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EFFECT OF REPEATED FOREST FIRES   193

for the purposes of this report to group the two aspens together, under the designation of " poplar."

It is difficult to tell, after the first few years, whether a tree has come from a seedling or from a root sucker, but it is probable that most of the trees on which the growth studies were made came from seedlings.

TABLE VI
RATE OF GROWTH OP POPLAR, SITE QUALITY II, BASED ON 166 TREES

Age

Average diameter, inside

bark, at ground,

inches

Average height,

feet

3

0.24

3.5

4

0.39

5.1

5

0.43

5.3

6

0.60

7.8

9

0.80

8.0

10

0.86

9.0

11

0.98

10.4

Average age

Diameter class,

Average height,

feet

Average merchant

able volume,

 

breast height

 

cubic feet

13

1

14

 

21

2

20

 

26

3

24

 

30

4

30

 

31

5

36

1.909

36

6

39

2.352

40

7

47

5.752

41

8

48

6.233

44

9

48

6.714

45

11

55

13.706

The rate of growth, as indicated in Table VI above, may seem very slow to many, for poplar is generally considered one of the most rapidly growing trees. If

these trees had been taken from the best soils, the rate of growth would have been considerably faster, but they were taken from the kind of soil in which the greater majority of the trees of the region were growing and this was of second quality. There is a tendency in the popular mind, however, to over-estimate the rate of growth of trees, for the judgment is usually made from trees growing in the most favourable soil, and other conditions, not from the average conditions actually found in the forest, where competition for food and light is generally severe.

13-c. c.

Rate of Growth of Poplar


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