SILVICULTURAL MANAGEMENT OF BLACK SPRUCE IN MINNESOTA 19 



Cutting may be done at any season of the year but the bulk of it is 

 performed in the periods November 1 to January 31 and May 10 to 

 July 31. Peeled pulpwood is produced only during the latter period. 

 Most of the bolts are peeled, for convenience, in the skid road and 

 the sheets of bark are dropped there where they often form an almost 

 continuous carpet. 



Within the skid roads, which occupy 10 to 15 percent of the logging 

 area, all trees large and small are destroyed by the clearing, but the 

 leveling, trampling, and skidding make the surface favorable for 

 germination and establishment of seedlings. However, if the bolts are 

 peeled and the bark is thrown on the ground, this carpet seriously in- 

 terferes with reproduction. 



In the area between the skid roads, a good many of the unmerchant- 

 able smaller trees are cut, broken off, or otherwise damaged. Much 

 of the damage is needless. Seedlings and saplings up to 6 feet in 

 height often are bent down and smothered by the tangled mass of 

 tops and limbs. Wherever the accumulation of branches is heavy, 

 the spruce needles which quickly drop from the twigs make a coarse, 

 dry layer of material that is decidedly unfavorable for the establish- 

 ment of seedlings. 



Despite the extensive damage to advance reproduction and the un- 

 favorable reproduction conditions created over much of the area, black 

 spruce is persistent and prolific. The result is that most cut-over areas 

 regenerate rather well if they are not burned. A survey made in 

 northeastern Minnesota in 1931 of cut-over spruce swamps showed that 

 four-fifths of the areas were reasonably well stocked with black 

 spruce. 14 O nthe average, 66 percent of the milacre quadrats exam- 

 ined had one or more black spruce trees present. 



Pulpwood logging on upland follows the same general system as in 

 swamps. However, black spruce in upland types tends to be replaced 

 by other species subsequent to logging ( table 3 ) . 



Table 3. — Effect of clear cutting on black spruce reproduction in 

 mixed upland forest in northeastern Minnesota 





Species 



Trees per acre 





Overstory 



stand before 



cutting 1 



Reproduction 

 3 years 

 later 2 



Black spruce 



Jack pine 



Number 



135 



265 



33 



23 



Number 



3 

 409 



Paper birch 



500 



Aspen : 



1, 000 









Total 



456 



1,909 



1 Trees over 3.5 inches d. b. h. 



2 Basis, 40 milacre quadrats. 



3 The initial reproduction included 192 black spruce seedlings per acre but 

 these were killed b}? - a severe drought. Ordinarily some can be expected to 

 survive. 



14 United States Forest Service. How to cut black spruce. U. S. Forest Serv., 

 Lake States Forest Expt. Sta. Tech. Notes 54, 1 p. May 1932. [Mimeographed.] 



