Fire-driven shifts in growth and reproduction strategies of Setaria parviflora in wetland ecosystems.

Climate change and land use are intensifying wildfires in the Brazilian Pantanal, altering the dynamics of natural grasslands. Grasslands subjected to burning can experience turnover in species composition depending on fire intensity and frequency. Understanding species persistence and regeneration strategies is essential for predicting when and where fire-induced changes in plant communities may occur. Our objective was to evaluate how fire affects the seedling stage and influences survival and development, and reproductive traits. We exposed seedlings of the grass Setaria parviflora to fire and then assessed seedling performance ( e.g. , survival rate, regrowth speed) and adult plant characteristics ( e.g ., reproduction speed, seed number per spikelet) of the surviving plants compared to those of a control group without fire exposure. We also evaluated attributes related to survival, such as culm length, leaves, architecture (tillers), and roots. The survival rate was high (77%), with regrowth speed increasing after the third day post-fire. Plants that regrew after the fire had longer roots and more tillers (± 3) compared to the control group, showing significant differences. In contrast, the control group had longer culms. Regrowth attributes reflect the primary strategy for species maintenance, and despite the faster reproduction, seed production was low. Our findings suggest that fire during the seedling stage reduces the number of seeds produced, even though it enhances reproduction speed, modifies plant architecture, and increases regeneration potential through rhizomes.