Fire Lines Volume 15, Issue 6
RESEARCH BRIEF
Effects of fire season on flowering phenology in a pine savanna
Authors: Cinnamon M. Dixon & Kevin M. Robertson
Fire plays a central role in maintaining pine savannas of the southeastern U.S., influencing plant reproduction, persistence, and overall ecosystem health. While lightning historically ignited most fires in the spring and summer, prescribed burning has traditionally been applied in the winter. Dixon and Robertson conducted an experiment at Tall Timbers Research Station in Florida to evaluate how burning in different seasons (winter, spring, summer, and fall) affects flowering phenology, or the timing and pattern of plant flowering. They monitored plots across all four seasonal burn treatments to assess the number of species flowering, the timing of first flowering, and changes in co-flowering communities.
The study recorded 175 species in bloom, with peak flowering occurring in September and October regardless of fire season. Overall flowering patterns were resilient across treatments, with no significant differences in the total number of species flowering or the general composition of flowering communities. However, fires caused short-term reductions in flowering immediately after fire, and some species delayed flowering or failed to flower altogether if burned just before their typical bloom period. Other species flowered both pre- and post-fire, especially following summer burns. These responses indicate that while most species recover quickly, a subset of plants may be more sensitive to the timing of fire.
For fire managers, these findings suggest that the season of prescribed fire has relatively minor long-term impacts on flowering phenology at the community level in the Red Hills region of north Florida. Maintaining frequent fires remains the most important factor for sustaining pine savanna ecosystems. Varying burn seasons can provide flexibility to meet management goals in response to operational constraints, while also catering to the seasonal fire needs of a wider range of plant species. Managers should remain aware of species-specific sensitivities, such as spring-flowering grasses that may miss a year of fire if burned in the winter or spring. Although the study showed modest responses in flowering phenology, it did not study the amount of flowering, seed productivity or viability, or germination success, any of which might be influenced by season of fire and influence population dynamics. However, the results support the use of prescribed fire in any season for most plants to flower in most years.
Research brief prepared by Christian Fernandez, edited by Kevin Robertson & David Godwin.
Dixon, C. M., & Robertson, K. M. (2025). Effects of fire season on flowering phenology in a pine savanna. Fire Ecology, 21(1). https://doi.org/10.1186/s42408-025-00370-7
