SECOND REMEASUREMENT OF PERMANENT SAMPLE 



PLOTS OF DOUGLAS FIR ON THE WEST SLOPE 



OF THE CASCADES IN OREGON 



By T. T. Munger 



In April, 1910, three one-acre sample plots were established in a 

 54-year-old stand of Douglas fir on the Cascade National Forest south 

 of the middle fork of the Willamette River near Blakleyville, Oregon. 



On June 3 and 4, 1920, Robert H. Weidman and Thornton T. 

 Munger re-examined and remeasured these plots. It was then five 

 years and six days since the former examination and ten years since 

 the initiation of the plots. This report treats of the history and growth 

 of these plots from 1915 to 1920. The stand is now 64 years old. 



Some of the more interesting facts to be deduced from the present 

 examination, by comparison with previous examinations, are set forth 

 below : 



I. Number of living Douglass firs per acre over 4 inches d. b. h. 



1910 1915 1920 



Plot 1 188 175 149 



Plot 2 r 214 198 161 



Plot 3 186 172 154 



Average 196 182 155 



The average diameter of the trees lost in the first half decade is 6.55 

 inches and in the second half decade 8.90 inches. This shows that 

 the loss has been greater in the last half decade than the preceding 

 in number and especially in volume. It is partly due to the extra loss 

 by snow and wind two years ago. The struggle for light is however 

 very keen and the loss from suppression is very great. This indicates 

 the silvicultural desirability of thinnings at this time. 



2. Number of living hardwoods per acre 



1910 1915 1920 



Plot 1 29 14 10 



Plot 2 8 5 4 



Plot 3 18 8 7 



.'Kverage 18 9 7 



The hardwoods have been practically suppressed out of the stand 

 and are silviculturally inconsequential. 



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