AMPHI-ATLANTIC ZONATION, NEMORAL TO 



ARCTIC 



Hugo Sjors 



Institute of Plant Ecology, University of Uppsala, Uppsala, Sweden 



Whereas in Canada a book called North of 55° (Wilson, 1954) tells the story 

 of a still almost uninhabited country, in Europe about 70 million people 

 live and work above this parallel. The difference in the northward extension of 

 natural ranges and vegetational zones is not quite so evident as the difference 

 in distribution of human population. Still, a considerable disparity also exists 

 between the two continents with respect to climatic conditions and natural 

 resources from a biogeographer's point of view. 



On the other hand, the two continents show very similar situations regard- 

 ing regional zonation. The European zonation is a mirror image of the 

 American one, much displaced toward the north, but Europe's Oceanic 

 West has no counterpart in North America (the "Maritime Provinces" of 

 Canada are far less oceanic). 



Broadly speaking, the southern Great Lakes area, extending northward 

 into the Niagara Peninsula of Ontario, has its European equivalent in south- 

 central Europe, as far north as southern Germany. The Canadian provinces 

 of Quebec and Ontario correspond to east-central Europe and the Baltic- 

 Scandinavian area as far north as Finland and northern European Russia. 

 The "Prairie Provinces" and northwestern Canada are better compared to 

 central and eastern European Russia and western Siberia. 



It seems of basic importance for any kind of detailed comparison that those 

 points, lines, and zones which correspond most closely to each other bio- 

 geographically should be determined on each side of the Atlantic Ocean. If 

 this were possible, much more of the experience from one side could be readily 

 used on the other, not only in pure biogeographical and ecological science but 

 also in practical management of arable land, pasture and forest. 



There is a serious obstacle against the direct use of climatic figures in this 

 respect. Northeastern America, except for a narrow zone confined mostly to 

 the "Maritime Provinces", is rather continental as to temperature but has 

 everywhere an adequate rainfall. In Eurasia we must go far east to obtain the 

 same degree of continental temperature, but then summer rainfall becomes 

 scanty. 



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