622 JOURNAL OF* FORESTRY 



Oregon, that these losses, if continued, would prohibit the selection 

 method of cutting. The results are reassuring on this point, inasmuch 

 as they indicate that, on areas subject to severe winds, a loss as great 

 as 25 per cent may be expected before the reserved stand becomes re- 

 sistant and that thereafter the big part of the stand will remain per- 

 manently on the ground. The results are also important in that they 

 furnish actual figures of windfall loss in number and volume of trees 

 per acre covering a long period of years, which can be used as a basis 

 for the correction of such loss in yield tables — a correction which has 

 heretofore been made upon assumption. 



It is unfortunate that it was beyond the possibilities of this study to 

 furnish information by means of which large windrisk areas may be 

 recognized in the virgin forest before cutting is begun. If such infor- 

 mation were available, it would be possible, by a modified treatment 

 of the area, to reduce greatly the loss which seems so certain to occur 

 in the first several years after cutting. 



The important conclusions of the study may be summarized as fol- 

 lows : Heavy windfall in the first few years following cutting, like that 

 of the timber sale in which 17^ per cent of the stand was blown down, 

 does not presage the total destruction of the reserved stand or even 

 endanger the method of cutting. As high a loss as 25 per cent by 

 volume on bad windrisk areas may be expected in the course of 20 

 years. Of all the windthrow which occurs over a long period of years, 

 a proportion as great as two-thirds or more usually takes place in the 

 first four or five years immediately after cutting, and the remainder is 

 thrown in rapidly decreasing percentages until about 20 years later 

 when the windfall is so slight as to be negligible. Measured by the 

 heaviest windfall loss encountered, the selection method of cutting is 

 not prohibitive in the yellow pine stands of eastern Oregon. 



