FOREST PATHOLOGY IN FOREST REGULATION. 57 



The entire silvicultural results obtainable by way of timber sales 

 are directly dependent upon proper marking, the importance of 

 which can not be overemphasized. Marking is by far the most 

 portentous of all silvicultural activities and requires a very specific 

 training, of which a complete knowledge of all components of the 

 total-loss factor must be a prominent part. 



Marking in the selection forest has a threefold object — to select 

 trees to be cut and utilized at once, to leave others as a basis for 

 future cuttings, and to establish desirable reproduction. Here the 

 interests of the Government as timber owner and timber producer 

 frequently conflict with those of the purchaser. The purchaser can 

 not be expected to take a strong interest in the future of the area he 

 is to cut over. He quite naturally wants as much sound merchant- 

 able timber from a given stand as possible. The larger the amount 

 of timber he can cut from an area the smaller the overhead charges 

 will be per thousand feet, board measure. In offering white fir for 

 sale it is, therefore, important to be able to estimate more or less 

 correctly the amount of sound timber on a given tract. If our 

 figures prove correct, the loss factor in white-fir trees will be com- 

 paratively small up to an age of about 130 years; after trees with a 

 combination of wounding and suppression have reached the age of 

 130 years they are liable to contain decay; after they have reached 

 the age of 150 years wounding alone, even in dominant trees, is 

 liable to lead to damaging decay. That trees with sporophores are 

 decayed, at least partly, is self-evident. The actual cull per cent 

 from decay is at present only guessed at. It is the constant aim of 

 forest pathology to reduce this guesswork to actual and concrete 

 figures. It is intended to repeat similar studies throughout the 

 range of white fir and later also on other species in the order of 

 thoir importance and finally to establish broad zones of equal path- 

 ological conditions, in which the rot percentage may be given in 

 definite figures. 



Marking can only be done correctly if the outcome of the marking 

 with regard to the trees left standing is constantly kept in mind. In 

 our specific case, for instance, white fir on typical lightning and frost 

 belts should be marked very heavily. Wo know that here the loss 

 from decay, particularly following frost cracks, is heavy and will grow 

 through cumulative risk. White firs with serious wounds, especially 

 with partly open fire wounds, must be marked heavily to as low a 

 diameter as pracl icable. 



On the oilier hand, thrifty unwounded trees, where desirable, may 

 \>c left without, much risk up to the ago of about 150 years, and prob- 

 ably much longer. 



