forestry Conditions in Sweden. 53 



left is often unable to continue its good growth. The soil dries 

 up, parasites increase, growth in height decreases, diameter 

 growth decreases rapidly and as a result of the diminished growth 

 and activity of the stand the balance between the water supply 

 of the soil and its absorption is destroyed. The deteriorating 

 spruce stand is not capable of sufficiently draining the soil. The 

 soil grows wet and swampy, which results not infrequently in the 

 death of the forest vegetation and a formation of a high moor. 

 This process is of common occurrence in the Swedish forests, 

 the more frequently the farther north one progresses. The 

 reclamation of these "watersick" soils, especially for pine, is 

 often very difficult and expensive. 



In the life history of the northern forests forest fires have 

 always played an important role. They have always successfully 

 driven back the thrifty spruce from the pine soils, as the spruce 

 and not the pine falls a victim to fires. The soil laid bare by the 

 fire is easily seeded with pine, resulting in an independent new 

 generation of pine, which after some time gradually becomes 

 mixed with spruce. After especially severe fires which have 

 robbed the soil of its entire humus and litter, the pine genera- 

 tion tends to come in under a preceding birch stand, which is 

 the only species at first able to take root. Under this protective 

 cover, first the pine and later the spruce stands develop. 



The example of nature is imitated successfully in many of the 

 northern districts by using fire to establish the natural reproduc- 

 tion of pine. 



On the swampy stretches of forest land drainage is provided 

 for by constructing ditches. Deteriorated and drowned forests 

 are cut over, the soil burned over after draining and then sowed 

 to pine. 



On fresh moraine soils, spruce forms thrifty pure stands from 

 which pine has been completely crowded out. Some of the soils 

 formed by disintegration of the fundamental rock, i. e. the lime 

 and Silurian soils, grow pure spruce stands of high quality. 



Until very recently spruce timber had very little if any eco- 

 nomic value at all, as the sawmills cut pine chiefly. But since 

 the growth of the wood-working industry spruce timber has found 

 quite a good market value. Since then it has also been possible 

 to so utilize the mixed spruce and pine stands as to aid the pine 

 in retaining its dominant position in the stand. As long as the 



