Post-fire regeneration strategies and flammability traits of California chaparral shrubs

Abstract

Fire behaviour is strongly influenced by fuel load and structure; however, efforts to describe fuel patterns have largely ignored differences among species or post‐fire regeneration strategies. In California chaparral, evergreen shrubs can be grouped into three post‐fire regeneration strategies that correlate with a wide variety of physiological and demographic characteristics including seasonal water status and the timing of reproduction in response to fire. To test if regeneration strategy is also associated with flammability, we compared the fuel loads and structure of two post‐fire seeders, Adenostoma fasciculatum and Ceanothus cuneatus, and two obligate resprouters, Heteromeles arbutifolia and Prunus ilicifolia. Species and post‐fire regeneration strategies did not differ in total fuel per area, or bulk density. The proportion of fuels smaller than 6 mm in diameter differed among species, but not consistently with regeneration strategy. However, species with a post‐fire seeding regeneration strategy had higher proportions of dead branches. We discuss how this difference could have arisen from evolutionary, demographic, or physiological processes.