North American boreal and western temperate forest vegetation

Salvador Rivas-Martínez, Daniel Sánchez-Mata & Manuel Costa

Itinera Geobotanica 12:5-316 (1999)


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Description of Plant Communities: Abieti grandis-Pseudotsugetum menziesii

5f. Abieti grandis-Pseudotsugetum menziesii associatio nova hoc loco

Oceanic Temperate (semicontinental), and in some eastern territories barely Continental Temperate (subcontinental); mainly submediterranean; supra- and lower orotemperate; subhumid and humid; macro- and megaforests usually with grand fir (Abies grandis) and coastal Douglas fir (Pseudotsuga menziesii var. menziesii) as dominant trees; some less frequent conifers are Tsuga heterophylla, Thuja plicata, Pinus ponderosa var. ponderosa and Picea engelmannii s. l. (incl. P. engelmannii var. glauca).

These climactical coniferous macro- and megaforests are broadly distributed throughout the Cascade Ranges Sector territories and grow on cambisols, luvisols or cambic-podzols, and also andosols on bedrocks rich in volcanic glass materials. As secondary fire dynamic forest communities are frequent pine forests or woodlands, organized by Pinus ponderosa var. ponderosa, Pinus contorta var. latifolia or Pinus contorta var. murrayana; the last Sierra lodgepole pine (Pinus contorta var. murrayana) is distributed mainly throughout the southern areas of the Oregonian Cascade Subsector.

Bioclimatic diagnosis: Ic 18-23, Io 3.6-8.0, Tp 600-1050, Tps 380-550, Tmin < -4, m < -9, Ios2 < 2.5. [Teoc, Teco-Ste, Ote-Shum, Hum-Sbm].

Table 20 gives 14 relevés sampled throughout the Oregon and Washington territories, usually with many conifer trees in the canopy, and also with a lot of shrubs, dwarf shrubs and herbs in the understory. Among the commonest non-trees characteristic species are: Achlys triphylla, Chimaphila umbellata subsp. occidentalis, Clintonia uniflora, Galium triflorum, Goodyera oblongifolia, Linnaea americana, Maianthemum stellatum, Rosa gymnocarpa, Symphoricarpos albus var. laevigatus and Trientalis borealis subsp. latifolia.

The most significant floristical differences between the associations Gaultherio shallonis-Pseudotsugetum menziesi (euoceanic) and the more continental Abieti grandis-Pseudotsugetum menziesii (semicontinental and barely subcontinental) are for the first one: Gaultheria shallon, Polystichum munitum and Tiarella trifoliata var. trifoliata, and for the second: Abies grandis, Picea engelmannii s. l., and Rubus lasiococcus.

Type relevé (holotypus): Table 20, relevé n. 10. Rivas-Martínez reg. 1998b: 48. 24.08.98, made with Dr. Sánchez-Mata. Site: Oregon: Lane Co. Willamette National Forest, between Box Canyon Station and Three Sisters Wilderness. 43º57'N-122º05'W. 1170 m, N, 20%, 50 m, 150 cm, 2000 m2. Physiognomy and habitat: Mature coastal Douglas fir (Pseudotsuga menziesii var. menziesii) and grand fir (Abies grandis) megaforest. Estimated bioclimatic factors: Oceanic Temperate (Ic ~ 19), lower orotemperate (Tp ~ 750), submediterranean (Ios2 ~ 1.8), upper subhumid (Io ~ 5.5), Positive Summer Temperature Tps ~ 600. Biogeographic location: Californian Region, Northern Californian Province, Klamath Sector, Ciscascade Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 2 Abies grandis, 1 Acer circinatum, + Picea engelmannii var. engelmannii, 4 Pseudotsuga menziesii, + Tsuga heterophylla. Others: 3 Achlys triphylla, 1 Adenocaulon bicolor, + Amelanchier alnifolia, 1 Asarum caudatum, 1 Chimaphila umbellata subsp. occidentalis, 1 Chrysolepis chrysophylla var. minor, 2 Clintonia uniflora, 2 Cornus canadensis, 1 Galium triflorum, 1 Goodyera oblongifolia, 1 Hieracium albiflorum, 1 Linnaea americana, 3 Maianthemum stellatum, 1 Pedicularis racemosa subsp. alba, + Rosa gymnocarpa, 1 Rubus lasiococcus, 3 Symphoricarpos albus var. laevigatus, 2 Tiarella unifoliata, + Vaccinium membranaceum, 2 Vaccinium parvifolium, 2 Vancouveria hexandra, 2 Viola glabella, 1 Xerophyllum tenax. Companion species: 1 Bromus vulgaris, + Cornus nuttallii, 1 Corylus cornuta subsp. californica, 2 Fragaria virginiana subsp. platypetala, 2 Pteridium aquilinum var. pubescens.

Table 20
5f. Abieti grandis-Pseudotsugetum menziesii

(Tsugion heterophyllae
, Tsugetalia mertensiano-heterophyllae)

Altitude (1=10m) 92 78 132 108 107 104 148 90 108 117 95 72 108 87 103
Number of species 25 25 25 26 28 29 30 32 33 34 36 36 36 37 31
Ordinal number 1 2 3 4 5 6 7 8 9 10* 11 12 13 14 15
Trees:
Abies grandis 4 3 3 3 1 2 2 3 4 2 2 2 2 1 V
Pseudotsuga menziesii 2 2 3 3 3 3 2 4 3 4 3 4 3 4 V
Tsuga heterophylla + 3 . . . 2 3 . + + 2 . 3 2 IV
Thuja plicata 1 2 . . 4 . . + . . 1 + . . III
Pinus ponderosa + . 1 1 . . . 1 . . . + . 1 III
Characteristic species:
Chimaphila occidentalis + 2 4 2 2 2 1 3 1 1 2 1 2 3 V
Goodyera oblongifolia 2 2 . + 2 1 + 1 1 1 1 + + 1 V
Linnaea americana . 2 + 3 2 4 2 3 3 1 3 3 3 3 V
Mahonia nervosa 1 2 . + 2 3 . 2 + . 2 1 2 2 IV
Symphoricarpos laevigatus 2 + . 2 . 1 . 3 1 3 1 2 1 + IV
Galium triflorum 2 . + 1 1 . + + 1 1 . 1 + 1 IV
Clintonia uniflora 2 1 1 . 3 1 + . . 2 1 . 1 2 IV
Maianthemum stellatum 2 . 2 + 1 1 2 . 2 3 + 1 . . IV
Trientalis latifolia . 1 . 2 . 2 1 2 . . 2 2 2 2 IV
Rosa gymnocarpa . 1 . 2 . 1 . 2 . + 1 2 2 + IV
Achlys triphylla . . . 1 . 2 . 1 4 3 2 + 2 2 IV
Paxistima myrsinites 2 1 . 1 3 + . . 2 . 1 . . + III
Vaccinium membranaceum . 2 . . 1 1 1 . . + 2 . 1 + III
Orthilia secunda . . 2 1 2 . 2 2 + . 1 . + . III
Hieracium albiflorum . . . 1 . 1 . 1 . 1 + 1 1 1 III
Chimaphila menziesii 1 . . + . . + + . . + 1 + . III
Pyrola picta . . 1 + . . . + + . + . + + III
Trillium ovatum 2 1 . . . + + 1 . . . . + . III
Amelanchier alnifolia . 1 + . 1 + . . 1 + . . . . III
Rubus macropetalus . 1 2 . . . . . . . + + 1 1 III
Chrysolepis minor . . + . . 2 . 1 . 1 . . 1 1 III
Rubus parviflorus + . . . . . . . + . + + . + II
Adenocaulon bicolor . . . . + . . 1 . 1 . . 1 + II
Maianthemum amplexicaule 2 . . + . . . + . . + . . . II
Cornus canadensis . 3 . . . . 2 . . 2 2 . . . II
Tiarella unifoliata . . . . 2 1 2 . . 2 . . . . II
Pyrola asarifolia . . . . 1 . . . + . 1 . 1 . II
Asarum caudatum . . . . + . 1 . 1 1 . . . . II
Rubus lasiococcus . . . . . 1 1 . . 1 1 . . . II
Rubus leucodermis . . . . . 1 1 . . . . 2 . 1 II
Companion species:
Pteridium pubescens 1 1 + + . 1 + + 1 2 . . . + IV

Other species. Trees: Acer circinatum 2 in 1, 1 in 8 and 10, 3 in 11. Picea engelmannii 1 in 5 and 9, 2 in 7, + in 10. Tsuga xjeffreyi + in 6, 7 and 13, 1 in 14. Pinus monticola + in 6, 7 and 14. Lonicera conjugialis + in 1 and 9. Pinus murrayana 1 in 2 and 3. Larix occidentalis + in 4 and 12. Abies procera x grandis + in 7 and 13. Taxus brevifolia 2 in 7 and 14. Acer douglasii 2, Pinus latifolia 1 in 2. Characteristic species: Viola glabella + in 1, 1 in 9, 2 in 10. Cornus sericea + in 1, 9 and 12. Gaultheria ovatifolia 1 in 2 and 13, 2 in 6. Holodiscus discolor + in 3, 1 in 4 and 12. Campanula scouleri 2 in 3, 1 in 8 and 14. Anemone deltoidea 3 in 3, + in 11 and 12. Anemone lyallii 1 in 4 and 7, 2 in 13. Lonicera ciliosa 1 in 4 and 12, 2 in 8. Streptopus curvipes 1 in 4, + in 11 and 12. Pedicularis racemosa + in 6 and 11, 1 in 14. Pedicularis alba 1 in 10 and 12, + in 13. Thalictrum occidentale + in 1, 1 and 9. Vancouveria hexandra 1 in 2, 2 in 10. Pterospora andromedea + in 3, 1 in 8. Ribes montigenum 1 in 3, 2 in 9. Osmorhiza purpurea 1 in 3 and 13. Actaea arguta + in 5 and 9. Rosa ultramontana + in 5, 2 in 9. Spiraea lucida 1 in 5 and 12. Viola orbiculata 1 in 6 and 11. Xerophyllum tenax 1 in 8 and 10. Osmorhiza berteroi 1 in 8 and 12. Amelanchier humptulipensis + in 8, 1 in 13. Stellaria calycantha + in 11, 2 in 12. Disporum trachycarpum 1 in 11, + in 14. Disporum oreganum 1 in 1. Streptopus streptopoides 1 in 2. Oplopanax horridus 2, Gymnocarpium dryopteris 1, Listera caurina 1, Ribes laxiflorum 1, Platanthera orbiculata + in 5. Rhododendron macrophyllum 1, Vaccinium ovalifolium 1 in 7. Lilium columbianum 1, Pleuricospora fimbriolata + in 8. Elmera puberulenta 2, Corallorhiza trifida 1, Moehringia macrophylla 1, Osmorhiza depauperata 1, Circaea pacifica +, Oemleria cerasiformis + in 9. Vaccinium parvifolium 2 in 10. Aquilegia coerulea + in 12. Corallorhiza mertensiana +, Pityopus californica + in 13. Companion species: Corylus californica 1 in 6, 10 and 12, + in 11, 2 in 14. Brachypodium sylvaticum + in 1, 4 and 13, 10 and 11. Bromus vulgaris 2 in 3, 1 in 10 and 12. Fragaria bracteata 1 in 3 and 12, + in 13. Cornus nuttallii + in 10, 12 and 14. Satureja douglasii + in 12 and 13, 2 in 14. Kelloggia galioides 1 in 3, + in 14. Hylocomnium splendens 1 in 7, 2 in 14. Kindbergia oregana 1 in 7, 2 in 14. Piperia unalascensis 1 in 8 and 12. Fragaria platypetala 2 in 10, 1 in 14. Rhytidiopsis robusta 1 in 11, 3 in 13. Asyneuma prenanthoides 1 in 3. Athyrium americanum 2 in 5.

Localities: 1. Washington: Chelan Co. Wenatchee National Forest, between Berne and Merritt. Schilling Creek., Merrit Lake Trail. 47º47'N-120º57'W. S, 15%, 50 m, 150 cm, 2000 m2 (reg. 1998: 75). 2. Washington: King Co. Baker-Snoqualmie National Forest, between Denny Creek and Franklin Falls. 47º26"-N-121º31'W. E, 10%, 30 m, 80 cm, 2000 m2 (reg. 1994b: 4). 3. Oregon: Douglas Co. Umpqua National Forest. North Umpqua River between Toketee Falls and Steamboat. 43º18'N-122º31'W. S, 25%, 35 m, 100 cm, 2000 m2 (reg. 1998b: 27). 4. Washington: Yakima Co. Wenatchee National Forest, between White Pass and Dog Lake North close to South fork Clear Creek. 46º39'N-121º23'W. S, 20%, 30 m, 80 cm, 2000 m2 (reg. 1998b: 83). 5. Washington: Chelan Co., between Rainy Lake and Washington Pass. 48º31'N-121º01'W. N, 25% 50 m, 60 cm, 2000 m2 (reg. 1994b: 89). 6. Oregon: Jackson Co. Rogue River National Forest, between Union Creek and Crater Lake National Park, Union Creek. 42º55'N-122º23'W. N, 10%, 45 m, 150 cm, 2000 m2 (reg. 1998b: 13). 7. Oregon: Klamath Co. Deschutes National Forest, between Odell Lake and Willamette Pass. 43º36'N-122º02'W. W, 15%, 50 m, 120 cm, 4000 m2 (reg. 1998b: 34). 8. Oregon: Wasco Co. Mt. Hood National Forest, between Dahl Pine and Clear Lake. Clear Creek. 45º09'N-121º38'W. NE, 15%, 30 m, 100 cm, 2000 m2 (reg. 1998b: 51). 9. Washington: Chelan Co. Wenatchee National Forest. Tronsen-Swauk. Blewett Pass. 47º25'N-120º34'W. N, 10%, 50 m, 130 cm, 2000 m2 (reg. 1998: 77). 10. Oregon: Lane Co. Willamette National Forest, between Box Canyon Station and Three Sisters Wilderness. 43º57'N-122º05'W. N, 20%, 50 m, 150 cm, 2000 m2, holotypus ass. (reg. 1998b: 48). 11. Washington: Skamania Co. Gifford Pinchot National Forest, between Trout Lake and Taklakh, Mt. Adams Wilderness close to White Salmon River. 46º09'N-121º38'W. E, 15%, 50 m, 130 cm, 2000 m2 (reg. 1998b: 75). 12. Washington: Klickitat Co. Gifford Pinchot National Forest, Trout Lake Creek Road close to Trout Lake Creek. 46º02'N-121º35'W. E, 5%, 35 m, 100 cm, 2000 m2 (reg. 1998b: 74). 13. Oregon: Wasco Co. Mt. Hood National Forest, Clear Lake. 45º11'N-121º42'W. NE, 15%, 40 m, 120 cm, 2000 m2 (reg. 1998b: 52). 14. Oregon: Jackson Co. Rogue River National Forest, between Prospect and Union Creek. 42º49'N-122º30'W. N, 10%, 40 m, 130 cm, 2000 m2 (reg. 1998b: 12). 15. Synthesized table.

5g. Abieti amabilis-Tsugetum heterophyllae associatio nova hoc loco

Oceanic Temperate (euoceanic and semicontinental); supra and lower orotemperate; humid and hyperhumid; climactical macro- and megaforests of diverse coniferous dominated by western hemlock (Tsuga heterophylla) and Pacific silver fir (Abies amabilis). These forests are distributed throughout the Cascade Province areas, but mainly in the Cascade Ranges and Canadian Coastal Mountains Sectors, and also can be found in the Oregonian Vancouverian Coastal Sector territories mostly in the Olympic Mountains and Vancouverian Subsector territories.

Bioclimatic diagnosis: Ic 12-21, Io 8.0-18.0, Tp 600-1000, Tps 370-500, Tmin < 0, m < -2. [Teoc-Ste, Ote-Hum, Hhu].

Table 21 shows 14 relevés sampled throughout the British Columbia, Washington and Oregon territories which belong biogeographically to Olympic Mountains and Vancouverian Subsectors, and Cascade Ranges and Canadian Coastal Mountains Sectors. The commonest coniferous trees in the canopy are Pacific silver fir (Abies amabilis), western hemlock (Tsuga heterophylla), western red cedar (Thuja plicata) and coastal Douglas fir (Pseudotsuga menziesii var. menziesii), but in the most continental territories of the Cascade Ranges Sector can be also found as frequent trees Engelmann spruce (Picea engelmannii var. engelmannii) and noble fir (Abies procera), mainly under hybridogenous populations (Abies procera x amabilis).

The floristical differences between the associations Abieti amabilis-Tsugetum heterophyllae (euoceanic and semicontinental) and the more continental Piceo engelmanii-Tsugetum heterophyllae (semicontinental and barely cubcontinental) are among the coniferous trees for the first against the second association Abies amabilis and Pseudotsuga menziesii var. menziesii and, conversely, Pseudotsuga menziesii var. glauca. Among the understory characteristic species it could be mentioned in the same direction: Achlys triphylla, Blechnum spicant, Gaultheria shallon, Mahonia nervosa and Vaccinium parviflorum, against: Aralia nudicalis, Lonicera ciliosa and Maianthemum amplexicaulis.

Table 21
5g. Abieti amabilis-Tsugetum heterophyllae

(Tsugion heterophyllae, Tsugetalia mertensiano-heterophyllae)

Altitude (1=10m) 28 87 38 120 105 108 96 98 116 122 96 100 98 88 93
Number of species 21 22 23 24 25 26 27 28 28 29 32 33 33 33 26
Ordinal number 1 2 3 4 5 6 7* 8 9 10 11 12 13 14 15
Trees:
Tsuga heterophylla 4 3 4 3 4 3 3 3 3 2 3 4 3 3 V
Abies amabilis 2 2 3 3 2 3 4 2 3 4 4 2 1 3 V
Thuja plicata 2 3 1 1 . 2 1 1 2 . + 2 . . IV
Pseudotsuga menziesii . 2 . 1 1 1 . 2 1 + 1 1 3 + IV
Characteristic species:
Cornus canadensis 2 2 + 3 2 2 1 + 2 1 3 2 3 . V
Linnaea americana + 2 1 2 3 2 1 1 3 2 + 2 4 . V
Vaccinium membranaceum 1 2 2 + 3 1 3 1 1 2 . . 2 4 IV
Vaccinium ovalifolium 2 1 2 2 + 3 1 . . . 3 1 1 1 IV
Clintonia uniflora . . . 2 + + 2 . 1 2 1 2 2 2 IV
Achlys triphylla 1 + 1 2 . + . 2 1 . . . 2 2 IV
Orthilia secunda + 1 . 1 2 1 + . . 2 . 1 . + IV
Maianthemum stellatum . . + 1 . . 3 1 1 . + 2 3 2 IV
Chimaphila occidentalis . 2 . 2 1 2 . 2 . + . 1 1 . III
Goodyera oblongifolia . 2 . 1 . + 2 2 1 . + 2 . . III
Vaccinium parvifolium 2 2 2 . . . . 2 3 . . + + . III
Rubus pedatus 1 . 1 . . . 3 . . 2 2 + . 1 III
Rubus macropetalus 2 + 1 . . . . . 1 . 1 + . . III
Mahonia nervosa . 2 . . 2 3 . 2 3 1 . . 1 . III
Tiarella unifoliata . . . + + . 2 . . 1 . . 1 2 III
Paxistima myrsinites . . . . 2 1 . 2 . 2 . 1 1 . III
Pyrola asarifolia . . . . 1 1 . . 1 + . + 1 . III
Rubus lasiococcus . . . . 2 . 2 . 1 2 1 . . 3 III
Menziesia ferruginea . . . . . + 2 . + 2 1 . . 2 III
Gaultheria shallon 1 1 1 . . . . 2 2 . . . . . III
Tiarella trifoliata . 1 + . . . . . 2 . 3 3 . . III
Gaultheria ovatifolia . . . . + + . . . 1 1 . . + III
Oplopanax horridus . . . . . . 2 . . . 3 2 + 1 III
Viola orbiculata . . . . 1 . . 2 . 1 . . . 1 II
Trillium ovatum . . . . + . . . . . 1 . 1 + II
Viola glabella . . . . . . + . 2 . . . 2 1 II
Gymnocarpium dryopteris . . . . . . 2 . . . 2 2   3 II
Galium triflorum . . . . . . . 1 . + + + . . II
Companion species:
Pteridium pubescens 2 + 1 1 . . . . . . + . + . III
Blechnum spicant 2 . 2 . . + . . + . 2 . . 1 III
Rhytidiopsis robusta . . . 2 3 2 . . . 3 . . . 2 III

Other species. Trees: Picea engelmannii + in 4, 6 and 10, 1 in 13. Acer circinatum + in 2, 3 in 8, 2 in 13. Abies lasiocarpa x amabilis + in 5, 10 and 14. Alnus rubra + in 1 and 3. Tsuga xjeffreyi 1 in 6 and 14. Abies amabilis x procera +, Populus trichocarpa + in 4. Pinus monticola + in 5. Chamaecyparis nootkatensis 1 in 6. Acer macrophyllum 1 in 8. Betula papyrifera + in 9. Acer douglasii 1, Taxus brevifolia + in 13. Characteristic species: Maianthemum dilatatum 1 in 7 and 9, 2 in 11. Adenocaulon bicolor + in 1 and 3, 1 in 8. Xerophyllum tenax 1 in 6, 2 in 9, + in 13. Rubus spectabilis + in 7 and 14, 1 in 9. Petasites palmatus + in 4, 7 and 14. Vaccinium scoparium 1 in 1 and 3. Rubus parviflorus + in 2 and 6. Athyrium cyclosorum + in 4 and 12. Trientalis latifolia + in 5, 1 in 10. Sorbus sitchensis 1 in 5, + in 14. Polystichum munitum 1 in 8, + in 9. Hieracium albiflorum + in 8 and 14. Alnus sinuata + in 10, 1 in 13. Anemone lyallii + in 10 and 14. Osmorhiza purpurea + in 10 and 14. Dryopteris expansa + in 11, 1 in 12. Streptopus curvipes + in 11 and 12. Salix alaxensis var. alaxensis 1 in 1. Corydalis aurea + in 2. Phyllodoce empetriformis 1 in 3. Corallorhiza mertensiana +, Chimaphila menziesii + in 4. Rosa gymnocarpa 1 in 6. Osmorhiza depauperata 1, Viola renifolia + in 7. Disporum trachycarpum 1, Rosa nutkana 1, Rubus leucodermis 1 in 8. Corallorhiza maculata + in 9. Aquilegia formosa + in 10. Streptopus amplexifolius 1, Streptopus americanus 1, Vancouveria hexandra 1, Sambucus pubens +, Sorbus scopulina + in 11. Lycopodium annotinum 1, Moneses uniflora 1, Pyrola chlorantha 1, Disporum smithii +, Osmorhiza berteroi + in 12. Amelanchier alnifolia 1, Anemone deltoidea 1, Anemone parviflora 1, Asarum caudatum 1, Listera caurina 1, Rosa ultramontana 2 in 13. Arnica cordifolia 2, Valeriana sitchensis 1, Aruncus pubescens +, Veratrum viride + in 14. Companion species: Rhytidiadelphus loreus 2 in 2 and 3, 3 in 12. Hylocomium splendens 2 in 1 and 11, 5 in 3. Epilobium angustifolium 1 in 1 and 11, + in 9. Lycopodium clavatum 1 in 3, + in 11. Rhytidiadelphus triquetrus 3 in 5, 1 in 12. Dicranum fuscescens 1 in 5, + in 10. Claytonia lanceolata + in 7, 1 in 13. Brachythecium asperrimum 3, Digitalis purpurea +, Plagiomnium insigne 2 in 7. Whipplea modesta 2, Corylus californica 1, Fragaria platypetala 1 in 8. Parnassia fimbriata + in 10. Ptilium crista-castrensis 2, Mycelis muralis 1 in 12.

Localities: 1. British Columbia: Vancouver Island. Between Sayward and Adam River. 50º25'N-126º05'W. E, 10%, 1000 m2 (reg. 1997: 19). 2. Washington: Pierce Co. Between Dewey Lake and Mt. Rainier National Park, Cayuse Pass. 46º52'N-121º32'W. N, 500 m2 (reg. 1996b: 91). 3. British Columbia: Vancouver Island. Mt. Cain. 50º14'N-126º20'W. NW, 20%, 1500 m2 (reg. 1997: 20). 4. Oregon: Hood River Co. Mt. Hood National Forest, Mt. Hood Hwy., Bennett Pass. 45º32'N-121º39'W. N, 15%, 2000 m2 (reg. 1998b: 70). 5. Washington: Skagit Co., North Cascades National Park, Swamp Creek near Granite Creek. 48º34'N-120º46'W. W, 20%, 2000 m2 (reg. 1998b: 88). 6. Washington: Skamania Co., Taklakh, between Lewis River and East Canyon Creek. 46º17'N-121º37'W. SW, 10%, 2000 m2 (reg. 1998b: 80). 7. Washington: King Co. Mount Baker-Snoqualmie National Forest, between Skykomish and Leavenworth, Steven Pass. 47º45'N-121º05'W. SW, 20%, 50 m, 140 cm, 2000 m2, holotypus ass. (reg. 1998a: 71). 8. Oregon: Lane Co. Willamette National Forest, between Odell Lake and Heather, western side of Willamette Pass. 43º37'N-122º04'N. SW, 200 m2 (reg. 1996b: 114). 9. Washington: Pierce Co. Mount Baker-Snoqualmie National Forest. Mount Rainier National Park. MowickLake. 46º57'N-121º54'W. S, 20%, 2000 m2 (reg. 1997: 49). 10. Washington: Skagit Co., North Cascades National Park, Granite Creek. 48º35'N-120º48'W. S, 20%, 2000 m2 (reg. 1998b: 89). 11. Washington: King Co. Mt. Baker-Snoqualmie National Forest. Snoqualmie close to Snoqualmie Pass. 47º26'N-121º25'W. 60 m, 140 cm, 500 m2 (reg. 1994b: 2). 12. British Columbia: Between Mount Currie and Lilloeet. Joffre Lakes Provincial Recreation Area. 50º21'N-124º26'N. W, 500 m2 (reg. 1995c: 119). 13. Oregon: Linn Co., Willamette National Forest, Santiam Junction, Lost Lake. 44º26'N-121º56'W. SW, 20%, 2000 m2 (reg. 1998a: 43). 14. Washington: King Co. , Mt. Baker-Snoqualmie National Forest. Snoqualmie close to Snoqualmie Pass. 47º25'N-121º24'W. S, 15%, 2000 m2 (reg. 1998b: 84). 15. Synthesized table.

Type relevé (holotypus): Table 21, relevé n. 7. Rivas-Martínez reg. 1998a: 71. 15.06.98, made with Drs. Costa, Ladero & Sánchez-Mata. Site: Washington: King Co. Mount Baker-Snoqualmie National Forest, between Skykomish and Leavenworth, Steven Pass. 47º45'N-121º05'W. 960 m, SW, 20%, 50 m, 140 cm, 2000 m2. Physiognomy and habitat: Mature western hemlock (Tsuga heterophylla), Pacific silver fir (Abies amabilis) and western red cedar (Thuja plicata) megaforest. Estimated bioclimatic factors: Oceanic Temperate (Ic ~ 16), lower orotemperate (Tp ~ 700), lower hyperhumid (Io 700), lower hyperhumid (Io ~ 13), Positive Summer Temperature Tps ~ 650. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Cascade Ranges Sector, Washingtonian Cascade Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 4 Abies amabilis, 1 Thuja plicata, 3 Tsuga heterophylla. Others: 1 Cornus canadensis, 2 Clintonia uniflora, 2 Goodyera oblongifolia, 2 Gymnocarpium dryopteris, 1 Linnaea americana, 1 Maianthemum dilatatum, 3 Maianthemum stellatum, 2 Menziesia ferruginea, 2 Oplopanax horridus, + Orthilia secunda, 1 Osmorhiza depauperata, + Petasites frigidus var. palmatus, 2 Rubus lasiococcus, 3 Rubus pedatus, + Rubus spectabilis, 2 Tiarella unifoliata, 3 Vaccinium membranaceum, 1 Vaccinium ovalifolium, + Viola glabella, + Viola renifolia. Companion species: 3 Brachythecium asperrimum, 1 Claytonia lanceolata, + Digitalis purpurea, 2 Plagiomnium insigne.

5h. Piceo engelmannii-Tsugetum heterophyllae associatio nova hoc loco

Oceanic Temperate (semicontinental) or barely Continental Temperate (subcontinental); lower orotemperate; humid; climactical coniferous macroforests dominated by western hemlock (Tsuga heterophylla), western red cedar (Thuja plicata), Rocky Mountains Douglas fir (Pseudotsuga menziesii var. glauca) and Engelmann spruce (Picea engelmannii var. engelmannii), spreadeding into Columbia Mountains Sector territories, and growing in dystric, fenalic or gleyic podzols or cambic-podzols.

Bioclimatic diagnosis: Ic 18-23, Io 7.0-12.0, Tp 600-800, Tps 380-500, Tmin < -6, m < -12. [Teoc, Teco-Ote-Hum].

Table 22 shows eight relevés sampled throughout the British Columbia territories which biogeographically belong to Columbia Mountains Subsector. The most significant differences between the associations Abieti grandis-Pseudotsugetum menziesii and Piceo engelmannii-Tsugetum heterophyllae are for the first one: Abies grandis, Achlys triphylla, Chrysolepis chrysophylla var. minor, Pseudotsuga menziesii var. menziesii and Trillium ovatum, and for the second against the first: Aralia nudicaulis, Menziesia ferruginea and Pseudotsuga menziesii var. glauca.

Table 22
5h. Piceo engelmannii-Tsugetum heterophyllae

(Tsugion heterophyllae, Tsugetalia mertensiano-heterophyllae)

Altitude (1=10m) 88 94 86 115 72 60 60 124 86
Number of species 28 28 31 32 32 33 34 39 32
Ordinal number 1 2 3 4 5* 6 7 8 9
Trees:
Tsuga heterophylla 3 4 2 3 3 3 4 2 V
Thuja plicata 3 3 1 3 3 3 2 1 V
Picea engelmannii 1 1 2 1 2 1 2 1 V
Pseudotsuga glauca 3 2 3 . 2 2 . 2 IV
Characteristic species:
Linnaea americana 3 2 3 1 2 3 3 + V
Tiarella unifoliata 3 2 + 2 3 2 3 3 V
Clintonia uniflora 2 2 1 3 2 2 2 2 V
Maianthemum amplexicaule 2 2 + 1 2 1 + 1 V
Goodyera oblongifolia 2 + + 1 3 + 1 2 V
Gymnocarpium dryopteris 1 3 1 1 3 + 3 2 V
Rubus parviflorus 1 2 1 2 + 2 . + IV
Vaccinium membranaceum 1 1 1 1 1 + . 2 IV
Chimaphila occidentalis 2 1 2 . + 2 1 + IV
Paxistima myrsinites 2 . 1 3 2 2 1 2 IV
Amelanchier alnifolia + + 2 + . + . + IV
Galium triflorum + . + + 1 1 . + IV
Cornus canadensis 2 2 3 . 2 . 2 . IV
Rosa gymnocarpa + . + + . 1 1 . IV
Pyrola asarifolia 1 1 . 2 1 . + . IV
Aralia nudicaulis . . 1 2 1 2 2 . IV
Lonicera ciliosa . . . 1 + 1 1 1 IV
Viola glabella + . . + . . + 1 III
Menziesia ferruginea . 1 2 . 2 . 1 . III
Orthilia secunda . 2 . + . . 1 1 III
Oplopanax horridus . 2 . . 2 . 2 1 III
Dryopteris expansa . 1 . . 2 . 2 1 III
Disporum smithii . . . 2 . 1 . 1 III
Adenocaulon bicolor . . . . 1 2 + . III
Companion species:
Rhytidiadelphus triquetrus 3 2 2 2 + 2 2 3 V
Hylocomium splendens 3 5 4 . 3 1 4 . IV

Other species: Trees: Acer glabrum + in 1 and 2, 2 in 6 and 8, 1 in 5. Taxus brevifolia 1 in 4 and 7, 2 in 6. Pinus monticola + in 4, 5 and 7. Populus tremuloides + in 3, 1 in 4. Pinus latifolia + in 3 and 4. Betula papyrifera 1 in 3 and 5. Abies lasiocarpa 1 in 4, 3 in 8. Characteristic species: Athyrium cyclosorum 1 in 1, 2, 5 and 6. Diphasiastrum complanatum 1 in 2, 3 and 5. Ribes montigenum 2 in 1, 1 in 6, + in 8. Sorbus scopulina + in 1 and 8, 1 in 5. Viburnum edule 1 in 2 and 3. Aruncus pubescens 1 in 2 and 8. Maianthemum stellatum 2 in 3, 1 in 7. Corallorhiza trifida + in 4 and 6. Viola renifolia 1 in 4 and 7. Ribes laxiflorum + in 6 and 7. Asarum caudatum 2 in 6, + in 8. Osmorhiza purpurea 1 in 6, + in 8. Vaccinium ovalifolium 1 in 7, 2 in 8. Viola orbiculata 1 in 7 and 8. Vaccinium caespitosum 1, Shepherdia canadensis 1 in 3. Listera cordata +, Platanthera orbiculata + in 4. Symphoricarpos laevigatus 1 in 5. Disporum oreganum 2, Rubus pedatus 2 in 7. Thalictrum venulosum 1, Valeriana sitchensis 1, Hieracium albiflorum +, Lilium columbianum + in 8. Companion species: Fragaria bracteata 1 in 1, 5 and 6. Dicranum fuscescens 1 in 3, 2 in 8. Bromus vulgaris + in 4 and 8. Corylus californica 2 in 6, + in 7. Anaphalis margaritacea + in 1. Ptilium crista-castrensis 2 in 2. Pleurozium schreberi 2 in 8.

Localities: 1. British Columbia: Manning Park, Provincial Park near to Alysson Pass. 49º11'N-120º55'W. NW, 10%, 40 m, 80 cm, 1000 m2 (reg. 1992e: 120). 2. British Columbia: Between Yellowhead and Red Pass. Mount Robson Provincial Park, Robson Valley. 52º55'N-118º45'W. SE, 5%, 40 m, 100 cm, 1000 m2 (reg. 1992e: 75). 3. British Columbia: North Thompson River before Albreda. Columbia Mountains. 52º27'N-119º13'W. W, 5%, 40 m, 60 cm, 1000 m2 (reg. 1995d: 133). 4. British Columbia: Rosegan. Red Mountain Ski Area, near Christina Lake. 49º06'N-118º12'W. N, 5%, 30 m, 70 cm, 1000 m2 (reg. 1998b: 95). 5. British Columbia: Between Avola and Blue River. 51º55'N-119º20'W. S, 15%, 40 m, 80 cm, 1000 m2, holotypus ass. (reg. 1995d: 131). 6. British Columbia: Slocan, Slocan River close to Valhalla Provincial Park. 49º46'N-117º26'W. W, 10%, 45 m, 100 cm, 2000 m2 (reg. 1998b: 96). 7. British Columbia: Shelter Bay, Arrow Lakes (shelter Bay) Provincial Park. 50º38'N-117º57'W. E, 20%, 40 m, 120 cm, 4000 m2 (reg. 1998b: 100). 8. British Columbia: Revelstoke, Mt. Revelstoke National Park. 51º04'N-118º06'W. S, 35%, 30 m, 140 cm, 2000 m2 (reg. 1998b: 102). 9. Synthesized table.

Type relevé (holotypus): Table 22, relevé n. 5. Rivas-Martínez reg. 1995d: 131. 04.09.95, made with Dr. Costa. Site: British Columbia: Between Avola and Blue River. 51º55'N-119º20'W. 720 m, S, 15%, 40 m, 80 cm, 1000 m2. Physiognomy and habitat: Mature western hemlock (Tsuga heterophylla) and Engelmann spruce (Picea engelmannii var. engelamnnii) macroforest with western red cedar (Thuja plicata) and Rocky Mountain Douglas fir (Pseudotsuga menziesii var. glauca). Estimated bioclimatic factors: Continental Temperate, subcontinental (Ic ~ 22), lower orotemperate (Tp ~ 700), lower humid (Io ~ 8.0), Positive Summer Temperature Tps ~ 460. Biogeographic location: Rocky Mountain Region, North-Western Pacific Subregion, Cascade Province, Columbia Mountains Sector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: 1 Acer glabrum, 1 Betula payrifera, 2 Picea engelmannii var. engelmannii, + Pinus monticola, 2 Pseudotsuga glauca, 3 Thuja plicata, 3 Tsuga heterophylla. Others: 1 Adenocaulon bicolor, 1 Aralia nudicaulis, + Chimaphila umbellata subsp. occidentalis, 2 Clintonia uniflora, 2 Cornus canadensis, 2 Dryopteris expansa, 1 Galium triflorum, 3 Goodyera oblongifolia, 3 Gymnocarpium dryopteris, 2 Linnaea americana,+ Lonicera ciliosa, 2 Maianthemum racemosum subsp. amplexicaule, 2 Menziesia ferruginea, 2 Oplopanax horridus, 2 Paxistima myrsinites, 1 Pyrola asarifolia, + Rubus parviflorus, 1 Sorbus scopulina, 1 Symphoricarpos albus var. laevigatus, 3 Tiarella unifoliata, 1 Vaccinium membranaceum. Companion species: 1 Athyrium filix-femina var. cyclosorum, 1 Fragaria vesca subsp. bracteata, 3 Hylocomium splendens, + Rhytidiadelphus triquetrus.