PRECIPITATION IN A SPRUCE STAND 



119 



The reliability of this method is dependent on whether or not the cut part 

 of the plant does, in fact, give off the same quantity of water before and 

 after cutting. No generally appHcable answer can be given to this question, 

 since the effect of cutting may vary in different species. Moreover, it may 

 vary with such factors as the hydration and osmotic equipment of the plant, 



800r 



600 



£ AGO 



200 



O 



Precipitation 

 on open 

 g rou nd 



a 

 < 



I. 



a 



< 



I 



Precipitation 

 in the gaps 

 between the trees 



Precipitation 

 I. screened oFF 

 from the gaps 



Intercept, in the 

 J. top portion oF 

 the soil 



Precipitation 

 K.reaching the 

 root zone 



Precipitation 

 L. screened ofF 

 From the gaps 



Intercept, in the 

 M.top portion of 

 the soil 



Precipitation 

 '^reaching the 

 root zone 



Fig. 2. Precipitation in the gaps between the trees (mean value of 4 years). A and B. As 

 in Fig. I . /. Wind-driven precipitation collected by the tree canopy, and thus screened 

 off from the gaps: 205 mm (41-5% of 495 mm). J. Interception in the top portion of 

 the soil: 74 mm (14-8% of 495 mm). K. Precipitation reaching the root zone of the 

 trees: 216 mm (43 "7% of 495 mm). L. Wind-driven precipitation collected by the 

 tree canopy, and thus screened off from the gaps: 106 mm (35-6% of 298 mm). M. 

 Interception in the top portion of the soil : 92 mm (30-9% of 298 mm). N. Precipitation 

 reaching the root zone of the trees: 100 mm (33-5% of 298 mm). 



its xeromorphy and rapidity of reaction. Examples have been given by 

 Parker (1957) and by Eger (1958). Consequently, it is necessary in every 

 individual case to test the agreement between the size of transpiration before 

 and after cutting. 



9 



