22 BULLETIN 1200, U. S. DEPARTMENT OF AGRICULTURE. 
of reproduction and grass described above. A representative spot 
in the Columbia burn is illustrated by Figure 4. 
The most severe ground fires occur on dry sites and in localities 
where there is heavy litter and duff. They occur also where the 
fiames sweep the surface, as where a fire runs up hill. Under these 
conditions the soil is severely heated. The irregularity of the young 
growth on all sites led to the conclusion that where fire consumed 
iY) é Produc t/On we 
} AG / ; Was 
> 5 Lp iiegy 
fs, 
[ Area of dense//» 
4 //) 
reproduction of? OE 
noble ftir about TReproduetion | 
(30.000 seec//ings My 
/ per ecre . y | | 
; | 
\ + 
\ VG 7: 
yy 
No ground fire 
| a bergie is 
| Y Ao Geese 
‘ Yy, Ly 
Grass — No reproduction 
Pesu/t of ground fire 
WM, 
sproduGrion 
ey 
Fic. 4.—Effect ef ground fire on distribution of young growth. 
the duff and heated the soil no reproduction was possible except close 
to seed trees. 
With the recurrence of irregular patches of reproduction in areas 
where the litter and duff were not completely destroyed, and in 
moist places where the forest floor had not been heated, it was con- — 
cluded that the seed from which the young growth sprang on the 
Yacolt burn and on other similar burns that were studied, must 
have been stored in the duff or soil before the fire. (Pl. IV.) 
