150 



PLANT SOCIOLOGY 



wind relations. Every winter it is the same ridges, crests, and peaks 

 that are blown bare and the same depressions and corners sheltered 

 from wind which are overspread with great masses of snow. Hence 



Fig. 86. — Wind attack upon Elynetura at the Piz Padella (2,500 m.). {Photo ly 

 Klika and Braun-Blanquet.) 



shrub communities of Rhododendron, Vaccinium, and Jiiniperus, and in 

 the north Betula, Picea, and other species exposed to wind, are reduced 



(yr'ncJ erosion 



' ,.::. • .-•I,:..)*,':; 



> 1 I.l'i ' I ."■••'i ■ ' •'•'•.I i ' .' • 

 ..I'l,;;;!;'.;;','!';,.-}.!!.;.-". 



Fig. 87. — -Frontal wind erosion and soil profile in the Empetreto-Vaccinietum on lime- 

 stone in Tatra Mountains. 



to the height of the average thickness of the winter snow. Their 

 table-like tops mark the depth of the snow-cover. 



