FOREST PLANTING IN THE LAKE STATES 
51 
sions as to the growth on different sites are not possible. However, 
the range is from 2 to 4 feet in 10 years. 
All species for which there are sufficient records grow fastest on 
the cultivated soils and progressively slower on the heavy maple- 
basswood or, raspberry-covered soils, the better sands and sandy 
loams, and the jack pine-oak sands. Comparing these four soils 
on the basis of the height growth of northern white pine in the 
open and representing its growth on the jack pine-oak sands as 1, 
the growth on the better sands will be represented by 1.5, on the 
heavy soils by 2,4, and on the cultivated soils by 3.2. The relations 
for Norway pine are closely similar. Jack pine shows less relative 
increase as the soil conditions become more favorable. 
Figure 7. — Height growth of plantations on different sites 
The exceptionally rapid growth of the planted trees on soils which 
were cultivated either at the time of planting or years before, is 
striking. Moreover, this stimulating effect of cultivation outweighs 
the effect of other soil qualities to such a degree that the average 
growth of cultivated plantations on the poorest sands is superior 
to that of uncultivated plantations on the best loamy soils. This 
superiority in growth is maintained for the first 20 years, but it 
may not last in the same degree until the trees are mature. Its 
practical importance is not that it justifies the expense of cultivating, 
but that it proves abandoned fields to be very favorable sites for 
planting. 
All species on all soils, with the exception of Norway pine on the 
better sands or sandy loams, grow less rapidly on the average when 
planted under a cover of over 40 per cent of natural tree growth 
than they do in the open. If the growth of plantations in the 
open is taken as 1, the growth of underplantings varies from 0.8 to 
0.9. Reed (53) in New 7 England has shown in a Norway pine 
