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A0631 Larix lyallii Woodland Alliance
Type Concept Sentence: Vegetation within this alliance is defined by short-statured canopies of Larix lyallii found scattered through high-altitude habitats of the northern Rocky Mountains from central Idaho through northwestern Montana to the vicinity of Lake Louise, Alberta, Canada.
Common (Translated Scientific) Name: Subalpine Larch Woodland Alliance
Colloquial Name: Subalpine Larch Woodland
Hierarchy Level: Alliance
Type Concept: Vegetation within this alliance is found scattered through high-altitude habitats of the northern Rocky Mountains from central Idaho through northwestern Montana to the vicinity of Lake Louise, Alberta, Canada. A second, smaller distribution occurs on the eastern slope of the northern Cascades, from near Wenatchee, Washington, north into the mountains of southern British Columbia. Larix lyallii often occurs in pure stands, sometimes with variable amounts of Abies lasiocarpa also present to codominant. Other conifers that may be present include Pinus albicaulis or Picea engelmannii. These latter species are often at their upper elevational limits when found in stands of this alliance. In the Cascade Range, this alliance may grade into forests of Tsuga mertensiana. Understories are diverse in form, due to a variety of habitats within the range of this alliance. Common shrubs throughout the range of Larix lyallii-dominated woodlands include Phyllodoce empetriformis, Vaccinium deliciosum, and Vaccinium scoparium. Arnica latifolia and Luzula glabrata var. hitchcockii are common, widespread herbaceous associates. Adjacent vegetation is often alpine tundra or permanent snowfields at the upper elevation margin and coniferous forest (usually Tsuga mertensiana-dominated in the Cascades, Abies lasiocarpa-dominated in the northern Rockies) at the lower margin. At similar elevations, stands of Pinus albicaulis may occur on adjacent south-facing slopes or ridges with lower snow accumulations and seasonal soil drought. Stands usually occur above the upper limits of other trees on north-facing cirques or slopes where snowfields lie until June or July. Elevation ranges from 2000-2800 m, and frost may occur any time of the year. The climate is very snowy and moist with yearly snow accumulations of over 3 m in the northern Cascades and 2-3 m in the Rockies. Abrasion by wind-driven snow is characteristic and leads to stunted or flagged trees in most stands. Soils are poorly developed and almost exclusively of fractured granitic or quartzite rocks which have not been previously colonized by other vascular plants. The majority of sites where stands of this alliance occur are in areas which experienced heavy alpine glaciation less than 12,000 years ago.
Diagnostic Characteristics: This alliance is characterized by open stands of Larix lyallii which may occur purely or mixed with other conifer species. Trees may be dwarfed or even prostrate. The understory is defined by heath species with affinities for harsh conditions. Sites are windswept and yearly snow accumulation may be substantial.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: ~Larix lyallii - Abies lasiocarpa Forest [Placeholder] (CEGL000521)$$ is a very broadly defined type that represents several associations. Little work has been done to identify upper subalpine or krummholz plant associations in Montana, and Pfister et al. (1977) did not identify any associations within this alliance.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Stands of this alliance are characterized by an open to nearly closed canopy of a winter-deciduous, needle-leaved conifer which is often less than 15 m in height, but which may approach 25 m in protected locations. The shrub and herbaceous layers are generally sparse, but may contain scattered ericaceous dwarf-shrubs (<0.5 m) or graminoids in moist swales. Bare mineral substrate is common in many stands.
Floristics: Vegetation within this alliance often occurs in pure stands, but other conifers may be present, including Abies lasiocarpa, Picea engelmannii, or Pinus albicaulis. These latter species are often at their upper elevational limits when found in stands of this alliance. In the Cascades, this alliance may grade into forests of Tsuga mertensiana. Understories are diverse in form, due to a variety of habitats within the range of this alliance. Common shrubs throughout the range of Larix lyallii-dominated woodlands include Phyllodoce empetriformis, Vaccinium deliciosum, Vaccinium membranaceum, and Vaccinium scoparium. Arnica latifolia and Luzula glabrata var. hitchcockii (= Luzula hitchcockii) are common and widespread herbaceous associates. Adjacent vegetation is often alpine tundra or permanent snowfields.
Dynamics: Larix lyallii is a very slow-growing, long-lived tree, with individuals attaining up to 1000 years in age, and may outlive several generations of Abies lasiocarpa. It is generally intolerant of shade from other trees, but extreme environmental conditions limit competition in upper elevation stands. At lower elevations, shade-tolerant Abies lasiocarpa assumes canopy dominance in the absence of disturbance. For Larix lyallii, reproduction is typically by seed and is most favorable on moist mineral soil. Seedling growth is initially very slow and accelerates after an extensive root system becomes established. Major disturbances to stands of this alliance are typically windthrow and snow avalanches. Lightning damage to individual trees is common, but sparse canopies, cool, moist habitats, and rocky terrain serve to limit the spread of fire in upper elevation stands. Lower elevation stands may be colonized by Pinus contorta after fire.
Environmental Description: These forests and woodlands occur in high-elevation treeline habitats of the northern Rockies and northeastern Cascade Range extending into Canada. Stands of this alliance usually occur above the upper limits of other trees on north-facing cirques or slopes where snowfields lie until June or July. Elevation ranges from 2000-2800 m, and frost may occur any time of the year. It occurs on slopes of all degrees of inclination, with moderate to steep (30-70%) lee slopes (east- and north-facing) predominating. The climate is very snowy and moist with yearly snow accumulations of over 3 m in the northern Cascades and 2-3 m in the Rockies. Abrasion by wind-driven snow is characteristic and leads to stunted or flagged trees in most stands. Soils are poorly developed and almost exclusively of fractured granitic or quartzite rocks which have not been previously colonized by other vascular plants. The majority of sites where stands of this alliance occur are in areas which experienced heavy alpine glaciation less than 12,000 years ago.
Geographic Range: Vegetation within this alliance is found scattered through high-altitude habitats of the northern Rocky Mountains from central Idaho through northwestern Montana to the vicinity of Lake Louise, Alberta, Canada. A second, smaller distribution occurs on the eastern slope of the northern Cascade Range, from near Wenatchee, Washington, north into the mountains of southern British Columbia.
Nations: CA,US
States/Provinces: AB, BC, ID, MT, WA
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899006
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.g Whitebark Pine - Subalpine Fir - Subalpine Larch Northern Rocky Mountain Woodland Group | G223 | 1.B.2.Nb.5.g |
| Alliance | A0631 Subalpine Larch Woodland Alliance | A0631 | 1.B.2.Nb.5.g |
| Association | CEGL000623 Subalpine larch Woodland | CEGL000623 | 1.B.2.Nb.5.g |
| Association | CEGL000951 Subalpine Larch / Grouse Whortleberry / Smooth Woodrush Woodland | CEGL000951 | 1.B.2.Nb.5.g |
| Association | CEGL000952 Subalpine Larch / Cascade Bilberry Woodland | CEGL000952 | 1.B.2.Nb.5.g |
| Association | CEGL005884 Subalpine Larch / Thinleaf Huckleberry / Smooth Woodrush Woodland | CEGL005884 | 1.B.2.Nb.5.g |
Concept Lineage: A.421, A.631
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: ? Larix lyallii - Abies lasiocarpa Habitat Types (Pfister et al. 1977)
? Larix lyallii Series (Lillybridge et al. 1995)
>< Engelmann Spruce - Subalpine Fir: 206 (Eyre 1980)
? Larix lyallii Series (Lillybridge et al. 1995)
>< Engelmann Spruce - Subalpine Fir: 206 (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.
- Lillybridge, T. R., B. L. Kovalchik, C. K. Williams, and B. G. Smith. 1995. Field guide for forested plant associations of the Wenatchee National Forest. General Technical Report PNW-GTR-359. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. 335 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.