SILVICULTURAL MANAGEMENT OF BLACK SPRUCE IN MINNESOTA 



9 



of this — over 5 million cords — was situated in a comparatively narrow 

 band in the northernmost part of the State. These districts are thinly 

 settled and, to a large degree, poorly accessible. During the 10 years 

 subsequent to 1934, roughly 2 million cords of black spruce have been 

 cut for pulpwood, and there have been appreciable losses caused by 

 fire, wind, snow, glaze, decay, drought, and senility. To some extent 

 the depletion has been offset by growth, but the net result has been a 

 substantial reduction in supplies of merchantable timber. The most 

 recent Forest Survey estimate (1945) indicates a volume of 4,400,000 

 cords. 



Table 1. — Status of original coniferous swamp and spruce-fir types 



in 193 J^ 1 



Status or cover in 1934 



Original forest type 



Coniferous 

 swamp 



Spruce-fir 



Nonf orest use 



Deforested 



Aspen_ 



Spruce-fir 



Coniferous swamp: 



Black spruce 



Cedar 



Tamarack 



Nonproductive 2 . 



Total 



Thousand 

 acres 



900. 4 

 1, 608. 3 



260. 9 



Thousand 

 acres 



1, 978. 3 

 617. 5 



2, 615. 9 

 1, 088. 3 



1, 529. 8 

 380. 6 

 656. 9 

 763. 1 



6, 100. 



6, 300. 



1 See footnote 6, p. 3. 



2 Stands of spruce or tamarack in which it is estimated that trees will not attain 

 a 5-inch d. b. h. by the age of 100 years. 



Description of Stands and Growing Conditions 



swamps 



Black spruce occurs most commonly in peat swamps (fig. 8). On 

 such sites in Minnesota it usually is found in nearly pure stands al- 

 though it also grows in mixture with a number of other species. Tam- 

 arack was once a very common associate, but is much less abundant 

 now as the result of devastating attacks by the larch sawfly (Pristi- 

 phora erichsonii) about 1910 to 1915. Mixtures containing northern 

 white-cedar occur, although black spruce and white-cedar tend to seg- 

 regate into different types of swamps. Almost all black spruce swamp 

 forests contain a light sprinkling of balsam fir and paper birch (Betula 

 papyrifera) . 



The swamps of Minnesota, in which black spruce and associated tree 

 species grow, can be found in many stages of development. They 

 range from the relatively primitive ones with excessively wet, poorly 

 decomposed peat where black spruce is barely able to survive, up to the 

 more mature ones having drier, humuslike, surface peat where grow- 



792021°— 48 2 



