118 HUGO SJORS 



extends from the east coastal parts and the uplands of Newfoundland and 

 Labrador to Alaska. 



Rowe (1959) and Hare (1959) disagree in the mapping of easternmost 

 Labrador. The "coastal tundra" is probably caused here by high winds and 

 lack of soil, and has only partly been mapped as Woodland-Tundra sub-zone 

 on Fig. 2. The woodland farther inland is largely regarded as Sub-Arctic, 

 even if fairly dense, because of low stature. The Hudson Bay Lowland is 

 divided between the Main Boreal and Sub- Arctic (Sjors, 1959, 1961a and in 

 prep.), and is not as entirely Sub-Arctic as one may believe (Hustich, 1957; 

 Rowe, 1959). 



(d) The Hemi-Antic (Rousseau, 1952) or Woodland-tundra suh-zone. Here 

 tree growth is reduced to scattered clumps and low, shrubby stands in 

 sheltered localities, e.g. along riversides. Nearly or totally treeless barrens 

 occur between these outposts. Near the tree-line, the tundra areas become pre- 

 dominant and only a small percentage is actually covered by the woodland. 

 Any of the four species mentioned for the Sub-Arctic may form the actual 

 tree-line (or rather the outposts of potentially tree-forming species), but the 

 white spruce (Picea glauca) is the most common, particularly close to the sea 

 shore. 



The typical woodland-tundra is a feature of flat country, either continental 

 or adjacent to Arctic coasts. However, Rowe (1959) describes an "Alpine 

 Forest-Tundra Section" on the slopes west of the lower Mackenzie Valley, 

 and similar sites occur near the tree-line in interior Yukon Territory (Porsild, 

 1951), both areas being extremely continental as to climate. In mountainous 

 or hilly districts the altitudinal tree-line tends to be sharper than the latitudinal 

 tree-line in flat country, but some of the tree species develop a shrubby 

 appearance; what actually corresponds to the woodland tundra is often a 

 belt of stunted woods and, on exposed localities, even shrubs. Porsild (1951, 

 pp. 27-28) describes the dense shrub of alpine fir {Abies lasiocarpa) near the 

 tree-line in southeast Yukon. The Picea mariana and Abies balsaniea wood- 

 lands of coastal eastern Labrador and some parts of Newfoundland are 

 described as often very dense but dwarfed, and interspersed with barren 

 heaths, due to a wet. cool and windy climate (Hustich, 1939, 1949, p. 12; 

 Rowe, 1959; Ahti, 1959, p. 2). 



Russian Boreal, or Taiga 



As east Siberia is very aberrant, only west Siberia and European Russia are 

 considered here. Russian authors (cf. Lavrenko and Sochava, 1954; Sotchava, 

 1954; Tikhomirov, 1960) subdivide the Boreal zone, which they call the Taiga, 

 into the southern, central, and northern Taiga, in addition to which comes the 

 Lyeso-tundra (Sylvo-tundra, forest- or woodland-tundra). This subdivision 

 corresponds very well to the Canadian one. but the southern Taiga is a more 

 extensive sub-zone than the Canadian counterpart (a) mentioned above, 



