22 WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO. 
Under conditions best suited to its development—that is to say, in 
mixture with Douglas fir—the height growth of western yellow pine, 
as shown in Table 7, based on the measurements of 80 trees in the 
Apache National Forest, is most rapid at from 60 to 100 years of age. 
After 100 years the rate of height growth declines, until from 160 to 
180 years it falls below the mean annual growth of 0.37. 
TABLE 7.—Height growth of western yellow pine in mixture with Douglas fir. 






Annual Anna 
ae growt ) . growt 
Age. Height. for last Age. Height. for last 
20 years. 20 years. 
Years Feet. Foot. Years Feet. Foot. 
20S Ra ee 520 0. 25 2002 sae ee 95.8 0.28 
A (Veiner nee ee ts ee 13E5 -45 290 Be eee 100. 4 ae 
GOR eae es Sa Pas fe? .61 DAS lee Roe eer 104.3 .19 
SOME a 8 See eee 40.3 ie, 260 Saree ae 107.2 14 
TIC Vee ey ae Sas 54.0 = 7A 280 58 Seni ee oe 109.5 = 1Ul 
TIPLE Re Mel ves eyo 65. 4 AGYS BOOS A eee eee lhe .08 
CA QS oe eas eee 75.0 48 
GO ee eee 83.2 41 Mean annual growth. . -30 
SQ sce on 2 eee 90. 0 34 





The relation between diameter and height is shown in Table 8, the 
figures in which are derived from hypsometer measurements. A com- 
parison between height and age may be secured by substituting the 
ages in Table 7. On the Zuni Forest, distinction was made between 
blackjack and yellow pine, and the figures show that for the same di- 
ameters blackjack is shorter than yellow pine; yet on the Jemez 
Forest, where blackjack and yellow pine were also measured sepa- 
rately, this difference was not borne out, since the heights were prac- 
tically identical. 
TABLE 8.—Height of western yellow pine on basis of diameter. 












j: . iF : 
| Apache Forest Patil Zuni Forest Pr eseott 
Diameter orest, orest, 
breast Pure With | ee pure Jemez Average. 
high. western | Douglas ees Black- | Yellow ee Forest. 
yellow fir in eine jack pine. fae 
pine. | mixture. 
Inches. Feet Feet Feet. Feet Feet Feet. Feet. Feet 
DU ea eee ba ae eee roy Ci Bee nen freee a 40 64 52.7 
14 57 73 58 52 60 48 68 59. 4 
17 66 82 65 63 7 o7 73 67.6 
20 74 91 74 72 73 65 78 G23 
23 81 98 82 80 80 72 83 82.2 
26 85 103 89 88 90 78 88 88.7 
29 89 107 ofc | en yee dee 98 83 95 95.0 
32 91 AE. a ee ote oe | aa ene 105 87 104 99. 4 
35 92 TT 2-5 SSR eit ee ay a 110 QO: 5) Sao 101.0 




DIAMETER GROWTH. 
Tables 9 and 10, based on the measurements of 400 trees on the 
Coconino and Tusayan National Forests, give the diameter of yellow 
pine and blackjack at different stages. It is apparent that the 



