Photos from the Field: Does Fire Trigger Seed Germination in the Neotropical Savannas?

Santos Fichino et al., (2016). Does Fire Trigger Seed Germination in the Neotropical Savannas? Experimental Tests with Six Cerrado Species. Biotropica, 48: 181–187. doi: 10.1111/btp.12276

The Cerrado (Brazilian savanna) is a biodiversity hotspot with a history of fire that goes back as far as 10 million years. Fire has influenced the evolution of several aspects of the vegetation, including reproduction and life cycles. This study tested how fire by-products such as heat and smoke affect the germination of six species common to two Cerrado open physiognomies: wet grasslands and the campo sujo (grassland with scattered shrubs and dwarf trees). We subjected seeds collected in northern Brazil to heat shock and smoke treatments, both separately and combined, using different temperatures, exposure times, and smoke concentrations in aqueous solutions. High temperatures and smoke did not break seed dormancy nor stimulate germination of the Cerrado study species. However, seeds were not killed by high temperatures, indicating that they are fire-tolerant. Our findings differed from those of other fire-prone ecosystems (mostly of Mediterranean vegetation), where fire stimulates germination. Moreover, we provide important information regarding germination strategies of non-woody Cerrado plants, showing the importance of considering the tolerance of seeds to high temperatures when evaluating fire-related traits in fire-prone ecosystems.

Figure 1. Wet grassland vegetation with a mixture of Poaceae, Xyridaceae, Cyperaceae and Eriocaulaceae, Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)

Figure 1. Wet grassland vegetation with a mixture of Poaceae, Xyridaceae, Cyperaceae and Eriocaulaceae, Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)

Figure 2. Fire experiments conducted in wet grasslands to evaluate how fire affects vegetation composition, structure and dynamics. Local people usually burn the wet grasslands every two years in order to stimulate the production of flowering stalks of Syngonanthus nitens (“capim dourado “ - golden grass/ Eriocaulaceae), which is used in handcraft. (Photo: Alessandra Fidelis)

Figure 2. Fire experiments conducted in wet grasslands to evaluate how fire affects vegetation composition, structure and dynamics. Local people usually burn the wet grasslands every two years in order to stimulate the production of flowering stalks of Syngonanthus nitens (“capim dourado “ – golden grass/ Eriocaulaceae), which is used in handcraft. (Photo: Alessandra Fidelis)

Figure 3. Veredas are like isolated islands within the campo sujo. (Photo: Alessandra Fidelis)

Figure 3. Veredas are like isolated islands within the campo sujo. (Photo: Alessandra Fidelis)

Figure 4. Transition from the wet grasslands to the campo sujo, in Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)

Figure 4. Transition from the wet grasslands to the campo sujo, in Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)

Figure 5. Abolboda poarchon (Eriocaulaceae) - one of the study species in Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)

Figure 5. Abolboda poarchon (Eriocaulaceae) – one of the study species in Jalapão, Northern Brazil. (Photo: Alessandra Fidelis)