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A0424 Pinus contorta - Populus tremuloides Rocky Mountain Forest Alliance
Type Concept Sentence: This mixed evergreen-deciduous forest alliance is codominated by Pinus contorta and Populus tremuloides and has been described on mountain slopes and plateaus in Utah, Idaho, Colorado and Wyoming.
Common (Translated Scientific) Name: Lodgepole Pine - Quaking Aspen Rocky Mountain Forest Alliance
Colloquial Name: Rocky Mountain Lodgepole Pine - Aspen Forest
Hierarchy Level: Alliance
Type Concept: This mixed evergreen-deciduous forest alliance has been described on mountain slopes and plateaus in Utah, Colorado and Wyoming. Seral forests included in this alliance are characterized by an open to moderately closed, mixed evergreen-deciduous tree canopy that is codominated by Populus tremuloides and Pinus contorta. Several other species of conifers may be scattered within the stands, including Abies lasiocarpa, Picea engelmannii, Picea pungens, Pinus flexilis, and Pseudotsuga menziesii. Younger stands typically have dense Populus tremuloides with Pinus contorta mixed in. As stands age, Populus tremuloides cover is slowly reduced until Pinus contorta becomes dominant. The understory is moderately dense to sparse and becomes sparser as Pinus contorta becomes more dominant. The short-shrub layer is often dominated by Juniperus communis or Symphoricarpos oreophilus. Other shrubs may include Arctostaphylos uva-ursi, Artemisia tridentata, Mahonia repens, Paxistima myrsinites, Rosa woodsii, Shepherdia canadensis, and Symphoricarpos albus. Scattered tall shrubs Amelanchier alnifolia and Prunus virginiana may be present. The relatively sparse herbaceous layer is a mixture of graminoids and forbs and is often dominated by Calamagrostis rubescens, Carex geyeri, Lathyrus lanszwertii, or Thalictrum fendleri. Other common graminoids include Achnatherum occidentale, Bromus carinatus, Carex rossii, Elymus glaucus, and Elymus trachycaulus. Forbs, such as Achillea millefolium, Arnica cordifolia, Balsamorhiza spp., Fragaria vesca, Geranium spp., Lupinus argenteus, Osmorhiza berteroi, and Potentilla spp., may be present. The invasive species Poa pratensis and Taraxacum officinale are common in livestock-impacted stands. Sites occur on gentle to steep slopes on all aspects. Soils are derived from alluvium and colluvium.
Diagnostic Characteristics: Mixed deciduous-evergreen seral forests ultimately dominated by Pinus contorta, but in younger stands codominated by Populus tremuloides.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance is included in this group because disturbed stands may have significant cover of Populus tremuloides. However, conifers are always dominant.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation included in this minor alliance has a moderately dense to dense upper canopy of mixed deciduous broad-leaved and evergreen needle-leaved trees (5-20 m tall). The understory has a moderate to sparse short-shrub layer, typically dominated by an evergreen, scale-leaved or deciduous broad-leaved shrub species. A sparse tall-shrub layer dominated by deciduous broad-leaved shrubs may be present. A moderate to sparse herbaceous layer may also be present, dominated by perennial forbs or graminoids.
Floristics: The open to moderately closed, mixed evergreen needle-leaved and deciduous broad-leaved tree canopy is composed of short to moderately tall trees, and is codominated by Pinus contorta and Populus tremuloides. Several other species of conifers may be scattered within the stands, including Abies lasiocarpa, Pinus flexilis, Picea engelmannii, Picea pungens, and Pseudotsuga menziesii. Younger stands typically have dense Populus tremuloides with Pinus contorta mixed in. As the stands age, Populus tremuloides cover is slowly reduced until Pinus contorta becomes dominant (Mueggler 1988). The understory is typically moderately dense to sparse and becomes sparser as Pinus contorta becomes more dominant. The short-shrub layer is often dominated by Juniperus communis or Symphoricarpos oreophilus. Other shrubs may include Arctostaphylos uva-ursi, Artemisia tridentata, Mahonia repens, Paxistima myrsinites, Rosa woodsii, Shepherdia canadensis, and Symphoricarpos albus. The tall-shrub layer consists of scattered Amelanchier alnifolia and Prunus virginiana. The relatively sparse herbaceous layer is a mixture of graminoids and forbs and is often dominated by Calamagrostis rubescens, Carex geyeri, Lathyrus lanszwertii, or Thalictrum fendleri. Other common graminoids include Achnatherum occidentale (= Stipa occidentalis), Bromus carinatus, Carex rossii, Elymus glaucus, and Elymus trachycaulus. Forbs include Achillea millefolium, Arnica cordifolia, Balsamorhiza spp., Fragaria vesca, Geranium spp., Lupinus argenteus, Osmorhiza berteroi (= Osmorhiza chilensis), and Potentilla spp. The invasive species Poa pratensis and Taraxacum officinale are common in livestock-impacted stands (Mueggler 1988). Annuals are typically uncommon.
Dynamics: Both Pinus contorta and Populus tremuloides are thin-barked and readily killed by fire, and both are fire-adapted species that generally need disturbance to establish and maintain dominance in a forest. These mixed forests are seral and, in the absence of stand-replacing disturbance such as fire, will slowly convert to a Pinus contorta-dominated forest and then eventually to a Picea engelmannii - Abies lasiocarpa-dominated forest if subalpine or a Pseudotsuga menziesii-dominated forest if montane (Mueggler 1988). Most of the stands sampled by Mueggler (1988) had a history of livestock grazing as evidenced by relative abundance of the exotic plants Taraxacum officinale and Poa pratensis and the scarcity of grazing-susceptible plants (Mueggler 1988).
Environmental Description: Elevations range above 1700-3000 m. Climate is temperate with cold winters. Mean annual precipitation is greater than 38 cm and typically greater than 50 cm. Sites occur on gentle to steep slopes on all aspects. Soils are derived from alluvium and colluvium from sedimentary, metamorphic and igneous parent materials. However, stands are found mainly on sandstone and quartzite.
Geographic Range: Forests included in this alliance are scattered in the mountains and plateaus of Utah, Wyoming, and Idaho, and may occur elsewhere in the western United States where both Populus tremuloides and Pinus contorta are common.
Nations: US
States/Provinces: CO, ID, UT, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.898991
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: equivalent to A.424
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Aspen: 217 (Eyre 1980)
>< Lodgepole Pine: 218 (Eyre 1980)
>< Lodgepole Pine: 218 (Eyre 1980)
- 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.
- Mueggler, W. F. 1988. Aspen community types of the Intermountain Region. General Technical Report INT-250. USDA Forest Service, Intermountain Research Station, Ogden, UT. 135 pp.