﻿WHITE PINE UNDER FOREST MANAGEMENT. 13 



In dense young stands most of the Lower branches die from shade, 

 growth is largely concentrated in the tops, and height growth is there- 

 fore rapid. Since the amount of food manufactured hy the tree is 

 proportionate to the amount of foliage, which in dense stands is small, 

 wood is produced very slowly, and diameter growth is correspond- 

 ingly slow. Thus while trees in the open are relatively short, witli 

 tliick trunks and large, branching crowns, forest-grown trees are tall, 

 with long, slender trunks (comparatively free from large brandies if 

 in mixture with hardwoods), and relatively short and narrow crowns. 

 An open-grown tree actually contains more wood than a forest-grown 

 tree of the same age, but its value, volume for volume, is much ' less. 

 The difference lies not only in the better form of the forest-grown tree, 

 but also in the actual structure of its wood, which contains more 

 thick-walled mechanical tissue and less thin-walled water-conducting 

 cells than that of open-grown trees. 



In fully stocked sapling and pole stands, the stems are straight, 

 slender, tapering, and smooth barked, with numerous whorls of small 

 branches. At the end of tins period the live crown is usually con- 

 fined to the upper two-thirds of the stem. As the tree matures the 

 bole becomes more cylindrical, and the crown loses its regularity 

 and compactness. A characteristic defect of white pine, from a com- 

 mercial standpoint, is its retention of dead branches, winch causes the 

 lumber to be knotty. In dense stands the branches, and consequently 

 the knots they leave, are smaller than in the case of open-grown trees. 

 Moreover, wiien in mixture with hardwoods, the slender dead branches 

 are readily broken off by the swaying limbs of the broadleaf trees. 

 The exceptionally clear boles of the virgin white pine which grew in 

 dense hardwood forests were undoubtedly the result both of the 

 shading and death of the branches while still small, and of the 

 mechanical breakage of the small branches by the impact of spreading 

 limbs of near-by trees. (See PI. I.) 



When white pine grows on the thin soils of ridges at liigh altitudes 

 it produces a short and rapidly tapering trunk, while the crown, if 

 exposed to severe winds, is likely to be distorted. One of the first 

 considerations in planting wliite pine should be the quality of the site, 

 since upon this depends the rate of growth and also, to some extent, 

 the form which the trees will have. 



The classification of trees according to the number of logs they 

 will yield, practiced by timber estimators, illustrates the practical 

 importance of form in determining the value of trees. Foresters have 

 carried this still further, and on the basis of thousands of measure- 

 ments of felled white pines have determined the average contents in 

 board feet and cubic feet of trees of all the forms and sizes ordinarily 

 found. Such figures are given in the volume tables (pp. 64-68). 



