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: Populetalia angustifolio-deltoidis

Vf. Populetalia angustifolio-deltoidis ordo novo hoc loco

[Aceri-Populetalia Looman in Phytocoenologia 15(1) 56. 1987 (art. 5, 8), Populetalia balsamiferae Looman in Phytocoenologia 15(1) 74. 1987 (art. 5, 8), Alnetalia tenuifoliae Wali & Krajina ex Peinado, Aguirre & Cruz in Plant Ecology 137: 186. 1998 (art. 29) [holotypus: Alnion tenuifoliae Wali & Krajina ex Peinado, Aguirre & Cruz in Plant Ecology 137: 186. 1998 (art. 8, 29), holotypus: Urtico gracilis-Alnetum tenuifoliae Wali & Krajina ex Peinado, Aguirre & Cruz in Plant Ecology 137: 186. 1998 quoad descr.(art. 8)]

Typus nominis: Populion angustifolio-moniliferae alliancia nova hoc loco.

Rocky Mountain Subregion and North American Atlantic Region, cottonwood and riparian forests, mainly Continental Temperate but also Oceanic Temperate, and barely Pluviseasonal Continental and Xeric Continental Mediterranean (pluviseasonal and xeric), from infratemperate to hemiboreal and supra-oromediterranean, growing on gleysols and fluvisols (figures 34, 35, 36).

Bioclimatic diagnosis: Ic 17-38, Io 2.0-10.0, Itc < 450, Tp 740-2500, Tps 450-800, Tmin < 12, m < 7. [Teoc, Texe, Teco, Mexc, Mepc-Ste, Hbo, Mte, Tte, Mme, Sme-Dry, Shu, Hum].

Within the riparian and cottonwoods forest of the order Populetalia angustifolio-deltoidis we recognize two alliances. The first one westward: 14. Populion angustifolio-moniliferae, spreading into Rocky Mountain Subregion and Prairies Province and scattered in Great Basin Region areas. The second alliance: 14B. Platano occidentalis-Populion deltoidis, spreading into North American Atlantic Region, east side of Prairies Province, is only provisionally described.

Characteristic species: Cornus sericea subsp. sericea, Geranium viscosissimum, Populus xacuminata (P. angustifolia x deltoides), Populus xjackii (P. deltoides x balsamifera), Prunus americana, Prunus emarginata, Salix amygdaloides, Salix exigua, Sambucus racemosa subsp. pubens var. microbotrys, Symphoricarpos occidentalis.

To classify the associations and alliances of Populetalia angustifolio-deltoidis order we present an easy floristic, biogeographic and bioclimatic key as follows.

1 With Populus angustifolia or Populus monilifera, but without Populus deltoides, Platanus occidentalis or Acer saccharinum (Rocky Mountains and Prairies: 14. Populion angustifolio- moniliferae) 2
With Populus deltoides, Platanus occidentalis or Acer saccharinum, but without Populus angustifolia or Populus monilifera (North American Atlantic Region except Prairies Province) 14B. Platano occidentalis-Populion deltoidis
2 With Populus monilifera or Ulmus americana but without Betula occidentalis (Prairies Province and High Plains Rockies Sector) 14a. Populetum angustifolio-moniliferae
With Betula occidentalis but without Populus monilifera or Ulmus americana (Rocky Mountains Subregion, except High Plains Rockies Sector) 14b. Betulo occidentalis-Populetum angustifoliae
Syntaxa Ic Io Itc Tp Ts Tmin m Mb, Var
Vf. Populetalia angust.-deltoidis 17-38 2.0-10.0 < 470 740-2500 450-800 < 12 < 7 Te, Me
14. Populion angust.-moniliferae 21-38 2.0-5.2 - 740-2000 450-800 < 4 < -3 Te, Me
14a. Populetum angust.-molinifer. 24-30 2.0-4.8 - 800-1500 500-700 < 0 < -6 Te, Me, Stp, Sbm
14b. Betulo oc.-Populetum angus. 21-28 2.0-5.2 - 740-1400 450-650 < -1 < -7 Te, Me, Sbm
14B. Platano occ.-Populion delt. 17-35 4.5-10.0 < 470 800-2500 500-900 < 12 < 7 Te

Figure 34. Synopsis of the bioclimatic diagnoses of syntaxa belonging to Populetalia angustifolio-deltoidis order. Relationships between the potential natural vegetation forests and the thresholds of the bioclimatic indexes and climatic parameter values [14. Populion angustifolio-moniliferae (14a. Populetum angustifolio-moniliferae, 14b. Betulo occidentalis-Populetum angustifoliae), 14B. Platano occidentalis-Populion deltoidis]. 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 (Me: Mediterranean, Te: Temperate), Var: Bioclimatic variants (Sbm: Submediterranean, Stp: Steppic).

North American associations of 
Populetalia angustifolio-deltoidis

North American biogeographic sectors

4.3 4.4 4.4d 3.3 6 3.1 3.2 3.4 3.5
Vf. Populetalia angustifolio-deltoidis + + + + + + + + +
14. Populion angustifolio-moniliferae + + + + + . . . .
14a. Populetum angustifolio-moniliferae + + + + + . . . .
14b. Betulo occidentalis-Populetum angustifoliae + + . . . . . . .
14B. Platano occidentalis-Populion deltoidis . . . . . + + + +

Figure 35. Relationships between North American biogeographic sectors of North-Western Pacific Subregion and adjacent biogeographic territories and forest associations of Vf. Populetalia angustifolio-deltoidis (14. Populion angustifolio-moniliferae and 14B. Platano occidentalis-Populion deltoidis). 4.3. Northern Rocky Mountain Province. 4.4. Central-Eastern Rocky Mountain Province. 4.4d. High Plains Sector. 3.3. Prairies Province. 6. Great Basin Region. 3.1. Appalachian Province. 3.2. Great Lakes and Central Lowlands Province. . 3.4. Coastal Plains Province. 3.5. Texas Prairies Province.