37 



enough to keep the ground sufficiently shaded, it is some- 

 times advisable to keep the suppressed trees or a portion of 

 them to shade the ground. 



157. The proportion of the volume of the material re- 

 moved to the volume of the stand may serve as a check in 

 making thinnings. A moderate thinning would fall between 

 10 and 20 per cent of the volume of the stand. If, for ex- 

 ample, the stand runs about 30 cords to the acre, the amount 

 to be taken out would fall between 3 and 6 cords. If it falls 

 below 3 cords, the indication is that the thinning is too light 

 and that more should be taken. If it goes above 6 cords, it 

 indicates that the thinning is too heavy and that less should 

 be taken. 



158. If the stand is composed of several kinds of trees, 

 there may be a choice among the kinds as well as among the 

 individuals of the same kind. The desirability of a kind de- 

 pends on its market value, its usefulness on the tarm, its 

 habit of growth, and its adaptability to the soil. In thin- 

 ning the more desirable kinds should be given the preference 

 over the less desirable, when it is possible to show a prefer- 

 ence. For example, a black jack and a white oak are stand- 

 ing side by side and one must be removed for the good of 

 the stand; the black jack should be removed and the white 

 oak should be left. 



159. While thinning, strictly speaking, is the removal 

 of some trees for the betterment of the stand, it may be 

 combined with other work. When, for example, a stand is 

 uneven-aged, a thinning among the younger trees may go 

 hand in hand with harvesting the mature trees; and the cost 

 of each operation may be reduced by both being done at one 

 time. But for clearness of thinking the two operations 



