18 
BULLETIN 13, U. S. DEPARTMENT OF AGRICULTURE. 
of growth decreases rather abruptly when the tree is still far from 
decadence. Red pine, for example, has a fairly uniform and rapid 
growth until about 100 years old, when a marked falling off occurs, 
the tree growing at a slower rate until its death 100 or 200 years later. 
Jack pine exhibits a similar trait, though its period of rapid growth 
ceases very much earlier than that of red pine. It is this habit of 
sustained growth which gives white pine its great size as compared 
with the two other species. 
The rate of growth varies with the age of the tree, the amount of 
light received, and the fertility of the soil in which it grows. In 
general, growth is more rapid on good soils than on poor, and in 
youth than in old age. The period during which growth is most rapid 
comes earlier when the tree is favorably situated than when it grows 
on poor soil. 
Growth ix Height. 
White-pine seedlings grow very slowly, and few of them reach 
a height of more than a foot during the first o years. For the first 
3 years annual growth is little more than an inch. Thus 1, 2, and 
even 3 year old seedlings are so inconspicuous that they are likely 
to be overlooked, especially when among grass or weeds. During the 
following two seasons, when rapid growth commences, the top shoots 
of the seedlings appear everywhere, giving the impression that they 
have sprung up in a single year. 
The height growth of seedlings for the first 10 years under average 
conditions is shown in Table 2. In a nursery or under specially favor- 
able circumstances the rate of growth may be much faster, while under 
partial shade it will be slower. 
Table 
-Height growth of white-pine seedlings. 1 
Age. 
Height. 
Years. 
Inches. 
1 
1.0 
9 
1.5 
3 
3.5 
4 
7.0 

11.0 
Age. Height. 
Tears. 
I" 
Inches. 
17.0 
24.0 
32.0 
45.0 
64.0 
On good, moist soils height growth is most rapid at about the 
fifteenth year, when it often exceeds 3 feet annually. On poor, dry 
soils, however, the maximum may not occur before the fortieth year, 
and then not equal the growth on good soil. From the time when 
the growth culminates its rate gradually decreases until toward the 
end of the second hundred years it amounts to only 2 or 3 inches per 
year. 
1 From measurements of 1,600 young trees. 
Fields in New England," by S. N. Spring. 
1 able from " Natural Replacement of White Pine on Old 
