Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 1
Biogeosciences, 15, 233-243, 2018
https://doi.org/10.5194/bg-15-233-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 233-243, 2018
https://doi.org/10.5194/bg-15-233-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 11 Jan 2018

Research article | 11 Jan 2018

Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

Anna T. Trugman1,2, David Medvigy3, William A. Hoffmann4, and Adam F. A. Pellegrini5 Anna T. Trugman et al.
  • 1Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08544, USA
  • 2Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
  • 3Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
  • 4Department of Plant Biology, North Carolina State University, Raleigh, NC 27695, USA
  • 5Department of Earth System Science, Stanford University, Stanford, CA 94305, USA

Abstract. Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2) with (i) a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests), and (ii) plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

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Tree fire tolerance strategies may significantly impact woody carbon stability and the existence of tropical savannas under global climate change. We used a numerical ecosystem model to test the impacts of fire survival strategy under differing fire and rainfall regimes. We found that the high survival rate of large fire-tolerant trees reduced carbon losses with increasing fire frequency, and reduced the range of conditions leading to either complete tree loss or complete grass loss.
Tree fire tolerance strategies may significantly impact woody carbon stability and the existence...
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