158 PLANT SOCIOLOGY 



boundary parallel to the coast on both sides of Bering Strait and in 

 Labrador. Hence also the depression of the timber line on exposed 

 crests of the central Alps, in the Black Forest, in the Vosges, in the 

 Auvergne, in the southern Cevennes (Fig. 92). As a result of these 

 wind-induced timber lines, the beeches growing highest on the slopes 

 of the Black Forest (up to 1,450 m.) are at about the same altitude as 

 those that are highest up in the southern Cevennes, several degrees of 

 latitude farther south. And the high forest on exposed crests is 

 surrounded by a protective belt of creeping beeches, now, however, 

 much broken through. 



In Swedish Lapland, wind-induced timber lines are characteristic 

 of the isolated flat mountain summits. They often run considerably 

 below the forest boundary as determined by temperature (Fig. 93). 



