Fire-triggered flowering is the dominant post-fire strategy in a tropical savanna

Author(s)

Zirondi, Heloiza L. ^[1] ; Ooi, Mark K. J. ^{[2, 3]} ; Fidelis, Alessandra ^[1]

Affiliation

^[1] Univ Estadual Paulista UNESP, Inst Biociencias, Lab Vegetat Ecol, Av 24-A 1515, BR-13506900 Rio Claro - Brazil

^[2] Univ New South Wales UNSW, Sch Biol Earth & Environm Sci, Ctr Ecosyst Sci, Sydney, NSW - Australia

^[3] New South Wales Bushfire Risk Management Res Hub, Sydney, NSW - Australia

• Document type: Journal article
• Source: JOURNAL OF VEGETATION SCIENCE; v. 32, n. 2 MAR 2021.
• Web of Science Citations: 2

Abstract

Questions In fire-prone ecosystems, fire can enhance the flowering and fruiting of many species, a strategy assumed to be well represented in savanna. Despite this, there are surprisingly few studies assessing how prevalent fire-stimulated flowering is. Thus, we asked: (a) are there differences in the reproductive phenology of Cerrado plants between recently burned and unburned areas; (b) how does fire affect the speed of flowering and how does this differ between growth forms; and (c) what are the post-fire flowering (PFF) strategies of Cerrado species and is there evidence for high proportions of obligate PFF? Location Open savannas (campo sujo in the Cerrado) in Central Brazil (Reserva Natural Serra do Tombador - RNST, 13 degrees 35-13 degrees 38' S and 47 degrees 45'-47 degrees 51' W). Methods We established six plots, three recently and frequently burned (FB) and three excluded from fire for six years (E). In all treatments, the number of species flowering and fruiting was counted every 15 days for three months, and then at six, nine and 12 months after fire. We also counted the number of reproductive and vegetative shoots in 10 subplots (1 m x 1 m) per plot. Results Approximately 66% of species studied were fire-stimulated, with half of these only flowering after fire (obligate PFF). Fire-enhanced flowering was rapid, with the clearest differences between burned and unburned plots seen in the first 30 days, and up to three months after fire, where there were up to two times more species flowering in the FB than E areas. Conclusions The extremely high proportion of PFF species, at least five times that reported for heathlands and other shrub communities, highlights the role that short-interval fire regimes have in savanna ecosystems, selecting for resprouting life forms and PFF dominance, particularly in herbaceous species. Rapid post-fire reproduction may be a strategy to disperse large quantities of seed into an environment with a small recruitment window. (AU)

• FAPESP's process: 15/06743-0 - How does fire season affect Cerrado vegetation?
• Grantee: Alessandra Tomaselli Fidelis
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 18/08017-3 - Seed traits in fire-prone ecossystems
• Grantee: Heloiza Lourenço Zirondi
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• 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