STUDY OF WINDFALL LOSS 617 



exist, however, and for the purposes of this study the stands left after 

 cutting on these areas are not essentially different from those left in 

 Forest Service timbersale cuttings. The old private cuttings contain 

 just as great a proportion of trees left standing as the timber sales, 

 and sometimes a greater; and the trees are nearly as well distributed 

 over the ground. The degree of wind-firmness on the old private cut- 

 tings is not appreciably poorer than on those timbersale cuttings which 

 suffered so heavily a few years ago. The reason for this is that the 

 latter contained a greater number of tall and full-crowned trees which, 

 observation has shown, are just as lacking in windfirmness as the trees 

 with defective trunks and basal fire scars found on the private cut- 

 tings. Both classes of cuttings contain about the same number of 

 young trees. By old cuttings are meant those cut twenty years and 

 more ago, when logging in eastern Oregon was in its early stages and 

 the logger left a great many trees which he takes to-day with the pres- 

 ent closer utilization. 



In securing the present windfall data, plots 20 acres or larger were 

 laid out and all the standing and down trees over 12 inches in diameter 

 breast-height were cruised. In addition, the down trees were care- 

 fully analyzed as to the year when each tree was thrown, which was 

 readily determined from the number of accelerated annual rings the 

 down tree showed as compared with those of the standing trees. In the 

 few cases in which there was doubt as to whether the down trees had 

 first been killed by fungi or insects and had then been blown down, the 

 trees were not included as windfalls in the compilations of this article. 



The plots were located in representative conditions in and near three 

 National Forests in the Blue Mountain region of eastern Oregon. 

 There were three 20-acre plots, one 40-acre plot, and a total of 24 

 acres of smaller plots, primarily studied for another purpose, but upon 

 which careful notes of windfall occurrence were made. Plots I and 

 II were located in areas of severe wind risk, and Plots III and I\' in 

 con!^aratively sheltered areas. The numerous smaller plots were 

 located in both exposed and sheltered situations and the results given 

 for the aggregate plot are therefore average for a wide range of con- 

 ditions. The proportion of trees left standing at the time of cutting 

 amounted to the following percentages by volume of the original stand 

 in each case : 12 per cent on Plot I, 8 per cent on Plot II, 40 per cent 

 on Plot III, 8 per cent on Plot IV, and 10 per cent on Plot V. 



Table 1 shows for each plot the total number of trees thrown, the 

 volume of these trees, and the percentage of loss. The last is based 



