Ii8 



M. G. STALFELT 



calculated as half the precipitation (measured in mm) on these two surfaces. 

 This gives 87 mm (half of 73 + 100 mm) for May- August, and 202 mm (half 

 of 189 + 216 mm) for September- April, or totally 289 mm. 



The transpiration of the trees was determined by the 'momentan method* 

 (Stocker, 1929), i.e. by weighing severed leaves, shoots or parts of shoots. 



aoo 



600- 



L AOO 



200 



Precipitation 



on open 



g roun d 



3 

 < 



I 



(0 



Z 



Precipitation 

 upon and under 

 the crowns 



7/ 



B 



C Interception 

 in the crowns 



D Intercept, in 

 the top portion 

 oF the soil 



E , Precipit reaching 

 the root zone 



F. Interception in 

 the crovyns 



Intercept in the 

 top portion of 

 the soil 



H. Precipit reaching 

 the root zone 



Fig. I. Precipitation on and below 5 spruce trees (mean value of 4 years). A and B. 

 Annual precipitation on open ground: 793 mm; 495 mm in September-April (A) and 

 298 mm in May-August (B). C. Interception in the crowns during September-April: 

 260 mm (52-3% of 495 mm). The interception in the crowns includes the (unknown) 

 quantity of wind-driven precipitation collected, and thus screened-ofF from the gaps. 

 D. Interception in the top portion of the soil (moss, Utter and raw humus) in Septem- 

 ber-April: 46 mm (9-3% of 495 mm). E. Precipitation reaching the root zone of the 

 trees in September-April: 189 mm (38-4% of 495 mm). F. Interception in the crowns 

 during May-August: 170 mm (57-2% of 298 mm). The interception in the crowns 

 includes the (unknown) quantity of wind-driven precipitation collected, and thus 

 screened off from the gaps. G. Interception in the top portion of the soil (moss. Utter 

 and raw humus) in May-August: 55 mm (18-4% of 298 mm). H. Precipitation 

 reaching the root zone of the trees in May-August: 73 mm (24-4% of 298 mm). 



