548 
Journal oj Agricultural Research 
Vol. XXX, No. 6 
second-growth white spruce grows 
faster than either red spruce or balsam 
during the first 40 to 50 years, but after 
certain densities are reached its growth 
is retarded and it can not compete as 
well as red spruce. Considering the 
higher mortality of white spruce com¬ 
pared to that of red spruce in 60-year 
stands, the relatively lighter feeding 
(excepting the possibility that slow- 
growing trees maybe subject to heavier 
defoliation) and the average slower rate 
of growth for dying trees, it may be 
considered that white spruce is more 
susceptible to budworm attacks than 
red spruce. This suggests that it 
should be encouraged only when good 
vigor can be maintained. Also a 
higher percentage of white spruce, like 
balsam, enhances heavier average de¬ 
foliation of adjacent red spruce owing 
to the abundant food supply in the 
early feeding stages. 
Balsam is the most susceptible under 
all conditions, since it is completely 
defoliated in heavy outbreaks. On the 
other hand, the Metis plots indicate, as 
well as certain Bathurst plots, that 
vigorous stands are more immune. 
Since balsam is a very fast grower, and 
reproduces abundantly and under ad¬ 
verse conditions, it might well be en¬ 
couraged for the first 30 to 40 years. 
The only argument against it is that 
over wide areas it is considered the most 
important factor in giving impetus to 
an outbreak, though balsam is probably 
no more effective in this respect than is 
a mixture of white spruce and red 
spruce. 
HARDWOOD MIXTURES AND BUD- 
WORM MORTALITY 
Two series of plots (Tables XII, 
XIII, XIV, and XV) were taken in 
hardwood mixtures. The object was 
to obtain some idea of the effect of bud- 
worm feeding on the free and over¬ 
topped softwoods in such stands. It 
has been held by several investigators 
that the mortality in hardwood mix¬ 
tures is always considerably lower 
than in pure softwoods. 
Two types were considered. Tables 
XII and XIII summarize 19 plots, 
totaling 3 acres, in a 60 to 65 year 
birch-poplar type on the same area as 
the softwood plots of Tables IV, VI, 
and VIII. Tables XIV and XV 
summarize 11 plots, totaling 3J^ acres, 
in a northern hardwood type on the 
Bathurst area. This area has been 
subjected to periodic cuttings in the 
past. No white spruce occurred. The 
largest diameter for softwoods was 
about 20 inches. These plots were 
located on the top of a low ridge on the 
best growing site in the region. 
Percentage expressions are the same 
as for previous plots except that total 
percentage of hardwoods is calculated 
on the basis of all trees on the plots. 
This expression was not considered a 
fair indication of the hardwood canopy, 
so the percentage of overtopped soft¬ 
woods is used as indicating the amount 
of hardwood canopy. Two classes of 
softwoods were considered—overtopped, 
those whose terminals were under 
the softwood canopy, and free, those 
Table XII.— Birch and poplar type, composition of plots 
Balsam 
Bal¬ 
sam, 
over¬ 
topped 
Red 
spruce 
Red 
spruce, 
over¬ 
topped 
White 
spruce 
White 
spruce, 
over¬ 
topped 
Soft¬ 
woods, 
over¬ 
topped 
White 
birch 
Poplar 
Total 
hard¬ 
woods 
Aver¬ 
age 
num¬ 
ber 
trees 
per 
acre 
Soft¬ 
wood, 
aver¬ 
age 
diam¬ 
eter 
Basal 
area, 
A 
acre 
P. ct. 
34.2 
P. ct. 
39.2 
P. ct. 
50.3 
P. ct. 
38.6 
P. ct. 
15.4 
P. ct. 
32.0 
P. ct. 
60.7 
P. ct. 
70.7 
P. ct. 
29.3 
P. ct. 
24.2 
70 
In. 
6.3 
Sq.ft. 
15.34 
Table XIII.— Radial increment in millimeters at h. h. from 1903 to 1912 , 
inclusive, and mortality of trees in plots of Table XII 
Balsam, increment 
Red spruce, increment 
White spruce, increment 
Dead 
Liv¬ 
ing 
Dead 
All 
Dead 
Liv¬ 
ing 
Dead 
All 
Dead 
Liv¬ 
ing 
Dead 
All 
P. ct. 
Mm. 
Mm. 
Mm. 
P. ct. 
Mm. 
Mm. 
Mm. 
P. ct. 
Mm. 
Mm. 
Mm. 
Free.... 
78.5 
\ 17.1 
10.9 
11.9 
23.6 
10.8 
10.7 
10 8 
18.7 
11.9 
6.4 
10.9 
Overtopped___ 
38.8 
i 6.8 
6.6 
6.7 
7. 6 
8.7 
7.4 
8.6 
21.8 
8.9 
6.4 
8.4 
Average.. 
228 trees 
8.2 
293 trees 
9.5 
117 trees 
9.7 
