INCENSE CEDAR. 21 
A gradual increase in elevation from north to south is apparent, 
ranging from between 1,100 and 5,000 feet at its northern limits to 
between 4,000 and 9,000 feet at its southern. Similarly a rise is 
noticeable from west to east, the limit in the coast ranges being 1,100 
and 5,000 feet, on the west slope of the Sierras 3,000 and 7,000 feet, 
and in western Nevada 5,800 and 7,000 feet. 
SILVICAL REQUIREMENTS. 
MOISTURE. 
The minimum water requirement of incense cedar is low compared 
with other commercial timbers, as is shown by its frequent occur- 
rence on dry, exposed ridges and at the extreme lower limits of 
commercial tree growth. It does best, however, where the supply of 
soil moisture is fairly abundant. In its drought-resisting qualities 
it is second only to western yellow pine among the commercially 
important species of its range ; but extreme drought serves effectually 
to shut it out and, more than any other factor, prevents it from 
spreading to lower elevations. Excessive moisture, on the other 
hand, is equally effective in limiting its range. Hence we do not find 
it encroaching on wet mountain meadows or extending any great 
distance into the regions of excessive precipitation of the Pacific 
Northwest. 
Soil moisture and humidity complement each other to a certain 
extent, it being possible for an abundance of one to make up partially 
for a lack of the other. Where soil moisture is sufficiently abundant, 
however, incense cedar will grow in an almost arid climate, showing 
that no great amount of humidity is essential. 
LIGHT. 
Incense cedar is a shade-enduring tree and reaches its best develop- 
ment in fairly dense stands. It is surpassed in tolerance only by 
white fir and possibly, in northern California and southern Oregon, 
by Douglas fir. The reluctance with which it sheds its lower limbs 
is an indication of this extreme tolerance. To kill out incense cedar 
by shading is almost impossible, though, of course, too much shade 
hinders growth, and an abundance of light, if other conditions are 
favorable, helps it. 
TEMPERATURE. 
Temperature is undoubtedly an important factor in the distribu- 
tion of incense cedar, particularly in limiting its range at the higher 
elevations. The extreme cold, combined with the short growing sea- 
son, is probably responsible more than any other factor for ex- 
