Heart Rot 



463 



a critical factor. This is true, for ex- 

 ample, of the southern pines, white 

 oak, yellow-poplar, sugar maple, and 

 many other species. But in some species 

 decay definitely limits the desired cut- 

 ting age. In aspen in the Northeast 

 and the Lake States, stands much 

 older than 50 years are likely to be 

 badly decayed. Decay should limit the 

 cutting age of balsam fir to about 70 

 years. Most of the oaks will pass 150 

 years without major decay losses but 

 decay cull usually results in the seri- 

 ous break-up of scarlet oak stands over 

 80 years old. 



In the West, the thrifty, uninjured 

 young forest trees are generally free 

 from heart rots. After the virgin stands 

 have been replaced by second growth, 

 the most profitable cutting age occurs 

 before heart rots become serious. 



FREQUENT LIGHT GUTS in the large- 

 crowned hardwoods result in a maxi- 

 mum of logging damage. Clear cutting 

 in strips or blocks or adopting a mini- 

 mum number of cuts per rotation con- 

 sistent with good silviculture will cause 

 the least logging injury and the lowest 

 subsequent decay. Logging injuries 

 provide good opportunities for the 

 entrance of heart rot fungi. Careless 

 felling and frequent cutting can cause 

 considerable breaking of the tops and 

 branches of residual trees. Wounds ex- 

 posing only sapwood in resinous species 

 often become covered with pitch so 

 that fungi are largely excluded. Such 

 wounds in nonresinous species, how- 

 ever, readily permit the establishment 

 of sapwood fungi, and the subsequent 

 checking and sloughing of the decayed 

 sapwood exposes the heartwood be- 

 neath to heartwood destroyers. 



Selective logging with heavy tractors 

 often causes extensive wounding of 

 residual trees unless special precaution 

 is taken. All forms of damage, includ- 

 ing branch and top breakage, felling 

 scars, and butt injury from skidding 

 and yarding, increase as the frequency 

 of cutting in a given stand increases. 

 Heavy partial cuts in old spruce and 

 fir result in wind breakage to the re- 



maining stand, because these old trees 

 are commonly heavily butt-rotted. 

 Under such conditions some form of 

 clear cutting should be considered in 

 place of partial cutting. 



Where partial cuts are made, the 

 forester always aims to retain the trees 

 that are increasing the most in volume. 

 He marks for cutting the heavily de- 

 fective trees, particularly those that 

 are losing more wood from decay than 

 they are adding through growth. Aids 

 are available for estimating internal de- 

 fect from external signs in some east- 

 ern and western species. The timber 

 marker who can estimate the decay 

 situation in a given tree can greatly 

 enhance the net growth in selection 

 systems of silviculture by eliminating 

 defective trees in the earliest cuts. 



Heart rots in the overmature stands 

 of the West present a major problem in 

 forest management. Whether such 

 stands are clear-cut or selectively cut, 

 all highly defective trees should be cut 

 whether they are merchantable or not, 

 unless it is necessary to leave them for 

 seed trees to restock the area. In some 

 stands there are so many cull trees that 

 the sound timber available will not pay 

 for their cutting and still leave a profit 

 for the operator. Even if all were felled, 

 considerable damage would be done to 

 young trees and other timber left stand- 

 ing on the area, new young growth 

 would be obstructed, and a serious fire 

 hazard would develop. If they are left 

 standing, they occupy a large percent- 

 age of the area that should be taken 

 over by vigorous young trees. 



How to dispose of the obviously 

 worthless trees under these circum- 

 stances is a challenging problem. This 

 same problem arises in connection with 

 large areas of high-graded timberland 

 in both the East and West. On these 

 areas only the best trees were removed, 

 leaving a considerable stand of near- 

 worthless timber. The systematic elimi- 

 nation of these trees, most of which are 

 badly decayed, is now a prominent 

 phase of the forest land-improvement 

 operations in many sections of the 

 country. 



