Prescribed fire is a common restoration practice in grasslands. Research has focused on fire effects on woody plants and grasses, but less is known about forb responses, despite their importance to pollinators. It has been assumed that flowering increases after prescribed fires, but this has rarely been evaluated experimentally. We measured the effects of single, dormant season prescribed burns on plant density, plant size, and number of flowers for eight native forb species.
In spring 2018, single prescribed burns were conducted at seven low-quality grassland sites in central Texas and southern Oklahoma as part of a larger restoration project. Abundant forb species from the families Asteraceae, Fabaceae, or Rubiaceae were measured in both burned and unburned plots at seven sites in June 2018 and September 2018.
Results/Conclusions
Plants in burned plots were generally shorter but had more flowers per plant. An exception was Chamaecrista fasciculata collected in the fall, which was taller in the burned plot than in the unburned plot. All species except Dalea multiflora and Symphiotrichum ericoides had greater densities in burned plots than in unburned plots. Monarda punctata had greater relative frequency of juvenile plants after burning than the other species, which could be due to increased germination or recruitment.
Overall, plant morphology and density responded similarly to the prescribed fire treatment, though there is some evidence for species-specific responses related to flowering. These results, albeit preliminary, suggest that these forb species responded positively to dormant season prescribed burns.