52 BULLETIN 149 7, U. S. DEPARTMENT OF AGRICULTURE 
plantation 10 years from seed that the heights of individual trees 
increased with the amount of sunlight they received, in proportion 
from li/2 feet in complete shade to 5 or 6 feet in the open. 
COMPARISON OF GROWTH IN PLANTATIONS AND IN NATURAL FORESTS 
Height growth in the plantations at 10 years compares not unfa- 
vorably with natural growth of the same species at that age. The 
9 feet for planted jack pine on cultivated soil corresponds to the 
recorded average figure of 9 feet for natural seedlings (68, Tables 
1, 2, and 4)- The growth of 7 feet for northern white pine planta- 
tions in the Lake States on the best cultivated sites and 3 feet for 
the better sandy or loamy soils corresponds with the NeAv England 
(24) averages of 6 feet on average sites and 4 feet on poor sites. 
Natural white pine seedlings in northern Wisconsin were found by 
F. G. Wilson of the Wisconsin Department of Conservation to have 
an average height of 2y 2 feet in 10 years, or slightly more than 
the plantation average for the poorer sandy soils of the Lake States. 
The growth of 5 or 6 feet at 10 years for Norway pine in planta- 
tions, excepting those on the cultivated soils, is less than the 7 feet 
attained by natural saplings in northern Minnesota (77, Table 3), 
but greater than the 3 feet recorded by Sponsler in northern Wis- 
consin. The 3-foot height growth of Norway spruce at 10 years 
compares closely with the average height at that age on medium 
sites in Europe (59). 
The comparison between the growth of plantations in the Lake 
States and natural growth may be extended to the cubic-foot yields 
of the few older plantations. Northern white pine has an average 
volume of 800 cubic feet per acre at 20 years, as compared with a 
volume of 1,350 feet on a poor site, according to the New England 
yield table (24). It may be noted, however, that the New England 
yields were determined by the measurements of stands which had 
come up on abandoned fields or cultivated lands. Height growth 
in cultivated plantations in the Lake States is about twice that on 
the uncultivated sites, and therefore it would be unreasonable to 
expect the plantations on uncultivated sites in the Lake States to 
show as high yields as those given in the New England yield table. 
The Norway pine plantations, one 19 years old and two 21 years 
old, had volumes of JL.580, 1,100, and 2,645 cubic feet per acre, re- 
spectively. These yields are much higher than the 800 to 1,000 
cubic feet per acre for natural stands at corresponding ages in 
Minnesota (77, Table 15). 
Existing plantations of Scotch pine may be taken as indications 
of the productive capacity of the planting sites in the Lake States. 
The Scotch pine plantations up to 20 or 22 years show yields com- 
parable with those at corresponding ages on medium and poor sites 
in Europe (59). Planting of this species is not recommended. 
The conclusion may be drawn, therefore, that the growth and 
yields of jack pine and Norway pine plantations in the Lake States 
will be at least as high as those of natural stands of those species 
on corresponding sites (77). Northern white pine plantations will 
yield somewhat less than the amounts for a poor site in New England 
(24)i but certainly more than those given for Minnesota. 
