Post!burn reproduction of woody plants in a neotropical savanna] the relative importance of sexual and vegetative reproduction

0[ Burning typically occurs at intervals of 0Ð2!years in the Brazilian cerrado\ a rate that exceeds the precolonization _re regime[ To determine if woody plants of the cerrado successfully reproduce within the short span of time between burns\ exper! imental burns were used to quantify the e}ects of _re on sexual and vegetative reproduction of six species of resprouting trees and shrubs[ 1[ Four of the six species reproduce vegetatively by producing root suckers[ For three of these species\ Rourea induta\ Myrsine guianensis and Roupala montana\ sucker production was seven to 04 times greater in burned plots than in unburned controls[ 2[ Fire had a negative impact on sexual reproduction[ Fire caused an immediate reduction in sexual reproductive success by destroying developing reproductive struc! tures and seeds[ Additionally\ _ve of the six study species exhibited overall reductions in seed production in the years following _re[ Fire had this e}ect by reducing the individual size of all species and\ for three species\ by reducing size!speci_c repro! ductive output[ Only the tree Piptocarpha rotundifolia exhibited increased seed pro! duction following burning[ 3[ Fire caused substantial mortality to both seedlings and suckers[ Suckers were larger than seedlings and experienced lower mortality rates for two of three species[ Fire! induced mortality of seedlings varied greatly among species\ ranging from 22) to 099)[ 4[ The results indicate that vegetative reproduction is much more successful than sexual reproduction under the high _re frequency typical of current _re regimes[ It is concluded that current _re regimes must be causing a shift in species composition\ favouring species capable of vegetative reproduction[