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G222 Populus tremuloides Rocky Mountain Forest & Woodland Group
Type Concept Sentence: This group consists of upland forests dominated by Populus tremuloides without significant conifer cover and an understory structure of complex multiple shrub and herbaceous layers, or simply just an herbaceous layer. It is widespread in the southern and central Rocky Mountains but occurs in the montane and subalpine zones throughout much of the western U.S., south into northern Mexico and north into Canada.
Common (Translated Scientific) Name: Quaking Aspen Rocky Mountain Forest & Woodland Group
Colloquial Name: Rocky Mountain Subalpine-Montane Aspen Forest & Woodland
Hierarchy Level: Group
Type Concept: This widespread group is more common in the southern and central Rocky Mountains but occurs in the montane and subalpine zones throughout much of the western U.S., south into northern Mexico and north into Canada. An eastern extension occurs along the Rocky Mountains foothill front, in mountain "islands" in Montana (Big Snowy and Highwood mountains), and the Black Hills of South Dakota. In California, this group is in the Sierra Nevada adjacent to the Great Basin. Large stands are found in the Inyo and White mountains, while small stands occur on the Modoc Plateau. Elevations generally range from 1525 to 3050 m (5000-10,000 feet), but occurrences can be found at lower elevations in some regions. Distribution of this group is primarily limited by adequate soil moisture required to meet its high evapotranspiration demand. Secondarily, it is limited by the length of the growing season or low temperatures. These are upland forests and woodlands dominated by Populus tremuloides without a significant conifer component (<25% relative tree cover). The understory structure may be complex with multiple shrub and herbaceous layers, or simple with just an herbaceous layer. The herbaceous layer may be dense or sparse, dominated by graminoids and/or forbs. Associated shrub species include Symphoricarpos spp. (Symphoricarpos oreophilus being the most widespread and Symphoricarpos albus and Symphoricarpos mollis having limited distribution), Rubus parviflorus, Amelanchier alnifolia, Prunus virginiana, and Arctostaphylos uva-ursi.
Diagnostic Characteristics: Open to dense canopies of broad-leaved deciduous trees dominated by Populus tremuloides. It has Rocky Mountain floristics associated with it, as opposed to boreal floristics. The herbaceous layer may be dense or sparse, dominated by graminoids or forbs. Common shrubs include Acer glabrum, Amelanchier alnifolia, Artemisia tridentata, Juniperus communis, Prunus virginiana, Rosa woodsii, Rhamnus alnifolia, Lonicera utahensis, Shepherdia canadensis, Symphoricarpos oreophilus, and the dwarf-shrubs Mahonia repens and Vaccinium spp. The herbaceous layers may be lush and diverse. Common graminoids may include Bromus carinatus, Calamagrostis rubescens, Carex siccata, Carex geyeri, Carex rossii, Elymus glaucus, Elymus trachycaulus, Festuca thurberi, and Hesperostipa comata. Associated forbs may include Achillea millefolium, Eucephalus engelmannii, Delphinium spp., Aconitum columbianum, Geranium viscosissimum, Heracleum sphondylium, Ligusticum filicinum, Lupinus argenteus, Osmorhiza berteroi, Pteridium aquilinum, Rudbeckia occidentalis, Thalictrum fendleri, Valeriana occidentalis, Wyethia amplexicaulis, and many others.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This group differs from ~Northwestern Great Plains Aspen Woodland Group (G328)$$, which is limited to plains environments. The scattered occurrences in the Trans-Pecos of Texas are of interest as they represent disjunct outliers of the type occurring under highly limited circumstances. In Alberta and interior British Columbia, these forests transition to ~Alaskan Boreal Dry Aspen Forest Group (G349)$$. Associations where aspen is mixed with one or more Rocky Mountain conifers in the canopy, or even in the undergrowth, are placed into their respective conifer forest groups (e.g., into a spruce-fir group, or a mixed montane conifer group). Typically, in those associations, the floristics and species richness are more similar to conifer forest groups, than to the aspen group.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Occurrences typically have a somewhat closed canopy of trees 5-20 m tall that is dominated by the cold-deciduous, broad-leaved tree Populus tremuloides. Conifers my contribute up to 15% of the canopy cover. The open-spaced stems of Populus tremuloides often give way to a lush understory consisting of complex multiple shrub and herbaceous layers, or just an herbaceous layer.
Floristics: Occurrences have a somewhat closed canopy of trees of 5-20 m tall that is dominated by the cold-deciduous, broad-leaved tree Populus tremuloides. Conifers that may be present but typically in minor amounts include Abies concolor, Abies lasiocarpa, Picea engelmannii, Picea pungens, Pinus contorta, Pinus ponderosa, and Pseudotsuga menziesii. Conifer species may contribute up to 15% of the tree canopy before the occurrence is reclassified as a mixed occurrence. Because of the open growth form of Populus tremuloides, enough light can penetrate for lush understory development. Depending on available soil moisture and other factors such as disturbance, the understory structure may be complex with multiple shrub and herbaceous layers, or simple with just an herbaceous layer. The herbaceous layer may be dense or sparse, dominated by graminoids or forbs. Common shrubs include Acer glabrum, Amelanchier alnifolia, Artemisia tridentata, Juniperus communis, Prunus virginiana, Rosa woodsii, Rhamnus alnifolia, Lonicera utahensis, Shepherdia canadensis, Symphoricarpos oreophilus, and the dwarf-shrubs Mahonia repens and Vaccinium spp. The herbaceous layers may be lush and diverse. Common graminoids may include Bromus carinatus, Calamagrostis rubescens, Carex siccata (= Carex foenea), Carex geyeri, Carex rossii, Elymus glaucus, Elymus trachycaulus, Festuca thurberi, and Hesperostipa comata. Associated forbs may include Achillea millefolium, Eucephalus engelmannii (= Aster engelmannii), Delphinium spp., Aconitum columbianum, Geranium viscosissimum, Heracleum sphondylium, Ligusticum filicinum, Lupinus argenteus, Osmorhiza berteroi (= Osmorhiza chilensis), Pteridium aquilinum, Rudbeckia occidentalis, Thalictrum fendleri, Valeriana occidentalis, Wyethia amplexicaulis, and many others. In California, Symphyotrichum spathulatum (= Aster occidentalis) is a common forb. Exotic grasses such as the perennials Poa pratensis and Bromus inermis and the annual Bromus tectorum are often common in occurrences due to grazing disturbance.
Dynamics: Occurrences in this group often originate from, and are likely maintained by, stand-replacing disturbances such as avalanche, crownfire, disease and windthrow, or clearcutting by man or flooding by beaver. The stems of these thin-barked, clonal trees are easily killed by surface fires, but they can quickly and vigorously resprout in densities of up to 30,000 stems per hectare (Knight 1994). The stems are relatively short-lived (100-150 years), and the occurrences often succeed to longer-lived conifer forest if undisturbed. Occurrences are favored by fire in the conifer zone (Mueggler 1988). With adequate disturbance, a clone may live many centuries. Although Populus tremuloides produces abundant seeds, seedling survival is rare because the long moist conditions required to establish them are rare in the habitats where they occur. Superficial soil drying will kill seedlings (Knight 1994).
Environmental Description: Topography is variable; sites range from level to steep slopes. Aspect varies according to the limiting factors. Occurrences at high elevations are restricted by cold temperatures and are found on warmer southern aspects. At lower elevations, occurrences are restricted by lack of moisture and are found on cooler north aspects and mesic microsites.
Climate: Climate is temperate with a relatively long growing season, typically cold winters and deep snow. Mean annual precipitation is greater than 38 cm (15 inches) and typically greater than 51 cm (20 inches), except in semi-arid environments where occurrences are restricted to mesic microsites such as seeps or where large snow drifts develop. Distribution of this group is primarily limited by adequate soil moisture required to meet its high evapotranspiration demand (Mueggler 1988). Secondarily, its range is limited by the length of the growing season or low temperatures (Mueggler 1988).
Soil/substrate/hydrology: The soils are typically deep and well-developed with rock often absent from the soil. Soil texture ranges from sandy loam to clay loam. Parent materials are variable and may include sedimentary, metamorphic or igneous rocks, but it appears to grow best on limestone, basalt, and calcareous or neutral shales (Mueggler 1988).
Climate: Climate is temperate with a relatively long growing season, typically cold winters and deep snow. Mean annual precipitation is greater than 38 cm (15 inches) and typically greater than 51 cm (20 inches), except in semi-arid environments where occurrences are restricted to mesic microsites such as seeps or where large snow drifts develop. Distribution of this group is primarily limited by adequate soil moisture required to meet its high evapotranspiration demand (Mueggler 1988). Secondarily, its range is limited by the length of the growing season or low temperatures (Mueggler 1988).
Soil/substrate/hydrology: The soils are typically deep and well-developed with rock often absent from the soil. Soil texture ranges from sandy loam to clay loam. Parent materials are variable and may include sedimentary, metamorphic or igneous rocks, but it appears to grow best on limestone, basalt, and calcareous or neutral shales (Mueggler 1988).
Geographic Range: This group is more common in the southern and central Rocky Mountains but occurs in the montane and subalpine zones throughout much of the western U.S., south into northern Mexico and north into Canada. An eastern extension occurs along the Rocky Mountains foothill front, in mountain "islands" in Montana (Big Snowy and Highwood mountains), and the Black Hills of South Dakota. In California, this group is in the Sierra Nevada adjacent to the Great Basin. Large stands are found in the Inyo and White mountains, while small stands occur on the Modoc Plateau. Very small occurrences may be found in a few scattered locations of the Trans-Pecos of Texas.
Nations: CA,MX,US
States/Provinces: AB, AZ, BC, CA, CO, ID, MT, ND, NM, NV, OR, SD, TX, UT, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.835793
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.B Temperate & Boreal Forest & Woodland Subclass | S15 | 1.B |
| Formation | 1.B.2 Cool Temperate Forest & Woodland Formation | F008 | 1.B.2 |
| Division | 1.B.2.Nb Rocky Mountain Forest & Woodland Division | D194 | 1.B.2.Nb |
| Macrogroup | 1.B.2.Nb.5 Subalpine Fir - Engelmann Spruce - Whitebark Pine Rocky Mountain Forest Macrogroup | M020 | 1.B.2.Nb.5 |
| Group | 1.B.2.Nb.5.d Quaking Aspen Rocky Mountain Forest & Woodland Group | G222 | 1.B.2.Nb.5.d |
| Alliance | A2036 Quaking Aspen Rocky Mountain Forest & Woodland Alliance | A2036 | 1.B.2.Nb.5.d |
| Alliance | A3367 Paper Birch Rocky Mountain Forest & Woodland Alliance | A3367 | 1.B.2.Nb.5.d |
| Alliance | A3371 Bigtooth Maple Montane Forest Alliance | A3371 | 1.B.2.Nb.5.d |
| Alliance | A4078 Quaking Aspen Southern Rocky Mountain Woodland & Scrub Alliance | A4078 | 1.B.2.Nb.5.d |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: < Aspen Woodland (411) (Shiflet 1994)
< Aspen: 217 (Eyre 1980)
> Douglas-fir-White Fir (=Mixed Conifer) Series, Populus tremuloides subclimax Association - 122.314 (Brown et al. 1979)
> Engelmann Spruce-Alpine Fir Series, Populus tremuloides subclimax Association - 121.316 (Brown et al. 1979)
> Pine Series, Populus tremuloides subclimax Association - 122.326 (Brown et al. 1979)
< Aspen: 217 (Eyre 1980)
> Douglas-fir-White Fir (=Mixed Conifer) Series, Populus tremuloides subclimax Association - 122.314 (Brown et al. 1979)
> Engelmann Spruce-Alpine Fir Series, Populus tremuloides subclimax Association - 121.316 (Brown et al. 1979)
> Pine Series, Populus tremuloides subclimax Association - 122.326 (Brown et al. 1979)
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