34 Studies in Forestry [CHAP. n. 



shall, under ordinary circumstances, be equal to the annual pro- 

 duction of the total area during one year; and this is repre- 

 sented, as the total growth throughout x years, by the mature 

 timber standing on the fall about to be harvested. To cut down 

 more than this, is to consume a portion of the capital represented 

 by the growing stock ; whilst to utilize less, is simply not to treat 

 the woodlands in an economic manner. In order, however, 

 that such normal average increment may take place annually, 

 it is necessary that the woods must be of normal density, that 

 is to say, neither too crowded on the one hand, nor too sparsely 

 stocked on the other, although of course the suitable and 

 proper degree of density that may be termed normal varies 

 with each species of crop. Crowding is disadvantageous. If 

 the individual trees forming the crop have not a sufficiency 

 of growing-space, then they cannot possibly obtain the supplies 

 of light, air, and warmth requisite for their most favourable 

 development, and therefore soon fall into a sickly condition of 

 growth, which predisposes them to dangers from wind, snow, 

 insects, and fungoid diseases. The constant struggle, too, which 

 is being waged for supremacy among the individual trees in 

 woods becomes thereby unduly prolonged ; and in this is dissi- 

 pated the energy which, with judicious tending and thinning, 

 can be advantageously utilized for the better and more vigorous 

 formation and development of the individual poles or trees of 

 more robust growth, from among which the trees finally form- 

 ing the mature crop must ultimately be selected. But if the 

 number of individuals per acre falls below the normal average 

 density for any particular species of tree and any given class 

 of soil and situation, or, in other words, if the growing-space 

 allotted to each individual be in excess of what is requisite to 

 maintain the pole or tree in vigorous growth, then its vital energy 

 becomes dissipated in branch-formation, instead of being con- 

 served so as to be concentrated and utilized in the formation of 

 a long, straight, full-wooded bole or stem, free from knots, and 

 consequently of higher technical utility and commercial value. 



