FUNGI AS CONTRIBUTORY CAUSES OF WINDFALL "^09 



of Polyporus schivc'mitzii occupying the butt section and extending 

 downward into the larger roots. Of the windfall white pines there 

 were 60 trees, or 59 per cent of the total trees thrown, found infected 

 with P. schweinitsii. Three (two white pines and one spruce), or 3 

 per cent of the total trees thrown, had their roots rotted by Fames 

 annosiis. In the majority of cases where the main roots were rotted 

 they were found broken off short near the stump. Fungous attack and 

 a very moist and loose soil are the two secondary causes determined 

 as responsible for this windfall, the fungous action ranking first. From 

 the foregoing data it appears that the windfall damage attributable to 

 the species of fungi attacking the trees is in proportion to the preva- 

 lence of the various species of fungi in the stand, and also depends 

 upon the stage of development of the rot at the time of the windstorn. 

 An area of mixed windfalls on the Humbird Lumber Company's 

 land, near Priest River, Idaho, covering approximately four acres, was 

 examined in the fall of 1916, just after the area had been cut and before 

 the logs had been removed. Approximately 158 trees were overthrown 

 by a high wind on July 12, 1916. The windfall occurred upon a strip 

 of bottom land bordering the Priest River, and was timbered with an 

 old-age class of the western white pine — western hemlock type. The 

 soil was found to be a soft, sandy loam, very moist and very poorly 

 drained. The stand was densely stocked. Sixteen white pines were 

 carefully examined and field notes taken in conformity with the out- 

 line for windfall data (Table i). Of the 16 trees, 13 were of the 

 160-200-year age class and 3 of the 201 age class. All the trees were 

 ■found to exceed 125 feet in height and the tallest one measured 173 

 feet. Every tree was found heart-rotted, either with Trametcs pini or 

 Polyporus schzveinitaii. In eight cases this heart rot extended into the 

 roots of the infected trees 4 to 8 feet. Critical examination of the 

 roots showed that 14 of the trees had rotted roots, and the main roots 

 of 13 of these were broken off from 2 to 4^ feet from the stump. Of 

 the rot in the roots, six of the trees bore root rot traceable to Pomes 

 ainiosus, si.x to Trametes pini, and two to Polyporus schwcinitzii. Two 

 were found to be sound, and were pulled out of the ground instead of 

 being broken off short near the stump. All of the trees fell with their 

 tips pointing northeast, which was found to be the general path of the 

 wind causing the overthrow. All were prone upoti the ground except- 

 ing one, which was but partially overthrown. This tree was found to 

 have sound roots, and its overthrow can be ascribed to the impact re- 

 ceived from ;i neighboring windfall and to the softness of the soil. 



