Because of the roughness of the surface of slash, it was necessary to define 

 a depth called the bulk depth. It is an estimated mean that retains the bulk den- 

 sity of the inventoried fuel load and is confined to a cylinder 1 foot (0.30 m) in 

 radius whose central axis is perpendicular to the slope at the sample point. Four 

 estimates are made within the cylinder, each representative of 25 percent of the 

 area (not necessarily a quadrant) . Vertical gaps of more than 1 foot are subtracted 

 before each estimate is completed. Gaps less than 1 foot are assumed to maintain 

 vertical continuity through the potential flame height. The average of the four 

 estimates is recorded as the estimated mean depth. 



Each logged unit was measured in two stages. A grid of approximately 30 sample 

 plots was established for each unit. In the first stage, the load for each of the 

 four size classes was measured at each plot according to Brown (1974). In the 

 second stage, the unit was arbitrarily divided into four sections and a sample plot 

 was chosen at random from each section. At the first sample plot, a 100-foot 

 (30.5 m) transect was selected at random and oriented in one of three directions: 

 (1) 60° counterclockwise to the uphill direction, (2) uphill, and (3) 60° clockwise 

 from the uphill direction. A random selection of the two remaining orientations 

 was made at the second plot. The last remaining orientation was made at the third 

 plot. Orientation on the fourth plot was chosen at random from all three directions 

 as in the first plot. Sample planes 2 feet (0.6 m) across were oriented first along 

 the transect line a.nd then perpendicular to this line with the sample point as the 

 center. The bulk depth was recorded for each sample point (fig. 2). The lOh size 

 class load was measured at both orientations of the sample plane at one-third of 

 the sample points which were selected at random. The range of depths and loads ob- 

 tained from transects are given in figures 3 and 4. 



In stage two, only the lOh intercepts were counted. Data gathered in the first 

 stage provide the information for relating the load in the lOh class to the other 

 two classes (Ih and lOOh) . 



The resulting 2-foot sampling interval established a minimum cell size for the 

 hexagonal array. A smaller size would seriously degrade the accuracy of the load 

 estimate obtained from the planar intersect technique. If larger cells are re- 

 quired, they can be constructed by combining cells. 



Three of the four transects taken on the slash area had similar cumulative 

 depth distributions. The remaining transect was discarded leaving a data base 

 of 150 bulk depths and approximately 50 lOh-fuel load estimates. The unit was 

 generally described as having a light slash load. Consequently, this unit 

 should exhibit correspondingly low rates of spread and intensities. 



8 



