14 Prolonging the Cut of Southern Pine 



NECESSITY OF MARKING TREES TO BE CUT 



It is necessary to mark the trees to be cut instead of depending 

 on an arbitrary diameter limit for the following reasons : 



(1) Windfall. Opening a stand greatly increases the danger 

 of windfall. Trees differ greatly in their wind resistance. Those 

 growing in crowded clumps have weak roots, while thrifty trees 

 growing in partial openings have well-developed roots. By selec- 

 tion of wind-firm trees to be left the danger of windfall in the 

 remaining stand may be reduced to reasonable proportions. 



(2) Growth. The purpose of leaving these trees is to secure 

 growth which should be as rapid as possible. But trees differ 

 remarkably in their rate of growth, a fact that can be verified by 

 cutting into a few at random and counting annual rings of growth 

 in the last inch of radius. The trees best to leave for the second 

 crop are those making the largest growth per cent, based on the 

 present volume of the tree. A small thrifty tree makes a higher 

 growth per cent than a large tree because the volume of the former 

 is less at present and the relative increase is much greater. The 

 character of the crown indicates the vigor of the tree, since the 

 growth is directly dependent on the amount of foliage, which, in 

 turn, is determined by the available light and root space. Rapidly 

 growing trees are sure to have thrifty, large and well-developed 

 crowns. This can be told at a glance after a few days' practice. 



(3) Soundness. All trees left should be free from rot, and 

 sound at the base to lessen fire injury. Many trees below 14 

 inches in diameter are defective and unsuitable for leaving and 

 should be removed. 



(4) Welfare of the whole stand. Many stands of young tim- 

 ber are too crowded to make good growth during the next twenty 

 years. Such stands should be thinned of about half of the trees, 

 leaving, independent of diameter, those which show good crowns, 

 a clear length and fast growth, and removing large, limby trees, 

 and small, stunted, or slow-growing trees with poor crowns, and 

 those that are defective or crooked. 



GROWTH IN THINNED STANDS 



If cutting is done on the basis of a rigid diameter limit, at least 

 half the trees left will make poor growth. But if every tree left 

 is properly selected the growth to be expected in ten years is 

 indicated by measurements taken on 70 acres containing 8,837 

 feet b.m. per acre. The trees to be left after proper marking 

 contained 2,630 feet b.m. per acre, or 30 per cent of the whole, 



