A STUDY OF WINDFALL LOSS OF WESTERN YELLOW 



PINE IN SELECTION CUTTINGS FIFTEEN 



TO THIRTY YEARS OLD 



By Robert H. Weidman 



Forest B-vaniiner, U. S- Forest Service 



A few years ago several violent wind storms did a great deal of 

 damage in yellow pine timbersale cuttings on the Whitman and Crater 

 National Forests in Oregon. On one cutting with an area of 1,624 

 acres, nearly one million board feet of yellow pine was blown down in 

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

 included 17}^ per cent of all the reserved trees on the area. So heavy 

 a loss occurring so early in the local timbersale experience (the cut- 

 ting had been in progress only four years) was a most alarming condi- 

 tion, particularly since the Weather Bureau records showed that re- 

 gional winds of equal velocity occurred every three or four years. 

 It was feared that a similar heavy windfall loss might occur period- 

 ically and that at this rate all the reserved trees would eventually be 

 blown down and the selection method of cutting would become pro- 

 hibitive in this region. 



Since that time a comprehensive increment study of yellow pine on 

 old private cut-over areas has been in progress in Oregon, and has 

 ofifered an excellent opportunity to examine in detail the history of 

 windfall loss on areas upon which had been practiced, years ago. 

 partial cutting methods resembling the present selection cutting of 

 timbersales. This windfall study aimed to determine the volume of the 

 loss through a long period of years and to ascertain the actual years, 

 with relation to the time of cutting, in which the trees were blown 

 down. With this information at hand it would be possible to say 

 whether all the trees left standing in selection cuttings would event- 

 ually be blown down, or whether the greater precentage of them 

 would, in reality, become gradually windfirm and survive the later 

 storms. The ideal conditions for securing the data would have been 

 furnished by areas cut over by a regulated selection method, but forest 

 management is not old enough in this region to furnish such cuttings. 

 Old private cuttings in yellow pine up to thirty years old and more do 

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