North American boreal and western temperate forest vegetation

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

Itinera Geobotanica 12:5-316 (1999)


Go to: Contents - Show Table - Previous Page - Next Page

Description of Plant Communities: Salici pulchrae-Betulion glandulosae

16. Salici pulchrae-Betulion glandulosae alliancia nova hoc loco

[Potentillo fruticosae-Betulion glanduliferae Kojima in Phytocoenologia 14(1) 6. 1986 (art. 5, 8)]

Typus nominis: Salici barclayi-Betuletum glandulosae associatio nova hoc loco.

Boreal and arctic North-Western North America low and tall tundra, usually treeless, locally reaching the cryorotemperate (alpine) belt territories of Rocky Mountains. In the Boreal Alaska, Yukon Territories and British Columbia, mainly above timberline, we distinguish three associations growing in upper supra- and oroboreal subhumid to hyperhumid bioclimatic belt areas of the Yukonian-Alaskan and Boreal Oceanic Alaskan Provinces: 16a. Salici barclayi-Betuletum glandulosae, extensive low shrubby and thicket communities in areas with deep winter snow-packs; 16b. Vaccinio microphylli-Betuletum glandulosae, less exigent in winter snow cover than previous association, often in contact with Loiseleurio-Vaccinietea class communities in exposed ridges; and finally, 16c. Salici pulchrae-Betuletum exilis developing on boggy soils.

Bioclimatic diagnosis: Ic 10-40, Io 2.8-30.0, Tp 180-500, Tps 170-300, Tmin < 0, m < -2. [Boho, Booc, Bosc, Boxe, Boco, Teco, Pooc, Poco, Poxe-Mbo, Sbo, Obo, Ote, Cte, Mpo, Dry, Shu, Hum, Hhu, Uhh].

Table 66
16. Salici-Betulion glandulosae
(Short synthesized table syntaxa)

Number of relevés 5 5 2 12
Association number 16a 16b 16c  
Ordinal number 1 2 3 4
Characteristic species:
Salix barclayi V . . 1
Vaccinium microphyllum . V 2 1
Cassiope tetragona . III . 1
Betula exilis . . 2 1
Salix hastata . . 2 1
Carex lugens . . 2 1
Betula glandulosa V V 1 3
Empetrum hermaphroditum V V 1 3
Betula glandulosa x exilis II II 1 3
Artemisia arctica IV III . 2
Salix acutifolia III III . 2
Mertensia paniculata II I . 2
Salix pulchra IV . 2 2
Rubus arcticus IV . 1 2
Vaccinium minus . V 2 2
Ledum decumbens . IV 1 2
Companion species:
Festuca altaica II II . 2
Cetrania islandica I II . 2

Associations: 1. [16a] Salici barclayi-Betuletum glandulosae. 2. [16b] Vaccinio microphylli-Betuletum glandulosae. 3. [16c] Salici pulchrae-Betuletum exilis. 4. Synthesized table.

Characteristic species: Alnus viridis subsp. fruticosa, Artemisia arctica, Betula glandulosa x nana subsp. exilis, Betula xhornei (B. kenaica x B. nana subsp. exilis), Betula nana subsp. exilis, B. nana subsp. exilis x B. neoalaskana, Betula xuliginosa (B. neoalaskana x glandulosa), Kalmia microphylla, Salix arctica, Salix barclayi, Salix barrattiana, Salix glauca var. acutifolia, Salix glauca var. glabrescens, Salix phlebophylla, Salix planifolia subsp. pulchra, Salix polaris, Salix rotundifolia.

North American associations of
Ledo decumbentis-Betuletalia glandulosae
North American biogeographic sectors
1.1a  2.2 2.1c 4.1a 4.1b 4.1c 4.3a 4.4a 2.1a 2.1b 3.1a
16. Salici pulchrae-Betulion glandulosae + + + + + + + + . . .
16a. Salici barclayi-Betuletum glandulosae . + . + + + . . . . .
16b. Vaccinio microphylli-Betuletum glandulosae + + . . . . . . . . .
16c. Salici pulchrae-Betuletum exilis + + + + + + . . . . .
16B. Betulion minoris + . . . . . . . + + +

Figure 41. Relationships between North American biogeographic sectors of North-Western Pacific Subregion and adjacent biogeographic territories and dwarf-shrubby associations of Vf. Ledo decumbentis-Betuletalia glandulosae (16. Salici pulchrae-Betulion glandulosae, 16B. Betulion minoris). 1.1a. North American Continental Arctic Sector. 2.2. Yukonian-Alaskan Province. 2.1c. Western Canadian Boreal Sector, 4.1a. Boreal Oceanic Western Alaskan Sector, 4.1b. Boreal Oceanic Eastern Alaskan Sector, 4.1c. Aleutian and Alaska Peninsula Sector. 4.3a. Canadian Rockies Sector. 4.4a. High Missouri-Yelowstone Sector. 2.1a. Newfoundlandian Sector, 2.1b. Eastern Canadian Boreal Sector. 3.1a. Appalachian Sector.

Map Figure 42. Distribution of the snow, rocky slope and boggy dwarf willow and dwarf birch tundra communities belonging to the order Vh. Ledo decumbentis-Betuletalia glandulosae. 16. Salici pulchrae-Betulion glandulosae (western of Hudson Bay): 16a. Salici barclayi-Betuletum glandulosae (deep winter snowcover), 16b. Vaccinio microphylli-Betuletum glandulosae (shallow winter snow cover), 16c. Salici pulchrae-Betuletum exilis (bogs at timberline ecotone and above). 16B. Betulion minoris prov. (eastern of Hudson Bay):

16a. Salici barclayi-Betuletum glandulosae associatio nova hoc loco

Permanent snowdrift dwarf willow and dwarf birch tundra communities, spreading throughout the Boreal Oceanic Alaska and Yukonian-Alaskan Provinces and developing in Oceanic, Subcontinental and Continental Boreal; meso-, supra-, and oroboreal; humid to ultrahyperhumid territories. These communities grow on gleyic, gelic or histic podzols and gleysols.

Bioclimatic diagnosis: Ic 10-32, Io 6.0-30.0, Tp 300-500, Tps 240-300, Tmin <0, m < -2. [Boho, Booc, Bosc, Boco-Mbo, Sbo, Obo-Hum, Hhu, Uhh].

Table 67 gives five relevés from Alaska and British Columbia territories. In these localities a high number of dwarf willows (Salix barclayi, Salix myrtillifolia, Salix planifolia subsp. pulchra, Salix polaris, Salix reticulata, Salix acutifolia, etc.) are recognized as mixed plant species with the predominant dwarf birch (Betula glandulosa). In the subcontinental and continental territories, such as the type relevé, Arctostaphylos rubra and Empetrum nigrum subsp. hermaphroditum could be used as differential species against the hyperoceanic and oceanic geographical races of this association.

Table 67
16a. Salici barclayi-Betuletum glandulosae

(Salici-Betulion glandulosae, Ledo-Betuletalia glandulosae)

Altitude (1=10m) 102 102 87 102 103 99
Number of species 12 13 14 15 18 14
Ordinal number 1 2 3 4* 5 6
Characteristic species:
Betula glandulosa 4 3 2 4 3 V
Salix barclayi 3 3 2 2 3 V
Empetrum hermaphroditum 2 2 1 2 2 V
Artemisia arctica 2 + . 2 2 IV
Rubus arcticus + . 2 3 2 IV
Salix pulchra . 1 3 1 1 IV
Arctostaphylos rubra 3 . 2 1 . III
Salix acutifolia . . 1 1 1 III
Salix reticulata 2 . 3 . . II
Salix myrtillifolia . + 2 . . II
Salix alaxensis . 2 . . 2 II
Mertensia paniculata . . 2 . 1 II
Pentaphylloides floribunda . . 2 . + II
Betula glandulosa x exilis . . + . 1 II
Companion species:
Bryophyta gen. et sp. pl. 2 2 2 2 3 V
Cladina sp. pl. 2 1 . 1 1 IV
Festuca altaica 2 . . . 2 II

Other species. Characteristic species: Ledum decumbens 2, Lupinus arcticus 2 in 1. Valeriana capitata 1, Phyllodoce glanduliflora 1, Veratrum viride 1, Salix polaris 1 in 2. Thalictrum alpinum 2 in 3. Vaccinium caespitosum 1, Cornus canadensis 1, Veronica wormskjoldii 1 in 4. Solidago multiradiata 1, Castilleja unalaschcensis 1 in 5. Companion species: Polytrichum sp. 2, Cetraria islandica 1 in 4. Epilobium angustifolium 1, Sedum rosea 1 in 5.

Localities: 1. British Columbia: Chilkoot Pass. 59º43'N-135º04'W. N, 10%, 2 m, 60 m2 (reg. 1994a: 132). 2. British Columbia: Chilkoot Pass. 59º44'N-135º04'W. N, 10%, 2 m, 40 m2 (reg. 1994a: 137). 3. Alaska: Denali National Park, Denali Wilderness, Mckinley Park Road close to Jenny Creek. 63º44'N-147º47'W. N, 10%, 1 m, 100 m2 (reg. 1994a: 204). 4. British Columbia: Fraser, Chilkoot Pass. 59º43'N-135º04'W. N, 10%, 2 m, 60 m2, holotypus ass. (reg. 1994a: 129). 5. British Columbia: Fraser, Chilkoot Pass. 59º44'N-135º04'W. N, 10%, 1.5 m, 60 m2 (reg. 1994a: 130). 6. Synthesized table.

Type relevé (holotypus): Table 67, relevé n. 4. Rivas-Martínez reg. 1994a: 129. 24.08.94, made with Drs. Asensi, Costa, Fernández-González & Molero. Site: British Columbia: Fraser. Chilkoot Pass. 59º43'N-135º04'W. 10200 m, N, 5%, 20 m, 30 cm, 400 m2. Estimated bioclimatic factors: Subcontinental Boreal (Ic ~ 27), lower oroboreal (Tp ~ 360), upper humid (Io ~ 10.0), Positive Summer Temperature Tps ~ 260. Biogeographic location: North American Boreal Region, Yukonian-Alaskan Province, Cassiar and Mackenzie Mountains Sector. Floristic combination: Linnaeo-Piceetea characteristic species: 1 Arctostaphylos rubra, 2 Artemisia arctica, 4 Betula glandulosa, 2 Empetrum nigrum subsp. hermaphroditum, 3 Rubus arcticus subsp. arcticus, 2 Salix barclayi, 1 Salix glauca var. acutifolia, 1 Salix planifolia subsp. pulchra. Companion species: 2 Bryophyta gen. & sp. pl., 1 Cetraria islandica, 1 Cladina sp. pl.

16b. Vaccinio microphylli-Betuletum glandulosae associatio nova hoc loco

Subcontinental and Continental Boreal, as well as Continental Polar; meso-, supra-, oroboreal and mesopolar; subhumid, humid and hyperhumid; climactical and permanent heath and dwarf birch tundra vegetation spreading into Yukonian-Alaskan Province and North America Continental Arctic Sector territories and growing on gelic or gleyic podzols.

Bioclimatic diagnosis: Ic 21-38, Io 3.6-24.0, Tp 250-500, Tps 200-300, Tmin < -6, m < -10. [Bosc, Boco, Poco-Mbo, Sbo, Obo, Mpo-Shu, Hum, Hhu-Stp].

Tabla 68 shows five relevés from Alaska and Yukon Terrtories. In these localities the boreal-arctic heath species such as, Empetrum nigrum subsp. hermaphroditum, Ledum palustre subsp. decumbens, Vaccinium uliginosum subsp. microphyllum, Vaccinium vitis-idaea subsp. minus, etc., are frequent heaths, surrounded by dwarf-birches (Betula glandulosa).

Type relevé (holotypus): Table 68, relevé n. 4. Rivas-Martínez reg. 1994a: 90. 22.08.94, made with Drs. Asensi, Costa, Fernández-González & Molero. Site: Yukon Territory: Dempster Higway. North Fork Pass. 64º31'N-138º16'W. 1370 m, W, 15%, 1 m, 200 m2. Estimated bioclimatic factors: Continental Boreal, eucontinental (Ic ~ 38), upper supraboreal (Tp ~ 390), lower humid (Io ~ 6.5), Positive Summer Temperature Tps ~ 260. Biogeographic location: North American Boreal Region, Yukonian-Alaskan Province, Cassiar and Mackenzie Mountains Sector. Floristic combination: Linnaeo-Piceetea characteristic species: 1 Arctagrostis latifolia subsp. arundinacea, 1 Arctostaphylos rubra, 5 Betula glandulosa, + Cassiope tetragona var. tetragona, 2 Empetrum nigrum subsp. hermaphroditum, 4 Ledum palustre subsp. decumbens, 1 Petasites frigidus var. nivalis, 2 Salix glauca var. acutifolia, 2 Vaccinium uliginosum subsp. microphyllum, 3 Vaccinium vitis-idea subsp. minus. Companion species: 1 Bryophyta gen. & sp. pl., 1 Cetraria islandica, + Cladina sp. pl., 1 Poa arctica subsp. lanata, 1 Polygonum bistorta var. plumosum.

Table 68
16b. Vaccinio microphylli-Betuletum glandulosae

(Salici-Betulion glandulosae, Ledo-Betuletalia glandulosae)

Altitude (1=10m) 141 130 152 137 119 113
Number of species 13 14 14 15 17 15
Ordinal number 1 2 3 4* 5 6
Characteristic species:
Betula glandulosa 5 5 5 5 5 V
Empetrum hermaphroditum 2 4 3 2 3 V
Vaccinium microphyllum 1 1 3 2 3 V
Vaccinium minus 2 1 2 3 2 V
Ledum decumbens 1 . 3 4 2 IV
Artemisia arctica 1 . 1 . + III
Petasites nivalis 1 . . 1 + III
Salix acutifolia . + . 2 2 III
Cassiope tetragona . . 1 + + III
Arctagrostis arundinacea . . + 1 1 III
Lycopodium pungens 1 2 . . . II
Betula glandulosa x exilis + . 1 . . II
Arctostaphylos adenotricha . 1 . 1 . II
Companion species:
Cladina sp. pl. 5 2 2 4 3 V
Bryophyta gen. et sp. pl. 2 2 3 1 4 V
Poa lanata 2 . . 1 . II
Cetraria islandica 1 . . 1 . II
Festuca altaica . + 1 . . II

Other species. Trees: Picea glauca (S2) 1 in 5. Characteristic species: Linnaea americana 2, Calamagrostis purpurascens +, Salix arctica + in 2. Mertensia paniculata 1 in 3. Ledum groenlandicum 1, Pedicularis labradorica 1, Cornus canadensis +, Rosa sayi + in 5. Companion species: Epilobium angustifolium + in 2. Anemone interior 1 in 3. Polygonum plumosum 1 in 4.

Localities: 1. Yukon Territory: Dempster Highway, North Fork Pass. 64º20'N-138º16'W. 1m (reg. 1994a: 93). 2. British Columbia: Fraser, Chilkoot Pass. 59º42'N-135º04'W. SW, 5%, 0.4 m, 60 m2 (reg. 1994a: 165). 3. Yukon Territory: Dempster Higway, North Fork Pass. 64º31'N-138º16'W. N, 5%, 1 m, 40 m2 (reg. 1994a: 99). 4. Yukon Territory: Dempster Higway, North Fork Pass. 64º31'N-138º16'W. W, 15%, 1 m, 200 m2, holotypus ass. (reg. 1994a: 90). 5. Alaska: Davis Dome to Dawson, Top of the World Hwy. 64º04'N-141º04'W. S, 5%, 4 m, 200 m2 (reg. 1994a: 69). 6. Synthesized table.

16c. Salici pulchrae-Betuletum exilis associatio prov.

Hyperoceanic, Oceanic, Subcontinental, Continental and Xeric Boreal, Hyperoceanic, Oceanic and Continental Polar; supra-, oro- and mesopolar; dry, subhumid, humid, hyperhumid and ultrahyperhumid, occassionally steppic, low boggy tundra communities mostly above timberline and characterized by Betula nana subsp. exilis and Salix hastata. These communities are widespread throughout the North American Boreal Region, as well as North American Arctic and Boreal Oceanic Alaskan Provinces and grow on histosols.

Bioclimatic diagnosis: Ic 10-40, Io 2.8-30-0, Tp 180-450, Tps 170-280, Tmin < 0, m < -2. [Boho, Booc, Bosc, Boco, Boxe, Poho, Pooc, Poco-Sbo, Obo, Mpo-Dry, Shu, Hum, Hhu, Uhh-Stp].

Table 69 shows two relevés from Yukon Territories and Alaskan high plains, above timberline In these localities are frequent plants between the characteristic species Alnus viridis subsp. fruticosa, Betula glandulosa (and the hybrid swarms between both birches), Betula nana subsp. exilis, Carex lugens, Ledum palustre subsp. decumbens, Salix hastata (mostly var. subintegrifolia) and Salix planifolia subsp. pulchra. Our brief experience concerning this arctic dwarf birch community suggests its phytosociological provisional status.

Table 69
16c. Salici pulchrae-Betuletum exilis

(Salici-Betulion glandulosae, Ledo-Betuletalia glandulosae)

Altitude (1=10m) 103 120 116
Number of species 18 21 19
Ordinal number 1 2 3
Characteristic species:
Betula exilis 4 4 2
Vaccinium microphyllum 2 3 2
Salix hastata 2 2 2
Salix pulchra 2 2 2
Vaccinium minus 2 2 2
Rubus chamaemorus 2 1 2
Carex lugens 1 3 2
Alnus fruticosa 1 2 2
Petasites nivalis 1 2 2
Ledum groenlandicum 1 1 2
Picea mariana (S2) + + 2
Rubus arcticus 1 . 1
Ledum decumbens . 3 1
Empetrum hermaphroditum . 2 1
Salix arbusculoides . 2 1
Betula glandulosa . 1 1
Betula glandulosa x exilis . + 1
Companion species:
Sphagnum sp. 5 5 2
Polygonum plumosum + 1 1

Other species. Characteristic species: Picea glauca (S2) + in 1. Linnaea americana 1, Salix alaxensis var. alaxensis + in 2. Companion species: Bryophyta 3, Equisetum boreale 2, Carex aquatilis 1 in 1. Calamagrostis inexpansa 1 in 2.

Localities: 1. Yukon Territory: Between Dawson City and Fort McPherson. Dempster Hwy. North Fork Pass. 64º33'N-138º13'W. N, 5%, 1 m, 40 m2 (reg. 1994a: 84). 2. Alaska: Between Tetlin Junction and Chicken. Mount Fairplay. 63º41'N-142º12'W. W, 5%, 1 m, 100 m2 (reg. 1994a: 68). 3. Synthesized table.

Revealing relevé: Table 69, relevé n. 2. Rivas-Martínez reg. 1994a: 68. 20.08.94, made with Drs. Asensi, Costa, Fernández-González & Molero. Site: Alaska: Between Tetlin Junction and Chicken. Mount Fairplay. 63º41'N-142º12'N. 1200 m, W, 5%, 1 m, 100 m2. Physiognomy and habitat: Dwarf birch community organized by Betula nana subsp. exilis. Estimated bioclimatic factors: Continental Boreal, eucontinental (Ic ~ 36), lower oroboreal (Tp ~ 330), lower humid (Io ~ 8.0), Positive Summer Temperature Tps ~ 230. Biogeographic location: North American Boreal Region, Yukonian-Alaskan Province, Continental Alaskan Sector, Boreal Eucontinental Alaskan Subsector. Floristic combination: Linnaeo-Piceetea characteristic species, trees: + Picea mariana (S2). Others: 2 Alnus viridis subsp. fruticosa, 1 Betula glandulosa, + Betula glandulosa x nana subsp. exilis, 4 Betula nana subsp. exilis, 1 Calamagrostis stricta subsp. inexpansa, 3 Carex lugens, 2 Empetrum nigrum subsp. hermaphroditum, 1 Ledum groenlandicum, 3 Ledum palustre subsp. decumbens, 1 Linnaea americana, 2 Petasites frigidus var. nivalis, 1 Rubus chamaemorus, + Salix alaxensis var. alaxensis, 2 Salix arbusculoides, 2 Salix hastata, 2 Salix planifolia subsp. pulchra, 3 Vaccinium uliginosum subsp. microphyllum, 2 Vaccinium vitis-idaea subsp. minus. Companion species: 1 Polygonum bistorta var. plumosum, 5 Sphagnum sp.