). Associated plant species include Arctostaphylos nevadensis, Artemisia tridentata, Ceanothus cordulatus, Cercocarpus ledifolius (although not that common, just occasional in drier sites), Chrysolepis sempervirens, Phyllodoce breweri, and Ribes montigenum. Common graminoids include Carex exserta, Carex filifolia, Carex rossii, and Poa wheeleri.
Dynamics: Avalanche as well as tree mortality from insect outbreak and disease, drought and associated wildfire are drivers of vegetation structure and composition. Pinus contorta dominance is maintained by periodic disturbance from both fires and insect infestations. Unlike most Pinus contorta forests, most of these stands are not seral to another tree species (Chappell et al. 1997). Chappell et al. (1997) report that Pinus contorta woodlands on very deep Mazama pumice deposits in central Oregon are maintained by periodic disturbances from wildfire and insect infestations. Without fires and insects, stands become more closed-canopy forests and quite barren. Historically, surface fires were influential in maintaining relatively open canopy conditions in these woodlands in the Sierra Nevada (Barbour and Major 1977). With settlement and subsequent fire suppression stands have become denser than they once were, with many former woodlands having developed into forests.
Environmental Description: This alliance is widespread in glacial basins at upper montane to subalpine elevations of the central and northern Sierra Nevada and Transverse and Peninsular ranges where cold-dry conditions exist (1800-2450 m [6000-8000 feet] in the north and 2450-3600 m [8000-11,800 feet] in the south). It also occurs on extensive broad ridges and pumice plateaus of the southern Cascades in Oregon (the broad ridges that form the Cascade crest in southern Oregon tend to be dominated by extensive stands of lodgepole pine). Soils are often shallow and coarse-textured.
Geographic Range: This alliance occurs at upper montane to subalpine elevations of the central and northern Sierra Nevada and Transverse and Peninsular ranges where cold-dry conditions exist. It also extends south into Baja California, Mexico, in the San Pedro Martir Mountains. In Oregon, it is found in the southern Cascades on the broad ridges that form the Cascade Crest in southern Oregon (south of Crater Lake and north maybe to Mount Bachelor). There are also relatively large areas of lodgepole pine along the broad crest from Mount Jefferson to a little ways north of Olallie Butte that may also fit in this group and alliance better than the Rocky Mountain lodgepole pine type, as these stands are more likely dominated by Pinus contorta var. murrayana than Pinus contorta var. latifolia.
Nations: MX,US
States/Provinces: CA, MXBCN, NV, OR
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899679
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: includes parts of A.118 and A.512.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Pinus contorta ssp. murrayana (Lodgepole pine forest) Alliance (Sawyer et al. 2009) [87.080.00]
>< Lodgepole Pine Series (Sawyer and Keeler-Wolf 1995)
>< Lodgepole Pine: 218 (Eyre 1980)
>< Lodgepole Pine Series (Sawyer and Keeler-Wolf 1995)
>< Lodgepole Pine: 218 (Eyre 1980)
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