Biomass and fuel characteristics of chaparral in southern California

Abstract

Knowledge of biomass components and fuel characteristics of southern California chaparral plant communities is important for planning prescribed fires, suppressing wildfires, managing the fire regime, and understanding the ecological interactions between fire and chaparral community development and succession. To improve our understanding of the relationship between fuels and fire behavior in chaparral, biomass and fuels were sampled on sites spanning a broad geographic range, as well as a range in age, species composition, and productivity. Total aboveground biomass of chaparral stands greater than 15 years old can range from 10 to 40 Mg/ha (1 Mg/ha= 1000 kg/ha) for Adenostomafasciculatum, with canopy heights of 1.5 to 2.5 m, to as much as 120 Mg/ha for several Ceanothus species with canopy height as high as 5.5 to 6 m. Within a stand, coefficients of variation of biomass among plots are commonly 25 to 30 percent, and community structure can vary dramatically in relation to topographic and edaphic gradients over short distances of 5 to 10 m. Foliage accounts for 3 to 25 percent of total biomass in A. fasciculatum and Ceanothus-dominated stands. The fraction of stand biomass that is considered to be fuel available for fire propagation, which includes foliage, live twigs less than 6 mm in diameter, and dead woody material, ranges from approximately 30 percent to 75 percent in mature chaparral stands. This available fuel fraction is probably related to climatic factors such as prolonged drought periods, as well as species composition, species morphology, and site productivity. Our ongoing work is focused on improving efficiency of biomass and fuels sampling, and relating biomass development through time to site and climatic factors.

Citation

Regelbrugge, J.C.; Conard, S.G. 2002. Biomass and fuel characteristics of chaparral in southern California. Association for Fire Ecology Miscellaneous Publication No. 1: 308-317.