FUNGI AS CONTRIBUTORY CAUSES OF WINDFALL 705 



More accurate data relative to the loss in feet board measure due to 

 windfall alone for the areas covered by Forest Service Districts i, 2, 

 and 6 are given in Table i. These reports possibly do not cover every 

 individual windfall area within the indicated districts, but at least in- 

 clude all the larger and more important as well as the greater number 

 of smaller areas. From the totals secured from these reports, it is seen 

 that a loss of over 387,322,000 feet board measure of all species, valued 

 at approximately $260,800, has occurred over this area — the majority 

 of this during the past two years (1915-1916). A certain portion of 

 this loss is preventable, and all means possible should be applied in 

 reducing the annual loss from this source. 



FIELD DATA ON WINDFALL AREAS 



In the fall of 1916 questions on windfall damage were prepared and 

 sent out to the forest officers of the national forests included in Dis- 

 tricts I, 2, and 6 of the Forest Service; also to various logging com- 

 panies of the Northwest. The information secured upon the return of 

 these sheets was found to be extremely interesting, and the data were 

 summarized in a table (Table i). In all, 98 reports were received on 

 as many different windfall areas, scattered throughout the States of 

 Washington, Oregon, Idaho, Montana, Wyoming, Colorado, Minne- 

 sota, and Michigan. Of this number, 90 were used in the included 

 tables, those excluded being incomplete. These areas aggregate a total 

 loss of 387,322,000 feet, board measure, valued at approximately 

 $250,800. Of this total, 3 per cent by volume, or 12,275,000 feet, board 

 measure, valued at $23,642, was found to be directly traceable to fun- 

 gous attack as a secondary cause of windfall. The greater portion of 

 this loss is traceable to the action of root fungi and the remaining lesser 

 portion to butt and trunk rotting fungi, which latter are largely re- 

 sponsible for the direct breakage of the trunks. The striking point 

 brought out by a table not included in the text is the almost invariable 

 association of fungi as secondary causes in windfall wherever stands 

 of old-age trees are overthrown. This is to be expected, especially in 

 trees subject to root fungi and growing in damp, shaded, and poorly 

 drained sites. 



Of the 90 windfall areas reported u[)on ( Tal)le 2), 16, or iS per cent, 

 were found which had fungi as the principal sccondarv cause, and 9, 

 or 10 per cent, in which fungi were responsible for only a smaller por- 

 tion of the windfall, leaving 62, or /T, per cent, of the areas in which 

 other causes, such as exposure, tree heights, crown sizes, soil condi- 



