10 THE WOODLOT. 



IK EEGULAR, EVEX-AGED WOODS. 



(See PI. 11.) 



Even-aged stands are those which have started about the same time, 

 either from sprouts or from seed. In such stands there is a contest 

 between the different individuals for position, and in consequence a 

 mutual crowding of the crowns. The result of this struggle is that 

 some trees are entirely overtopped b}' their more successful neighbors 

 and are either shaded to death or retarded in growth. Other trees 

 are only partially suppressed, and remain fairly thrifty. l)ut grow 

 slower than the leaders. This mutual crowding and the greater or 

 less success of the different trees in the struggle for position accoants 

 for the wide variation in diameter of trees of the same age. It is 

 customar}^ to classif}^ the trees in an even-aged forest in four divisions: 

 First, the dominant trees, whose tops form the chief cover; second, the 

 intermediate trees, whose crowns are slighth^ below and crowded by 

 the dominant trees; third, the suppressed trees, which are those entirely 

 covered b}^ the main canopy and which are usualh^ in a puny condi- 

 tion; and fourth, the dead trees. Generally speaking, it is mainly the 

 dominant trees and the larger specimens of the intermediate trees 

 which are to form the ultimate stand, and which are to be helped by 

 the removal of the others. 



The general rule for thinning is to remove all dead and dying trees, 

 suppressed trees, and such individuals of the intermediate class as are 

 crowding- the dominant trees or the more thrifty intermediate trees. 

 The cutting of intermediate trees allows more space for the remaining 

 trees to spread, and admits more light to the lower parts of their 

 crowns. The trees left standing grow more rapidly and reach a mer- 

 chantable size much sooner than when the woods are left untouched 

 until maturit}'. It is estimated that through this kind of thinning the 

 time required for forests to grow from seed to merchantable size may 

 be shortened from ten to twenty years. 



The removal of dead and entirely' suppressed trees does not affect 

 the growth of those which remain. They are cut in order to use the 

 wood before it decays. Sometimes the dead and dying trees make 

 breeding places for insects, which may attack living trees. This is 

 especially true of evergreens. Moreover, the dead trees fall, and 

 make fuel for forest fires. Suppressed trees should be left if needed 

 to shade the ground. 



It is to be emphasized that in improvement cuttings the trees taken 

 out are chiefly the backward ones, and that their removal does not 

 break the even cover of the dominant trees, except temporaril3\ 

 Sometimes, however, dominant trees have to be cut. This should be 

 done when the dominant class contains straggling specimens of poor 

 species, like Butternut, Sassafras, or Mulberry, which are overtopping 

 healthy specimens of valuable species, such as Oak or Hickor3\ But 



