Post-fire demography of resprout and seedling establishment by Adenostoma fasciculatum in the California chaparral

Abstract

Adenostoma fasciculatum (chamise) forms the dominant element of chaparral ecosystems in California. This evergreen, ericoid-leaved shrub occurs as a codominant in mixed chaparral or an overwhelming dominant in chamise chaparral, being present in over 70% of the chaparral stands in the state (Hanes 1971). No other chaparral shrub approaches A. fasciculatum in community importance. Unlike the majority of chaparral shrubs which respond to fire by either resprouting or reseeding, A. fasciculatum , utilizes both reproductive strategies (Wells 1969; Keeley and Zedler 1978; see also Hilbert in this volume). Although there have been numerous studies of succession in chamise chaparral (Horton and Kraebel 1955; Hanes 1971), no research to date has focused on the important questions of the demography of resprouting and seedling establishment by A. fasciculatum in the first few years following chaparral fires. Is there significant mortality of chamise burls during fires? How do fire seasonality and intensity affect resprout survival and growth? How do chamise seedlings compete with resprouts for establishment in postfire stands? What factors limit chamise seedling survival and growth? These are all important questions. In this paper we present results of a three-year study of the demographics of resprout mortality and growth and of seedling establishment for A. fasciculatum following burn and clip treatments at two seasons of the year in mature stands of chamise chaparral in the southern Sierra Nevada, California.