THE BEHAVIOUR OF NORWAY SPRUCE 



I5f 



But here also much accessible water remains in the different horizons and 

 the reason may also here be an insufficient number of root tips per unit of 

 root volume. The physiological water capacity of the Kompedal profile is 

 at most 40 mm of rain. 



Locahty 3 , the experimental plantation near Loendal mentioned in sec- 

 tion 2. The soil was previously cultivated and no 'natural' profdes occur. 

 Both in the grass-covered and in the bare, light-coloured sand, roots 

 occurred down to a depth of 40-45 cm. On 22 July the whole rooted 

 volume of the grassy soil was devoid of available water and by i September 

 the bare soils had also reached the wilting capacity. In the spring of 1957 

 the field capacity was determined, and a definitive account is presented 

 in Table 3 . 



Table 3 

 Water-holding properties of soil near Loendal 



As will be remembered the plants on bare soil survived whereas many of 

 those on grass-covered soil died; in the late-flushing plot all the latter died. 

 The cause may be a high consumption of water by grass and a very intense 

 root penetration by spruce in the previous field-soil rich in humus. 



Locahty 4, a very good forest soil on moraine. On a sHght, north facing 

 slope in Silkeborg Sonderskov, dpt. 232, Norway spruce 25 years ago 

 succeeded beech. Samples were taken in September 1955 and three times 

 during the summer of 1957. The profile, which was rooted to 85 cm, was 

 presumed to be fairly represented by samples from three different depths, 

 and a rough estimation showed that there was left more than 50 mm 

 accessible water in September 1955 before any important shower had 

 fallen after the drought. Water content increased with depth, and in no 



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