674 JOURNAL OF FORESTRY 



both in the operation of felHng and in the operation of disposal of in- 

 fected unmerchantable trees or parts of such trees. The pathological 

 marking rules will be useful as a guide in the appraisal of each sale area. 

 The amount that can be expended for forest sanitation can be computed 

 with these rules as a basis, modified by such economic factors as are 

 present. The marking can then be carried out according to the stipula- 

 tions in the appraisal. The aid of men thoroughly familiar with forest 

 sanitation work should be employed in outlining definite pathological 

 marking rules for individual sales. 



The JVestern White Pine Type 



Recently, in the formulating of marking rules by the Forest Service 

 in District i (Montana District),^ a classification of western white pine 

 stands has been made, under two main heads, A and B, having two sub- 

 heads under A and three under B. The A stands contain a minimum 

 of about fifty trees per acre, between 6 and 14 inches d. b. h., thrifty 

 trees, suitable to increase in growth after a cutting and exclusive of 

 hemlock and defective trees of other species. The A^ stands contain 

 practically all trees below 14 inches d. b. h. The A2 stands contain 

 sufficient trees over 14 inches d. b. h. to justify a logging operation. The 

 B stands contain less than about fifty trees per acre, as described above, 

 and the B^ stands are those in which small trees of desirable species 

 between 6 and 14 inches d. b. h. occur frequently. The B, stands con- 

 tain practically no small trees, but contain thrifty trees, including some 

 white pines, capable of living through a second rotation. In the B, 

 stands there are no white pines evidently capable of living through a 

 second rotation. 



In general the A^ and A^ stands are managed so as to secure a 

 second cut from the trees already established. This is secured by im- 

 provement thinnings and partial cuttings. The Bj, B., and Bg stands 

 are managed so as to harvest the crop and establish a new stand of 

 white pine and other desirable species. Reproduction cutting and clean 

 cutting are the methods proposed to secure this result. 



With this outline in mind and taking into consideration the various 

 factors concerned in the infection of trees previously discussed, it is 

 readily seen that on A^ and A^ stands, where a second cut is expected 

 from the trees already established, there is a greater need for forest 

 sanitation than on any of the B stands. In the A stands the reserved 

 growth may be approaching the infection age, and no diseased trees 

 should be left upon the area to menace this future crop. 



