Fire-stimulated flowering enhances multiple plant fitness components

Fire is a key ecological driver shaping reproductive strategies in fire-prone ecosystems. One distinctive strategy is fire-stimulated flowering, whereby plants flower more profusely under post-fire conditions than in the absence of fire. Despite its widespread occurrence, the reproductive benefits of this strategy remain poorly quantified. We hypothesized that fire-stimulated flowering is an adaptive strategy that enhances plant fitness by increasing success across multiple reproductive stages.

We compared multi-year data on all stages of reproduction, from flowering density to seedling recruitment, in four Mediterranean geophytes (Asphodelus cerasifer, Dipcadi serotinum, Drimia maritima and Narcissus assoanus), between burned and adjacent unburned areas across six natural wildfires.

Plants in burned areas showed higher flowering density, flower production and total seed output, and in some species, this was also associated with increased pollinator visitation and pollen deposition. Seedling recruitment was consistently higher in burned areas.

Our results provide evidence of the adaptive value of fire-stimulated flowering, which allows plants to exploit the unique abiotic and biotic conditions of the immediate post-fire environment, and highlight fire as a key driver of plant life-history evolution in Mediterranean ecosystems.