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A4079 Pinus contorta Rocky Mountain Woodland Alliance
Type Concept Sentence: This woodland alliance is characterized by open-canopy woodlands dominated by Pinus contorta and is found in mainly montane and subalpine zones of the northern Rocky Mountains and eastern Cascade Range, but extends into the southern Rocky Mountains.
Common (Translated Scientific) Name: Lodgepole Pine Rocky Mountain Woodland Alliance
Colloquial Name: Rocky Mountain Lodgepole Pine Woodland
Hierarchy Level: Alliance
Type Concept: This woodland alliance includes upland plant associations found mainly in the montane and subalpine zones of the northern Rocky Mountains and eastern Cascade Range, but some associations extend into the southern Rocky Mountains. Pinus contorta is usually the only mature tree in these woodlands, but occasionally other conifers will be present. A short-shrub layer is usually present, but is often patchy and rarely has substantial cover. Important shrubs and dwarf-shrubs include Amelanchier alnifolia, Arctostaphylos patula, Arctostaphylos uva-ursi, Artemisia tridentata, Juniperus communis, Mahonia repens, Paxistima myrsinites, Purshia tridentata, and Ribes cereum. The herbaceous layer is typically sparse and has low species richness. Cespitose graminoids or forbs tolerant of dry conditions are dominant. Diagnostic of this widespread woodland alliance is the dominance of Pinus contorta in a relatively open tree canopy (<60% cover) and the lack of significant Abies lasiocarpa regeneration. Sites include canyons, ridges, swales, plateaus, toeslopes, basins, flats, and benches. Slopes and aspects are not consistent. Soils are variable, but tend to be coarse-textured and well-drained. The open tree canopy is related to unusually dry or cold topo-edaphic situations such as excessively well-drained pumice deposits, shallow rocky soils with little water-holding capacity often on warm aspects, and well-drained to xeric stabilized sand dunes.
Diagnostic Characteristics: Diagnostic of this widespread woodland alliance is the dominance of Pinus contorta in a relatively open tree canopy (<60% cover) and the lack of significant Abies lasiocarpa regeneration.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance is derived from a series concept, in which associations are distinguished by the dominance of Pinus contorta in the tree canopy and the lack of regeneration of other conifers. In the habitat-typing classification system, stands dominated by Pinus contorta but with significant regeneration of other conifers, such as Abies grandis, Abies lasiocarpa, Picea engelmannii, Pseudotsuga menziesii, Thuja plicata, or Tsuga heterophylla, have typically been placed into series named for those conifers.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These are typically open (<60% cover), sparsely-stocked 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: Although these are usually monotypic stands dominated by Pinus contorta, some other trees may occasionally be present, including Abies grandis, Larix occidentalis, Picea engelmannii, Pinus flexilis, Pinus ponderosa, Populus tremuloides, Pseudotsuga menziesii, and Tsuga mertensiana. A short-shrub layer is usually present, but is often patchy and rarely has substantial cover. Purshia tridentata is an important shrub in several associations, particularly on ash or volcanic sands (Volland 1976, Pfister et al. 1977). Other important to dominant shrubs include Amelanchier alnifolia, Arctostaphylos patula, Arctostaphylos uva-ursi, Artemisia tridentata, Juniperus communis, Mahonia repens, Paxistima myrsinites, and Ribes cereum. The herbaceous layer is typically somewhat sparse and dominated by cespitose graminoids or forbs tolerant of dry conditions. Important species include Achnatherum occidentale (= Stipa occidentalis), Arnica cordifolia, Carex rossii, Chamerion angustifolium (= Epilobium angustifolium), Elymus elymoides, Eriogonum umbellatum, Festuca idahoensis, Potentilla fissa, Sedum stenopetalum, and species of Antennaria, Eriophyllum, Fragaria, Lupinus, and Penstemon.
Dynamics: In Pinus contorta forests, establishment is episodic and linked to stand-replacing disturbances. The reproductive and seral dynamics of Pinus contorta woodlands are less well-described. 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. The incidence of serotinous cones varies within and among varieties of Pinus contorta, being most prevalent in Rocky Mountain populations. Closed, serotinous cones appear to be strongly favored by fire, and allow rapid colonization of fire-cleared substrates (Burns and Honkala 1990a).
Environmental Description: Pinus contorta occupies the broadest array of habitats of any coniferous species in the western United States. This alliance occurs in the montane and subalpine zones of the Rocky Mountains and eastern Cascade Range with elevations ranging from just over 1200 m in the Cascades to over 3050 m in the Rockies. Temperature regimes are extreme throughout this region and frequent growing-season frosts occur. Annual precipitation in these montane and subalpine habitats ranges from less than 40 cm to over 150 cm annually, usually with the majority falling as snow. Late-melting snowpacks provide the majority of growing-season moisture, particularly in the Cascades. The dominance of Pinus contorta in associations in this alliance is related to fire history and topo-edaphic conditions (Pfister et al. 1977, Steele et al. 1983, Mauk and Henderson 1984, Hess and Alexander 1986). Following stand-replacing fires, Pinus contorta will rapidly colonize and dominate sites. Most woodlands in this alliance are early- to mid-successional, having developed following fires. However, the persistence of these woodland associations is related to their occurrence on unusually dry or cold topo-edaphic situations. These include excessively well-drained pumice deposits in central Oregon (Volland 1976), obsidian-sand benchlands of alluvial origin in the Yellowstone area of Montana (Pfister et al. 1977), warm and droughty soils with gravelly loam textures (Mauk and Henderson 1984, Hess and Alexander 1986), and well-drained to xeric stabilized sand dunes (Alpert 1984). Slopes and aspects are variable, and can include moderately steep to very steep ridge and canyon slopes, gentle to moderate slopes, ridges and swales, plateaus, butte toeslopes, basins, flats, and benches.
Geographic Range: Associations of this alliance occur mainly in the montane and subalpine zones of the northern Rocky Mountains and eastern Cascade Range, although some associations extend into the southern Rocky Mountains.
Nations: CA,US
States/Provinces: AB, CO, ID, MT, NV?, OR, UT, WA?, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.902782
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: A.512, in part
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Lodgepole Pine: 218 (Eyre 1980)
- Alpert, P. 1984. Inventory and analysis of Oregon coastal dunes. Unpublished manuscript prepared for the Oregon Natural Heritage Program, Portland, OR.
- Burns, R. M., and B. H. Honkala, technical coordinators. 1990a. Silvics of North America: Volume 1. Conifers. Agriculture Handbook 654. USDA Forest Service, Washington, DC. 675 pp.
- Chappell, C., R. Crawford, J. Kagan, and P. J. Doran. 1997. A vegetation, land use, and habitat classification system for the terrestrial and aquatic ecosystems of Oregon and Washington. Unpublished report prepared for Wildlife habitat and species associations within Oregon and Washington landscapes: Building a common understanding for management. Prepared by Washington and Oregon Natural Heritage Programs, Olympia, WA, and Portland, OR. 177 pp.
- Eyre, F. H., editor. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Hess, K., and R. R. Alexander. 1986. Forest vegetation of the Arapaho and Roosevelt national forests in northcentral Colorado: A habitat type classification. Research Paper RM-266. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 48 pp.
- Mauk, R. L., and J. A. Henderson. 1984. Coniferous forest habitat types of northern Utah. General Technical Report INT-170. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 89 pp.
- Pfister, R. D., B. L. Kovalchik, S. F. Arno, and R. C. Presby. 1977. Forest habitat types of Montana. General Technical Report INT-34. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 174 pp.
- Steele, R., S. V. Cooper, D. M. Ondov, D. W. Roberts, and R. D. Pfister. 1983. Forest habitat types of eastern Idaho - western Wyoming. General Technical Report INT-144. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 122 pp.
- Volland, L. A. 1976. Plant communities of the central Oregon pumice zone. USDA Forest Service R-6 Area Guide 4-2. Pacific Northwest Region, Portland, OR. 113 pp.