DISCUSSION AND RESULTS. DESCRIPTION OF PLANT COMMUNITIES

6c. Tsugo mertensianae-Abietetum procerae associatio nova hoc loco

Oceanic Temperate (euoceanic and semicontinental); orotemperate; humid and hyperhumid; noble fir (Abies procera), mountain hemlock (Tsuga mertensiana), Engelmann spruce (Picea engelmannii var. engelmannii), coastal Douglas fir (Pseudotsuga menziesii var. menziesii), Pacific silver fir (Abies amabilis), and western hemlock (Tsuga heterophylla) climactical coniferous macro- or megaforests, growing on dystric, ferric or gleyic podzols throughout the Cascade Ranges Sector territories, mainly in Oregonian Cascade Subsector areas.

Bioclimatic diagnosis: Ic 16-21, Io 9.0-18.0, Tp 450-650, Tps 300-400, Tmin < -3, m < -5. [Teoc-Ote-Uhum, Lhhu].

Table 25 shows 13 relevés sampled throughout the Oregon and Washington territories which biogeographically belong to Oregonian Cascade and Washingtonian Cascade Subsectors. Abies procera (noble fir), characteristic species of the association Tsugo mertensianae-Abietetum procerae, is an impressive columnar true fir, with many bicentennial specimens commonly taller than 50 m. Abies procera has its optimum within lower hyperhumid and lower orotemperate bioclimatic belt territories, into Cascade Ranges Sector areas, mainly windward in the high mountains of northern Oregon and Washington, between Mount Baker-Snoqualmie National Forest near Stevens Pass in King Co., Washington (47º30'N) until Winema National Forest and Crater Lake National Park in Klamath Co., Oregon (42º30'N). Isolated populations grow also along Coast Ranges summits of both states spreading throughout the high mountains areas to southern Oregon (Siskiyou Mountains, Jackson and Klamath Counties) and northern California (Siskiyou Co.). Ancient hybridations with Abies magnifica (California red fir) had been originated Abies shastensis (Lemmon) Lemmon, which have a good representation throughout the high mountains areas between north of Mount Lassen (California) and Crater Lake in Oregon (both National Parks) spreading throughout the Klamath-Siskiyou Mountains territories (Abietetum shastensis: Abietetalia magnifico-lowianae, Calocedro-Pinetea jeffreyi).

When Tsugo mertensianae-Abietetum procerae forests are in ecotone with Abieti amabilis-Tsugetum heterophyllae forest association the number of conifer species in the canopy increases and with Tsuga heterophylla and Abies amabilis are frequent the hybrids Tsuga xjeffreyi and Abies amabilis x procera (Abies xbarbouri inedit.).

 Table 25
6c. Tsugo mertensianae-Abietetum procerae
(Tsugion mertensianae, Tsugetalia mertensiano-heterophillae)

Other species. Trees: Pinus murrayana + in 1, 2 and 5, 1 in 3. Abies grandis 1 in 1 and 5, 2 in 3, + in 8. Pinus monticola 1 in 1, 2, 6 and 8. Abies procera x grandis + in 1, 3 and 5. Abies shastensis + in 3, 1 in 5. Abies procera x lasiocarpa + in 6, 1 in 8. Acer circinatum + in 9, 1 in 13. Pinus latifolia + in 8. Taxus brevifolia 1 in 11. Characteristic species: Viola renifolia + in 4, 1 in 10, 2 in 12. Pyrola picta 1 in 2, + in 7. Allotropa virgata 2 in 2, + in 11. Anemone deltoidea 1 in 3, 2 in 5. Viola adunca 1 in 3 and 5. Arnica longifolia 1 in 3, + in 5. Veratrum viride + in 3 and 5. Pentaphylloides floribunda 1 in 3 and 7. Pleuricospora fimbriolata + in 6 and 11. Sorbus cascadensis + in 7 and 12. Ribes montigenum 1 in 8 and 11. Pyrola asarifolia 1 in 9 and 13. Pityopus californica + in 10 and 12. Sorbus grayi 2 in 10, + in 13. Viola orbiculata 1 in 10 and 13. Rosa gymnocarpa + in 11, 1 in 13. Apocynum pumilum + in 2. Carex concinnoides 1 in 3. Rubus pedatus 1, Corallorhiza trifida + in 4. Erythronium montanum + in 5. Rhododendron macrophyllum 1, Ribes sanguineum + in 9. Arnica cordifolia 1 in 10. Rubus macropetalus 1 in 11. Amelanchier humptulipensis +, Campanula scouleri +, Symphoricarpos laevigatus + in 12. Menziesia ferruginea 1, Streptopus curvipes + in 13. Companion species: Carex multicaulis 1 in 2. Epilobium angustifolium + in 6 and 7. Carex rossii 1 in 6 and 11. Dicranum fuscescens 1 in 6.

Localities: 1. Oregon: Douglas Co. Diamond Lake, Thielsen Creek. 43º14'N-122º09'W. NW, 10%, 35 m, 80 cm, 1000 m2 (reg. 1998a: 38). 2. Oregon: Klamath Co. Crater Lake Hwy. near Castle Creek. 42º53'N-122º14'W. NW, 15%, 35m, 100 cm, 1000 m2 (reg. 1998b: 17). 3. Oregon: Douglas Co. Diamond Lake. 43º10'N-122º08'W. SW, 10%, 35 m, 120 cm, 2000 m2 (reg. 1998a: 35). 4. Oregon: Clackamas Co. Mt. Hood National Forest, Mt. Hood between Government Camp and Timberline Lodge. 45º19'-121º43'W. SW, 10%, 30 m, 110 cm, 1000 m2 (reg. 1998b: 66). 5. Oregon: Douglas Co. Diamond Lake. 43º10'N-122º09'W. SW, 20%, 35 m, 120 cm, 2000 m2 (reg. 1998a: 36). 6. Oregon: Klamath Co. Willamette Pass, southern side. 43º36'-122º02'W. S, 15%, 30 m, 90 cm, 2000 m2 (reg. 1998b: 39). 7. Oregon: Deschutes Co. Deschutes National Forest, Elliott R. Corbett II Memorial State Park-Santiam Junction, Santiam Hwy., Santiam Pass. 42º26'N-121º50'W. NW, 10%, 30m, 90 cm, 2000 m2 (reg. 1998a: 42). 8. Oregon: Klamath Co. Deschutes National Forest. Odell Lake, Trapper Creek Trail, Diamond Peak Wilderness. 43º34'N-122º04'W. SE, 10%, 40m, 100 cm, 2000 m2, holotypus ass. (reg. 1998b: 37). 9. Oregon: Wasco Co. Mt. Hood National Forest. Blue Box Pass, between Clear Lake and Frog Lake. 45º13'-121º41'W. SW, 20%, 45 m, 150 cm, 2000 m2 (reg. 1998b: 55). 10. Oregon: Hood River Co. Mt. Hood National Forest. Mt. Hood Wilderness, Bennett Pass. 45º19'-121º39'W. N, 20%, 45 m, 80 cm, 2000 m2 (reg. 1998b: 69). 11. Oregon: Klamath Co. Deschutes National Forest. Odell Lake close to Trapper Creek. 43º35'N-122º03'W. SE, 30%, 50m, 120 cm, 2000 m2 (reg. 1998b: 35). 12. Oregon: Clackamas Co. Mt. Hood National Forest. Mt. Hood Hwy. Barlow Pass, southern side. 45º17'-121º41'W. S, 15%, 40 m, 80 cm, 2000 m2 (reg. 1998b: 57). 13. Washington: Skamania Co. Gifford Pinchot National Forest. Mt. Adams Wilderness, between Swampy Meadows and Grand Meadows. 46º10'-121º38'W. S, 15%, 50 m, 120 cm, 2000 m2 (reg. 1998b: 76). 14. Synthesized table.

Type relevé (holotypus): Table 25, relevé n. 8. Rivas-Martínez reg. 1998b: 37. 24.08.98, made with Dr. Sánchez-Mata. Site: Oregon: Klamath Co. Deschutes National Forest. Odell Lake. Trapper Creek Trail, Diamond Peak Wilderness. 43º34'N-122º04'W. 1470 m, SE, 10%, 40 m, 100 cm, 2000 m2. Physiognomy and habitat: Mature noble fir (Abies procera) and mountain hemlock (Tsuga mertensiana) macroforest with common fir and hemlock hybridogenous populations (Abies procera x lasiocarpa, Tsuga xjeffreyi). Estimated bioclimatic factors: Oceanic Temperate, euoceanic (Ic ~ 17), lower orotemperate (Tp ~ 640), lower hyperhumid (Io ~ 13), Positive Summer Temperature Tps ~ 400. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Cascade Ranges Sector, Oregonian Cascade Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: + Abies grandis, 3 Abies procera, 1 Abies procera x lasiocarpa, 2 Picea engelmannii, + Pinus contorta var. latifolia, 1 Pinus monticola, + Pseudotsuga menziesii, + Tsuga xjeffreyi, + Tsuga heterophylla, 3 Tsuga mertensiana. Others: 1 Achlys triphylla, 3 Chimaphila umbellata subsp. occidentalis, 1 Clintonia uniflora, 1 Cornus canadensis, 2 Gaultheria ovatifolia, 2 Linnaea americana, + Maianthemum stellatum, 1 Orthilia secunda, 1 Ribes montigenum, 1 Rubus lasiococcus, + Tiarella trifoliata var. unifoliata, 2 Vaccinium membranaceum, 2 Vaccinium ovalifolium, 1 Vaccinium scoparium. Companion species: + Pteridium aquilinum var. pubescens.

6d. Tsugo mertensianae-Piceetum sitchensis associatio nova hoc loco

Oceanic Boreal (euoceanic and semicontinental) and barely subcontinental (Subcontinental Boreal); upper mesoboreal and supraboreal; upper humid to ultrahyperhumid; mountain hemlock (Tsuga mertensiana) and Sitka spruce (Picea sitchensis) climactical coniferous meso- and macroforests growing on dystic, gleyic, stagnic or gelic podzols throughout the Boreal Oceanic Alaskan Province territories.

Bioclimatic diagnosis: Ic 14-23, Io 9.0-30.0, Tp 380-570, Tps 280-380, Tmin < -5, m < -9. [Booc, Boco-Mbo, Sbo-Uhum, Hhu, Uhhu].

Table 26 shows six relevés from Alaska and British Columbia which biogeographically belong to Kenai Peninsula and Haines-Juneau Subsectors. Many Tsugion mertensianae and Tsugetalia mertensiano-heterophyllae characteristic species cannot grow in this boreal and wet forest association. Among them it could be mentioned some trees such as Abies amabilis, Abies lasiocarpa, Picea engelmannii var. engelmannii and Thuja plicata and among shrubs and herbs: Clintonia uniflora, Elliottia pyroliflorus, Erythronium montanum, Rhododendron albiflorum, Rubus lasiococcus, Tiarella trifoliata var. unifoliata and Vaccinium membranaceum. Conversely, Rubus chamaemorus is a good differential species of this association in front of the rest of the Tsugion mertensianae alliance associations.

Type relevé (holotypus): Table 26, relevé n. 4. Rivas-Martínez reg. 1994a: 11. 31.08.94, made with Drs. Asensi, Costa, Fernández-González & Molero. Site: Alaska: Kenai Peninsula, Turnagain Pass. 60º48'N-149º11'W. 40 m, N, 20%, 30 m, 60 cm, 400 m2. Physiognomy and habitat: Mature Sitka spruce (Picea sitchensis) and mountain hemlock (Tsuga mertensiana) mesoforest. Estimated bioclimatic factors: Oceanic Boreal, semicontinental (Io ~ 20), lower supraboreal (Tp ~ 480), lower hyperhumid (Io ~ 16), Positive Summer Temperature Tps ~ 320. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Boreal Oceanic Alaskan Province, Boreal Oceanic Western Alaskan Sector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 3 Picea sitchensis, 5 Tsuga mertensiana. Others: 2 Cornus canadensis, 1 Dryopteris expansa, 2 Gymnocarpium dryopteris, + Heuchera glabra, 1 Linnaea americana, 2 Lycopodium annotinum, 3 Menziesia ferruginea, 1 Oplopanax horridus, + Orthilia secunda, + Pentaphylloides floribunda, + Ribes laxiflorum, 3 Rubus chamaemorus, 1 Trientalis europaea var. arctica, 1 Vaccinium ovalifolium, + Vaccinium vitis-idaea subsp. minus. Companion species: 5 Hylocomium splendens, 2 Pleurozium schreberi, 2 Ptilium crista-castrensis, 3 Sphagnum girgensohnii.

Table 26
6d. Tsugo mertensianae-Piceetum sitchensis
(Tsugion mertensianae, Tsugetalia mertensiano-heterophyllae)

Altitude (1=10 m)	2	80	13	4	23	3	21
Number of species	20	20	21	21	25	29	23
Ordinal number	1	2	3	4*	5	6	7
Trees:
Picea sitchensis	4	2	3	3	5	5	V
Tsuga mertensiana	.	5	5	5	1	1	IV
Characteristic species:
Cornus canadensis	1	3	3	2	3	1	V
Lycopodium annotinum	1	+	1	2	1	3	V
Rubus chamaemorus	+	1	4	3	1	1	V
Gymnocarpium dryopteris	4	2	.	2	4	2	IV
Dryopteris expansa	3	.	+	1	3	2	IV
Ribes laxiflorum	1	.	1	+	2	.	IV
Orthilia secunda	+	.	2	+	.	2	IV
Oplopanax horridus	4	.	.	1	3	2	IV
Vaccinium ovalifolium	.	4	2	1	.	1	IV
Moneses reticulata	+	.	2	.	.	2	III
Pyrola asarifolia	+	.	+	.	.	1	III
Streptopus amplexifolius	2	.	.	.	1	2	III
Alnus sinuata	1	.	.	.	+	+	III
Menziesia ferruginea	.	2	4	3	.	.	III
Heuchera glabra	.	+	.	+	.	1	III
Linnaea americana	.	.	2	1	+	.	III
Rubus pedatus	.	2	.	.	4	1	III
Companion species:
Hylocomium splendens	3	3	5	5	3	2	III
Equisetum boreale	3	.	1	.	+	1	IV
Ptilium crista-castrensis	.	.	1	2	2	.	III

Other species. Trees: Populus balsamifera 2 in 1. Tsuga heterophylla 1 in 3, Betula kenaica + in 3. Betula neoalaskana 1, Picea xlutzii + in 5. Characteristic species: Athyrium cyclosorum 2 in 1, 1 in 5. Rubus spectabilis 2 in 1, 1 in 3. Vaccinium minus 1 in 3, + in 4. Pentaphylloides floribunda + in 4, 2 in 6. Trientalis arctica 1 in 4, 3 in 5. Circaea alpina 2, Geum macrophyllum 1 in 1. Luzula divaricata 2, Streptopus brevipes 1, Arnica latifolia 1, Vaccinium caespitosum 1, Luetkea pectinata 1, Veratrum viride +, Valeriana sitchensis +, Platanthera stricta +, Empetrum hermaphroditum + in 2. Calamagrostis langsdorfii 1, Viburnum edule +, Sorbus sitchensis +, Spiraea stevenii + in 5. Listera cordata 1, Stellaria calycantha 1, Aconitum chamissonianum +, Equisetum sylvaticum + in 6. Companion species: Sphagnum girgensohnii 3 in 1 and 4. Carex mertensii 1 in 1, + in 5. Pleurozium schreberi 2 in 4, 3 in 6. Alectoria sarmentosa 3, Dicranum scoparium 2, Carex macrochaeta 2, Athyrium americanum 1, Lupinus polyphyllus + in 6.

Localities: 1. Alaska: Valdez. 61º04'N-146º04'W. W, 10%, 30 m, 40cm, 80 cm, 500 m2, gleyic podzol (reg. 1994a: 17). 2. British Columbia: Rainy Hollow. 59º57'N-136º44'W. N, 20%, 25 m, 50 cm, 400 m2 (reg. 1994a: 164). 3. Alaska: Kenai Peninsula, Moose Pass, Primrose. 60º29'N-149º22'W. N, 20%, 30 m, 70 cm, 400 m2 (reg. 1994a: 13). 4. Alaska: Kenai Peninsula, Turnagain Pass. 60º48'N-149º11'W. N, 20%, 30 m, 60 cm, 400 m2, holotypus ass. (reg. 1994a: 11). 5. Alaska: Valdez, Thompson Pass. 61º11'N-145º38'W. S, 20%, 25 m, 50 cm, 400 m2 (reg. 1994a: 44). 6. Alaska: Anchorage, Portage Lake. 60º47'N-148º50'W. N, 10%, 15 m, 50 cm, moraine 100 years, 500 m2 (reg. 1994a: 10). 7. Synthesized table.

6e. Abieti lasiocarpae-Pinetum albicaulis Rivas-Martínez, Sánchez-Mata & Costa 1999

Oceanic Temperate (euoceanic and semicontinental) and barely subcontinental (Continental Temperate); upper orotemperate; upper humid and hyperhumid; subalpine fir (Abies lasiocarpa) whitebark pine (Pinus albicaulis) and mountain hemlock (Tsuga mertensiana) coniferous micro- and mesoforest and chionophobic permanent communities growing on dystric podzols soils throughout the Cascade Ranges Sector territories.

Bioclimatic diagnosis: Ic 16-23, Io 9.0-18.0, Tp 380-500, Tps 280-360, Tmin < -5, m < -10. [Teoc, Teco-Ote-Uhum, Lhhu].

Table 27 shows six relevés sampled throughout the Crater Lake National Park (Oregon) and Mount Hood areas (Oregon), which biogeographically belong to Oregonian Cascade Subsector. Pinus albicaulis (whitebark pine) is a territorial characteristic species of this chionophobic association (Cascade Ranges Sector). In similar ecological high mountain conditions but more continental, this forest association is also common throughout the southern territories of the Columbia Mountains and Canadian Rockies Sectors as well as in the Flathead and Salmon Mountains and the High Missouri-Yellowstone Sectors. In Oceanic oromediterranean, subhumid bioclimatic belt, we have described from Northern Sierra Nevada Subsector areas (Lassen Volcanic National Park) the association Carici rossii-Pinetum albicaulis (Abietion magnificae: Abietetalia magnifico-lowianae, Calocedro-Pinetea jefreyi). In the future could be arranged a new xerophytic and chionophobic alliance (Pinion albicaulis) with the whitebark pine micro-, mesoforests and woodlands.

Table 27
6e. Abieti lasiocarpae-Pinetum albicaulis
(Tsugion mertensianae, Tsugetalia mertensiano-heterophyllae)

Other species. Characteristic species: Vaccinium membranaceum 2, Alnus sinuata 1 in 1. Arnica latifolia 1, Veratrum viride 1, Pterospora andromedea + in 2. Spiraea lucida 1 in 3. Juniperus montana 3, Calamagrostis rubescens 1, Pedicularis racemosa 1 in 5. Companion species: Carex heliophila 1 in 2. Carex simulata 2, Juncus parryi 1 in 4. Phlox pumila 1 in 5.

Localities: 1. Oregon: Klamath Co. Crater Lake National Park, Phamton Ship Overlook. 42º54'N-122º05'W. SE, 25%, 8 m, 30 cm, 100 m2 (reg. 1998b: 20). 2. Oregon: Klamath Co. Crater Lake National Park, Cloudcap Overlook. 42º56'N-122º03'W. S, 25%, 8 m, 60 cm, 100 m2 (reg. 1998b: 22). 3. Oregon: Klamath Co. Crater Lake National Park, Llao Rock. 42º56'N-122º05'W. SW, 15%, 12 m, 60 cm, 100 m2 (reg. 1992e: 202). 4. Oregon: Klamath Co. Crater Lake National Park, Mount Scott Trail. 42º55'N-122º01'W. S, 10%, 12 m, 60 cm, 100 m2, holotypus ass. (reg. 1998b: 24). 5. Oregon: Clackamas Co. Mt. Hood, Timberline Trail. 45º20'N-121º42'W. S, 20%, 6 m, 40 cm, 50 m2 (reg. 1998b: 63). 6. Synthesized table.

Type relevé (holotypus): Table 27, relevé n. 4. Rivas-Martínez reg. 1998b: 24. 23.08.98, made with Dr. Sánchez-Mata. Site: Oregon: Klamath Co. Crater Lake National Park, Mount Scott Trail. 42º55'N-122º01'W. 2320 m, S, 10%, 12 m, 60 cm, 100 m2. Physiognomy and habitat: Mature whitebark pine (Pinus albicaulis), subalpine fir (Abies lasiocarpa) and mountain hemlock (Tsuga mertensiana) open mesoforest. Estimated bioclimatic factors: Oceanic Temperate, semicontinental (Ic ~ 20), upper orotemperate (Tp ~ 420), lower hyperhumid (Io ~ 14.0), Positive Summer Temperature Tps ~ 310. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Cascade Ranges Sector, Oregonian Cascade Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 1 Abies lasiocarpa, 5 Pinus albicaulis, + Tsuga mertensiana. Others: 2 Luzula glabrata var. hitchcockii, 2 Poa stenantha, + Ribes montigenum, 1 Sorbus sitchensis var. grayi, 2 Vaccinium scoparium. Companion species: + Arctostaphylos klamathensis, 1 Carex rossii, 1 Epilobium angustifolium, 1 Juncus parryi, 1 Polygonum davisiae.

6f. Phyllodoco glanduliflorae-Laricetum lyallii associatio nova hoc loco

Oceanic Temperate (semicontinental) and barely subcontinental (Continental Temperate); upper orotemperate; upper humid to lower hyperhumid; subalpine larch (Larix lyallii), mountain hemlock (Tsuga mertensiana), subalpine fir (Abies lasiocarpa) and Engelmann spruce (Picea engelmannii var. engelmannii) coniferous micro- or mesoforests and chionophilous permanent communities growing on dystric, gleyic or stagnic podzols throughout the Cascade Ranges areas (Washingtonian Cascade Subsector). In the Columbia Mountains and the Canadian Rockies Sectors could be recognized this forest association in a geovicariant community with Abies bifolia.

Bioclimatic diagnosis: Ic 18-23, Io 9.0-14.0, Tp 380-500, Tps 270-350, Tmin < -7, m < -14. [Teoc, Teco-Ote-Uhum, Lhhu].

Table 28 holds three relevés from Washington, close to eastern boundary of North Cascades National Park. Larix lyallii (subalpine larch) is a territorial characteristic species of this chionophilous forest association, endemic of the upper orotemperate (subalpine) humid and lower hyperhumid territories of the Washingtonian Cascade Subsector (North Cascade Range), in which Abies lasiocarpa (Cascade and Coastal Canadian Ranges subalpine fir) is the differential tree species against the geovicariant community "Abieti bifoliae-Larix lyallii" in which Abies bifolia (Rocky mountain subalpine fir) is the characteristic tree. The differentiation between both subalpine firs in Canada, presented by R.S. Hunt and published in Flora of North America (Morin, ed., 1993: 359) looks unclear, particularly in Selkirk and Cariboo Mountains (Columbia Mountains Sector territories), where following our personal experience we recognize also Abies lasiocarpa. In any case, in the ecotone zones of the North American Abies species, many populations show an hybridogenous origin and it is too easy to find intermediates.

 Table 28
6f. Phyllodoco glanduliflorae-Laricetum lyalli
(Tsugion mertensianae, Tsugetalia mertensiano-heterophyllae)

Localities: 1. Washington: Okanogan Co. Okanogan National Forest, Washington Pass, eastern side. 48º32'N-120º38'W. E, 30%, 6 m, 70 cm, 100 m2 (reg. 1994b: 95). 2. Washington: Chelan Co. Okanogan National Forest, between Blue Lake Trail and Washington Pass. 48º31'N-120º38'W. S, 25%, 15 m, 100 cm, 100 m2, holotypus ass. (reg. 1994b: 92). 3. Washington: Chelan Co. Okanogan National Forest, between Blue Lake Trail and Washington Pass. 48º31'N-120º38'W. S, 25%, 20 m, 110 cm, 200 m2 (reg. 1994b: 93). 4. Synthesized table.

Type relevé (holotypus): Table 28, relevé n. 2. Rivas-Martínez reg. 1994b: 92. 08.09.94, made with Dr. Costa. Site: Washington: Okanogan Co. Okanogan National Forest, between Blue Lake Trail and Washington Pass, at the bottom of Early Winters Spires Peak. 48º31'N-120º38'W. 1670 m, E, 25%, 15 m, 100 cm, 100 m2. Physiognomy and habitat: Subalpine larch (Larix lyallii) and subalpine fir (Abies lasiocarpa) open mesoforest. Estimated bioclimatic factors: Oceanic Temperate, semicontinental (Ic ~ 19), upper orotemperate (Tp ~ 400), upper humid (Io ~ 11), Positive Summer Temperature Tps ~ 420. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Columbia Mountains Sector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 3 Abies lasiocarpa, 3 Larix lyallii, + Picea engelmannii var. engelmannii, 2 Tsuga mertensiana. Others: 1 Arnica latifolia, 3 Arnica longifolia, 2 Cassiope mertensiana, 3 Phyllodoce glanduliflora, 1 Pyrola chlorantha, 1 Vaccinium membranaceum, + Valeriana sitchensis. Companion species: 1 Achillea millefolium var. alpicola, + Epilobium angustifolium.

6g. Ribesio acerifolii-Chamaecyparetum nootkatensis associatio prov.

Oceanic Temperate (euoceanic and semicontinental); upper orotemperate; upper humid to hyperhumid; Alaska cedar (Chamaecyparis nootkatensis) and mountain hemlock (Tsuga mertensiana) coniferous micro- or mesoforests and chionophilous permanent communities, growing in deep snow-pack areas in windward slopes, snow avalanches areas or little valleys, on gleyic or stagnic podzols in the Oregonian-Vancouverian and Cascade Ranges Sectors.

Bioclimatic diagnosis: Ic 16-21, Io 9.0-18.0, Tp 380-500, Tps 280-360, Tmin < -5, m < -10. [Teoc-Ote-Uhum, Lhhu].

Table 29 holds two relevés from Washington sampled close to Chinook Pass (Mount Rainier National Park). We are still in doubt if this clear avalanche and snow-pack micro- or mesoforest community deserves the syntaxonomical association level or, conversely, if it is only a snowy variant and aspect of the most general geographic association Abieti lasiocarpae-Tsugetum mertensianae.

 Table 29
6g. Ribesio acerifolii-Chamaecyparetum nootkatensis
(Tsugion mertensianae,Tsugetalia mertensiano-heterophyllae)

Other species. Characteristic species: Vaccinium ovalifolium 1 in 1. Ligusticum grayi 1, Luzula piperi 1, Pedicularis racemosa 1, Pulsatilla occidentalis 1 in 2.

Localities: 1. Washington: Pierce Co. Mount Rainier National Park, Chinook Pass. 46º52'N-121º30'W. S, 40%, 15 m, 60 cm, 200 m2 (1996b: 87). 2. Washington: Pierce Co. Mount Rainier National Park, Chinook Pass. 46º52'N-121º31'W. S, 40%, 10 m, 50 cm, 200 m2 (1996b: 86). 3. Synthesized table

Revealing relevé: Table 29, relevé n. 1. Rivas-Martínez reg. 1996b: 87. 02.09.96, made with Drs. Llorens and Sánchez-Mata. Site: Washington: Pierce Co. Mount Rainier National Park, Chinook Pass. 46º52'N-121º30'W. 1730 m, S, 40%, 15 m, 60 cm, 200 m2. Physiognomy and habitat: Alaska cedar (Chamaecyparis nootkatensis) and mountain hemlock (Tsuga mertensiana) open mesoforest. Estimated bioclimatic factors: Oceanic Temperate, semicontinental (Ic ~ 20), uper orotemperate (Tp ~ 410), lower hyperhumid (Io ~ 15), Positive Summer Temperature Tps ~ 300. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Cascade Ranges Sector, Washingtonian Cascade Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 5 Chamaecyparis nootkatensis, 1 Tsuga mertensiana. Others: 2 Mertensia paniculata var. borealis, 2 Moehringia lateriflora, 2 Ribes acerifolium, 1 Rubus lasiococcus, + Saussurea americana, 1 Sorbus sitchensis, + Trillium ovatum, 4 Vaccinium membranaceum, 1 Vaccinium ovalifolium, 2 Valeriana sitchensis, 2 Veratrum viride. Companion species: 1 Epilobium angustifolium.