2500 



Figure 1. — This example for Libby, Montana, 1973, illustrates the fireline intensity 

 for fuel model C with perennial grass (live/dead ratio 0.5). Intensity decreased 

 markedly during the green-up period in the first three weeks of June, then increased 

 again as the live herbaceous fuel moisture decreased during the summer. 



Herbaceous Fuels 



Living herbaceous fuels were assumed to have a constant moisture content in the 

 1972 NFDRS; however, the proportion of living herbaceous fuel varied. Range forage 

 transects were used to estimate percentage of the fine fuels by volume that consisted 

 of live herbaceous material. There were several disadvantages with this subjective 

 procedure: 



1. Transect location was critical. Microtopography produced significant 

 differences in conditions between transects in close proximity. 



2. Percent-green estimates made by different observers on a single transect were 

 not consistent. 



Important changes in the condition of herbaceous fuels were not necessarily 

 observed or reported at appropriate times. 



2 



