to increase natural regeneration should be complete by the same date to 

 take full advantage of the natural seed supply. 



Effects of stand density. — The periodic measurements of seed fall did 

 not reveal any effect of stand density on time of seed dispersal (fig. 2); 

 however, the total amount of seed fall was related to stand density (table 

 2). The total seed fall in the stand of intermediate density was signifi- 

 cantly greater (1 -percent level) than that in the other two stands in 1965. 

 The much smaller seed crop of 1968 did not differ significantly among 

 densities. This lack of a significant difference in 1968 was related to the 

 light seed fall, which resulted in a high sample variability. In both seed 

 years the ratio of seed fall in the intermediate-density stand to that in the 

 other stand densities was similar. 



The effects of stand density were logical. The uncut high-density stand 

 with a basal area of 187 square feet was too crowded for maximum seed 

 production; the crowns, though numerous, were small. In the inter- 

 mediate-density stand, the trees were well-spaced and had larger crowns. 

 In the low-density stand, crown development was slightly better still, 



1968 



Figure 2.— Periodic seed 

 fall as influenced by 

 stand density. 



200 400 600 800 200 



THOUSANDS OF SEEDS PER ACRE 



4 



