International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 
  
  
  
  
  
  
a) 
  
b) 
Figure 3. Three-dimensional graphical visualization of a) IFSAR X-band elevation measurements (color-coded by height) overlaid 
on P-band digital terrain model and b) corresponding orthophoto. 
3. METHODOLOGY 
3.1 Field-based canopy fuel estimates 
Field-based estimates of canopy fuels were generated using the 
methodology developed for the Fire and Fuels Extension to the 
Forest Vegetation Simulator (FFE-FVS) (Beukema et al., 1997). 
In this approach, the foliage of each tree is estimated using the 
equations developed by Brown and Johnson (1976). These 
equations generate estimates of the total dry weight of live and 
dead material for each individual tree crown, and provide a 
break-down of the proportion of the total crown weight that is 
associated with foliage and different size classes of 
branchwood. Following the methodology of Scott and 
Reinhardt (2001), crown fuels are defined as foliage and fine 
branchwood (50 percent of the 0 to 6 mm diameter 
branchwood). These crown weight equations can then be used 
to generate total crown fuel weight estimates for each tree in a 
plot given a tree list with information including species, 
diameter at breast height (DBH), crown ratio, and crown class. 
It should be noted that since crown class was not collected for 
all plots used in this study, crown weight could not be adjusted 
for relative position of the tree within the stand. 
In this model, it is assumed that the crown material on each tree 
crown is evenly distributed along a crown’s length. In order to 
generate an aggregate measure of canopy bulk density at the 
plot level, the total fuel weight for all trees within the plot are 
summed at 0.3048 meter increments from the ground to the top 
of the tallest tree. The canopy bulk density is then defined as 
the maximum 4.6 m running mean of crown fuel density within 
the plot. Following Scott and Reinhardt (2001), canopy base 
height is calculated as the lowest height at which the canopy 
fuel density exceeds a critical threshold (0.011 kg/m ). 
Analogously, canopy height is defined as the highest height at 
which the canopy fuel density is greater than 0.011 kg/m’. 
Using this methodology, estimates of canopy fuel weight, 
canopy bulk density, canopy base height, and canopy height 
were generated for each plot within the study area. An example 
of fuel parameter estimates for an inventory plot in the control 
unit is shown in Figure 4. 
    
  
  
  
  
  
  
  
  
  
  
  
   
   
  
  
  
   
    
  
  
  
  
  
  
  
  
   
   
   
  
  
  
  
  
  
  
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