50 SECOND-GROWTH HARDWOODS IN CONNECTICUT. 



and fill the openings left, moderate thinnings may be conducted at 

 this time without much danger of seriously interfering with the rate 

 of height growth. Thinnings in young stands of average density may 

 be made with advantage as soon as it is apparent that the number of 

 cords of merchantable wood which can be removed without unduly 

 opening up the stand is sufficient to pay the cost of thinning. 



If too much of the stand is removed, leaving the remaining trees 

 in more or less isolated positions, the volume growth, while greatly 

 accelerated, will take place largely in the branches, giving the tree a 

 bushy appearance. There is a medium grade in thinning, however, 

 whereby the growth may be stimulated without resulting in the 

 development of large branches. In chestnut and oak stands this is 

 when the crown cover is opened up to an extent that the trees left will 

 fill up the openings within a period of about five years. Except in 

 young stands this ordinarily means increasing the space between the 

 crowns by from 3 to 5 feet. Often it is necessary to leave even more 

 space, as when a large diseased tree has been removed; but even then 

 little damage to the form of the neighboring trees is likely to result, 

 while the growth increase will be correspondingly greater or more 

 prolonged. In all except very young stands thinnings will remove 

 enough wood not only to pay for the thinning but to yield a profit. 



TIME AND SEVERITY. 



Thinnings should be begun early in the life of the stand and con- 

 tinued at 5 or 10 year intervals until it is mature and ready to be cut 

 clear. It is better to thin lightly and often than heavily and at longe*r 

 intervals. The amount to be removed in thinnings in general depends 

 upon the age, type, quality, and density of the stand and the chief 

 products desired. In young stands more trees per acre should be 

 removed than in older ones of the same type or quality, though the 

 per cent of volume cut may be no greater. Thinnings may be heavier in 

 chestnut stands on fertile soil where the trees grow rapidly and straight 

 than in chestnut or oak stands on poorer sites. When fuel wood is to 

 be the product thinnings should be the heaviest, since in this case there 

 is no objection to the abundant protection of branches, the one essen- 

 tial being to utilize every bit of the growing space. Heavy thinnings 

 will also result in the rapid production of short logs suitable for ties. 

 The long clear trunks necessaiy for poles and lumber are best pro- 

 duced in well-closed stands, and thinnings should be light. 



In 18 typical thinnings made in the course of this and former 

 studies in Connecticut, the amount removed varied from 20 to 40 

 per cent of the cubic volume. Most thinnings will fall between these 

 extremes. Damage from chestnut blight, fire, or insects may some- 

 times necessitate much heavier thinnings than would otherwise be 

 desirable, and " damage cuttings" may often exceed 50 per cent of 



