14 



BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



for the stand as a whole was classed as good, only 38 per cent of the 

 trees actually bore a good seed crop. Table 6 gives the results of 

 similar surveys near Fort Valley in 1918 and 1921 on four plots, 

 from 10 to 25 years after cutting. This table confirms the common 

 observation that the smaller blackjacks, especially in large groups, 

 bear very little seed. Undoubtedly the 1909 and 1913 figures are 

 at least 50 per cent too high for blackjack. Yellow pine, however, 

 is not subject to the same reduction, because the yellow pines left 

 for seed are selected for this purpose and are therefore better seed 

 trees than the average yellow pine in a virgin stand. Although the 

 records in Table 6 are valuable as a general indication of seed pro- 

 duction, they are inadequate as an expression of yield. What is 

 needed is an actual measure of cones and germinable seed for each 

 tree. Accurate data of this character can be secured only by collect- 

 ing the cones from each tree, preferably after it is felled. Such an 

 investigation is entirely feasible and should be carried out at the 

 first opportunity. 



Table 6. — Seed production in relation to diameter of trees. 





Diam- 

 eter. 



Total 



number 



of 



trees. 





Percentage of trees 



in each yield class. 





Plot. 



Very light 

 or none. 



Light. 



Medium to 

 good. 



Heavy. 





1918 



1921 



1918 



1921 



1918 



1921 



1918 



1921 



1A 



Inches. 

 8-11 

 12-15 

 16-20 

 21-25 

 26-30 



14 



27 

 42 

 28 



1 



86 



33 



9 



93 



37 



9 



14 

 56 

 55 

 50 

 100 



7 

 48 

 53 

 61 

 100 













11 

 29 

 32 



15 

 36 

 29 









7 

 18 



2 

 11 

























Total.. 



112 























22 



24 



50 



48 



21 



24 



7 



4 





8-11 

 12-15 

 16-20 

 21-25 

 26-30 

 Over 30 







IB 



4 

 5 

 22 

 18 

 10 

 6 



100 

 60 

 14 



75 

 60 

 14 

 6 



""26" 

 45 

 22 

 10 



25 

 40 

 45 

 38 

 20 

 17 













20 

 36 

 50 

 50 

 67 











41 

 56 

 70 

 50 



5 



28 

 40 

 33 



" "io 









33 













Total 



65 























15 



15 



25 



35 



42 



45 



IS 







8-11 

 12-15 

 16-20 

 21-25 

 26-30 

 Over 30 







3a... 



64 

 70 

 45 

 41 

 8 

 12 



70 



31 



13 



3 



90 

 41 

 15 

 10 



25 

 50 

 31 

 39 

 25 

 17 



9 



42 

 36 

 27 

 25 

 8 



5 

 16 

 45 

 34 

 62 

 33 



1 



17 

 49 

 58 

 75 

 75 







I 



3 

 11 

 24 

 13 

 42 



5 





8 



17 





Total 



240 























31 



41 



35 



27 



24 



31 



10 



1 





8-11 

 . 12-15 

 16-20 

 21-25 

 26-30 

 Over 30 







3b.. 



28 

 70 

 86 

 77 

 15 

 2 



71 

 37 

 19 

 8 

 20 



82 

 44 

 22 

 10 

 20 



25 

 49 

 37 

 27 

 20 



18 

 46 

 55 

 47 

 53 



4 



10 

 38 

 53 

 60 











10 



23 

 43 

 27 

 100 



4 

 6 

 12 







166 



















Total 



278 























26 



30 



35 



46 



32 



24 



7 













Note. — Nearly all the trees below 20 inches are blackjack, and nearly all above 30 

 Inches are yellow pine. 



