836 JOURNAL OF FORESTRY 



is due partly to retardation from overcrowding which is more intense 

 than in 1910. 



Including the trees lost by wind and snow damage shown in No. 5 

 above, following is the data for trees killed by both suppression (58 

 per cent) and by extraordinary loss (42 per cent) : 



p. Volume of trees lost by suppression and otherwise 



Number of trees Cubic foot volume 



1910-1915 1915-1920 1910-1915 1915-1920 



Plot 1 13 26 88.30 335.80 



Plot 2 16 37 145.3.5 604.50 



Plot 3 14 18 88.55 377.70 



Average 14 27 107.40 439.37 



It is striking that the volume of the trees lost in 1915-1930 is over 

 four times that lost in the preceding half decade. Were the dead 

 trees for both periods added to the increment of the living trees, the 

 cubic volume growth for the last half decade would have been almost 

 the same as for the preceding half decade. This table also shows the 

 need for thinnings and indicates the material amount of wood, now lost, 

 that might be salvaged by making thinnings every ten or twenty years. 



10. Contents of the average living Douglas fir (cubic feet) 

 1910 1915 1920 



Plot 1 42 50 63 



Plot 2 44 52 65 



Plot 3 50 60 69 



Average . . . ^^ 45 54 66 



While the loss by number of trees is greater during 1915-1920 than 

 during 1910-1915, yet the increment of the average living tree is 

 considerably greater. 



