4 BULLETIN 426, U..S. DEPARTMENT OF AGRICULTURE. 
graceful downward. sweep to the limb. Even in this position they 
can not escape the squirrels that depend on the rich-flavored seed 
for a winter food supply and cut large numbers befcre maturity. 
SIZE AND LONGEVITY. 
- Sugar pime attains a greater size than yellow pine, white fir, incense 
cedar, or any of its ‘associates, except the huge Sequoias of the 
Sierras, which tower far above it in the scattered localities where 
the two species occur together. Its average maximum height is 175 
feet and the corresponding diameter 44 feet. The maximum height 
reached is 240 feet and the maximum diameter 11 feet, measured 
outside the bark at 44 feet above the ground. The average number 
of logs per thousand feet board measure, ascertained from sales of 
National Forest stumpage, varies from 4 in unfavorable situations to 
1.5 in the best localities. This species attains an age of 500 years, 
but rarely more than that. 
SUSCEPTIBILITY TO INJURY AND DISEASE. 
Various injuries tend to shorten the life of sugar pme, but none 
result in the immediate death of a high percentage of mature stands 
except those caused by destructive insects. 
FIRE. 
3 
Repeated fires cause butt scars or ‘‘cat faces,’ and thus weaken 
the tree mechanically, retard growth, and bring about conditions 
favorable to disease. Such scars also decrease the value of butt 
logs. Seedlings, saplings, and poles are destroyed in large numbers, 
but very few trees over 12 inches in diameter at breast height are 
killed, except on steep slopes during very high winds. | 
LIGHTNING, WIND, FROST, AND SNOW. 
Sugar pine undoubtedly is injured more frequently by lightning 
than its associated species, yellow pine, fir, and incense cedar, because 
of its greater height and occurrence at relatively high elevations, 
where such storms are common; but because of the brief season dur- 
ing which lightning storms are prevalent, and their local character, 
the aggregate amount of damage wrought is not serious. Insects 
almost invariably attack lightning-damaged trees and complete the 
destruction, when the wound in itself would not prove fatal. 
The strong, widespreading, lateral root system and the thick, 
sturdy bole of this tree resist winds of extraordinary velocity. Some- 
times weakened trees in exposed situations yield to exceptionally 
severe storms. Large trees are subject to a mechanical defect known 
as windshake, the result of stresses in the butt section caused by 
severe wind in conjunction with low temperature. Circular seams 
are opened up and the value of the trees for lumber is lowered. 
