514 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



made, but none has been executed long enough to yield conclusive 

 results. 



The study at AYagon AVheel Gap. Colo., to determine the effect of 

 forest cover on streamflow, described last year, yielded valuable 

 records, although final results can not be obtained until after the 

 denudation of one of the watersheds. Points of great interest 

 alroadv determined are that the surface rim-oif contributing to what 

 may be called a flood in either stream is less than 1 per cent of the 

 rainfall of any storm yet recorded; that the amount of soil erosion 

 from the forested Avatersheds is practically negligible; that the rela- 

 tion of maximum flow to minimum flow in 11)11 was about 13 to 1, 

 while other watersheds of the region more sparsely covered usually 

 have a ratio of from 20 to 1 to 100 to 1, and that the crest of a flood 

 after heavy fall rains lasting 72 hours occurred in one stream in 2 

 days and in the other in 4 days, while neither stream had recovered 

 its normal flow 2 months after the r tin. 



At the Fort Valley Station observations during the year upon the 

 effects of forests on climate proved that the forest is very effective 

 in checking excessive wind movement and evaporation. Conclusive 

 proof will be sought of the influence of the forest in moderating low- 

 temperature extremes. 



A contribution of the Forest Service to the final report of the 

 National Waterways Commission (S. Doc. 469, 62d Cong., 2d sess.) 

 Ijrought out an entirely new point of view as to the relation between 

 the forests of the Coastal Plains and Appalachian Mountains and 

 the humidity of the central and prairie regions. 



The damage caused by light surface fires, which find some advo- 

 cates among lumbermen, was the subject of investigation on a num- 

 ber of forests. A record of 1,184 butt logs on the AVhitman Forest, 

 in Oregon, showed 22.8 per cent to be more or less scarred, while 18.6 

 per cent lost an average of 46 board feet apiece by scale through fire 

 damage, and many more were pitchy. 



In cooperation with the Bureaus of Entomology and Plant Indus- 

 try studies were conducted on a number of forests of insect infesta- 

 tion and tree diseases. 



On the Klamath National Forest 927 acres were treated for insect 

 infestation, the area protected by such treatment amounting to 29,000 

 acres, with a stand of 330,000.000 feet of timber, valued at $660,000. 

 The cost of combating the infestation amounted to $3,000. 



Attempts to eradicate the dendroctonus beetle on the White River 

 Forest by cutting and barking infected trees and on the San Isabel 

 by girdling did not prove entirely successful. On the Pike Forest, 

 however, infestation was checked. 



Studies of Phoradendron juniperium in burls of incense cedar, of 

 Hypodermn sp. on shore pine, and of the age of infection of incense 

 cedar with dry-rot were completed. 



A pathological survey of the Mono, Tahoe, Eldorado, Stanislaus, 

 Sierra, Lassen, Klamath, and Shasta Forests and the Yosemite 

 National Park was made during the year. A manual of forest-tree 

 diseases was prepared by the forest pathologist in California for the 

 use of forest officers. 



A study of the deterioration of fire-killed timber in Montana and 

 Idaho showed conclusively that in western white pine blue stain and 

 check set in almost immediately after a fire; that the blue stain is con- 



