SILVICULTURAL MANAGEMENT OF BLACK SPRUCE IX MINNESOTA 41 



Some black spruce stands have considerable white-cedar or balsam 

 fir reproduction. White-cedar and balsam fir are not particularly 

 desirable to have in mixture with black spruce. Neither one grows 

 well in true spruce swamps and the balsam has the further drawback 

 of being the chief host for spruce budworm {13). Such reproduction 

 can be prevented by cutting the trees that produce the seed. Since 

 many white-cedars and balsam firs are culls, their removal may have 

 to be conducted as a stand improvement operation which does not 

 always pay its way. 



The slash created by light partial cutting is so scattered as to be of 

 little consequence either as a fire hazard or a factor in reproduction. 

 In heavier cuttings the slash is proportionately more dense and hence 

 is more of a problem. On State land, loggers are required to lop the 

 tops as a fire hazard reduction measure. The practice on national 

 forest timber sales is to require lopping or piling. The latter method 

 is being tested as a means of reducing the amount of area covered by 

 slash in order to favor reproduction. In an experiment designed to 

 test the effect of several kinds of slash disposal on reproduction in a 

 moderately heavy partial cutting on the Superior National Forest, the 

 results 7 years after logging were : 



Black spruce 

 seedlings per 

 acre 1 {number) 

 Slash disposal method : 



No disposal 1, 860 



Lop and scatter 1, 500 



Pile 3,184 



Pile and burn 2, 533 



1 Roe, E. I. slash removal an important factor in restocking cvt-over 

 spruce swamps. U. S. Forest Serv., Lake States Forest Expt. Sta., Technical 

 Note 249, 1946. [Mimographed.] 



Even the lowest stocking, that which resulted from no slash dis- 

 posal, is satisfactory. In theory, piling and burning should give 

 the best results of all because the burned spots are particularly favor- 

 able for seedling establishment. However, piling and burning is not 

 recommended, because of the additional cost and the probability of 

 scorching residual trees. 



POSTCUTTING MORTALITY 



The variations in size among the trees in a black spruce stand and 

 the shade-tolerance of this species naturally suggest the possibility that 

 it can be managed by the selection system (7). On the other hand, 

 the reputation black spruce has for lack of windfirmness has caused 

 many to believe that partial cutting would lead to serious windthrow 

 losses. Hence, no attempts at partial cutting were undertaken in 

 spruce swamps in Minnesota until 12 or 15 years ago (fig. 24). 



In recent years evidence has been gathered which shows that wind- 

 throw and other postcutting mortality in black spruce swamp stands 

 are not nearly so serious as once was supposed. In 1939 a series of 

 plots was established in recently cut-over black spruce swamps 

 scattered widely over northern Minnesota. Cuttings on private. State. 

 and Federal lands were sampled indiscriminately wherever they could 

 be found. On some areas all of the merchantable volume and up to 

 93 percent of the basal area in trees over 2.5 inches d. b. h. had been 



