To define the drying rates, the endpoints of the drying curves were required. 

 Weather data from several locations within each climate class were used to plot sea- 

 sonal 1000-h TL fuel moisture profiles. Then typical plant moistures for each climate 

 class and vegetation type (woody, annual, perennial) were matched with these profiles. 

 Because measurements of seasonal moisture variation in woody and herbaceous plants were 

 not generally available from different parts of the United States, the live fuel model 

 was calibrated to produce reasonable moisture values. Performance objectives are shown 

 in table 2. 



Table 2.--Minimm moisture content for Z-ive fuels 



Type of 

 season 



Grasses and forbs 



Annuals 



Wet 



Normal 

 Dry 



'\^30 

 (Late cure) 

 <30 



(Normal cure) 

 <30 



(Early cure) 



Perennials 



Shrubs, twigs, 

 and foliage 



Peroem 



>80 

 50-80 



<50 



>110 

 80-100 

 50-80 



The highest live fuel moistures were defined to be 250 percent for the herbaceous 

 fuels and 200 percent for the live woody shrubs at a 25 percent 1000-h TL fuel moisture. 

 At the lower end of the moisture scale, herbaceous plants were considered cured at 30 

 percent moisture content and woody plants dead or dormant if their moisture content 

 dropped to 50 percent. The minimum woody and herbaceous moistures were matched with 

 typical minimum 1000-h TL moistures and XIOOO values, respectively, for each climate 

 class. The slopes and intercepts of the drying curves for each climate class are pro- 

 vided in table 3. 



The live fuel moisture algorithm gives the fuel models a dynamic character by 

 simulating the curing of the herbaceous fuels. This is accomplished by transferring 

 fuel load from the live herbaceous class to the 1-h TL class as herbaceous fuel moisture 

 drops below 120 percent during the growing season. 



Table --Slopes and interoepts for the drying rates of the live fuel models 



Climate 

 Class 



: Woody 



Fue 1 s : 







Herbaceous 



Fuels 







Annuals and 



Perennials : 





Annuals 





Perennials 



Green 



Stage : 



Transition Stage 



: Transition Stage 



: Slope : 



Intercept : 



Slope : 



Intercept : 



Slope 





Intercept 



: Slope 



: Intercept 



1 



7.S 



12.5 



12.8 



-70.0 



18.4 





-150.5 



7.4 



11.2 



2 



8.2 



-5.0 



14.0 



-100.0 



19.6 





-187.7 



8.3 



-10.3 



3 



8.9 



-22.5 



15.5 



-137.5 



22.0 





-245.2 



9.8 



-42.7 



4 



9.8 



-45.0 



17.4 



-185.0 



24.3 





-305.2 



12.2 



-93.5 



6 



