24 BULLETIN 544, I*. S. DEPARTMENT OF AGRICULTURE. 
decay by that time. There are so many twigs or lops, however, that 
they must be piled out of the way of logging, and thus elevated from 
the ground they remain hi an anflammable condition for a long time. 
Windrows of spruce lops even under fairly moist conditions will sup- 
port the weight of a man. thus showing them to be in comparatively 
sound condition, at least from 7 to 10 years after cutting. Even 
if they could be scattered over the ground, then- bowed form and 
elasticity would render it difficult to secure an intimate contact with 
the ground unless they were cut up into small pieces. Their rapid 
decay is still further hindered by the resinous character of the wood. 
FROST. 
Spruce is rather generally subject to splitting, particularly in very 
cold exposed situations. This defect is caused by an unequal shrink- 
age between the heart and sapwood under the action of a sudden drop 
hi temperature below freezing. It may also be accentuated to some 
extent by the swaying of the tree in the wind when in a frozen con- 
dition. Spruce having this defect is known among lumbermen as 
1 'seamy" spruce. If the grain of the wood is straight, the defect 
will not cause much loss in sawing; but if it is not straight, the tree is 
useless except for pulp. As frost crack results from climatic condi- 
tions, its prevention is not feasible. Spruce is not particularly sus- 
ceptible to the defect known as "cup or ring shake." 
SUN. 
Trees grown hi a dense forest usually have their boles well cleared 
of branches. Therefore when a portion of the stand is removed 
injury mav result from sun scald through exposure of the remaining 
trees to direct insolation. The damage is generally confined to the 
side of the tree facing the southeast, and conditions are most favor- 
able to its occurrence in the late winter and early spring. It may 
result from the cambium on that side of the tree becoming prema- 
turely active under the influence of a period of mild weather and a 
heavy freeze coming on afterwards and killing the new growth. A 
thawing of one part of the tree under the influence of direct insolation 
while the rest remains frozen might also cause it. Separation of 
bark and wood and the collection of moisture in the cavity almost 
inevitably follow such thawing and afford suitable opportmiite for the 
entrance and development of fungous spores. Such a condition 
gives rise to a defect known as "spruce canker." 
INUNDATION AND ICE GIRDLING. 
Although spruce will grow and thrive in moist situations, it is 
permanently injured if not killed outright by inundation, depending 
upon the duration of the flooding. Spruce is also killed by girdling ■ 
when the inundation is accompanied by the formation of ice about the 
tree trunks. 
i See d. 57. Bulletin 26. U. S. DeDartment of Aericulture. Division of Forestry, Oct. 1S99. 
