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: Pseudotsugo glaucae-Abietetalia bifoliae

Vd. Pseudotsugo glaucae-Abietetalia bifoliae ordo novus hoc loco

[Pinetalia scopulorum Knapp in Geobot Mitt. 4: 24. 1957 (art. 8), Pseudotsugetalia glaucae Knapp in Geobot Mitt. 4: 25. 1957 (art. 8), Piceetalia engelmannii Knapp in Geobot Mitt. 4: 31. 1957 (art. 8), Pinetalia latifoliae Knapp in Geobot Mitt. 28: 8. 1964 (art. 8), Calamagrostis-Pseudotsugetalia Knapp in Geobot Mitt. 28: 8. 1964 (art. 8), Pseudotsugo-Piceetalia pungentis Knapp in Geobot Mitt. 28: 8. 1964 (art. 8)]

Typus nominis: Piceo engelmannii-Abietion bifoliae alliancia nova hoc loco.

Climactical and permanent edapho-xerophilous coniferous micro-, meso- and macroforests of the Rocky Mountain Subregion spreading into Continental Temperate (subcontinental and barely eucontinental) territories; mostly supra- and orotemperate; dry, subhumid and humid; sometimes submediterranean or steppic, but also in Continental Pluviseasonal Mediterranean areas, supra- and oromediterranean in the High Plains Rockies Sector, and leeward in the inner valleys of Rocky Mountains as well as in the ecotones with Great Basin Region territories. These coniferous forests grow in all kind of substrata on cambisols, cambipodzols, podzols, andosols or occasionally on luvisols and regosols. In despite of they have their major biodiversity throughout the Rocky Mountain Subregion territories, the Pseudotsugo-Abietetalia forest communities, are also present in the most continental and driest areas of the Cascade Province (Columbia Mountains Sector), and in certain cold and subhumid summit areas of high eastern ranges in the Great Basin Region (Intermountain and Neomexican-Arizonan Middlands Provinces).

Bioclimatic diagnosis: Ic 21-34, Io 2.0-9.0, Tp 380-1300, Tps 270-650, Tmin < -3, m < -7. [Teco, Texe, Mepc-Ste, Ote, Hbor, Sme, Ome-Dry, Shu, Lhu-Stp, Sbm].

Within the order Pseudotsugo glaucae-Abietetalia bifoliae we recognize two alliances with different bioclimatic requirements but similar biogeographic distribution: 9. Piceo engelmannii-Abietion bifoliae (Northern and Central-Eastern Rocky Mountain Provinces, orotemperate, and sometimes submediterranean and steppic, barely upper dry, subhumid to lower humid), 10. Pino scopulorum-Pseudotsugion glaucae (Northern and Central-Eastern Rocky Mountain Province, but spreading into High Plains Rockies Sector territories, supra- and lower orotemperate, supra- and oromediterranean, commonly steppic, dry and subhumid).

In a short synthesized table (table 39) we assemble ninety-four original relevés, from Rocky Mountain Subregion areas, belonging to Piceo engelmannii-Abietion bifoliae and Pino scopulorum-Pseudotsugion glaucae alliances. A synopsis of the bioclimatic and biogeographic diagnoses of the thirteen associations and the two alliances which we recognize in the Pseudotsugo glaucae-Abietetalia bifoliae order are also given (figures 28, 29, 30). Within the most significant characteristic coniferous species in the Rocky Mountain Subregion territories, mostly subcontinental and barely eucontinental, dry to humid, it could be mentioned: Picea engelmanniivar. engelmannii (Engelmann spruce), Picea albertiana (Alberta spruce), Picea pungens (blue spruce), Abies bifolia (Rocky Mountain subalpine fir), Abies concolor, (Rocky Mountain white fir), Pinus albicaulis (whitebark pine), Pinus ponderosa var. scopulorum (Rocky Mountain ponderosa pine), Pinus flexilis, Pinus contorta var. latifolia (lodgepole pine), Pinus aristata (Colorado bristlecone pine), Larix occidentalis (western larch) and Pseudotsuga menziesii var. glauca (Rocky Mountain Douglas fir).

Table 39
9. Piceo-Abietion bifoliae
and 10. Pino-Pseudotsugion glaucae
(Short synthesized table syntaxa)

Number of species 18 18 18 28 17 28 20 18 27 16 12 19 19
Number of relevés 3 14 5 6 7 11 11 12 10 6 5 4 94
Association number 9i 9a 9b 9c 9d 9e 9f 9h 10a 10b 10c 10d .
Ordinal number 1 2 3 4 5 6 7 8 9 10 11 12 13
Trees:
Pinus albicaulis 3 . . . . . . . . . . . I
Pinus flexilis . I V . . . . . . . . 4 II
Picea albertiana . . . . . V . II . . . . I
Picea pungens . . . . . . V . . . . . I
Larix occidentalis . . . . . . . . V . . . I
Abies bifolia 1 V II V V IV IV III . . . . IV
Picea engelmannii 3 V V V V V IV III II . . . IV
Pinus scopulorum . . . . . . I . I III V 2 II
Populus tremuloides . . IV . . I III II I I I 4 IV
Pinus latifolia . II . II I III IV V III I . 1 IV
Pseudotsuga glauca . I I I . II IV II V V I 4 V
Characteristic species:
Aster engelmannii . IV . . . . I . . . . . I
Arctostaphylos patula . . V . . . . . . . . . I
Menziesia ferruginea . . . V . . . . . . . . I
Empetrum hermaphroditum . . . . V . . I . . . . I
Arctostaphylos rubra . . . . V . . . . . . . I
Viburnum edule . . . . . IV . . . . . . I
Thalictrum sparsiflorum . . . . . . III I . . . . I
Maianthemum stellatum . . . . . . . I IV . . . I
Rhus trilobata . . . . . . . . . . IV   I
Elymus glaucus . . . . . . . . . . . 4 I
Galium boreale . . . . . II III I . . .   II
Moneses uniflora . II . . I . I . . . .   II
Ledum groenlandicum . . . II III II . II . . .   II
Aster conspicuus 3 . . III I I . I . . .   III
Juniperus scopulorum . . . . . . . . . IV IV . I
Prunus melanocarpa . . . . . . . . . II V 1 II
Symphoricarpos oreophilus . . . . . . . . . III V 2 II
Chimaphila occidentalis . . II . . II I I IV . . . III
Cornus canadensis . . . V II V . II II . . . III
Goodyera oblongifolia . . . V . I II . III I . . III
Ribes montigenum 3 IV IV IV . . III . III . . . III
Spiraea lucida . . . IV . III I III IV II . . III
Pyrola asarifolia . . . V I V III II II . . . III
Orthilia secunda 3 IV . V . II II II V . . . III
Vaccinium scoparium 3 V . V V . I V II . . . III
Amelanchier alnifolia . . . V . IV II II IV V III . IV
Mahonia repens . I I . . I I II III II . 4 IV
Paxistima myrsinites 2 II . I . I IV I V . . 2 IV
Calamagrostis rubescens . II . III . I II III I V I 1 IV
Linnaea americana 2 II . IV III V I III V I . . IV
Shepherdia canadensis . I . V II IV I V I V . . IV
Juniperus depressa 1 III V . IV II III V . V IV 2 V

Associations: 1. [9i] Vaccinio scoparii-Pinetum albicaulis (Piceo-Abietion bifoliae). 2. [9a] Vaccinio-Abietetum bifoliae (Piceo-Abietion bifoliae). 3. [9b] Arctostaphylo-Pinetum flexilis (Piceo-Abietion bifoliae). 4. [9c] Menziesio-Abietetum bifoliae (Piceo-Abietion bifoliae). 5. [9d] Empetro-Abietetum bifoliae (Piceo-Abietion bifoliae). 6. [9e] Piceetum engelmannio-albertianae (Piceo-Abietion bifoliae). 7. [9f] Piceetum pungentis (Piceo-Abietion bifoliae). 8. [9h] Vaccinio-Pinetum latifoliae (Piceo-Abietion bifoliae). 9. [10a] Larici-Pseudotsugetum glaucae (Pino-Pseudotsugion glaucae). 10. [10b] Shepherdio-Peudotsugetum glaucae (Pino-Pseudotsugion glaucae). 11. [10c] Rhoo-Pinetum scopulorum (Pino-Pseudotsugion glaucae). 12. [10d] Pseudotsugo glaucae-Pinetum flexilis (Pino-Pseudotsugion glaucae). 13. Synthesized table.

Characteristic species: Acer glabrum var. glabrum, Amelanchier utahensis, Antennaria luzuloides, Arabis drummondii, Arceuthobium cyanocarpum, Arnica cordifolia, Arnica longifolia, Aster conspicuus, Aster engelmannii, Ceanothus martinii, Hieracium gracile, Lonicera utahensis, Mertensia lanceolata var. nivalis, Monardella odoratissima subsp. odoratissima, Osmorhiza occidentalis, Picea engelmannii var. engelmannii, Pinus contorta var. latifolia, Pinus flexilis, Prunus virginiana var. melanocarpa, Pyrola picta, Ribes cereum var. cereum, Ribes montigenum, Senecio eremophyllus var. kingii, Senecio serra var. admirabilis, Senecio serra var. serra, Senecio streptanthifolius, Solidago multiradiata var. multiradiata, Solidago multiradiata var. scopulorum, Symphoricarpos oreophilus var. utahensis, Thermopsis rhombifolia var. montana, Vaccinium myrtillus var. oreophilum, Xerophyllum tenax.

Syntaxa Ic Io Itc Tp Ts Tmin m Mb, Var
Vd. Pseudotsugo gl.-Abietetalia bi. 21-34 2.0-9.0 - 380-1300 270-650 < -3 < -7 Te, Me
9. Piceo engelm.-Abietion bifoliae 23-30 3.2-9.0 - 380-800 270-450 < -7 < -13 Te
9a. Vaccinio sc.-Abietetum bifoliae 23-28 3.6-7.0 - 380-600 300-380 < -11 < -18 Te, Sbm
9b. Arctostaphylo p.-Pinetum flexilis 25-28 3.2-4.8 - 450-700 320-420 < -10 < -16 Te, Me
9c. Menziesio fer.-Abietetum bifoliae 23-30 4.8-9.0 - 380-700 300-420 < -11 < -16 Te
9d. Empetro her.-Abietetum bifoliae 23-26 6.0-9.0 - 380-500 270-340 < -13 < -18 Te
9e. Piceetum engelm.-albertianae 25-30 3.2-6.0 - 500-800 390-440 < -10 < -15 Te, Stp
9f. Piceetum pungentis 23-28 3.6-7.0 - 600-800 380-450 < -7 < -13 Te, Stp
9g. Penstemono w.-Pinetum aristat. 23-28 3.2-6.0 - 380-700 300-420 < -11 < -18 Te, Stp
9h. Vaccinio sc.-Pinetum latifoliae 23-30 3.2-9.0 - 400-700 300-420 < -8 < -14 Te, Sbm
9i. Vaccinio sc.-Pinetum albicaulis 24-28 3.6-9.0 - 380-600 300-380 < -12 < -17 Te, Sbm
10. Pino sc.-Pseudotsugion glaucae 21-34 2.0-6.0 - 500-1300 400-650 < -3 < -7 Te, Me
10a. Larici-Pseudotsugetum glaucae 21-26 3.6-6.0 - 650-1000 420-550 < -3 < -7 Te, Me
10b. Shepherdio-Peudotsugetum gl. 23-28 2.8-4.8 - 700-1100 420-600 < -6 < -12 Te, Me, Stp
10c. Rhoo trilob.-Pinetum scopulor. 26-34 2.0-3.6 - 800-1300 500-650 < -8 < -15 Te, Me, Stp
10d. Pseudotsugo g.-Pinetum flexilis 26-30 2.0-3.6 - 500-1000 400-550 < -5 < -11 Te, Me, Stp

Figure 28. Synopsis of the bioclimatic diagnoses of syntaxa belonging to Pseudotsugo glaucae-Abietetalia bifoliae order. Relationships between the potential natural vegetation forests and the thresholds of the bioclimatic indexes and climactical parameter values [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)]. Ic: Continentality Index, Io: Ombrothermic Index, Itc: Compensated Thermicity Index, Tp: Yearly Positive Temperature, Tps: Positive Summer Temperature, Tmin: Average temperature value of the coldest month of the year, m: Average minimum temperature of the coldest month of the year (Tmin and m in degrees Celsius), Mb: Macrobioclimate (Bo: Boreal, Te: Temperate), Var: Bioclimatic variants (Sbm: Submediterranean, Stp: Steppic).