STUDY OF WINDFALL LOSS 621 



five-year period was 1.4, 0.05 and O.TT tree per acre, respectively. 

 Thus, it is seen that the loss on the Eccles timbersale is less as com- 

 pared with one plot and only slightly more as compared with the 

 others ; and the cutting which had a more alarming loss in the first 

 years of its existence still has over 75 per cent of its reserved trees 

 standing after 20 years of exposure. 



It is of interest and practical value to express windfall loss in num- 

 ber of trees per acre. In order to have a uniform basis with respect 

 to the time element, the loss for the five plots of this study was com- 

 puted for the first 15 years following cutting in each case. On Plots 

 I to V this was found to be, respectively: 2.1, 1.0, 0.1, 0.2, and 1.12 

 trees per acre. 



In predicting the future yield of areas under management, it is 

 useful to have these actual figures of windfall loss in order to make 

 allowance therefor. It will immediately be said, however, that such 

 allowance is of little value if loss through other causes than windthrow 

 is not considered also. This point was kept in mind in the present 

 study and total loss was carefully investigated on Plots Hi and V and 

 on another area. The results of this investigation are quite inter- 

 esting and will be presented very briefly. The total loss on the 21 

 acres of Plot V amounted to 46 trees in 15 years, as follows : 34 wind- 

 falls, 8 insect-killed and 4 killed by unknown causes. On the 20 acres 

 of Plot III, where the total loss was very light, it amounted in the 27 

 years since cutting to 29 trees. The causes were recorded as : 11 wind- 

 falls, 8 insect-killed, and 10 killed by agencies which could not be defi- 

 nitely determined though believed to be mostly insects. Though fewer 

 trees were windthrown than lost through other causes, the windfall 

 volume loss was 11,775 board feet as compared with 10,245 board feet 

 through other causes. Total loss has also been observed annually on a 

 permanent 45-acre sample plot in a timbersale cutting which is now 

 six years old. On this plot, which suffered in its first year from the 

 severe storm of September 18, 1914, 75 trees have been lost to date: 

 61 windfalls, 11 insect-killed, 2 fungi- weakened and withthrown, and 

 1 lightning-killed. It is apparent that windfall makes up the great 

 proportion of total loss, comprising 53 per cent by volume on Plot III 

 and 80 per cent on the other two plots. It should be added that 

 Plot III was located near a large area which suffered a severe epidemic 

 infestation of Dendroctonus 10 or 12 years ago. 



The value of this study is that it dispels the fear, inspired by the 

 alarming losses experienced on several yellow pine timber sales in 



