42 
•RT TTF. TT'S- BfaL I". S. DEPAET^IEXT OF AGPJCnLTTTRE. 
PEEVAiEXCE OE INJUETE; 
Most incense cedars do not attain any great age or size without 
suffering some injury. Many old trees, and more rarely young ones, 
show numerous injuries, often fire, fro-t. and lightning having com- 
bined in the wounding of a single tree. Of the 509 trees on the 
intermediate area only 116. or 22.8 per cent, escaped without injury, 
while on the optimum area 3S.9 per cent, or 220 of the total 566. were 
free from wounds. This difference is explained by the fact that the 
risk from injury has been greater on the intermediate area than on 
the optimum area, while a greater number of young trees were cut 
on the last-named area than on the first The risk of injury is 
cumulative, increasing with the age of the tree. 
This cumulative risk of wounding is shown clearly in Table IX. 
in which the trees from all areas are combined and arranged by 40- 
year age Masses. Only those trees the ages of which it was possible 
to determine exactly are included in this table, while the data on 
wounds previously presented include all the trees. This accounts 
for the apparent slight discrepancy between the figures on the total 
number of trees involved. 
Tabis IX. — Incense-cedar - " g cumulative wounding in the combined areas. 
frees 
rees 
with 
with 
Hota] 
severe 
Total 
severe 
Number 
■ ; 
Xam t: 
with 
-wounds 
Age class. 
- ; tree* 
wounds 
""-: -r.:- 
Age .'-ass. 
:: :tt? 
~ : ar_ 15 
t-t::---- 
:-. 
Cper 
^~t :: 
:asis 
7- 
:• r- :: 
3eni 
total 
:•--: 
total 
wounds > 
1 
2 
3 
4 
1 
a 
3 
4 
: :: -: years 
1 
{, 
- 
2S1 to 320 rears 
--': 
- ; 
62.5 
flfo SO years 
.51 
a i 
6.7 
:._ ;: ;: _ ear5 
is 
::• 
H : 
«: - i- - ^ irs 
1S5 
U 6 
14.4 
: :1 " : ±.». "ears. . . . 
-- 
::•: 
100 
121 to I:.: years 
59.2 
- . :■: — . ~~ars. . . 
■i 
100 
-v 
161 to 2:-: years 
2 '. - .-: years 
233 
IM 
74.3 
82 : 
44.4 
Combined.... 
■ -_- 
57 E 
: ; : 
MI :: 28G years 
i 
92.6 
43.6 
In considering the figures in Table IX the reader should keep in 
mind the fact that since branch stubs are not treated as wounds, 
wounded trees practically mean fire-scarred trees, as the number of 
wounds from causes other than fire have been shown to be insig- 
nificant. 
Considering column 3. which expresses the ratio of the wounded 
trees to the total trees, it is seen that the trees are subject to con- 
siderable wounding at a very early age and that this percentage 
increases very rapidly, until in the older age classes every tree has 
been wounded and consequently at some time exposed to infection. 
