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Simulated post-fire temperature affects germination of native and invasive grasses in cerrado (Brazilian savanna)

2014; Taylor & Francis; Volume: 8; Issue: 2 Linguagem: Inglês

10.1080/17550874.2014.910714

1755-1668

Carolina Musso, Heloísa S. Miranda, Stefano Salvo Aires, Ana Catarina Bastos, Amadeu M.V.M. Soares, Susana Loureiro,

Seed Germination and Physiology

AbstractBackground: Although fire is an important factor in determining cerrado vegetation, information about its effect on seed banks is sparse. Cerrado fires are rapidly moving surface fires with low residence time, producing only short-term heating of the uppermost centimetres of the soil. However, the reduction in vegetation cover and deposition of ashes increases the daily amplitude of soil temperature by as much as 35 °C.Aims: To assess the effect of post-fire daily soil temperatures on the germination of one alien and nine native grasses.Methods: Seeds were stored at alternating temperatures of 45 ºC/10 ºC (10 h/14 h) for 7 d or 30 d, simulating two different storage times in the soil seed bank before the onset of the rainy season. Germination was monitored over 30 d.Results: The variation in temperature had a significant effect on the rate of seed germination in some species, either enhancing it (Aristida setifolia) or reducing it (Schizachyrium sanguineum). Increased storage time reduced the viability of S. sanguineum and Echinolaena inflexa. The invasive Melinis minutiflora had the highest germination rate and it also showed the best toleration of post-fire conditions (45 ºC/10 ºC) after 7 d, with significant reduction in the germination time after 30 d.Conclusions: Fire seems to have a significant effect in the early life of cerrado grasses. Some native species responded positively to temperature oscillation, suggesting that they should be better prepared to compete with alien species after a fire, with more of their seeds germinating and/or at a more rapid rate.Keywords: alien grassburnmean time of germinationseed germinationseed viabilitysoil seed banksoil temperature AcknowledgementsWe wish to acknowledge the provision by the Fundação para Ciência e Tecnologia (FCT) of a doctoral grant to Carolina Musso (SFRH/BD/64938/2009) and by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/Brasil) for the Project grant (A058/2013) to Amadeu M.V.M. Soares. This work was supported by European Funds through COMPETE and by National Funds through the Portuguese Science Foundation (FCT) within project PEst-C/MAR/LA0017/2013.We are also grateful to the staff of the IBGE for their authorisation to collect seeds for the project.We thank particularly Carlos Romero Martins, Ricardo Carmona, Adalberto Café Filho and the technicians of the Department of Agronomy, Phytopathology and Ecology of the Universidade de Brasília for their collaboration and technical support, Raimundo P.B. Henriques for a number of useful discussions, and Marcela Manara for laboratory and field assistance.