




THE TRER. 23 
mature yellow pine when in the blackjack form grew much slower 
than the present blackjack of the same size. This difference in 
diameter growth during the youth of the yellow pine is difficult to 
explain, unless it is because the more recent blackjack forests have 
been thinned by fire and the diameter growth stimulated. The cur- 
rent annual growth falls below the mean annual growth after 80 
years in the blackjack form, and after 100 years in the yellow pine. 
TABLE 9.—Age of yellow pine and blackjack on basis of diameter breast high. 

Diameter Yellow see ee 
breast high. pine, | Blackjack. 
Inches. Years. Years. 
pa a Ae 21.0 355 
Sy Ps eee ee 38. 0 26. 0 
Ce a eee BY GS) 39.5 
11) espe ieee Sa 79.5 5355) 
1. EI te es a ee 108. 0 70.5 
BA eee eee eerie 145.5 91.5 
71 LE eas Saat Seas 190.5 127.0 
Dot ee ae PEY EO Al Atk seo ess 
DORA SRLS Se oe 2855 Og |Pemerees sere 




TABLE 10.—Diameter growth of yellow pine and blackjack on basis of age. 





Blackjack. © Yellow pine. 
: Age. 
Diameter Growth Diameter Growin f 
breast high.| per year. |breast high. P ie 2 
st 20. 
Years Inches. Inch Inches. Inch 
PLS a Ea Se ee ONOO ME Seco seeees SH) =" [earn ae 
A () eat pes pere operas ere on 8.15 0. 227 5 0.170 
C50) eer ar nec oe Ae 12. 20 . 202 8. 45 160 
C0 Sa Ee Go een eae 15. 50 . 165 11.10 132 
NOD Me eee a A 17.95 B22 13. 20 105 
IS 3 ae ee le oe ee 19. 70 . 087 14. 95 087 
A) Bee en eee dee She. Be es 20. 80 . 055 16. 55 080 
GO Remmi c peer Palys 17.95 070 
De se Se SS HOSED CAS eee ee (nee oe ae 19. 30 067 
POO) So Sect ee RE Se (are aero) (eee ee ae 20. 65 067 
RANE 5 Se sheae SO Coan | Cee area ee Pennie eee 21. 90 062 
sah Sas Se eS ee ee ee eee eens 23. 20 065 
A) pee ne eames 2 ws Ne Ao [ee ot es 24. 50 065 
Mean annual diame- 
(HOLRO  aB Sess SEA Cmemaeroe S148 eee se . 094 

In Table 11, which is based on measurements of from 17 to 205 
trees, on five National Forests, no distinctions were made between 
blackjack and yellow pine, although most of the trees measured be- 
longed to the latter class. The average for the five Forests gives the 
diameter of 160-year yellow pine at 19 inches, while the Srna for 
the Coconino Forest, in Table 10, gives it as 17.95 inches. 
