0-20 20-40 40-60 60-80 80-100 100-120 



Slash depth (cm.) 



Figure 3. — Bulk density of old and new slash at 20 -centimeter depth levels. The aver- 

 age depth was 73 centimeters for old slash and 68 centimeters for new slash. 



Void Volume to Surface Area Ratio (A) 



The ratio A is also a measure of the porosity of a fuel complex and expresses the 

 amount of void space associated with a unit area of fuel surface. Generally, as A 

 increases, movement of air and other gases is freer because the space between particles 

 is greater. But, at the same time, the distance radiant heat must travel between par- 

 ticles is greater. 



In this study, A increased vertically with old slash generally being more porous 

 as shown in the tabulation below: 



Slash age 



Slash depth 



Old 



New 



(cm. ) 



(cm. ^/cm. 2 ) 



( cm. ^/cm. 2 -) 



0-19 



9 



6 



20-39 



14 



10 



40-59 



37 



20 



60-79 



62 



95 



80-99 



283 



82 



100-119 



284 



250 



120-139 



922 



454 



140-159 



1,150 



937 



8 



