Mar. 15,1925 Mortality of Trees Attacked by the Spruce Budworm 553 
were bored. For this reason they can 
hardly be used to express the rate of 
growth of the regions as a whole so 
well as can the plot increments. 
On the softwood plots the rate of 
growth for the 10-year period following 
first feeding (i. e., including 4-year 
feeding period and 6 years’ recovery) 
was only about one-half that of the 
previous 10 years, while in the northern 
liardwood type this increment was 
The Metis Lake plots (Tables X and 
XI) unfortunately (due to misunder¬ 
standing) were based on too few trees 
to make fair comparisons possible. 
SUGGESTED APPLICATION 
The recent widespread series of bud- 
worm epidemics in eastern Canada and 
northeastern United States, coming as 
they did at a time when the softwood 
supplies of these regions are becoming 
20 
2 3 4 5 6 
Ten Years Before |=§ Ten Years After 
Ten Years Before From Trees Which Died 
1 Balsam-Spruce Flat Type 
2 Balsam-Northern Hardwood Type 
3 Balsam-Softwood From Metis Lake 
4 Red Spruce - Spruce Flat Type 
5 Red Spruce-Northern Hardwood Type 
6 White Spruce - Spruce Flat Type 
Fig. 5.—Diagram showing rate of growth of spruce and fir, occurring in various forest types, for the 10- 
year periods preceding and following spruce budworm defoliation 
about two-thirds the previous 10-year 
period. This may be due to greater 
ability of the trees to recover in the 
latter type, though possibly the trees 
scattered through these hardwoods 
were not so severely defohated. These 
figures, as do previous tabulations, 
show that the white spruce dying from 
defoliation was growing at a slower rate 
than the red spruce which died. 
depleted and when considerable in¬ 
terest in putting the forests on a sus¬ 
tained-yield basis is being manifested, 
will no doubt stimulate more intensive 
forest practices. At all events, the bud¬ 
worm is an ever-present menace to the 
growing of spruce and fir in these re¬ 
gions and must be given due consider¬ 
ation in the application of any silvi¬ 
cultural systems. 
