620 JOURNAL Or FORESTRY 



that it is not so marked in Plot III. where but eleven trees fell in 27 

 years and most of these were large trees between 24 and 38 inches in 

 diameter. 



This concentration of windfalls in the first few years after cutting, 

 with the gradual decrease thereafter, is a striking but not unnatural 

 condition. When the forest in a region of severe winds is opened by 

 heavy selection cutting, it is quite obvious that the weakest of the 

 remaining trees will be blown down by the first strong winds, and that 

 thereafter there will be a natural falling off of the loss as the less 

 weak trees become gradually windfirm. 



It will be remarked, however, that the uniform decrease of per- 

 centages in Table 2 is disturbed in the later half-decades by unusually 

 high percentages of volume. As can be readily seen from a com- 

 parison of the small number of trees thrown with the corresponding 

 high percentages of volume, the trees must have been of unusually 

 large size. This was actually the case, for on Plot I the last tree 

 thrown was 30 inches in diameter, on Plot III the last tree lost was 

 35 inches, and on Plot V there were two large trees, 26 and 30 inches, 

 included in the last half-decade. Because of their large size and the 

 deep basal fire scars on several of them, these trees were exceedingly 

 bad windrisks, and would not have been left standing under any cir- 

 cumstances by a timbersale marker. 



The concentration of windthrow immediately after cutting now sug- 

 gests the question : Have not the several discouraging windfall losses 

 on timbersale cuttings in the Whitman and Crater National Forests 

 been the result of normally severe storm-winds striking remaining 

 stands when they are most susceptible ; that is, in the first few years 

 after cutting, just as in the case of the losses in the old private cut- 

 tings described in this article? The specific case of the loss on the 

 Eccles timbersale affords an opportunity for comparison. On this 

 timbersale cutting, which was less than four years old, 17^ per cent 

 by volume of the yellow pine trees in the reserved stand were blown 

 down by the storms of May 26, 1913, and September 18, 1914. This 

 amounted to an average loss of one tree per acre on 1,624 acres. On a 

 permanent 45-acre sample plot, which was established on this timber- 

 sale area in 1914 and has been examined annually, the loss for the 

 remainder of the five-year period following the two severe storms was 

 an average of 0.2 tree per acre. Accordingly the loss on this area was 

 1.2 tree per acre for the first half decade. On the three plots of this 

 study which suffered the heaviest windthrow, the loss for the first 



