18 COMPOSITE TYPE ON THE APACHE NATIONAL FOREST. 



Table 7. — Form factors of western yellow pine, Douglas fir, and blue spruce. 1 



Age. 



Height. 



Diameter breast high, 

 outside bark. 



Merchantable form 

 factor.2 



Pine. 



Fir. 



Spruce. 



Pine. 



Fir. 



Spruce. 



Pine. 



Fir. 



Spruce. 



Years. 

 10 

 20 

 30 

 40 

 50 

 60 

 70 

 80 

 90 

 100 

 110 

 120 

 130 

 140 

 150 

 160 

 170 

 180 

 190 

 200 

 210 

 220 

 230 

 240 

 250 

 260 

 270 

 280 

 290 

 300 

 310 

 320 

 330 

 340 

 350 

 360 



Feet. 

 2.2 

 5.0 

 9.0 

 13.6 

 19.4 

 26.0 

 33.1 

 40.2 

 47.2 

 54.0 

 60.0 

 65.5 

 70.5 

 75. 1 

 79.3 

 83.1 

 86.9 

 90.0 

 93.0 

 95.9 

 98.2 

 100.4 

 102.3 

 104.1 

 105.8 

 107.2 

 108.5 

 109.6 

 110.6 

 111.3 

 111.9 

 112.4 

 112.8 

 113.1 

 113.4 

 113.6 



Feet. 

 1.3 

 4.1 

 9.0 

 15.4 

 22.8 

 30.2 

 37.7 

 44.6 

 51.1 

 57.4 

 63.3 

 68.8 

 73.8 

 78.6 

 83.0 

 87.1 

 91.0 

 94.5 

 97.8 

 101.0 

 103.6 

 106.1 

 108.2 

 110.0 

 111.5 

 112.9 

 114.0 

 114.9 

 115.7 

 116.3 

 116.9 

 117.4 



Feet. 

 1.5 

 4.0 

 7.0 

 14.0 

 23.0 

 34.3 

 46.7 

 58.0 

 69.0 

 78.0 

 86.0 

 92.0 

 98.0 

 104.0 

 108.0 



Inches. 

 0.6 

 1.3 

 2.2 

 3.4 

 4.6 

 6.0 

 7.5 

 9.0 

 10.5 

 12.0 

 13.4 

 14.8 

 16.2 

 17.5 

 18.8 

 20.0 

 21.2 

 22.4 

 23.6 

 24.7 

 25.8 

 26.9 

 27.9 

 28.9 

 29.8 

 30.6 

 31.4 

 32.2 

 32.9 

 33.5 

 34.1 

 34.7 

 35.2 

 35.7 

 36.2 

 36.6 



Inches. 

 0.6 

 1.4 

 2.3 

 3.4 

 4.6 

 6.0 

 7.4 

 9.0 

 10.6 

 12.2 

 13.9 

 15.6 

 17.2 

 18.8 

 20.4 

 22.0 

 23.5 

 25.0 

 26.4 

 27.7 

 28.9 

 30.1 

 31.2 

 32.1 

 33.1 

 34.0 

 34.8 

 35.6 

 36.4 

 37.2 

 37.8 

 38.4 



Inches. 

 0.4 

 1.1 

 2.2 

 3.8 

 6.0 

 9.2 

 12.3 

 14.8 

 16.8 

 18.4 

 19.8 

 21.0 

 22.0 

 22.8 

 23.5 

















































0.219 

 .234 

 .236 

 .248 

 .259 

 .265 

 .268 

 .273 







0.245 

 .281 

 .313 

 .332 

 .350 

 .356 

 .366 

 .371 

 .376 

 .377 

 .379 

 .381 

 .381 

 .381 

 .382 

 .383 

 .384 

 .387 

 .389 

 .391 

 .395 

 .398 

 .400 

 .405 

 .407 

 .409 

 .411 



0.229 

 .239 

 .281 

 .283 

 .290 

 .290 

 .288 

 .287 

 .285 

 .284 

 .284 

 .287 

 .290 

 .290 

 .295 

 .298 

 .302 

 .307 

 .310 

 .313 

 .316 

 .320 

 .325 























































1 Based on the measurements of 180 western yellow pines; 185 Douglas fir; and 135 blue spruce. 



2 The form factors are based on the volume of wood over 8 inches in diameter. The volume of the stump 

 is not included. 



It is interesting to note the manner in which the form factors 

 given in Table 7 vary with the increase in age of the tree. This is 

 true for each species and shows the difference in the form of the tree 

 at youth and at maturity. In fact, the greatest difference in the 

 three species is found in the form of the bole. At no age do the form 

 factors for the three species closely correspond, although at 100 

 years pine and fir are comparatively close. The form factor for 

 yellow pine at 100 years of age is 0.245. From this point it increases 

 steadily with the age of the tree until at 360 years it is 0.411. The 

 form factor for Douglas fir at 100 years is even lower than that for 

 pine, and remains so throughout the life of the tree. At the age of 

 320 years it is 0.325. Since breast-high measurements were used 

 in computing the cubical contents of the trees for use in determining 

 the form factors, the small figures for Douglas fir are due only to a 

 very slight extent to butt swell. Spruce resembles Douglas fir in 

 form of bole, although it is somewhat more tapering. The indica- 

 tions are that this species will not fill out as much as either yellow 

 pine or Douglas fir even at maturity. 



