294 TYGE W. BOCHER 



It divides the North Atlantic area into a true Arctic (High Arctic) part, 

 including Baffin Island, Ellesmere Island, northern Greenland, Spitsbergen, 

 Franz Josephs Land, and northern Novaya Zemlya, and a southern Sub-Low- 

 Arctic-Montane part ranging from southern Labrador to the southern part of 

 Greenland, Iceland, the Faeroes, the Scottish Highlands, and the Scandina- 

 vian Mountains. Connected with the true Arctic part are those continental 

 areas warm enough for Boreal or Temperate plants which do not require 

 oceanic humidity at their northern limits. Typical examples of such regions 

 are found in the inland of middle west Greenland, inland at Scoresbysound, 

 and undoubtedly in Canada and northern Russia. In northernmost Scandi- 

 navia many places will approach this transitional type between Arctic and 

 Boreal Continental floristic regimes (see Fig. 5). 



Many plant communities are distributed on one of two sides of this main 

 boundary hne. In a previous paper (Bocher, 1954) an attempt was made to 

 divide the southwest Greenland vegetation into two complexes, an Oceanic 

 and a Continental. Ecologically and floristically the communities of these 

 complexes are clearly closely related and merge into one another. A natural 

 group of the Oceanic complex is formed by snow-bed vegetation, herb fields, 

 snow-protected heaths of the Phyllodoce type, and willow copses with hygro- 

 philous herb vegetation. A similar Continental complex consists of dry rock 

 vegetation, steppe communities, dry heath vegetation, and willow copses with 

 xerophytes. In spite of the interest, however, connected with the study of 

 such complexes it is felt that the old dividing system using life-forms as 

 primary criteria should not be abandoned. In a recent paper (Bocher, 1963) 

 an attempt has been made to classify the middle Greenland vegetation using 

 life-forms in the main division and distributional types in the first sub- 

 division while dominance and floristic composition are used only in the defini- 

 tions of the smallest entities, e.g. the plant sociations. 



REFERENCES 



Bocher, T. W. (1933). Phytogeographical studies of the Greenland flora. Medd. om 

 Gronl. 104 (3), 1-56. 



Bocher, T. W. (1938). Biological distributional types in the flora of Greenland. Medd. om 

 Gronl. 106 (2), 1-339. 



Bocher, T. W. (1951). Distributions of plants in the circumpolar area in relation to ecologi- 

 cal and historical factors. J. Ecology 39, 376-395. 



Bocher, T. W. (1954). Oceanic and continental vegetational complexes in Southwest 

 Greenland. Medd. om Gronl. 148 (1), 1-336. 



Bocher, T. W. (1956). Area-limits and isolations of plants in relation to physiography 

 of the southern parts of Greenland. Medd. om Gronl. 124 (8), 1-40. 



Bocher, T. W. (1963). Phytogecgraphy of Middle West Greenland. Medd. om Gronl. 148 

 (3) (in press). 



Bocher, T. W., Holmen, Kj., and Jakobsen, K. (1957). Grdnlands Flora. Copenhagen. 



Bocher, T. W., Holmen, Kj., and Jakobsen. K. (1959). A synoptical study of the Green- 

 land Flora. Medd. om Gronl. 163 (1), 1-32. 



