THE BEHAVIOUR OF NORWAY SPRUCE (PICEA 



ABIES (L.) KARST) IN CENTRAL JUTLAND, 



DENMARK, IN THE SUMMER OF 1955 



E.B.Oksbjerg 

 Royal Forestry College, Stockholm 



THE WEATHER CONDITIONS 



The summer of 1955 was very hot and dry in large parts of northern 

 Europe. Observations made at the meteorological station Loendal, in 

 Central Jutland, are shown in Fig. i comprising temperatures at 2 p.m. 

 and rainfall, computed as averages and sums respectively, for 5-day periods. 

 Compared with 'normal figures' from cHmate tables, April, May and 

 June of 1955 were very cold, humid and windy and the cloudy weather 

 reduced the occurrence of night frosts to five occasions. At Loendal 

 station (a cupboard on poles 1-5 m above soil surface) the five lowest 

 minimum temperatures were between —0-2 and — i-8°C. At an experi- 

 mental field between Loendal and Salten mentioned below, the night 

 temperatures measured on the soil surface were lower and frosts occurred 

 more frequently (Oksbjerg, 1956). 



OBSERVATIONS ON GROWTH AND INJURY IN 

 SPRUCE PLANTATIONS 



The extension growth of leader shoots of late- and early-flushing spruces 

 during the sprouting period, shown in Fig. i, was observed in 1955 in an 

 experimental plantation 2 kilometres north of Loendal. The two plots 

 were estabhshed in 1952 by separate planting of four-year-old spruce 

 plants which in the spring of 19 51 in the nursery were marked out as 

 extremely late- and extremely early-flushing individuals. 



The flushing process of spruce is strongly influenced by temperature, 

 and the belated sprouting appearing in Fig. i for both spruce types, about 

 three weeks later than usual, is undoubtly due to the coldness. 



Some scattered frost injury occurred in the early-flushing plot on the 

 new shoots of the lowermost branches which, as is well known, flush 

 before the leader. 



In the years 1952, 1953 and 1954 the shoot growth of the two plots had 

 been equal, and as the differences shown in Fig. i cannot be due to soil 



