18 
BULLETIN 139, IT. S. DEPARTMENT OF AGRICULTURE. 
Table 6. — Minimum, average, and maximum growth in diameter, Bayfield County, 
Wis., on basis of age. 
[Based on 139 stumps from 108 to 202 years old.] 
Age 
(years). 
Diameter breast-high (inches). 
Age 
(years). 
Diameter breast-high (inches). 
Minimum. 
Average. 
Maximum. 
Minimum. 
Average. 
Maximum. 
10 
0.2 
0.6 
1.3 
110 
9.3 
17.9 
25.2 
20 
1.0 
2.8 
5.4 
120 
10.3 
18.9 
26.2 
30 
1.9 
5.7 
10.3 
130 
11.3 
19.8 
27.1 
40 
2.7. 
8.0 
13.8 
140 
12.4 
20.8 
28.0 
50 
3.7 
9.9 
16.6 
150 
13.5 
21.7 
28.7 
60 
4.6 
11.7 
18.8 
160 
14.6 
22.7 
29.5 
70 
0. 
13.2 
20.5 
170 
15.7 
23.7 
30.3 
80 
6.5 
14.6 
21.9 
180 
16.9 
24.6 
30.9 
90 
7.4 
15.9 
23.1 
190 
18.0 
25.5 
31.7 
100 
8.3 
16.9 
24.2 
200 
19.2 
26.5 
32.4 
Table 7 shows the diameter growth of trees which are now occu- 
pying a dominant position in the stand. Figures in the column 
headed " Maximum" are for trees which have grown practically in 
the open for their entire life. The column headed " Average" shows 
trees which have been somewhat crowded, but which from the start 
have dominated the remaining timber in height growth. The " mini- 
mum" is for trees which have been suppressed by jack pine. The 
growth in both diameter and height of such Norway pines is stunted. 
In 80 years the trees have reached a diameter of but 4.3 inches, as 
contrasted with 19.2 inches in the case of open-grown trees. At 
this age jack pine dies out, and by 100 years has entirely disappeared 
from these even- aged stands. The surviving Norway pines, freed 
from competition and with plenty of crown space, develop good 
crowns and take the position of intermediate or dominant trees. 
Only their record of diameter growth remains to show the former 
existence of the jack pine in mixture. Had these trees grown in 
pure stands, they would have been killed in competition. 
Table 7. — Minimum, average, and maximum diameter growth of dominant trees on basis 
of age, Cass and Itasca Counties, Minn. 
[Based on 739 stumps from 27 to 303 years old.] 
Diameter breast-high (inches). 
Diameter breast-high (inches). 
Age 
(years). 
Age 
(years). 
Minimum. 
Average. 
Maximum. 
Minimum. 
Average. 
Maximum. 
10 
20 
0.8 
2.8 
2.7 
6.8 
110 
120 
6.8 
7.6 
14.7 
15.5 
22.1 
22.8 
0.4 
30 
.8 
4.9 
10.1 
130 
8.4 
16.1 
23.5 
40 
1.3 
6.6 
12.6 
140 
9.1 
16.7 
24.1 
50 
2.0 
8.2 
14.6 
150 
9.8 
17.3 
24.7 
60 
2.7 
9.6 
16.4 
160 
10.4 
17.8 
25.2 
70 
3.5 
10.9 
17.9 
170 
10.9 
18.4 
25.7 
80 
4.3 
12.0 
19.2 
' 180 
11.3 
18.9 
26.3 
90 
5.2 
13.0 
20.3 
190 
11.8 
19.5 
26.7 
100 
6.0 
13.9 
21.3 
' 200 
12.1 
20.0 
27.2 
