Crown Space of Western Yellow Pine. 331 



Table I. 



Showing for the average acre, on three representative areas, after surface 

 nres, the number of trees per acre of Yellow pine and their proportions in 

 the total stand, in four classes, according to the damage which they sus- 

 tained in the fire. 



Scarred 

 by O. K. Total 



Fire 



No. % of No. % of No. % of No. % of No. % of 

 Trees Total Trees Total Trees Total Trees Total Trees Total 

 per Stand per Stand per Stand per Stand per Stand 

 Acre. Acre. Acre. Acre. Acre. 



Wallowa 



N F 

 Average ^'^^ ^'^^ 7-70 32.59 8.92 37.75 17.83 75-46 



70 Acres. 



Wallowa 



N F 

 Average '^ ^-^^ ^^o 30.90 9-27 32.92 18.57 65.94 



30 Acres. 

 Wallowa 



Average '^^ ^"^^ '43 i-3i 8.34 25.23 9.02 27.24 18.29 55-30 

 30 Acres. 



It will be seen from this table that surface fires in Yellow pine 

 have a decided tendency to thin out the trees, especially if the 

 fires are repeated many times during the life of a stand. But, 

 if the damage to the large trees is considerable, the damage to 

 the seedlings, saplings, and poles is very much greater. Indeed 

 it seems almost certain that in times gone by, when the Indians 

 were in the habit of setting great numbers of fires to drive game, 

 very few seedlings were able to reach maturity solely because of 

 the frequent fires. 



(2) Insects, especially bark beetles, have also had a strong 

 tendency to thin out forests of Yellow pine. The most de- 

 structive of the bark beetles working in Yellow pine is the Den- 

 droctonus species, of which there are a considerable number of 

 varieties. These beetles work in colonies, flying from one group 

 of trees to another and killing each group in succession, thus 

 opening up spaces of considerable size in the forest. 



The injury wrought by these beetles is usually more severe 

 than the injury done by fire, and beetles are harder to subdue than 

 fire. They are probably present in all Yellow pine forests in 

 Washington and Oregon. In the Black Hills, a few years ago. 



