The effect of fire history on reproductive phenology and seed and germination traits of Cerrado species

Author(s)

Heloiza Lourenço Zirondi

• Document type: Master's Dissertation
• Press: Rio Claro. 2019-07-03.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2019-06-26
• Advisor: Alessandra Fidelis; Mark Ooi

Abstract

In Cerrado one of the abiotic factors that influences plant phenology is fire, which is a natural disturbance that interferes with several ecosystems in the world. Fire changes the conditions of the habitat and can affect flowering, fruiting and seeds and germination traits. Therefore, this project aimed to understand the effect of fire on reproductive phenology and on seed and germination traits of Cerrado community. For this purpose, the counting of the number of branches (vegetative and reproductive) by species was carried out in 30 subplots of 1x1m in areas with different fire histories (C = 6 years without burning and FB = recently burned). We also marked individuals of different dominant species in both areas. The community and individuals had their flowering counted every 15 days for 3 months after burning and then at 6, 9 and 12 months. The following seed and germination traits were measured: seed shape and mass/weight, water content, germinability, mean germination time and synchrony. Our results showed that fire increased flowering in burned areas. Already after 30 days up to 3 months after the burning there were up to 2-fold more species flowering in the FB areas compared to C. There was also a significant increase in the proportion of reproductive shoots at 3 months post-fire in the community, showing that the reproductive profusion occurs in the first few months after burning. Among the species of the community 66.39% can be considered stimulated by fire. Seed and germination traits were affected by fire frequency. Results showed that 67% of the species presented at least one of their germination altered in FB area when compared to area C. In general, some species showed an increase and others a decrease in germination in FB. However, viability was lower and germination faster in seeds of FB areas. Seed traits (mass/weight, shape and water content) of eight species also differed between areas. Among these species, the majority presented smaller seeds with higher water content in burned areas compared to C. Therefore, fire not only alters the reproductive phenology, mainly stimulating flowering and fruiting of many species but also fire frequency can lead to rapid changes in germination and seed traits. This provides some insight on the evolution of Cerrado plant traits facing fire. (AU)

• FAPESP's process: 17/16149-4 - The effect of fire on phenology, seed and germination traits of cerrado species
• Grantee: Heloiza Lourenço Zirondi
• Support Opportunities: Scholarships in Brazil - Master