22 
BULLETIN" 604, U. S. DEPARTMENT OF AGRICULTURE. 
eluding this tree from the higher mountains. To a limited extent, 
heat may have some influence in fixing its lower limits. However, in 
view of the continued high temperatures which the tree is known to 
endure, it is doubtful whether heat has this effect, except as it reduces 
an already meager supply of moisture by causing excessive evap- 
oration. 
SOIL. 
Of all the various factors affecting the occurrence of incense cedar, 
soil is probably the least important. The best proof of its adapta- 
bility in this respect is the fact that throughout its range it is found 
growing on soils of every description, bowlder wash and wet adobe 
excepted. 
GROWTH. 
Incense cedar is naturally a slow-growing tree. Under favorable 
conditions, however, its growth is fairly rapid, although it can not 
compete successfully with its more aggressive associates, sugar pine, 
yellow pine, and white fir. 
HEIGHT GEOWTH. 
Table 12, which is based on stem analysis of 1,000 seedlings, shows 
the extremely slow growth of this species during the seedling stage 
under the average conditions prevailing in virgin stands. 
Table 12. — Incense cedar, seedling growth {age-height) ; oasis, 1,000 seedlings. 
[curved.] 
Age. 
Height in feet. 
Age. 
Height in feet. 
Average 
heights 
of-all 
seedlings 
below the 
mean. 
Mean, 
height. 
Average 
heights 
of all 
seedlings 
above the 
mean. 
Average 
heights 
of all 
seedlings 
below the 
mean. 
Mean, 
height. 
Average 
heights 
of all 
seedlings 
above the 
mean. 
Years. 
5 
10 
15 
20 
0.2 
.5 
.9 
1.3 
0.5 
1.1 
1.6 
2.2 
1.0 
2.0 
2.9 
3.9 
Years. 
25 
30 
35 
1.7 
2.1 
2.6 
2.7 
3.3 
3.9 
5.1 
Under ordinary conditions, suppression is doubtless responsible 
to a large extent for this extremely slow growth, since reproduction, 
as a rule, occurs only in small openings or under the half light of 
a high forest, where the encouragement for rapid growth is small. 
In the larger openings and on cut-over lands, where light is abund- 
ant seedlings shoot up rapidly after they have once become thor- 
oughly established. In fact, in all cases except those of extreme 
