AMPHI-ATLANTIC ZONATION, NEMORAI. lO ARCTIC 1 19 



whereas the central Taiga, in Siberia, may be less w ide than the Main Boreal 

 (b) of the Canadian West. 



The conifer trees of the Taiga (except east Siberia) are only five. Piceo is 

 mainly represented by P. ohovata, which is better regarded as a sub-species of 

 P. abies. The two "species" of Larix (L. Sukatchewii in Europe. L. sihirica in 

 west and central Siberia) are probably also conspecific races. Pinus sihirica is 

 very close to the central European P. cembra. The other two trees are Pinus 

 silvestris and Abies sibirica. Picea and Laiix reach the woodland-tundra. 

 In northwest Russia (Kola Peninsula and Karelia) Abies is absent and Larix 

 and Pinus sibirica are extremely rare. For geological and phytogeographical 

 reasons this area is better included in Fennoscandia (as is always done by 

 western botanists). Pinus silvestris is prevalent in most of the Russian Fenno- 

 scandia, except on eastern Kola where Picea reaches farther coastward. but 

 both are ultimately superseded on Kola by the mountain birch [Betula 

 pubescens ssp. tortuosa). Elsewhere in Russia, birch only exceptionally forms 

 the northern tree-line. 



The northern limit of the woodland-tundra in Fig. 3 was taken from a 

 sketch-map by Andreyev (1956; reproduced in Tikhomirov. 1961). It is 

 somewhat more northern than on the vegetation map by Lavrenko and 

 Sochava (1954). 



Boreal Fennoscandia 



Zonal problems in northern Fennoscandia are simplified by the low number 

 of coniferous trees, only Pinus silvestris and Picea abies occurring there. 

 Otherwise, the situation is quite complicated. 



Two vegetation regions are generally accepted for the Fennoscandian part 

 of the Boreal zone, viz. the "Northern coniferous forest region (without oak)" 

 and the "Sub-alpine birch woodland region". Only Hustich (1960) gives a 

 slightly different treatment. The former region has been subdivided both in 

 Finland and Sweden (Kalela. 1958, 1961: Du Rietz, 1950, 1952; Sjors, 1950. 

 1956). but unfortunately the proposed sub-regions agree neither in extent nor 

 in number; probably none of them corresponds exactly to any of the above- 

 mentioned Canadian and Russian sub-zones. 



The Boreal sub-zonation in Fennoscandia is largely due to other factors 

 than latitude. In Norway and Sweden altitude is apparently more effective 

 than latitude, and the influence of the altitude is also evident on recent Finnish 

 maps (Kalela. 1958, 1961). Moreover, the absence of spruce in several 

 western and northern parts of the Scandinavian Peninsula has often been 

 considered of regional iniportance. 



Both in Norway and in Sweden as well as in Finland, a transitional 

 Southern Boreal sub-zone has some scattered occurrences of Nemoral species, 

 particularly Tilia cordata, Acer platanoides, and the scrub Corylus avellana. 

 The upper and northern limit of this sub-zone is very ill-defined in Norway 



