CHAMISE 



Chamise has been studied more extensively 

 than most other wildland fuels. Because of its 

 growth habit, physical makeup, moisture rela- 

 tions, and chemical characteristics, chamise is 

 an extremely hazardous fuel — probably the 

 most serious single fuel problem in California 

 brushlands. 



This species makes up about 50 percent of 

 the chaparral fuel type in California and up to 

 70 percent in southern Cahfornia (Leonard 

 and Carlson 1957). Chamise often occurs in 

 pure stands and deteriorates rapidly upon ma- 

 turity and during periods of drought, losing 

 its leaves and dying back. About one-third of 

 mature chamise stands are dead material. 



The needlelike leaves of chamise are ar- 

 ranged in groups of 10-15 per node on very 

 small stems (fig. 3) and their surface area-to- 

 volume ratio ( a ) is 184 in. ^ /in. ^ High values 

 of a imply rapid preheating and ignition and 



Figure 3. — Chamise stem with leaves. 



high burning rates. The leaves make up 67 

 percent of the total plant surface area but 

 only 16 percent of the volume and 10 percent 

 of the weight.^ The form of the plant is gen- 

 erally conducive to rapid burning because 

 several stems arise from the soil surface and 

 branch into many smaller stems that support 

 the leaves. All of this relatively small fuel 

 becomes available for combustion under 

 moderate burning conditions. 



The seasonal moisture trends of this spe- 

 cies were determined by Olsen (1960). He 

 found the moisture content of the foliage to 

 be highest during active growth and lowest 

 during late September and fall months. This 

 trend generally coincides with fire season 

 severity (Buck 1951). The moisture content 

 of all aerial parts of this plant falls as low as 

 60 percent dry weight in September (Dell and 

 Philpot 1965). 



The chemical characteristics of chamise 

 have not been studied to any great extent. Its 

 approximate heat content is known, but not 

 how this changes with time and location. The 

 extractive content of the leaves is quite high, 

 and by our own measurements has reached 13 

 percent dry weight. The seasonal changes in 

 inorganic constituents, which may indicate 

 changes in flammability, are currently being 

 investigated at the Northern Forest Fke 

 Laboratory. 



^Countryman, C. M., and C. W. Philpot. The physical 

 characteristics of chamise as a wildland fuel. Pacific 

 Southwest Forest and Range Exp. Station. (In prep- 

 aration.) 



METHODS OF ANALYSIS 



The chamise samples were obtained from 

 the 4,500-ft. level, southwest exposure, on 

 the North Mountain Experimental Area in 

 southern California.^ Two sets of data are in- 



^ Cooperatively managed by the Riverside Fire Labo- 

 ratory of the USDA Forest Service and the California 

 Division of Forestry. 



eluded in this paper: the 1963 samples repre- 

 senting three dates and the much more com- 

 plete 1966-67 samples representing eight 

 dates. The leaves and stems (V4 inch or less) 

 were clipped from each of three randomly 

 picked plants in the same six subplots at each 

 sample date during 1966-67 and were imme- 



4 



