SILVICULTURAL MANAGEMENT OF BLACK SPRUCE IN MINNESOTA 21 



to where they were produced. In one test it was found that hardly 

 any were blown 300 feet into a clearing from the edge of a forest (18), 

 The distribution of seeds in a 100-foot cleared strip and in adjoining 

 uncut black spruce timber is shown in figure 14. Near the center of 

 the strip, only 50 feet from the timber, seed fall was about one-third 

 as much as that 50 feet inside the stand. 



Black spruce cones rather frequently are found to have been damaged 

 by insects. The small yield of seed from upland trees in 1939 (table 

 2) was at least partly the result of extensive insect damage to the 

 cones. The insects had departed before the cones were collected and 

 hence could not be indent ified. The cones also are commonly gathered 

 by red squirrels (Sciurus hiidsonicus) . Large masses of chewed and 

 separated cone scales accumulate around stumps and logs where squir- 

 rels have a habit of extracting the seeds. When squirrels gather black 

 spruce cones, they clip off entire twigs with the cones attached. 

 Sometimes this results in a considerable amount of pruning near the 

 tops of the trees where the cones are borne. Examinations of the 

 upper portions of numerous trees has shown that the characteristic 

 "bunchy ' ? appearance of black spruce tops (fig. 15) is caused by such 

 pruning. This has been observed in Ontario 16 as well as in Minne- 

 sota. 



25 50 75 



DISTANCE (FEET) 



Figure 14. — Dispersal of black spruce seed into a cleared strip from adjoining 

 uncut timber. Kawishiwi Experimental Forest, August 1, 1934 to July 31, 

 1939. The prevailing wind, which is from the southwest, accounts for slightly 

 greater drift of the seed toward the north. 



Germination and Establishment of Seedlings 



Black spruce germinates rather promptly when temperature and 

 moisture conditions are favorable. Seeds sown in a nursery seedbed 

 in July and covered with one-eighth inch of sand commenced to germi- 

 nate on the tenth day and practically completed their germination on 

 the nineteenth day. Under natural conditions where moisture is likely 

 to be less continuously available, germination is considerably slower. 

 In a test designed to determine the relationship between date of seed 

 fall and date of germination, seeds were sown in a freshly clear-cut 



See footnote 13, p. 15. 



