840 JOURNAL OF FORESTRY 



from 1893 to 1902, and that thereafter for 12 years no such storms 

 took place at all. In assuming any minimum severity of wind to blow 

 down trees, as 40 miles in this instance, it should be kept in mind 

 that it must be qualified by the effect of other conditions, such as 

 the season of the year and the age of the cutting. If a minimum wind 

 of 40 miles is required to throw trees in the spring when the ground 

 is soft, it would take a stronger wind in the winter. Likewise it 

 would take a stronger wind to blow down trees 10 years after cutting, 

 when they had developed windfirmness, than it would in the first 

 two or three years. In this connection, it is interesting to note that 

 of the six storms here considered, three occurred in winter months and 

 two of these were 49 and 50 mile winds. If these winter storms are 

 eliminated as a cause of windthrow, the windfall storms would have 

 occurred only in 1892, 1897, 1902, and 1914, which would indicate a 

 minimum frequency of five years. It is further of interest to note 

 that the Baker office recorded two storms in 1914; the least severe 

 of these was 42 miles an hour and occurred in September, and the 

 other was 49 miles an hour and came in January. The first caused 

 the heaviest windfall yet experienced on the Whitman timber sales, 

 while the other and stronger storm caused no appreciable loss. 



To supplement what could be learned from Weather Bureau records 

 an attempt was made on the ground to study the character and the 

 frequency of the several destructive winds which have visited the 

 Crater Forest, as reflected by evidence existing in the forest itself 

 and obtained from old settlers. As already pointed out and as shown 

 on the map, the effect of the storms of 1915 and 1918 was localized 

 in single spots of comparatively small area, while that of the April, 

 1920, storm, was spread over a considerable stretch of country. Since 

 no wind records are regularly kept in the Klamath region, the velocity 

 in these several storms is not known. The winds, however, are known 

 to have been straight-blowing and exceedingly violent ; the direction 

 of the first two was from the south, while that of this year was from 

 the west. Evidence of the great velocity of the 1915 storm wind is 

 the result of its tree-throwing power in February when the ground was 

 hard and firm. 



As to frequency, timber-sale cutting in this region began in 1909 

 and therefore has been in progress 11 years. When a storm occurred, 

 preceding that of 1915. is not known ; but since this was not within the 

 history of the first cutting, there was an interval of at least 6 years 



