42 Forest Club Annual 



According to a technical report by Forest Assistant John 

 Murdock, Jr., which Supervisor Paul Kelleter permitted the 

 writer to inspect, drops of 40 or 50 degrees in a single hour 

 occurred. Mr. Irwin states, presumably referring to the drop 

 in temperature of January 8, that the change was immediately 

 preceded by a heavy fog. 



Mr. Murdock states that there was snow in the northwest 

 part of the forest, but little elsewhere. It appears that snow 

 on the ground had little influence. In general, he states that 

 the ground was frozen quite deeply. He says that needles 

 of the Western Yellow Pine (Pinus ponderosa), the dominant tree 

 in this region, began to turn brown when warm weather started 

 after this period of chinooks and freezes. He estimated the area on 

 which there was damage as not less than 40,000 acres, on 

 one-third of which area the damage was to reproduction ; on 

 two thirds of the remaining ^area the proportion of the mature 

 stand killed ranged from to 2 per cent ; and on the remainder, 

 two-ninths of the total affected portion, four to five per cent of 

 the mature stand is said to have been killed. The total amount 

 of timber killed is given as not over 3,000,000 feet B. M., 

 scattered through the roughest and most inaccessible parts of 

 the forest. He says that in the northern part of the forest, 

 the northwest slopes were most injured, while in the eastern 

 part the northeast slopes were hardest hit ; that everywhere 

 the north sides of the trees were most injured; that degree of 

 slope seemed to have little influence, and density of stand 

 no effect whatever. Sites based on sandstone, limestone, 

 po<rphyry, and granite are said to be all equally injured. Basal 

 branches, which were covered with snow during the winter, 

 were uninjured. 



Observations made near Deadwood by the writer in Sep- 

 tember, 1909, in general agreed with Mr. Murdock 's state- 

 ments. Injury was mainly on the upper parts of slopes, and 

 on the ridges. Trees on the upper northwest slopes were most 

 injured, while those on the tops of the hills and on the upper 

 north and upper west slopes were somewhat less injured. In- 

 jury to trees on northeast slopes was not so great at this point. 

 Some trees were killed also on upper slopes having southerly 

 exposures. The greater injury at the higher points and slight 

 injury in the valleys and on the lower slopes was conspicuous. 



