DECAY IN DOUGLAS FIR. 
11 
DEAD LIMBS. 
Large trees with many dead limbs in the lower crown are no more 
likely to be decayed than a normal tree. Such “wolf trees/’ as they 
are known to the forester, merely grew faster than their neighbors, 
and their branches did not die so soon through lack of light; conse¬ 
quently it requires a longer time for these large limbs to drop off 
and for the branch stub to heal over. 
BRANCH FANS. 
Groups of branches, radiating like a fan from one point, are not 
uncommon on Douglas fir. These branch fans have been considered 
by some persons as indications of decay. A little thought will show 
that this is not within the realm of probability. That decay in the 
dead heartwood could directly affect the vital growing portion of 
the trunk of a tree in such a way as to cause abnormal branching is 
directly contrary to all our knowledge of growth and development 
of trees. In all, these branch fans were found on 32 trees, varying 
from 1 to 15 on a single tree, with an average of 4.4. Of these 32 
trees, 2 were free from decay, while in 19 the infections were very 
light, rarely causing a loss of more than 10 board feet, and the branch 
fans were not on the same portion of the trunk as the decay. There 
was a considerable volume of decay in each of the 11 remaining 
trees, but in 7 of these the decay was in the lower or middle portion 
of the trunk, while the branch fans were above it in the crown. In 
only 4 trees were part or all of the branch fans found on the decayed 
section of the trunk. These figures indicate the complete lack of 
even an empirical relation between branch fans and decay. 
BURLS. 
Douglas fir when bruised is subject to burls at the point of injury, 
but it is questionable whether or not all burls are caused by wound¬ 
ing. Such burls are a disorganized mass of wood tissue with a 
gnarled or twisted grain. This formation is a direct response to the 
irritation caused by the injury. Burls are often considered to 
indicate decay. Plate VII shows a tree left uncut on a logging oper¬ 
ation because it was presumed from the presence of the burl that the 
tree was badly decayed. Data showing the relation of decay to burls 
in the trees studied are presented in Table 11. The number of burls 
to the tree varied from 1 to 20, with an average of 3.6. 
Table 11 .—Relation of burls to decay in Douglas fir. 
Character of data. 
Number. 
Per cent. 
Trees with hurls . ... 
43 
Trees with burls and no decay . ... 
6 
14.0 
Trees with burl 5 and decay on different sections of the trunk... 
19 
44.2 
Tree 5 with hu 1 *! 5 apd decav on the same section of the trunk ._. 
18 
41.9 
Analysis of the data in Table 11 demonstrates that the presence of 
burls does not mean decay in the tree. Of the trees with burls 14 
per cent were free from decay, while in 44.2 per cent the rot and 
burls did not occupy the same section of the bole. Burls on the 
butt of the tree, however, are sometimes an indication of decay, since 
burls in this position often result from wounding by fire, and fire 
scars are quite commonly infected with red-brown butt-rot. 
