[77] SUMMARY OF THE PROGRAMME 77 



3- Diseases and Injuries to Forest trees. 



a) Injuries caused by insects (E). 



Continued investigations. 



Investigations on the occurrence of the pine beetles, with special attention 

 to the small one; studies in different parts of the country concerning the 

 influence of the removing of the bark on the frequency of the pine beetles 

 on wood cut in winter time, observations on the effect of the injuries in the 

 crowns on the increment of the affected trees; studies on the distribution, 

 biology and importance of the bark-beetles in the different parts of the 

 country; studies of the development of the spruce bark-beetle and of the 

 correlation with climatic factors, the progress of the outbreak, observations 

 on the colour of the crown at different stages of the attack; experiments 

 with different methods of preparing trap-trees, and the influence of the time 

 for cutting, the degree of exposition and of removing the bark; investiga- 

 tions on insects, injurious to spruce and pine cones, with special attention to 

 the cone fauna in summer time, and experiments in killing the larvae of the 

 spruce cone moth by hydrocyanic acid; studies of the insects coming after 

 forest fires, with a view of ascertaining the danger of burned forests being 

 centres of injurious insects, and the possibility of treating the slightly damaged 

 trees in such a way that the technical deterioration caused by some borers 

 may be prevented. 



New investigations. 



The fauna of the ground in different types of forest, see also mom. 5 f. 



4. Races of Forest trees and the acclimatization of foreign forest 



trees in Sweden. 



Continued investigations. 



Studies of the races of Spruce and Pine. Revision and completion of the 

 plantations of spruce already existing (N); 



German Spruce-seed. Revision of plantations of spruce from different parts 

 of Central Europé (S); 



Larch. Rearrangement of the material with the object of obtaining yield 

 tables for the larch species in Sweden (S); experiments with cultivation of 

 different races of larch (S); 



Silver Fir. Comparison between the production of the silver fir and of 

 the common Swedish spruce (S). 



New investigations. 



Douglas Fir. The production in stånds, cultivation with seed of known 

 origin (S). 



5. Investigations concerning Forest Land. 



a) Types of soil and humus covering. 



Continued investigations. 



Investigations of the humus covering and the problem of acid humus (N). 



