18 



BULLETIN 1105, U, S. DEPARTMENT OF AGRICULTURE. 



that some of the older trees in Group 3 were formerly more pro- 

 ductive and that they are slowly declining. The blackjacks in 

 Group 2 appear to be rising. This is probably a response to the 

 increased light after cutting. Although it is not proved that the 

 variations in seed production are inherent, we know that important 

 differences do exist. Mature trees which show no signs of active 

 cone production have little chance to become more productive as a 

 result of cutting, and should therefore be discriminated against in 

 selecting seed trees. Immature trees, on the other hand, may improve 

 under the influence of increased light and moisture after cutting. 

 Other things being equal however, preference should be given to 

 those individuals which have the best record of past performance, 

 as indicated by cones on the trees or at their bases. 



Table 7. — Sample record of seed crops for individual trees. 



[H=heavy, G=goo(i, M==medium, L=light, VL==very light, 0=none.] 



Group 1. — Good Seed Peoducees. 



Tree 

 No. 



Diam- 

 eter 

 breast- 

 high, 

 1919. 



Blackjack 



or 



yellow 



pine. 



Seed crop by years. 



1913 1914 1915 1916 1917 1918 1919 



1920 



1921 



970 

 996 

 997 

 1007 

 1037 

 1041 



Blackjack 



do.... 



Yellow pine, 



do.... 



do.... 



Blackjack 

 Yellow pine 



O 



O 



O 



O 

 VL 



M 

 VL 



O 



O 



VL 

 VL 



O 



VL 

 VL 



Geoup 2.— Inteemediate Seed Peoducees. 



991 



22 



1000 



22 



1035 



27 



1056 



21 



1131 



32 



Blackjack... 



....do 



....do 



....do 



Yellow pine. 



L 











VL 







L 











L 



() 



C) 











L 







O 



L 















O 



(J 



O 











C) 



o 











G 







O 



L 











L 







H 











Geoup 3.— Pooe Seed Peoducees. 



1026 

 1051 

 1066 

 1068 

 1132 

 1151 

 1186 



23 



Blackjack... 



L 











VL 



O 



M 







VL 



21 



do 



O 



















L 



O 







32 



Yellow pine. 



L 



O 







O 







L 







VL 



24 



do 



L 















() 



VL 



() 



VL 



25 



Blackjack... 



L 











o 







L 











21 



Yellow pine- 



L 



O 



L 







i) 



VL 



() 



O 



23 



Blackjack... 























L 











L 

 L 

 M 

 L 

 L 



VL 

 L 



DISTRIBUTION OF SEED. 



Next in importance to quantity of seed is distribution. The 

 densest seeding takes place within a radius of 20 feet from the trees. 

 The real test of the efficiency of the seed trees on a given area is 

 made by determining the density of seeding in the more remote 



