Community Field Guide
Scientific Name:
Abies lasiocarpa / Calamagrostis canadensis Forest
Common Name:
Subalpine fir / bluejoint reedgrass Forest
Community Description
Summary:
This is a common, small patch to linearly configured wetland association found in mountainous terrain throughout the Intermountain West from Alberta south to Utah and Colorado. It is associated with sites that are temporarily flooded to saturated for extended periods during the growing season, these usually being toe-slopes at the base of long collecting inclines and subirrigated terraces of riparian corridors of moderate- to low-gradient streams/rivers or a pond-margin zone, usually well-removed from standing water. The tree canopy is usually moderately open to closed, co-dominated by Abies lasiocarpa and Picea (Picea engelmannii, Picea glauca X Picea engelmannii). Sites are sufficiently wet that seral tree species, with the exception of Pinus contorta are usually a minor component. The undergrowth cover, dominated by the diagnostic Calamagrostis canadensis, is ostensibly related to tree canopy cover with relatively open stands supporting Calamagrostis canadensis so tall and dense that ancillary undergrowth species are obscured. This type is widely distributed both geographically, and with respect to elevation range, there are regional expressions (expressed as phases in "habitat type" terminology) that vary considerably.
Environment:
This association has a very broad elevation distribution found as low as 3,600 feet to above 10,000 feet (5,000 feet range in Montana alone). It is usually confined to small (less than 5 acres) or linearly array areas that are poorly drained or sub-irrigated sites; surface water may be present during late spring and early summer. These sites often border on streams and wet- to moist-, Juncus or Carex dominated meadows. This type occurs on mountain slopes where impermeable layers direct water to the surface. In general the stand size of Abies lasiocarpa / Calamagrostis canadensis is smaller than can be delineated on 1:24,000 scale maps, except as inclusions or a component of a complex.
Vegetation: Calamagrostis canadensis (bluejoint reedgrass) and/or Calamagrostis stricta (narrow-spiked reedgrass) are considered indicator species for the type (in Montana, Hansen et al. 1995) and are the dominant graminoids, generally occurring with greater than 5% canopy cover and averaging around 30%. Senecio triangularis (alternate indicator species for this type in Montana [Hansen et al. 1995]), Veratrum viride, Trollius laxus, Streptopus amplexifolius, and Dodecatheon jeffreyi constitute the forbs of highest constancy associated with these wet sites. Thalictrum occidentale, Geranium richardsonii, and Arnica latifolia, generally associated with merely moist sites also have high constancy and may be well represented. Shrubs are a minor component except where Ribes lacustre, Ledum glandulosum, Vaccinium cespitosum and Vaccinium scoparium are abundantly representated on hummocks and raised areas surrounding tree bases; Vaccinium scoparium has high constancy throughout the association.
The cool, wet conditions restrict the tree flora to predominantly three species. Picea (including pure populations of Picea engelmannii, hybrid swarms of Picea engelmannii, and Picea glauca at least in Montana and northwestern Wyoming occurrences) is usually the dominant taxon in mature to old-growth stands and persists as a minor climax or co-climax species with Abies lasiocarpa. This type has been defined and described in “habitat type” manuals and Pinus contorta often is cited as the major seral species (stands younger, less than 100 to 120 years). Pinus albicaulis (whitebark pine) is a minor component associated with drier hummocks in higher elevation stands.
Range:
The subalpine fir / bluejoint reedgrass forest association is found in the Northern, Middle and Southern Rocky Mountains and outlying mountain ranges in the Interior West from Alberta south to Colorado.
Dynamics:
Seasonal flooding occurs in many stands of this community. In the Vaccinium cespitosum phase (Vaccinium cespitosum is well represented, indicating frost pocket environments) of this association climax tree species are slow to establish and stands are long-term dominated by Pinus contorta.
Global Rank: G5 State Rank: S5
Community References
Identifier:
CEGL000300
Author:
99-11-16 / S. V. Cooper, MTNHP
Citations:
Cooper and Cottrell 1990, Cooper et al. 1987, Hess and Alexander 1986, Johnston 1987, Kettler and McMullen 1996, Komarkova et al. 1988, Mauk and Henderson 1984, Osborn et al. 1998, Pfister et al. 1977, Richard et al. 1996, Steele et al. 1981, Steele et al. 1983
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This information is from the:
Montana Natural Heritage Program
Montana State Library--Natural Resource Information System
1515 East Sixth Ave., Helena, MT 59620-1800
406 444-3989
mtnhp.org
mtnhp@mt.gov
