Fire effects on germination response of the native species Daucus carota and the invasive alien species Helichrysum foetidum and Oenothera glazioviana

Abstract

Fire is an ecological factor that affects ecosystem structure and functioning and determines later recovery of the ecosystem through the modification of biological processes, such as seed germination and seedling establishment. Another factor that modifies ecosystems is the presence of invasive alien species, which easily colonize new habitats after disturbances such as forest fires. Within this research, we analysed the germination response to fire of three species that share a habitat, one native species (Daucus carota L.) and two invasive alien species (Helichrysum foetidum (L.) Moench and Oenothera glazioviana Micheli) to identify and compare the effects of fire on the germination of these three species. For this purpose, germination tests were performed by using seeds treated with heat, smoke, charcoal and ash, simulating conditions of forest fires.

The three species showed slightly different responses to fire factors. At high levels, heat and ash prevented the germination of the three species. In contrast, intermediate heat shocks and some smoke treatments stimulated O. glazioviana germination, while the other species remained unaffected. H. foetidum presented high germination success for most treatments. The difference in the germination response of the three species can change the current balance among three species in natural fire-prone ecosystems, contributing to the spread of O. glazioviana and H. foetidum to new areas and potentially reducing native D. carota populations.