WHITE PINE UNDER FOREST MANAGEMENT. 11 
best for all trees. Where the species differ is in their ability to 
thrive under less favorable conditions. In the North woods, for 
example, maple, beech, and hemlock need better soil conditions 
than white pine and do not thrive well enough on poorer soil 
to compete with it. White pine also grows best in deep, fresh, 
loamy soils, and the largest white pine trees were found scattered 
among the hardwood forests on such sites. The heavy shade cast 
by the broadleaf trees, together with their capacity, not shared by 
the pine, to sprout abundantly when cut or burned down, made it 
impossible for white pine to monopolize the best soils, and its forests 
were found, therefore, in drier and less fertile situations. Sand is the 
principal constituent of the soils on which grew the best white pine 
forests. The deeper, moister, and more loamy the sand the better 
are the trees developed. By its rapid growth on such soils the pine 
is able to exclude slower-growing species like hemlock, beech, and 
maple, and more light-needing trees like red, pitch, and jack pine. 
The last three species are less exacting than white pine, and will 
form forests' on soils too dry for the latter. On the other hand, 
white pine is often found in poorly drained, somewhat swampy 
situations, in company with fir, arborvitse, tamarack, and other 
swamp-inhabiting species. In such places, however, its growth is 
apt to be relatively slow. 
Compared with the size of its trunk and crown, the root system 
of white pine is small. There is no taproot, but three or four stout 
roots grow downward slantingly, and in time give the tree a firm 
hold on the soil. On shallow soils with impervious hardpan or 
underlying rock strata the roots spread out close to the surface; in 
deeper soils they penetrate downward for 3 or 4 feet. Growth is 
less vigorous on shallow than on deep soils, because the former more 
quickly lose their moisture. 
Tree leaves give up daily to the air great quantities of water, which 
the roots have absorbed from the soil. The more foliage a tree has 
the larger and more active must be its root system. Since the 
amount of light received by a tree directly influences the amount of 
its foliage, it must also influence the development of the roots. 
Thus, pine trees which grow in the open and have heavy foliage also 
possess deep and extensive root systems, while those .in dense stands 
and with little foliage may have deep but rarely large or extensive 
roots. 
LIGHT REQUIREMENT. 
Light is the agency by which plant leaves manufacture food for 
the tree out of water drawn up through the roots and carbon dioxide 
obtained from the air. The amount of light necessary to sustain 
life, however, varies with different species. Compared with other 
trees, white pine may be classed as intermediate in its light require- 
