Effects of heat and smoke on the germination of six Florida scrub species

Ecological disturbances in ecosystems are often essential for the continued success of many species, acting to increase resource availability and allowing recruitment of new individuals. Fire, a common disturbance, has been shown to influence seed germination in many ecosystems worldwide. The goal of this study was to determine the effects of fire, in the form of heat and smoke, on seed germination of six Florida scrub species (Chrysopsis highlandsensis, Eryngium cuneifolium, Hypericum cumulicola, Lechea cernua, Liatris tenuifolia, and Polygonella polygama). We applied dry heat, wet heat, and aqueous smoke treatments to the target species with control, low, and high levels for each treatment, using a novel approach with individual seeds closely monitored for germination time in microplate wells. Smoke treatments resulted in significantly higher germination percentages for three Florida scrub species, C. highlandsensis, E. cuneifolium, and L. cernua, as well as decreased time to germination for C. highlandsensis, but had no effect on the other three species. Dry heat treatments either had no effect or reduced percent germination in all species, while wet heat treatments resulted in virtually no germination. These results show fire effects in Florida scrub do include smoke-stimulated germination in some species, and most of our study species would not have reduced germination due to heat, especially if located within the insulating sands. Determining how fire influences seed germination will allow for more effective management techniques and higher success in propagating native plants.