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G219 Picea engelmannii - Abies lasiocarpa - Pinus contorta Dry-Mesic Forest & Woodland Group

Type Concept Sentence: This group consists of matrix forests of the drier sites within the subalpine zone of the Cascades and Rocky Mountains with Picea engelmannii and Abies lasiocarpa dominating either mixed or alone. These forests often represent the highest elevation forests in an area, and the relatively xeric understory species are diagnostic.

Common (Translated Scientific) Name: Engelmann Spruce - Subalpine Fir - Lodgepole Pine Dry-Mesic Forest & Woodland Group

Colloquial Name: Rocky Mountain Subalpine Dry-Mesic Spruce - Fir Forest & Woodland

Hierarchy Level:  Group

Type Concept: Engelmann spruce and subalpine fir forests comprise a substantial part of the subalpine forests of the Cascades and Rocky Mountains from southern British Columbia east into Alberta, and south into New Mexico and the Intermountain West region. They also occur on mountain "islands" of north-central Montana. They are the matrix forests of the subalpine zone, with elevations ranging from 1275 m in its northern distribution to 3355 m in the south (4100-11,000 feet). Despite their wide distribution, the tree canopy characteristics are remarkably similar, with Picea engelmannii and Abies lasiocarpa dominating either mixed or alone. Pseudotsuga menziesii may persist in occurrences of this group for long periods without regeneration. Pinus contorta is common in many occurrences, and patches of pure Pinus contorta are not uncommon, as well as mixed conifer/Populus tremuloides stands. In some areas, such as Wyoming, Picea engelmannii-dominated forests are on limestone or dolomite, while nearby codominated spruce-fir forests are on granitic or volcanic rocks. Upper elevation examples may have more woodland physiognomy, and Pinus albicaulis or Pinus flexilis can be a seral component. Relatively xeric understory species are diagnostic of this group and may include Amelanchier alnifolia, Juniperus communis, Mahonia repens, Physocarpus malvaceus, Shepherdia canadensis, Vaccinium myrtillus, or Vaccinium scoparium. In the Bighorn Mountains, Artemisia tridentata is a common shrub. These forests often represent the highest elevation forests in an area. Sites within this group are cold year-round, and precipitation is predominantly in the form of snow, which may persist until late summer. Snowpacks are deep and late-lying, and summers are cool. Frost is possible almost all summer and may be common in restricted topographic basins and benches. Disturbance includes occasional blowdown, insect outbreaks and stand-replacing fire. Mean return interval for stand-replacing fire is 222 years as estimated in southeastern British Columbia.

Diagnostic Characteristics: These subalpine forests and woodlands are characterized by diagnostic subalpine trees Picea engelmannii, Abies lasiocarpa, and sometimes with Pinus contorta with dry to mesic understory shrub species such as Juniperus communis, Mahonia repens, or Vaccinium scoparium. [expand list of diagnostic shrubs and herbs?]

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: What have been called "ribbon forests" or "tree islands" by some authors [citations?] are included in this group; they can be found at upper treeline in many areas of the Rockies, including the central and northern ranges in Colorado and the Medicine Bow and Bighorn ranges of Wyoming. These are more typically islands or ribbons of trees within open-meadow areas. These patterns are controlled by deposition of windblown snow where deep drifts prevent trees from establishing. The relationship of G218 and G219 may be complicated, given that they are wide-ranging groups, and it could be very hard to cleanly place associations into each group, floristically and geographically.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This group is composed of needle-leaved evergreen forests and woodlands dominated by tall (>30 m) trees. Canopy is generally closed to moderately open.

Floristics: This forest and woodland group has a tree canopy typically dominated by Picea engelmannii and Abies lasiocarpa, either mixed or alone, with a xeric understory species. Pseudotsuga menziesii may persist in occurrences of this group for long periods without regeneration. Pinus contorta is common in many occurrences, and patches of pure Pinus contorta are not uncommon, as well as mixed conifer/Populus tremuloides stands. In some areas, such as Wyoming, Picea engelmannii-dominated forests are on limestone or dolomite, while nearby codominated spruce-fir forests are on granitic or volcanic rocks. Upper elevation examples may have more woodland physiognomy, and Pinus albicaulis or Pinus flexilis can be a seral component. Xeric understory species may include shrubs and dwarf-shrubs such as Jamesia americana, Juniperus communis, Mahonia repens, Physocarpus malvaceus, Ribes inerme, Rubus parviflorus, Shepherdia canadensis, Vaccinium cespitosum, and Vaccinium scoparium. In the Bighorn Mountains, Artemisia tridentata is a common shrub. Vaccinium myrtillus occurs both on dry and mesic sites. More northern occurrences often have taller, more mesic shrub and herbaceous species such as Empetrum nigrum. Dry to mesic herbaceous species that are characteristic of this group include Arnica cordifolia, Arnica latifolia, Calamagrostis rubescens, Carex geyeri, Carex rossii, Carex siccata, Leymus triticoides, and near alpine elevation Geum rossii and Trifolium dasyphyllum. Mosses may also dominate the understory without significant cover of vascular plants.

Dynamics:  Picea engelmannii can be very long-lived, reaching 500 years of age. Abies lasiocarpa decreases in importance relative to Picea engelmannii with increasing distance from the region of Montana and Idaho where maritime air masses influence the climate. Disturbance includes occasional blowdown, insect outbreaks and fire. Fire is an important disturbance factor, but fire regimes have a long return interval and so are often stand-replacing. Mean return interval for stand-replacing fire is 222 years as estimated in southeastern British Columbia. Picea engelmannii can rapidly recolonize and dominate burned sites, or can succeed other seral species such as Pinus contorta or Populus tremuloides. Due to great longevity, Pseudotsuga menziesii may persist in occurrences of this group for long periods without regeneration. Old-growth characteristics in Picea engelmannii forests will include treefall and windthrow gaps in the canopy, with large downed logs, rotting woody material, tree seedling establishment on logs or on mineral soils unearthed in root balls, and snags [citations?].
Environmental Description:  Engelmann spruce and subalpine fir forests comprise a substantial part of the subalpine forests of the Cascades and Rocky Mountains from southern British Columbia east into Alberta, and south into New Mexico and the Intermountain West region. They also occur on mountain "islands" of north-central Montana. They are the matrix forests of the subalpine zone, with elevations ranging from 1275 m in its northern distribution to 3355 m in the south (4100-11,000 feet). They often represent the highest elevation forests in an area. Sites within this group are cold year-round, and precipitation is predominantly in the form of snow, which may persist until late summer. Snowpacks are deep and late-lying, and summers are cool. Frost is possible almost all summer and may be common in restricted topographic basins and benches. In some areas, such as Wyoming, these forests are on limestone or dolomite, while nearby forests are on granitic or volcanic rocks. Stands found at upper treeline in many areas of the Rockies, including the central and northern ranges in Colorado and the Medicine Bow and Bighorn ranges of Wyoming, are more typically islands or ribbons of trees, sometimes with a krummholz form, with open-meadow areas in a mosaic. These patterns are controlled by snow deposition and wind-blown ice. Climate: Sites within this group are cold year-round, and precipitation is predominantly in the form of snow, which may persist until late summer. Snowpacks are deep and late-lying, and summers are cool. Frost is possible almost all summer and may be common in restricted topographic basins and benches.
Geographic Range: This group is found in the eastern Cascades and throughout the Rocky Mountains from southern interior British Columbia east into Alberta, south into New Mexico and the Intermountain West region. This type tends to be very limited in the northern Oregon Cascades.

Nations: CA,US

States/Provinces:  AB, AZ, BC, CO, ID, MT, NM, NV, OR, UT, WA, WY


Confidence Level: Moderate

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.b Engelmann Spruce - Subalpine Fir - Lodgepole Pine Dry-Mesic Forest & Woodland Group G219 1.B.2.Nb.5.b
Alliance A3641 Subalpine Fir - Engelmann Spruce Southern Rocky Mountain Dry-Mesic Forest Alliance A3641 1.B.2.Nb.5.b
Alliance A3642 Subalpine Fir - Engelmann Spruce Treeline Dry-Mesic Forest Alliance A3642 1.B.2.Nb.5.b
Alliance A3643 Subalpine Fir - Engelmann Spruce Rocky Mountain Dry-Mesic Forest Alliance A3643 1.B.2.Nb.5.b
Alliance A3644 Subalpine Fir - Engelmann Spruce Dry-Mesic Scree & Talus Woodland Alliance A3644 1.B.2.Nb.5.b
Alliance A3645 Subalpine Fir - Quaking Aspen Rocky Mountain Dry-Mesic Forest Alliance A3645 1.B.2.Nb.5.b
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: < EF Engelmann Spruce - Sub-alpine Fir Dry Forested (Ecosystems Working Group 1998) [Dry Grouseberry/Crowberry sites, Azalea/Rhododendron sites in ESSFdv dv1 dv2 xc 3 xc4 xv1 xv2]
< Engelmann Spruce - Subalpine Fir: 206 (Eyre 1980)
Concept Author(s): F.H. Eyre (1980)

Author of Description: K.A. Schulz

Acknowledgements: D. Tart

Version Date: 10-08-13
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