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=good. M=medium, L=light. VL=very light. 0=none.] 



(.roup 1.— Good Seed Producers. 



Tree 

 No. 



Diam- 

 eter 

 breast- 

 high, 

 1919. 



Blackjack 



or 



yellow 



Seed crop by years. 























pine. 



1913 



1914 



1915 



1916 



1917 



1918 



1919 



1920 



1921 



968 



26 



Blackjack... 



G 



O 



L 



O 



O 



H 



O 



O 



G 



970 



25 



do 



G 



() 



L 



O 



O 



H 



O 







G 



996 



24 



Yellow pine. 





O 



L 



O 



O 



H 







VL 



G 



997 



31 



do 



G 







L 



O 



O 



H 







VL 



G 



1007 



32 



do 



G 







M 



VL 



O 



G 



o 



O 



M 



1037 



25 



Blackjack... 



G 







M 



M 



O 



H 







VL 



H 



1041 



32 



Yellow pine. 



H 







M 



VL 



O 



M 







VL 



G 







Group 2— Inte 



rmediate Seed Produc 



BBS. 









991 



22 



Blackjack... 



L 



O 



O 



VL 



O 



L 







O 



G 



1000 



22 



do 



\. 







o 



O 



O 



L 







O 



G 



1035 



27 



do 



L 







o 



O 



O 



G 







O 



G 



1056 



21 



do 



O 



o 







o 



O 



G 











M 



1131 



32 



Yellow pine. 



I. 











L 



° 



H 











L 







Group 3 — 



Poor Seed Producers. 











1026 



23 



Blackjack... 



L 











VL 



o 



M 







VL 



L 



1051 



21 



do 



O 











O 







L 







O 



L 



1066 



32 



Yellow pine. 



L 











O 







L 







VL 



M 



1068 



24 



do.. 



L 











() 







VL 







VL 



L 



1132 



25 



Blackjack... 



L 



















L 







O 



L 



1151 



21 



Yellow pine. 



L 







L 



o 







VL 







O 



VL 



1186 



23 



Blackjack... 



O 



















L 







o 



L 



DISTRIBUTION OF SEED. 



Xext 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 



