Print Report

CEGL000344 Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium Forest

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Subalpine Fir - Engelmann Spruce / Grouse Whortleberry Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This widespread subalpine forest association occurs throughout the Rocky Mountains extending to the mountains in the eastern Cascades. Elevations range between 2590 and 3800 m (7760-12,500 feet) in Colorado to 1525-2590 m (5000-8500 feet) in Montana and 1005-1900 m (3300-6230 feet) in central Washington. This type is characterized by deep snowpack and brief, cool summers. Sites are relatively xeric and cold. Stands are common in the middle to upper subalpine zone. Soils are variable but are often shallow, rocky, well-drained, sandy loam (to sandy clay) soils derived from andesite, conglomerate, granite, quartzite, sandstone, shale, and various other rocks. Litter and duff and downed wood cover a significant portion of the ground surface. The vegetation is characterized by a moderately dense to dense conifer tree canopy codominated by Picea engelmannii and Abies lasiocarpa, with an understory characterized by a dwarf-shrub layer strongly dominated by Vaccinium scoparium. Pinus albicaulis or Pinus flexilis may be present in canopy of some stands. Pinus contorta, Populus tremuloides, and Larix occidentalis (northern stands) are the most common seral species, though Pseudotsuga menziesii may occur in lower elevation stands. In the understory, Vaccinium myrtillus may be present but is usually trace to less than half the cover of Vaccinium scoparium. Other shrubs may be present at low cover such as Lonicera involucrata, Lonicera utahensis, Mahonia repens, Paxistima myrsinites, Spiraea betulifolia, and Vaccinium membranaceum. Herbaceous species such as Arnica spp., Calamagrostis rubescens, Carex geyeri, Carex rossii, Chamerion angustifolium, Erigeron peregrinus, Erythronium grandiflorum, Eucephalus engelmannii, Hieracium gracile, Lupinus argenteus, Luzula parviflora, Orthilia secunda, Poa nervosa, Pedicularis racemosa, Polemonium pulcherrimum, Orthilia secunda, Thalictrum occidentale, and Trisetum spicatum are commonly present with low cover values.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: No Data Available

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This conifer forest association has a moderately dense to dense tree canopy codominated by Picea engelmannii and Abies lasiocarpa, with an understory characterized by a dwarf-shrub layer dominated by Vaccinium scoparium. Pinus albicaulis or Pinus flexilis may be present in the canopy of some stands. Pinus contorta, Populus tremuloides, and Larix occidentalis (northern stands) are the most common seral species, though Pseudotsuga menziesii may occur in lower elevation stands. In the understory, Vaccinium myrtillus may be present but is usually trace to less than half the cover of Vaccinium scoparium. Other shrubs may be present at low cover such as Lonicera involucrata, Lonicera utahensis, Mahonia repens, Paxistima myrsinites, Spiraea betulifolia, and Vaccinium membranaceum. Herbaceous species such as Arnica cordifolia, Arnica latifolia, Calamagrostis rubescens, Carex geyeri, Carex rossii, Chamerion angustifolium, Erigeron peregrinus, Erythronium grandiflorum, Eucephalus engelmannii, Hieracium gracile, Lupinus argenteus, Luzula parviflora, Orthilia secunda, Poa nervosa, Pedicularis racemosa, Polemonium pulcherrimum, Orthilia secunda (= Pyrola secunda), Thalictrum occidentale, and Trisetum spicatum are commonly present with low cover values.

Dynamics:  No Data Available
Environmental Description:  This widespread subalpine forest association occurs throughout the Rocky Mountains extending to the mountains in the eastern Cascades. Elevations range between 2590 and 3800 m (7760-12,500 feet) in Colorado to 1525-2590 m (5000-8500 feet) in Montana and 1005-1900 m (3300-6230 feet) in central Washington. This type is characterized by deep snowpack and brief, cool summers. Sites are relatively xeric and cold. Stands are common in the middle to upper subalpine zone. Soils are variable but are often shallow, rocky, well-drained, sandy loam (to sandy clay) soils derived from andesite, conglomerate, granite, quartzite, sandstone, shale, and various other rocks. Litter and duff and downed wood cover a significant portion of the ground surface.
Geographic Range: This subalpine forest association occurs throughout the Rocky Mountains and extends into the mountains in the eastern Cascades.

Nations: US

States/Provinces:  AZ?, CO, ID, MT, NM?, OR, UT, WA, WY


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G5

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 A3643 Subalpine Fir - Engelmann Spruce Rocky Mountain Dry-Mesic Forest Alliance A3643 1.B.2.Nb.5.b
Association CEGL000344 Subalpine Fir - Engelmann Spruce / Grouse Whortleberry Forest CEGL000344 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: >< Abies lasiocarpa - Picea engelmannii / Vaccinium myrtillus - Vaccinium scoparium Plant Association (Baker 1984a)
= Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium (Jones and Ogle 2000)
= Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium Forest (DiPaolo et al. 2018)
= Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium Plant Association (Johnston 1987)
= Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium Plant Association (Baker 1984a)
>< Abies lasiocarpa - Vaccinium scoparium Habitat Type, Phyllodoce empetriformis phase (McLean 1970)
? Abies lasiocarpa / Vaccinium scoparium (Lillybridge et al. 1995) [ABLA2/VASC WEN ASSOCIATION CES426]
= Abies lasiocarpa / Vaccinium scoparium Community Type (Cole 1982)
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Wasser and Hess 1982)
= Abies lasiocarpa / Vaccinium scoparium Habitat Type (Cooper 1975)
= Abies lasiocarpa / Vaccinium scoparium Habitat Type (Komarkova et al. 1988b)
= Abies lasiocarpa / Vaccinium scoparium Habitat Type (Mauk and Henderson 1984)
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Hess and Alexander 1986)
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Hoffman and Alexander 1983) [Includes seral Pinus contorta-dominated stands.]
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Hoffman and Alexander 1980) [Includes seral Pinus contorta-dominated stands.]
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Hoffman and Alexander 1976) [Includes seral Pinus contorta-dominated stands.]
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Daubenmire and Daubenmire 1968)
= Abies lasiocarpa / Vaccinium scoparium Habitat Type (Alexander et al. 1986)
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Steele et al. 1983) [Includes seral Pinus contorta-dominated stands.]
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Steele et al. 1981) [Includes seral Pinus contorta-dominated stands.]
< Abies lasiocarpa / Vaccinium scoparium Habitat Type (Pfister et al. 1977) [Includes seral Pinus contorta-dominated stands.]
= Abies lasiocarpa / Vaccinium scoparium Habitat Type/Association (Komarkova 1986)
< Abies lasiocarpa / Vaccinium scoparium Plant Association (Williams et al. 1995)
= Abies lasiocarpa / Vaccinium scoparium Plant Association (Johnson and Clausnitzer 1992)
< Abies lasiocarpa / Vaccinium scoparium Plant Association (Williams et al. 1990b) [Pinus contorta dominates overstory of most sampled stands.]
= Abies lasiocarpa / Vaccinium scoparium Plant Association (Johnson and Simon 1987)
< Abies lasiocarpa / Vaccinium scoparium Plant Association (Williams and Smith 1990) [Pinus contorta dominates overstory of most sampled stands.]
< Abies lasiocarpa / Vaccinium scoparium Plant Association (Williams and Lillybridge 1983) [Pinus contorta dominates overstory of most sampled stands.]
= Abies lasiocarpa / Vaccinium scoparium Plant Community (Hall 1973)
< Abies lasiocarpa / Vaccinium Habitat Type (DeVelice and Ludwig 1983a)
= Abies lasiocarpa-Picea engelmannii/Vaccinium scoparium Woodland (Crawford et al. 2009)
? Abies lasiocarpa/Vaccinium myrtillus (John et al. 1988)
< Picea engelmannii - Abies lasiocarpa / Vaccinium scoparium Habitat Type (Hess and Wasser 1982) [Vaccinium myrtillus occurs with Vaccinium scoparium in the dwarf-shrub layer.]
< Picea engelmannii / Vaccinium scoparium / Polemonium delicatum Habitat Type (Moir and Ludwig 1979) [Upper treeline type; Abies lasiocarpa is codominant is some stands.]
= Picea engelmannii / Vaccinium scoparium Habitat Type (Hess 1981)
< Spruce - Fir Climax Community (Harrington 1978)
< Xeric Picea, Abies Forest (E5) (Peet 1981)
< Xeric Picea, Abies Forest (E5) (Peet 1980)
Concept Author(s): Western Ecology Group

Author of Description: K.A. Schulz

Acknowledgements: No Data Available

Version Date: 07-18-05
  • Alexander, R. M. 1986. Classification of the forest vegetation of Wyoming. Research Note RM-466. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 10 pp.
  • Alexander, R. R., G. R. Hoffman, and J. M. Wirsing. 1986. Forest vegetation of the Medicine Bow National Forest in southeastern Wyoming: A habitat type classification. Research Paper No. RM-271. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.
  • Amundsen, C. C. 1967. The subalpine forest of Wild Basin, Front Range, Colorado. Unpublished dissertation, University of Colorado, Boulder. 129 pp.
  • Baker, W. L. 1984a. A preliminary classification of the natural vegetation of Colorado. Great Basin Naturalist 44(4):647-676.
  • Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
  • Boyce, D. A. 1977. Vegetation of the South Fork of the White River Valley, Colorado. Unpublished dissertation, University of Colorado, Boulder. 312 pp.
  • CNHP [Colorado Natural Heritage Program]. 2006-2017. Tracked natural plant communities. Colorado Natural Heritage Program, Colorado State University, Fort Collins. [https://cnhp.colostate.edu/ourdata/trackinglist/plant_communities/]
  • Cogan, D., K. Varga, and G. Kittel. 2005. USGS-NPS Vegetation Mapping Program: Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway. Final Project Report 2002-2005 Vegetation Mapping Project. Technical Memorandum 8260-06-02. USDI Bureau of Reclamation, Denver, CO. 87 pp. plus Appendixes A-F.
  • Cole, D. N. 1977b. Man''s impact on wilderness: An example from Eagle Cap Wilderness, northeastern Oregon. Ph.D. dissertation, Oregon State University, Corvallis. 307 pp.
  • Cole, D. N. 1982. Vegetation of two drainages in Eagle Cap Wilderness, Wallowa Mountains, Oregon. Research Paper INT-288. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 26 pp.
  • Cooper, S. V. 1975. Forest habitat types of northwestern Wyoming and contiguous portion of Montana and Idaho. Unpublished dissertation, Washington State University, Pullman. 190 pp.
  • Cooper, S. V., K. E. Neiman, R. Steele, and D. W. Roberts. 1987. Forest habitat types of northern Idaho: A second approximation. General Technical Report INT-236.USDA Forest Service, Intermountain Research Station, Ogden, UT. 135 pp. [reprinted in 1991]
  • Crawford, R. C., C. B. Chappell, C. C. Thompson, and F. J. Rocchio. 2009. Vegetation classification of Mount Rainier, North Cascades, and Olympic national parks. Plant association descriptions and identification keys: Appendices A-G. Natural Resource Technical Report NPS/NCCN/NRTR--2009/D-586. National Park Service, Fort Collins, CO. 586 pp.
  • Daubenmire, R. F., and J. B. Daubenmire. 1968. Forest vegetation of eastern Washington and northern Idaho. Washington State University Agricultural Experiment Station Technical Bulletin No. 60. 104 pp.
  • DeVelice, R. L. 1983. Forest vegetation of northern New Mexico and southern Colorado. Unpublished dissertation, New Mexico State University, Las Cruces. 191 pp.
  • DeVelice, R. L., and J. A. Ludwig. 1983a. Climax forest series of northern New Mexico and southern Colorado. Pages 45-53 in: Proceedings of the Workshop on Southwestern Habitat Types, 6-8 April 1983, Albuquerque, NM. USDA Forest Service, Southwest Region, Albuquerque, NM.
  • DiPaolo, D. A., D. C. Odion, K. M. Rolih, P. Adamus, and D. A. Sarr. 2018. Vegetation classification and mapping: Crater Lake National Park. Natural Resource Report NPS/CRLA/NRR--2018/1663. National Park Service, Fort Collins, CO. 550 pp.
  • Dix, R. L., and J. D. Richards. 1976. Possible changes in species structure of the subalpine forest induced by increased snowpack. Pages 311-322 in: Steinhoff and Ives, editors. Ecological impacts. Final Report, San Juan Ecology Project, Colorado State University, Fort Collins, CO. Prepared for USDI Bureau of Reclamation, Division of Atmos. Water Resource Management, Denver, Colorado.
  • Fritz, R. J. 1981. Alpine vegetational patterns around isolated tree islands on the eastern and western slopes of the Tenmile Range, Summit County, Colorado. Unpublished thesis, University of Colorado, Boulder, CO. 233 pp.
  • Giese, T. G. 1975. The ecology of the Middle Blue River Valley, Summit County, Colorado, with an analysis of modifications due to powerline construction. Unpublished thesis, University of Colorado, Boulder. 109 pp.
  • Hall, F. C. 1973. Plant communities of the Blue Mountains in eastern Oregon and southeastern Washington. R6 Area Guide 3-1. USDA Forest Service, Pacific Northwest Region, Portland, OR. 62 pp.
  • Harrington, F. A., Jr. 1978. Ecological segregation of ungulates in alpine and subalpine communities. Unpublished dissertation, Colorado State University, Fort Collins. 142 pp.
  • Hess, K. 1981. Phyto-edaphic study of habitat types of the Arapaho-Roosevelt National Forest, Colorado. Unpublished dissertation, Colorado State University, Fort Collins. 558 pp.
  • Hess, K., and C. H. Wasser. 1982. Grassland, shrubland, and forest habitat types of the White River-Arapaho National Forest. Unpublished final report 53-82 FT-1-19. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 335 pp.
  • Hess, K., and R. R. Alexander. 1986. Forest vegetation of the Arapaho and Roosevelt national forests in northcentral Colorado: A habitat type classification. Research Paper RM-266. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 48 pp.
  • Hoffman, G. R., and R. R. Alexander. 1976. Forest vegetation of the Bighorn Mountains, Wyoming: A habitat type classification. Research Paper RM-170. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 38 pp.
  • Hoffman, G. R., and R. R. Alexander. 1980. Forest vegetation of the Routt National Forest in northwestern Colorado: A habitat type classification. General Technical Report RM-221. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 41 pp.
  • Hoffman, G. R., and R. R. Alexander. 1983. Forest vegetation of the White River National Forest in western Colorado: A habitat type classification. Research Paper RM-249. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 36 pp.
  • John, T., D. Tart, and R. Clausnitzer. 1988. Forest associations of the Yakama Indian Reservation. Draft. Yakama Indian Nation. Toppenish, WA. 133 pp.
  • Johnson, C. G., Jr., and S. A. Simon. 1987. Plant associations of the Wallowa-Snake Province Wallowa-Whitman National Forest. Technical Paper R6-ECOL-TP-255A-86. USDA Forest Service, Pacific Northwest Region, Wallowa-Whitman National Forest. 399 pp. plus appendices.
  • Johnson, C. G., and R. R. Clausnitzer. 1992. Plant associations of the Blue and Ochoco mountains. R6-ERW-TP-036-92. USDA Forest Service, Pacific Northwest Region, Wallowa-Whitman National Forest. 163 pp. plus appendices.
  • Johnston, B. C. 1987. Plant associations of Region Two: Potential plant communities of Wyoming, South Dakota, Nebraska, Colorado, and Kansas. R2-ECOL-87-2. USDA Forest Service, Rocky Mountain Region. Lakewood, CO. 429 pp.
  • Jones, G. P., and W. Fertig. 1999d. Ecological evaluation of the potential Lake Creek Research Natural Area within the Shoshone National Forest, Park County, Wyoming. Prepared for the Shoshone National Forest, USDA Forest Service by the Wyoming Natural Diversity Database. 46 pp.
  • Jones, G., and S. Ogle. 2000. Characterization abstracts for vegetation types on the Bighorn, Medicine Bow, and Shoshone national forests. Prepared for USDA Forest Service, Region 2 by the Wyoming Natural Diversity Database, University of Wyoming.
  • Kagan, J. S., J. A. Christy, M. P. Murray, and J. A. Titus. 2004. Classification of native vegetation of Oregon. January 2004. Oregon Natural Heritage Information Center, Portland. 52 pp.
  • Klish, M. W. 1977. The vegetation of Summit County, Colorado Unpublished thesis, Colorado State University, Fort Collins. 103 pp.
  • Komarkova, V. 1986. Habitat types on selected parts of the Gunnison and Uncompahgre national forests. Unpublished final report prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station. Fort Collins, CO. 270 pp. plus appendices.
  • Komarkova, V. K., R. R. Alexander, and B. C. Johnston. 1988b. Forest vegetation of the Gunnison and parts of the Uncompahgre national forests: A preliminary habitat type classification. Research Paper RM-163. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 65 pp.
  • Langenheim, J. H. 1962. Vegetation and environmental patterns in the Crested Butte area, Gunnison County, Colorado. Ecological Monographs 32:249-285.
  • 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.
  • MTNHP [Montana Natural Heritage Program]. 2002b. List of ecological communities for Montana. Montana Natural Heritage Program, Montana State Library, Helena, MT.
  • Marr, J. W., D. Buckner, and C. Mutel. 1973a. Ecological analyses of potential shale oil products pipeline corridors in Colorado and Utah. Unpublished report prepared for Colony Development Operation, Atlantic Richfield Company, Denver, by Thorne Ecological Institute and University of Colorado, Boulder. 96 pp. plus appendices.
  • Mauk, R. L., and J. A. Henderson. 1984. Coniferous forest habitat types of northern Utah. General Technical Report INT-170. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 89 pp.
  • McLean, A. 1970. Plant communities of the Similkameen Valley, British Columbia, and their relationships to soils. Ecological Monographs 40(4):403-424.
  • Mills, R. C. 1962. A study of near climax conditions in a spruce-fir ecosystem. Unpublished thesis, University of Colorado, Boulder. 66 pp.
  • Moir, W. H., and J. A. Ludwig. 1979. A classification of spruce-fir and mixed conifer habitat types of Arizona and New Mexico. Research Paper RM-207. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 47 pp.
  • Peet, R. K. 1975. Forest vegetation of the east slope of the northern Colorado Front Range. Unpublished dissertation, Cornell University, Ithaca, NY.
  • Peet, R. K. 1980. Forest vegetation of the northern Colorado Front Range, USA: I. Community composition. Unpublished manuscript prepared for Cornell University, Ithaca, NY. 83 pp.
  • Peet, R. K. 1981. Forest vegetation of the Colorado Front Range. Vegetatio 45:3-75.
  • Pfister, R. D. 1972. Vegetation and soils in the subalpine forests of Utah. Unpublished dissertation, Washington State University, Pullman. 98 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.
  • Raven, K. A. 1948. Ecology of a timberline area in the Colorado Front Range. Unpublished thesis, University of Colorado, Boulder. 83 pp.
  • Reed, R. M. 1976. Coniferous forest habitat types of the Wind River Mountains, Wyoming. The American Midland Naturalist 95(1):159-173.
  • Salas, D., J. Stevens, and K. Schulz. 2005. USGS-NPS Vegetation Mapping Program: Rocky Mountain National Park, Colorado. Technical Memorandum No. 8260-05-02. USDI Bureau of Reclamation, Denver, CO. 161 pp. plus Appendices A-L (733 pp.).
  • Steele, R., R. D. Pfister, R. A. Ryker, and J. A. Kittams. 1981. Forest habitat types of central Idaho. General Technical Report INT-114. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 138 pp.
  • Steele, R., S. V. Cooper, D. M. Ondov, D. W. Roberts, and R. D. Pfister. 1983. Forest habitat types of eastern Idaho - western Wyoming. General Technical Report INT-144. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 122 pp.
  • Terwilliger, C., K. Hess, and C. Wasser. 1979a. Key to the preliminary habitat types of Region 2. Addendum to initial progress report for habitat type classification. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station. Fort Collins, CO.
  • WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.
  • WNHP [Washington Natural Heritage Program]. 2018. Unpublished data files. Washington Natural Heritage Program, Department of Natural Resources, Olympia, WA.
  • Wasser, C. H., and K. Hess. 1982. The habitat types of Region II. USDA Forest Service: A synthesis. Final report prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 140 pp.
  • Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.
  • Whipple, S. A. 1975. The influence of environmental gradients on vegetational structure in the subalpine forest of the southern Rocky Mountains. Unpublished dissertation, Colorado State University, Fort Collins.
  • Williams, C. K., B. F. Kelly, B. G. Smith, and T. R. Lillybridge. 1995. Forest plant associations of the Colville National Forest. General Technical Report PNW-GTR-360. USDA Forest Service, Pacific Northwest Region, Portland, OR. 140 pp.
  • Williams, C. K., T. R. Lillybridge, and B. G. Smith. 1990b. Forested plant associations of the Colville National Forest. Report prepared for USDA Forest Service, Colville National Forest, Colville, WA. 133 pp.
  • Williams, C. K., and B. G. Smith. 1990. Forested plant associations of the Wenatchee National Forest. Unpublished draft prepared by the USDA Forest Service, Pacific Northwest Region, Portland, OR. 217 pp.
  • Williams, C. K., and T. R. Lillybridge. 1983. Forested plant associations of the Okanogan National Forest. R6-Ecol-132b-1983. USDA Forest Service, Pacific Northwest Region, Portland, OR. 140 pp.