Community Field Guide
Scientific Name:
Abies lasiocarpa / Ribes (montigenum, lacustre, inerme) Forest
Common Name:
Subalpine fir / gooseberry Forest
Community Description
Summary:
Throughout the northern portion of its range, Montana east of the Continental Divide, central Idaho and throughout Wyoming’ s isolated ranges, Abies lasiocarpa / Ribes montigenum forest is a small- to large-patch, minor community type; at the type’s austral extent in Utah it occurs as a major large patch and matrix community. It is found within the upper subalpine zone from 8,200 feet to timberline at its northwestern limits to 9,000 feet and higher in Utah’s Uintas, where most of the type occurs above 10,500 feet on vast plateaus. Most of the type is generally beyond the cold limit of Pseudotsuga, and well within an environment wherein Pinus albicaulis is an important seral component, though the tree component varies markedly with geographic region. Abies lasiocarpa and Picea engelmannii are capable of establishing directly and not preceded by seral trees. Thus they often co-dominate all seral stages and typify the long-term stable conditions as well. The undergrowth composition and cover also varies considerably by location; to the north the modal condition has Ribes montigenum present and the dominant shrub in depauperate undergrowth. This condition contrasts with the relatively lush and forb-rich undergrowth described from central and southern Utah, wherein Ribes montigenum is still the dominant and diagnostic shrub.
Environment: >Regardless of the region, this association is associated with upper subalpine habitats and usually it is found on northerly slopes. In the Centennial Range of Montana it has been noted as low as 7,500 feet on steep, north-facing slopes and extending to upper treeline (circa 9,600 feet) always on sites observed or inferred to receive abundant snow deposition followed by late meltoff. At upper elevations of its distribution Abies lasiocarpa / Ribes montigenum forest occurs on all aspects but seems to be consistently associated with slopes having late snow release. This association occurs on a wide variety of parent materials, apparently favoring none. If the information from Montana can be extrapolated, these high elevation sites develop very acidic soils. This type generally grades to Abies lasiocarpa / Arnica cordifolia, Abies lasiocarpa / Calamagrostis rubescens and Abies lasiocarpa / Carex geyeri at lower elevations, Abies lasiocarpa / Juniperus communis or Abies lasiocarpa / Mahonia repens on drier exposures and to Abies lasiocarpa / Vaccinium scoparium on more moist sites. At highest elevations groves of Abies lasiocarpa / Ribes montigenum (on north slopes or depressions) forms a mosaic with Artemisia tridentata var. vaseyana dominated shrublands, Festuca idahoensis dominated grasslands or graminoid-forb meadows of various composition.
This association is found between 2409-3415 m (7300-11,200 feet). @It occurs on plateaus, benchlands, and slopes ranging from gentle to very steep, but is normally on cold northwest to northeast aspects. The forest is often broken by large meadows occupying the deeper soils of gentle basins along drainage systems. These meadows may be fairly dry and dominated by Artemisia, or fairly moist and dominated by grass, forbs, and sedges (Pfister 1972). Because of its wide distribution and broad range of altitudes, this association is found on a variety of substrate types, but soils are derived primarily from calcareous parent materials (Cooper and Pfister 1985). Soils are weakly developed, usually with only a structural B horizon, and generally have high rock and gravel content with pH ranging from 4.8-7.2. All of the soils have low temperatures. Textures range from loamy sands to silty clays, gravel content averages 18% and the percentage of surface rock averages about 11% (Pfister 1972).<
Vegetation: >Only older or mature stands were sampled in the northern distribution of the type (Montana and Idaho). From their structure it appears that the early seral tree species are Pinus albicaulis and Abies lasiocarpa and to a much lesser degree Picea engelmannii. These species persist until and into the climax state. Pinus contorta and Pseudotsuga menziesii occur as “accidentals”. At sites above the cold limit of Pseudotsuga, but lacking Pinus contorta with stand break-up (heavy mortality in Pinus albicaulis and Abies lasiocarpa at 150 to 200 years, or older), a second flush of Abies lasiocarpa and Picea engelmannii is established. In this type’s southern representation a different successional sequence occurs, with Populus tremuloides and Pinus contorta often being the primary seral trees and Pseudotsuga being present according to the phase represented (see Dynamics section). Stands with closed canopies are quite depauperate with most of the diagnostic Ribes montigenum present encircling tree bases. However, with decreasing tree cover Ribes montigenum is well represented to abundant, usually in openings that appear to receive greater snow deposition than the majority of the stand. Forbs with a consistent presence across the range of the type include Pyrola secunda, Aquilegia flavescens, Osmorhiza chilensis and Arnica cordifolia. Undergrowth of the northern expressions of the type is almost invariably depauperate, whereas to the south, especially in Utah’s central and southern ranges, canopy cover can range upwards of 40% with forbs of mesic moisture regimes consistently present (for example Geranium richardsonii Mertensia ciliata, Mertensia arizonica, and Erigeron peregrinus). The higher elevations of the type are often used as sheep range, which may account for the greater than expected cover of Poa pratensis and lesser amounts of forbs.
This type is consistently dominated by Picea engelmannii and Abies lasiocarpa. Late successional stands may have a dominant overstory of Picea engelmannii possibly resulting, in part, from a reproductive advantage over Abies through exposure of mineral soil seedbeds by heavy grazing (Roe et al. 1970). Steele et al. (1981) note that Pinus albicaulis codominates with Abies lasiocarpa, with Picea becoming increasingly prevalent to the south and east. Both Abies and Picea are found layering in the understory (Cooper and Pfister 1985, Youngblood and Mauk 1985). Although an important early seral associate, Populus tremuloides is usually present in mature stands only as remnant stems of poor vigor. Pinus contorta is a minor seral species. This association is generally above the cold limits of Pseudotsuga, but the species does occur at lower elevations of the type. ^The shrub layer is sparse, with scattered clumps of Ribes montigenum, usually confined to near the base of large trees. Other shrubs, which may occur in openings or on recently disturbed areas, include Sambucus racemosa, Symphoricarpos oreophilus, and Shepherdia canadensis. The undergrowth is characteristically depauperate. Forbs with high constancies are Aquilegia caerulea, Arnica cordifolia, Arnica latifolia, Achillea millefolium, Astragalus miser, Chamerion angustifolium (= Epilobium angustifolium), Ligusticum porteri, Lupinus argenteus, Mertensia arizonica, Thalictrum fendleri, Thalictrum occidentale, Fragaria virginiana, Polemonium pulcherrimum, Pseudocymopterus montanus, Orthilia secunda (= Pyrola secunda), Frasera speciosa, Osmorhiza berteroi (= Osmorhiza chilensis), and Osmorhiza depauperata. Graminoids are weakly represented. Carex rossii is the only sedge encountered with any regularity. Under disturbed conditions, or in seral stands with incomplete conifer canopies, Lupinus argenteus, Lathyrus lanszwertii, Hymenoxys hoopesii (= Helenium hoopesii), Chamerion angustifolium, Aquilegia caerulea, and Achillea millefolium are expected to increase.<
Range:
The Abies lasiocarpa / Ribes montigenum association extends from the mountains and high plateaus of southern Utah, where it was first described (Pfister 1972) and is best developed. From there it ranges northward sporadically distributed across Wyoming to central Idaho and southern Montana’s high subalpine and eastward to north-central Colorado.
Dynamics: >The uneven-aged climax stand usually has abundant Abies lasiocarpa seedlings and saplings in addition to vegetative layering. Picea engelmannii is found on raised root mounds and depressions in the understory, resulting from windthrow of the shorter lived Abies lasiocarpa following root rot (Youngblood and Mauk 1985). Abies lasiocarpa is almost uniformly susceptible to decay by Fomes annosus, which increases the chances of windthrow. Stands of Abies may also become infected with yellow witches' broom rust, Melampsorella caryophyllacearum. Windthrow continually removes individuals or small groups of large-crowned old trees, allowing replacement of Populus, Abies, and Picea in the resultant openings. Devastation of old-growth Picea engelmannii overstories by the Engelmann spruce bark beetle (Dendroctonus rufipennis) creates sufficient disturbance to allow regeneration and release of all three tree species. The combination of these factors creates the characteristic all-aged structure of this type, in dynamic equilibrium with present environmental conditions and showing periodic fluctuations due to natural small-scale perturbations (Pfister 1972).
Evidence from stands burned by wildfire indicate that this type will be difficult to reforest and may persist as Artemisia tridentata ssp. vaseyana and bunchgrass-dominated communities (Cooper and Pfister 1985). However, according to Youngblood and Mauk (1985), following a major stand-destroying fire, remnant Populus tremuloides root systems resprout, creating clones. Invasion of Abies lasiocarpa follows, and saplings may develop quickly under this nurse crop of Populus tremuloides. Invasion of Picea is much slower and may be restricted to areas of bare soil. Pfister (1972) suggests this progression to a pure Abies-Picea climax, without further disturbance, may require at least 1000 years. <
Global Rank: G5 State Rank: S4
Community References
Identifier:
CEGL000331
Author:
L.D. Engelking, mod. 01-03-12 / S. V. Cooper, MTNHP
Citations:
Baker 1984a, Bourgeron and Engelking 1994, Cooper and Pfister 1985, Driscoll et al. 1984, Henderson et al. 1976, Henderson et al. 1977, Johnston 1987, Kettler and McMullen 1996, Kittel et al. 1994, Kittel et al. 1999, Langenheim 1962, Mauk and Henderson 1984, Peet 1975, Pfister 1972, Pfister et al. 1977, Shepherd 1975, Steele et al. 1981, Steele et al. 1983, Youngblood and Mauk 1985
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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
