Plant Ecology

, Volume 212, Issue 12, pp 2057–2069 | Cite as

Bark thickness determines fire resistance of selected tree species from fire-prone tropical savanna in north Australia

  • Michael J. LawesEmail author
  • Anna Richards
  • Josefine Dathe
  • Jeremy J. Midgley


We investigated the fire resistance conferred by bark of seven common tree species in north Australian tropical savannas. We estimated bark thermal conductance and examined the relative importance of bark thickness, density and moisture content for protecting the cambium from lethal fire temperatures. Eucalypt and non-eucalypt species were contrasted, including the fire-sensitive conifer Callitris intratropica. Cambial temperature responses to bark surface heating were measured using a modified wick-fire technique, which simulated a heat pulse comparable to surface fires of moderate intensity. Bark thickness was a better predictor of resistance to cambial injury from fires than either bark moisture or density, accounting for 68% of the deviance in maximum temperature of the cambium. The duration of heating required to kill the cambium of a tree (τc) was directly proportional to bark thickness squared. Although species did not differ significantly in their bark thermal conductance (k), the thinner barked eucalypts nevertheless achieved similar or only slightly lower levels of fire resistance than much thicker barked non-eucalypts. Bark thickness alone cannot account for the latter and we suggest that lower bark moisture content among the eucalypts also contributes to their apparent fire resistance. Unique eucalypt meristem anatomy and epicormic structures, combined with their bark traits, probably facilitate resprouting after fire and ensure the dominance of eucalypts in fire-prone savannas. This study emphasises the need to take into account both the thermal properties of bark and the mechanism of bud protection in characterising the resprouting ability of savanna trees.


Cambium Bark thermal conductance Bark density Resprouting Topkill 



We are grateful to Lindsay Hutley for assistance with setting up data-loggers and thermocouples, and to Florence Durillon for trialling the thermocouples in the field. CSIRO Tropical Ecosystems Research Centre is acknowledged for allowing us to conduct experiments on their property. JD was supported by a travel scholarship from the CLAAS Foundation during this study.

Supplementary material

11258_2011_9954_MOESM1_ESM.doc (82 kb)
Supplementary material 1 (DOC 82 kb)


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Michael J. Lawes
    • 1
    Email author
  • Anna Richards
    • 2
  • Josefine Dathe
    • 3
  • Jeremy J. Midgley
    • 4
  1. 1.Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinAustralia
  2. 2.CSIRO Ecosystem Sciences, PMB 44WinnellieAustralia
  3. 3.University of Applied ScienceEberswaldeGermany
  4. 4.Botany DepartmentUniversity of Cape TownCape TownSouth Africa

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