l62 



WALTER TRANQUILLINI 



covered places and parts of which stick out of the snow is not interrupted 

 as a rule. Of course the absorption of water is reduced at low temperatures. 

 Doring (1935) has found that spruce trees absorb one third less water at 

 o°C than at 20°C. The absorption is also reduced because the roots do not 

 grow in winter, therefore the soil moisture near the roots is soon exhausted. 

 From the parts of soil still wet water moves to the roots slowly. Abundant 

 moistening of the root zone takes place at the time of snow melting, which 

 occurs between February and March. Therefore those plants wiU suffer the 

 greatest deficits until February. 



In a snosA/- covered place 



Fig. 6. Tautochrones of monthly averages of the soil temperature at different depths 

 in the soil. The region where the temperature falls below o°C is indicated by grey 

 shading. (From AuHtzky, 1961.) 



The Siberian pine tree (Pintis cemhra) winters in three different ways in 

 our station area. Above the timber-hne young plants grow on windblown 

 ridges which are without any snow during the winter ; at the timber-line 

 there are many young plants which are entirely covered with snow through- 

 out the winter, and there are also taller plants and adult trees, which protrude 



