708 JOURNAI, OF FORESTRY 



large portion of the windfall damage, it is important that the subject of 

 seed trees be taken up in this connection. Forest Examiner Rockwell, 

 of the Cceur d'Alene National Forest of Idaho, has collected data upon 

 areas aggregating 21 acres, which show that a large portion of the wind- 

 fall seed trees of western white pine on cut-over areas are overthrown 

 by the wind on account of the weakening of the roots due to fungous 

 activity. In many cases, no doubt, the exposure has its effect upon the 

 seed trees suddenly exposed to the wind, but this is at the same time 

 augmented by the weakening and subsequent breakage of the root sys- 

 tem through the rotting of the roots. The figures given for four acres 

 representing dift'erent sites were averaged and the following figures 

 secured : The per cent of down trees to total trees reserved, by species, 

 is white pine ii.i and Douglas fir 15.9. The per cent of down trees 

 to total trees reserved, whose secondary cause of windfall is determined 

 due to fungi, by species, is white pine 5.3 and Douglas fir 3.5. Com- 

 paring these percentages, it is seen that in white pine fungi are respon- 

 sible for 47 per cent of the windfalls and in Douglas fir 22 per cent. 

 These figures show that in white pine fungi are responsible for nearly 

 50 per cent of the windfalls in such areas where seed trees are re- 

 served, and that fungi are important, though not to as great an extent, 

 in Douglas fir. 



It is, therefore, evident that all seed trees left on a cut-over area 

 should, for the purposes of forest sanitation as well as for the wind- 

 resisting qualities, be trees which are absolutely free from fungous in- 

 fection. This not only applies to seed trees, but likewise to all trees 

 left upon an area after cutting, whether seed trees or trees left as a 

 result of selection cutting. The retention of sound trees in all cases 

 on a cut-over area would insure the maximum of wind resistance, pro- 

 viding other conditions contributing to the hazard of windfall are con- 

 sidered. If sound trees only are allowed to remain, forest sanitation 

 will be benefited and there will be much less danger of windthrow. 



A sample acre on a windfall area occupying a portion of the Honey- 

 suckle sale area, on the Coeur d'Alene National Forest of Idaho, throws 

 some light upon the part played by root and butt rotting fungi attack- 

 ing western white pine. On this sample area 78 per cent, or loi out of 

 129 trees of various species, were windthrown during the spring of 

 1913. The majority, approximately 85 per cent, of the windfall trees 

 were western white pine. The remaining 15 per cent were Engelmann 

 spruce, grand fir, and western hemlock. The white pines were of an 

 old-age class (141-160 years) and had a full development of the rot 



