Table 2.— Total viable seed fall per acre 



Stand-density 

 level 



Viable seeds 





1965 



1968 



High 



1,139,820 



297,660 



Intermediate 



1,793,220 



408,980 



Low 



1,253,560 



297,660 



but too few trees remained to fully occupy the site; consequently potential 

 seed production was limited by lack of sufficient crown area. 



Cone production per tree was similar in both the intermediate- and low- 

 density stands, but there were approximately 50 percent more trees in 

 the intermediate stand. As a result, seed fall in the intermediate stand 

 exceeded by about 40 percent that of the low-density stand. 



Number of viable seeds per pound. — The number of ovendry viable 

 seeds per pound was determined once in 1965 and weekly in 1968. In 

 early October 1965 the average number of seeds per pound was 31,700. 

 The weekly determination made in 1968 showed the heaviest seed (28,700 

 per pound) fell in late September. From this time on, the mean seed 

 weight declined about 6 percent per week, causing the average number 

 of seeds per pound to increase. By mid-November, the average number 

 of seeds per pound had risen to 45,000. But, because most of the seeds 

 had fallen by mid-October, the overall average for the season was 31,000 

 viable seeds per pound. 



Seed viability. — The percentage of viable seeds was especially high in 

 1965, the heavy seed year. Viability averaged 86.7 percent in 1965 and 73.4 

 percent in 1968. Seed viability varied widely during the time of seed fall. 

 The period of maximum seed fall coincided with the highest viability. 



In 1965 the viability was 20 percent during the first week of September, 

 peaked at 93.6 percent in the fourth week of September, and dropped to 

 10 percent by the end of November. Seed viability followed a similar 

 trend in 1968. 



Seed losses caused by birds and small mammals.— In late September 

 and October 1965, during the period of maximum seed fall, many seeds 

 were conspicuously exposed on the ground. At this time, roving flocks of 

 30 to 50 rusty blackbirds (Euphagus carolinus) were noted in the seed- 

 bearing stands of pine. The flocks of blackbirds were observed on many 

 occasions scratching and feeding in the pine litter. After these birds had 

 worked through an area, very little seed could be found. 



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