DISCUSSION AND RESULTS. DESCRIPTION OF PLANT COMMUNITIES

9. Piceo engelmannii-Abietion bifoliae alliancia nova hoc loco

Typus nominis: Vaccinio scoparii-Abietetum bifoliae associatio nova hoc loco.

Continental Temperate (subcontinental and barely eucontinental); orotemperate and hemiboreal; upper dry, subhumid and lower humid; often steppic and submediterranean; climactical and permanent edapho-xerophilous coniferous micro-, meso- and macroforests spreading into Rocky Mountain Subregion territories, and also localized in certain cold summit areas of the high mountains ranges of Great Basin Region (Intermountain and Neomexican-Arizonian Middlands Biogeographic Provinces). These forests grow on all kind of substrata on cambisols, cambipodzols, podzols, andosols, luvisols and regosols.

Bioclimatic diagnosis: Ic 21-30, Io 3.2-9.0, Tp 380-800, Tps 270-450, Tmin < -7, m < -13. [Teco, Texe-Ote-Udry, Sh, Lhu-Stp, Sbm].

Within the alliance Piceo engelmannii-Abietion bifoliae we recognize nine easily distinguishable different associations by their floristic, bioclimatic and biogeographic features [see "Key to identify the coniferous forest associations", pg. 39].

Characteristic species: Abies bifolia, Abies bifolia x lasiocarpa, Anemone lithophila, Angelica grayi, Antennaria racemosa, Aquilegia jonesii, Arnica parryi, Arnica rydbergii, Arnica sororia, Erigeron leiomerus, Erigeron mancus, Heuchera parvifolia var. utahensis, Ligusticum filicinum, Ligusticum porteri, Luzula parviflora subsp. fastigiata, Penstemon leiophyllus var. francisci-pennellii, Penstemon whippleanus, Picea glauca var. albertiana (Picea engelmannii x glauca), Pinus albicaulis, Pinus aristata, Polemonium pulcherrimum subsp. delicatum, Ribes cereum var. pedicellare, Rudbeckia occidentalis var. montana, Senecio sphaerocephalus.

Regarding their biogeographic distribution and also their succesional, phyto-topographical and floristic peculiarities, the nine associations of Piceo-Abietion bifoliae alliance could be grouped and discriminated using the following diagnostic key.

1	Forests distributed throughout the Rocky Mountains Subregion: Northern Rocky Mountain and Central-Eastern Rocky Mountain Provinces [succesional or permanent communities originated by fires or on xero-edaphic habitats, with Pinus latifolia as main tree]	9h. Vaccinio scoparii-Pinetum latifoliae
	Forests not distributed in all Rocky Mountain Subregion territories	2
2	Forests distributed in the North Rocky Mountain Province and the High Missouri-Yellowstone Sector [snowless permanent communities with Pinus albicaulis as dominant tree]	9i. Vaccinio scoparii-Pinetum albicaulis
	Forests not distributed in North Rocky Mountain Province and the High Missouri-Yellowstone Sector.	3
3	Forests distributed in the summit areas of the eastern high ranges in the Intermountain Province territories [climactical communities with Pinus flexilis and Picea engelmannii as dominant trees]	9b. Arctostaphylo patulae-Pinetum flexilis
	Forests located in the Great Basin Region territories and absent in the Intermountain Province [mainly climactical forests with Picea engelmannii and Abies bifolia as dominant trees in the forest canopy]	4
4	Forests distributed in the North Rocky Mountain Province	5
	Forests distributed in the Central-Eastern Rocky Mountain Province	7
5	Forests distributed only in the Canadian Rockies Sector [climactical communities, only located until two or three hundred meters below the timberline area: Tp < 500, with Empetrum hermaphroditum, Betula glandulosa or Arctostaphylos rubra in the understory ]	9d. Empetro hermaphroditi-Abietetum bifoliae
	Forests distributed furthermore in the Fraser Interior Plateau or Flathead and Salmon Mountain Sectors [usually without Empetrum hermaphroditum, Betula glandulosa or Arctostaphylos rubra]	6
6	Forests distributed only in the Canadian Rockies and Fraser Interior Plateau Sectors [climactical communities with Picea albertiana and occasionally Picea glauca in the canopy, but without Menziesia ferruginea in the understory]	9e. Piceetum engelmannio-albertianae
	Forests distributed throughout the Northern Rocky Mountain Province territories [climactical communities without Picea albertiana or Picea glauca, but with Menziesia ferruginea in the understory]	9c. Menziesio ferrugineae-Abietetum bifoliae
7	Forests only distributed in the Colorado Rockies Sector [climactical dry and lower subhumid-temperate and permanent communities on dolomitic or ultramafic soils]	9g. Penstemono whippleani-Pinetum aristatae
	Forests distributed furthermore in the High Missouri-Yellowstone or Utah Rockies Sectors [climactical communities without Pinus aristata]	8
8	Forests distributed in the Colorado Rockies and the Utah Rockies Sector territories [climactical and sometimes barely edapho-hygrophilous communities, mostly in the lower orotemperate bioclimatic belt, with Picea pungens in the canopy]	9f.Piceetum pungentis
	Forests distributed throughout the Central-Eastern Province territories [climactical orotemperate communities without Picea pungens but with Picea engelmannii and Abies bifolia in the canopy]	9a. Vaccinio scoparii-Abietetum bifoliae

 

Figure 29. Distribution of coniferous forests associations belonging to Vd. Pseudotsugo glaucae-Abietetalia bifoliae [9. Piceo engelmannii-Abietion bifoliae (9a. Vaccinio scoparii-Abietetum bifoliae, 9b. Arctostaphylo patulae-Pinetum flexilis, 9c. Menziesio ferrugineae-Abietetum bifoliae, 9d. Empetro hermaphroditi-Abietetum bifoliae, 9e. Piceetum engelmannio-albertianae, 9f. Piceetum pungentis, 9g. Penstemono whippleani-Pinetum aristatae, 9h. Vaccinio scoparii-Pinetum latifoliae, 9i. Vaccinio scoparii-Pinetum albicaulis), 10. Pino scopulorum-Pseudotsugion glaucae (10a. Larici occidentalis-Pseudotsugetum glaucae, 10b. Shepherdio canadensis-Pseudotsugetum glaucae, 10c. Rhoo trilobatae-Pinetum scopulorum, 10d. Pseudotsugo glaucae-Pinetum flexilis].

Figure 30. Relationships between North American biogeographic sectors of the Rocky Mountain Subregion and adjacent biogeographic territories and forest associations of Vd. Pseudotsugo glaucae-Abietetalia bifoliae (9. Piceo engelmannii-Abietion bifoliae and 10. Pino scopulorum-Pseudotsugion glaucae). 4.2. Cascade Province (Columbia Mountains Sector). 4.3. Northern Rocky Mountain Province: 4.3a. Canadian Rockies Sector, 4.3b. Fraser Interior Plateau Sector, 4.3c. Flathead & Salmon Mountains Sector. 4.4. Central-Eastern Rocky Mountain Province: 4.4a. High Missouri-Yellowstone Sector. 4.4b. Utah Rockies Sector. 4.4c. Colorado Rockies Sector. 4.4d. High Plains Rockies Sector. 6.2. Intermountain Province.

9a. Vaccinio scoparii-Abietetum bifoliae associatio nova hoc loco

Continental Temperate (subcontinental); upper orotemperate; subhumid and lower humid, frequently submediterranean; climactical Rocky Mountain subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii) mesoforests, spreading into Central-Eastern Province territories: High Missouri-Yellowstone, Colorado Rockies, Utah Rockies and High Plains Rockies (Big Horn Mountains) Sectors. These forests grow on haplic, cambic and ferric podzols, podzo-luvisols and dystric cambisols.

Bioclimatic diagnosis: Ic 23-28, Io 3.6-7.0, Tp 380-600, Tps 300-380, Tmin < -11, m < -18. [Teco-Uote-Shu, Lhu-Sbm].

Table 40 shows fourteen original relevés from Colorado, Wyoming and Montana, sampled in several upper orotemperate subhumid bioclimatic belt areas of the High Missouri-Yellowstone and Colorado Rockies Sectors. Abies bifolia (Rocky Muntain subalpine fir) and Picea engelmannii var. engelmannii (Engelmann spruce) are the dominant trees. In the ecotone between the climactical associations Vaccinio-Abietetum bifoliae and Piceetum pungentis, (transition between the upper and lower orotemperate thermoclimatic belt) the natural hybrid between Picea engelmannii var. engelmannii and Picea pungens can be easily found. Lodgepole pine forests (Vaccinio scoparii-Pinetum latifoliae) represent the pyrogenic succesional forest from Vaccinio-Abietetum bifoliae climactical association, mainly at lower altitudes, as well as the quacking aspen woodlands (Symphoricarpo-Populetum tremuloidis) are the seral forest communities on mesic and wet habitats. Vaccinium scoparium, Arnica cordifolia, Aster engelmannii, Orthilia secunda and Vaccinium myrtillus var. oreophilum are the commonest plants in the understory.

Table 40
9a. Vaccinio scoparii-Abietetum bifoliae
(Piceo-Abietion bifoliae, Pseudotsugo-Abietetalia bifoliae)

Other species. Trees: Pinus latifolia + in 6 and 14, 1 in 13. Pinus flexilis 2 in 10, + in 12. Acer glabrum 1, Pseudotsuga glauca 1 in 8. Characteristic species: Sambucus pubens 1 in 1, + in 8. Antennaria rosea 1 in 1 and 9. Polemonium delicatum 1 in 3, 2 in 7. Heuchera parvifolia 1 in 4 and 11. Valeriana sitchensis 2 in 5, 1 in 14. Penstemon procerus 1 in 7 and 9. Moneses uniflora 1 in 7 and 11. Luzula parviflora + in 7, 1 in 11. Clematis tenuiloba + in 8, 2 in 14. Thalictrum occidentale 2 in 10, 1 in 12. Ligusticum filicinum 1 in 12, + in 13. Ligusticum porteri 1, Senecio admirabilis 1 in 2. Vaccinium caespitosum 1 in 3. Mahonia repens + in 6. Oxypolis fendleri 2, Angelica grayi 1, Delphinium barbeyi + in 7. Actaea arguta 1 Corallorhiza trifida 1 in 8. Aquilegia jonesii 1, Sorbus scopulina 1 in 10. Streptopus americanus 2, Mitella pentandra 1 in 11. Lonicera involucrata 2, Pyrola minor 1 in 13. Streptopus chalazatus 1 in 14. Companion species: Poa fendleriana + in 1 and 9, 1 in 3 and 4. Fragaria bracteata 1 in 6, 2 in 8, + in 13 and 14. Senecio fendleri 2 in 2, + in 9. Dicranum scoparium 2, Trifolium uintense 2, Artemisia arctica + in 4. Castilleja dubia 1, Linanthus nuttallii + in 2. Pedicularis surrecta 2 in 7. Achillea occidentalis 1 in 9. Achillea alpicola + in 11. Ribes inebrians 1 in 13.

Localities: 1. Wyoming: Albany Co. Medicine Bow National Forest, Snowy Range Pass. 41º21'N-106º18'W. N, 20%, 25 m, 40 cm, 400 m2 (reg. 1995d: 192). 2. Colorado: Jackson Co. Routt National Forest, Rabbit Ears Pass. 40º23'N-106º37'W. NW, 15%, 20 m, 60 cm, 400 m2 (reg. 1995d: 45). 3. Colorado: Grand Co. Rocky Mountain National Park, Between Timber Lake Trail and Milner Pass. 40º24'N-105º50'W. S, 30%, 20 m, 50 cm, 400 m2 (reg. 1995d: 32). 4. Colorado: Clear Creek Co. Arapaho National Forest, Mt. Evans Hwy., Mt. Evans Wilderness, Mt. Evans. 39º39'N-105º50'W. E, 20%, 20 m, 40 cm, 400 m2 (reg. 1995d: 26). 5. Montana: Carbon Co. Custer National Forest. Between Red Lodge and Beartooth Pass. 45º01'N-109º24'W. N, 35%, 35 m, 100 cm, 1000 m2 (reg. 1994b: 53). 6. Wyoming: Park Co. Yellowstone National Park, E Entrance Road close to Yellostone Lake. 44º31'N-110º16'W. SE, 5%, 25 m, 50 cm, 2000 m2 (reg. 1996b: 49). 7. Colorado: Larimer Co. Routt National Forest, Cameron Pass. 40º32'N-105º53'W. NE, 20%, 25 m, 60 cm, 400 m2 (reg. 1995d: 201). 8. Wyoming: Albany Co. Medicine Bow National Forest, Medicine Bow Mountains, Between Centennial and Lost Lake Trail. 41º21'N-106º14'W. N, 20%, 25 m, 30 cm, 400 m2 (reg. 1995d: 191). 9. Colorado: Grand Co. Arapaho National Forest. Between Winter Park and Empire Berthoud Pass. 39º49'N-105º47'W. SE, 20%, 20 m, 40 cm, 400 m2, holotypus ass. (reg. 1995d: 29). 10. Wyoming: Teton Co. Teton Range, Between Wilson and Teton Pass. 43º30'N-110º57'W. N, 30%, 25 m, 50 cm, 400 m2 (reg. 1994b: 21). 11. Colorado: Larimer Co. Rocky Mountain National Park, Fall River Pass. 40º27'N-105º45'W. N, 30%, 25 m, 40 cm., 400 m2 (reg. 1995d: 12). 12. Wyoming: Fremont Co. Bridger-Teton National Forest. Between Moran Junction and Dubois, Togwotee Pass. 43º46'N-110º04'W. S, 30%, 20 m, 80 cm, 600 m2 (reg. 1994b: 30). 13. Wyoming: Teton Co. Jenny Lake Lodge, String Lake. 43º47'N-110º43'W. W, 20%, 20m, 30 cm, 600 m2 (reg. 1994b: 28). 14. Montana: Carbon Co. Custer National Forest. Between Red Lodge and Beartooth Pass. 45º02'N-109º25'W. N, 35%, 30 m, 50 cm, 1000 m2 (reg. 1994b: 52). 15. Synthesized table.

Type relevé (holotypus): Table 40, relevé n. 9. Rivas-Martínez reg. 1995d: 29. 28.08.95, made with Dr. Costa. Site: Colorado: Grand Co. Arapaho National Forest. Between Winter Park and Empire, Berthoud Pass. 39º49'N-105º47'W. 3270 m, SE, 20%, 20 m, 40 cm, 400 m2. Physiognomy and habitat: Mature Rocky Mountain Subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii) mesoforest. Estimated bioclimatic factors: Continental Temperate, subcontinental (Ic ~ 24), upper orotemperate (Tp ~ 550), lower humid (Io ~ 6.5), Positive Summer Temperature Tps ~ 320, submediterranean (Ios2 ~ 2.0). Biogeographic location: Rocky Mountain Region, Rocky Mountain Subregion, Central-Eastern Rocky Mountain Province, Colorado Rockies Sector, Colorado-Wyoming Rockies Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 4 Abies bifolia, 3 Picea engelmannii var. engelmannii: Others: 1 Antennaria rosea, 2 Arabis drummondii, 2 Arnica rydbergii, + Aster engelmannii, + Calamagrostis rubescens, 1 Carex rossii, 1 Hieracium gracile, 1 Penstemon procerus, 2 Penstemon whippleanus, + Poa fendleriana, 1 Ribes montigenum, + Senecio fendleri, 1 Vaccinium oreophilum, 5 Vaccinium scoparium. Companion species: 1 Achillea millefolium var. occidentalis, + Epilobium angustifolium.

9b. Arctostaphylo patulae-Pinetum flexilis associatio nova hoc loco

Climactical Engelmann spruce (Picea engelmannii var. engelmannii) and limber pine (Pinus flexilis) mesoforests distributed in territories which show mainly a Continental Pluviseasonal Mediterranean bioclimate character, and in a few cases a Continental and Xeric Temperate (subcontinental) bioclimate character; oromediterranean and orotemperate; dry and lowerhumid. These forests spreading into high altitude areas in the mountain ranges of the eastern Intermountain Province territories such as Snake Range and Great Basin National Park (Wheeler Peak 3962 m), Schell Creek Range (3568 m), East Humboldt Range (3429 m) and Ruby Mountains (3454 m) and growing on podzo-luvisols and distric cambisols with tangel humus.

In the future, with more experience and data, the relict, permanent and dry climactical micro- and mesoforest communities of bristlecone pines (Pinus aristata, Pinus balfouriana and Pinus longaeva), whitebark pine (Pinus albicaulis) and limber pine (Pinus flexilis), could be unified in a particular dry, xeric and relict syntaxa (Pinetalia albicaulis-flexilis prov.). Floristically this provisional named alliance is related to the present climactical coniferous forest orders: Abietetalia magnifico-lowianae (Mediterranean, Californian Region), Pseudotsugo glaucae-Abietetalia bifoliae (Temperate and Mediterranean, Rocky Mountain Subregion) and Tsugetalia mertensiano-heterophyllae (Temperate and Boreal, North-Western Pacific Subregion).

Bioclimatic diagnosis: Ic 25-28, Io 3.0-4.8, Tp 450-700, Tps 320-420, Tmin < -10, m < -16. [Mepc, Teco, Texe-Ote, Ome-Udry, Lshu-Sbm, Stp].

Table 41 gives five relevés from Nevada, at the bottom of Wheeler Peak, in Great Basin National Park, placed in eastern Upper Nevada Basin Sector (Intermountain Province, Great Basin Region). The dominant trees are Engelmann spruce (Picea engelmannii var. engelmnannii) and limber pine (Pinus flexilis), and less common are some trees such as a particular corky and dark-grey barked race of Rocky Mountain subalpine fir (Abies bifolia var.), and a small leather-leaved quacking aspen clonal race (Populus tremuloides var.). In the understory are frequent some shrub such as Juniperus communis var. depressa and the Californian Sierra Nevada manzanita (Arctostaphylos patula), as well as other plants such as Comandra umbellata var. pallida, Carex rossii, Pseudostellaria jamesiana, Monardella odoratissima s. l. and Arabis lemmonii, which show a clear ancestral relation with the Californian mountain flora.

Table 41
9b. Arctostaphylo patulae-Pinetum flexilis
(Piceo-Abietion bifoliae, Pseudotsugo-Abietetalia bifoliae)

Altitude (1=10m)	303	300	302	308	310	304
Number of species	16	16	18	19	19	18
Ordinal number	1	2*	3	4	5	6
Trees:
Picea engelmannii	3	3	5	4	5	V
Pinus flexilis	3	5	2	2	2	V
Populus tremuloides	+	+	.	2	+	IV
Abies bifolia	2	2	.	.	.	II
Characteristic species:
Juniperus depressa	2	1	2	2	2	V
Comandra pallida	2	1	1	1	+	V
Arabis lemmonii	2	+	1	1	1	V
Ribes montigenum	.	1	+	+	1	IV
Penstemon francisci-pennellii	1	2	+	.	.	III
Ribes pedicellare	+	+	1	.	.	III
Monardella odoratissima	.	.	+	2	1	III
Symphoricarpos utahensis	1	+	.	.	.	II
Pterospora andromedea	+	+	.	.	.	II
Ceanothus martinii	.	1	.	1	.	II
Luzula parviflora	.	.	1	.	+	II
Arnica cordifolia	.	.	+	.	1	II
Companion species:
Arctostaphylos patula	2	3	1	1	+	V
Carex rossii	2	1	1	2	.	IV
Pseudostellaria jamesiana	2	.	2	3	2	IV
Trifolium plummerae	.	.	2	3	2	III
Poa fendleriana	.	.	2	2	1	III
Calamagrostis stricta	.	.	+	1	1	III

Other species. Trees: Pseudotsuga glauca 1 in 1. Characteristic species: Erigeron leiomerus 2, Mahonia repens 2 in 4. Saxifraga odontoloma + in 5. Companion species: Cercocarpus ledifolius 2 in 1, 1 in 2. Carex microptera 2 in 3, 2 in 5. Bromus carinatus 1, Stipa lettermanii 1 in 4. Gentianella acuta 1, Juncus mertensianus + in 5.

Localities: 1. Nevada: White Pine Co. Baker, Great Basin National Park, Whealer Peak Parking. 39º01'N-114º-14'W. NE, 30%, 20 m, 100 cm, 400 m2 (reg. 1995d: 72). 2. Nevada: White Pine Co. Baker, Great Basin National Park, Whealer Peak Vista Point. 39º01'N-114º-14'W. S, 30%, 20 m, 150 cm, 400 m2, holotypus ass. (reg. 1995d: 71). 3. Nevada: White Pine Co. Baker, Great Basin National Park, Bristlecone Trail, Trail to Whealer Peak. 39º01'N-114º-15'W. N, 15%, 22m, 80 cm, 400 m2 (reg. 1995d: 75). 4. Nevada: White Pine Co. Baker, Great Basin National Park, Trail to Whealer Peak. 39º01'N-114º-16'W. W, 20%, 20m, 70 cm, 400 m2 (reg. 1995d: 73). 5. Nevada: White Pine Co. Baker, Great Basin National Park, Trail to Whealer Peak. 39º01'N-114º-16'W. E, 15%, 20 m, 80 cm, 400 m2 (reg. 1995d: 74). 6. Synthesized table.

Type relevé (holotypus): Table 41, relevé n. 2. Rivas-Martínez reg. 1995d: 71. 30.08.95, made with Dr. Costa. Site: Nevada: White Pine Co. Baker, Great Basin National Park. Whealer Peak Vista Point. 39º01'N-114º14'W. 3000 m, S, 30%, 20 m, 150 cm, 400 m2. Physiognomy and habitat: Mature limber pine (Pinus flexilis), Rocky Mountain subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii) mesoforest. Estimated bioclimatic factors: Pluviseasonal Continental Mediterranean, subcontinetal (Ic ~ 26), upper oromediterranean (Tp ~ 550), upper dry (Io 550), upper dry (Io ~ 3.4), Positive Summer Temperature Tps ~ 360. Biogeographical location: Great Basin Region, Intermountain Province, Upper Nevada Basin Sector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 2 Abies bifolia, 3 Picea engelmannii var. engelmannii, 5 Pinus flexilis, + Populus tremuloides Others: + Arabis lemmonii, 1 Ceanothus martinii, 1 Comandra umbellata subsp. pallida, 1 Juniperus communis var. depressa, 2 Penstemon leiophyllus var. francisci-pennelli, + Pterospora andromedea, + Ribes cereum var. pedicellare, 1 Ribes montigenum, + Symphoricarpus utahensis. Companion species: 3 Arctostaphylos patula, 1 Carex rossii, 1 Cercocarpus ledifolius.

9c. Menziesio ferrugineae-Abietetum bifoliae associatio nova hoc loco

Continental Temperate (subcontinental and barely eucontinental); orotemperate; upper subhumid and lower humid; climactical Rocky Mountain subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii), meso-macroforests. These coniferous forests are distributed throughout the Northern Rocky Mountain Province territories and grow on haplic, ferric and gleyic podzols, podzo-luvisols and dystric cambisols. This association is replaced in the upper orotemperate humid bioclimatic belt of the Canadian Rockies Sector by the micro- and mesoforest association Empetro hermaphroditi-Abietetum bifoliae, and is replaced by fire mainly by the seral lodgepole pine mesoforest association Vaccinio scoparii-Pinetum latifoliae.

Bioclimatic diagnosis: Ic 23-30, Io 4.8-9.0, Tp 380-700, Tps 300-420, Tmin < -11, m < -16. [Teco-Ote-Shu, Lhu].

Table 42 shows six relevés from Montana and British Columbia, in the Canadian Rockies and Flathead and Upper Kootenay River Subsectors. Rocky Mountain subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii) are the predominant trees in the forest. The understory is regularly plenty of false azalea (Menziesia ferruginea), and also are frequent shrubs such as Vaccinium scoparium, Shepherdia canadensis and Amelanchier alnifolia s.l., as well as the herbs Goodyera oblongifolia, Arnica cordifolia, Orthilia secunda, Cornus canadensis, Linnaea americana, etc. Xerophyllum tenax becomes abundant in somewhat disturbed habitats, particularly by ancient fires.

 Table 42
9c. Menziesio ferrugineae-Abietetum bifoliae
(Piceo-Abietion bifoliae, Pseudotsugo-Abietetalia bifoliae)

Altitude (1=10m)	215	182	169	169	138	163	173
Number of species	26	27	27	28	29	30	28
Ordinal number	1	2	3	4*	5	6	7
Trees:
Abies bifolia	5	3	3	4	2	3	V
Picea engelmannii	1	3	4	3	5	4	V
Characteristic species:
Menziesia ferruginea	4	3	4	3	3	4	V
Vaccinium scoparium	4	1	3	2	2	3	V
Goodyera oblongifolia	2	1	1	2	1	+	V
Arnica cordifolia	1	3	2	3	2	2	V
Orthilia secunda	1	2	3	1	1	2	V
Viola orbiculata	1	2	+	+	1	1	V
Cornus canadensis	1	+	1	+	3	2	V
Shepherdia canadensis	1	1	1	1	.	+	V
Pyrola asarifolia	+	1	1	+	.	1	V
Amelanchier alnifolia	+	2	+	1	+	.	V
Xerophyllum tenax	2	3	3	2	.	.	IV
Osmorhiza purpurea	+	2	1	2	.	.	IV
Galium triflorum	+	1	1	1	.	.	IV
Linnaea americana	2	1	.	.	2	3	IV
Ribes montigenum	+	.	+	1	.	+	IV
Spiraea lucida	.	1	.	1	+	1	IV
Lonicera involucrata	.	.	+	1	1	+	IV
Veratrum viride	1	2	.	1	.	.	III
Clintonia uniflora	+	.	1	2	.	.	III
Aster conspicuus	.	2	.	.	1	1	III
Sorbus scopulina	.	+	1	.	+	.	III
Calamagrostis rubescens	.	.	1	.	1	+	III
Actaea arguta	.	.	1	1	.	+	III
Vaccinium membranaceum	.	.	1	1	+	.	III
Companion species:
Epilobium angustifolium	+	1	1	+	+	+	V
Ptilium crista-castrensis	2	1	2	.	4	3	V
Pleurozium schreberi	2	.	3	2	2	2	IV

Other species. Trees: Pinus latifolia + in 5 and 6. Pseudotsuga glauca 2 in 6. Characteristic species: Chimaphila occidentalis 2 in 1 and 2. Rosa gymnocarpa + in 1 and 2. Ledum groenlandicum 2 in 5, 1 in 6. Betula glandulosa + in 5, 1 in 6. Hieracium albiflorum + in 1 and 2. Aster foliaceus + in 3, 2 in 4. Lonicera utahensis + in 2, 2 in 4. Vaccinium globulare 2 in 1. Thalictrum dasycarpum 2 in 2. Senecio indecorus + in 3. Paxistima myrsinites 2, Thalictrum occidentale 3, Stenanthium occidentale 2 in 4. Rubus pedatus 3, Lycopodium annotinum 2, Gymnocarpium dryopteris 1, Alnus sinuata +, Diphasiastrum complanatum +, Rubus parviflorus + in 5. Ledum glandulosum 2, Senecio eremophyllus 1, Streptopus chalazatus 1, Rosa arkansana +, Thalictrum venulosum + in 6.

Localities: 1. Montana: Beaverhead Co. Chief Joseph Pass. 45º41'N-113º56'W. NE, 20%, 25 m, 60 cm, 1000 m2 (reg. 1998b: 123). 2. Montana: Ravalli Co. Bitterroot National Forest, Sula, Camp Creek. 45º44'N-113º54'W. 35m, 100 cm, 1000 m2 (reg. 1998b: 121). 3. Montana: Flathead Co. Flathead National Forest. Marias Pass, Skyland Creek. 48º18'N-113º21'W. NW, 15%, 30 m, 80 cm, 1000 m2 (reg. 1996b: 71). 4. Montana: Flathead Co. Flathead National Forest. Marias Pass, Skyland Creek. 48º19'N-113º21'W. W, 15%, 30 m, 80 cm, 1000 m2, holotypus ass. (reg. 1996b: 72). 5. British Columbia: Kootenay National Park, Numa Falls. 50º53'N-116º05'W. W, 10%, 25 m, 60 cm, 1000 m2 (reg. 1998b: 118). 6. British Columbia: Banff National Park, Vermillion, between Boom Lake and Vermillion Pass. 51º31'N-116º04'W. SW, 20%, 25 m, 50 cm, 1000 m2 (reg. 1998b: 117). 7. Synthesized table.

Type relevé (holotypus): Table 42, relevé n. 4. Rivas-Martínez reg. 1996b: 72. 01.09.96, made with Drs. Llorens and Sánchez-Mata. Site: Montana: Flathead Co. Flathead National Forest. Marias Pass, Skyland Creek. 48º19'N-113º21'W. 1690 m, W, 15%, 30 m, 80 cm, 100 m2. Physiognomy and habitat: Rocky Mountain Subalpine fir (Abies bifolia) and Engelmann spruce (Picea engelmannii var. engelmannii) macroforest. Estimated bioclimatic factors: Oceanic Temperate (Ic ~ 14), lower orotemperate (Tp ~ 400), upper hyperhumid (Io ~ 23), Positive Summer Temperature Tps ~ 300. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Columbia Mountains Sector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: Others: 4 Abies bifolia, 3 Picea engelmannii. Others: 1 Actaea rubra subsp. arguta, 1 Amelanchier alnifolia, 3 Arnica cordifolia, 2 Aster foliaceus, 2 Clintonia uniflora, + Cornus canadensis, 1 Galium triflorum, 2 Goodyera oblongifolia, 1 Lonicera involucrata, 2 Lonicera utahensis, 3 Menziesia ferruginea, , 1 Orthilia secunda, 2 Osmorhiza purpurea, + Pyrola asarifolia, 1 Ribes montigenum, 1 Shepherdia canadensis, 1 Spiraea betulifolia var. lucida, 2 Stenanthium occidentale, 1 Vaccinium membranaceum, 2 Vaccinium scoparium, 1 Veratrum viride, + Viola orbiculata, 2 Xerophyllum tenax. Companion species: + Epilobium angustifolium, 2 Pleurozium schreberi.