Comparative fire ecology of tropical savanna and forest trees

Authors

  • William A. Hoffmann,

    Corresponding author
    1. Departamento de Engenharia Florestal, Universidade de Brasília, Caixa Postal 04357, Brasília, DF 70919–970;
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  • Birgit Orthen,

    1. Departamento de Botânica, Universidade de Brasília, Caixa Postal 04457, Brasília DF 70919–970
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    • §

      Present address: Institut für Ökologie der Pflanzen, Westfälische Wilhelms-Universität, Hindenburgplatz 55, 48143 Münster, Germany.

  • Paula Kielse Vargas do Nascimento

    1. Departamento de Engenharia Florestal, Universidade de Brasília, Caixa Postal 04357, Brasília, DF 70919–970;
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‡Author to whom correspondence should be addressed: W.A. Hoffman, Department of Botany, Campus Box 7612, North Carolina State University, Raleigh, NC 27695-7612, USA. E-mail: hoffmann@unb.br

Summary

  • 1Fire is important in the dynamics of savanna–forest boundaries, often maintaining a balance between forest advance and retreat.
  • 2We performed a comparative ecological study to understand how savanna and forest species differ in traits related to fire tolerance. We compared bark thickness, root and stem carbohydrates, and height of reproductive individuals within 10 congeneric pairs, each containing one savanna and one forest species.
  • 3Bark thickness of savanna species averaged nearly three times that of forest species, thereby reducing the risk of stem death during fire. The allometric relationship between bark thickness and stem diameter differed between these two tree types, with forest species tending to have a larger allometric coefficient.
  • 4The height of reproductive individuals of forest species averaged twice that of congeneric savanna species. This should increase the time necessary for forest species to reach reproductive size, thereby reducing their capacity to reach maturity in the time between consecutive fires.
  • 5There was no difference in total non-structural carbohydrate content of stems or roots between savanna and forest species, though greater allocation to total root biomass by savanna species probably confers greater capacity to resprout following fire.
  • 6These differences in fire-related traits may largely explain the greater capacity of savanna species to persist in the savanna environment.

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