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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 17 | Copyright
Biogeosciences, 14, 3873-3882, 2017
https://doi.org/10.5194/bg-14-3873-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 31 Aug 2017

Research article | 31 Aug 2017

Fire-regime variability impacts forest carbon dynamics for centuries to millennia

Tara W. Hudiburg1, Philip E. Higuera2, and Jeffrey A. Hicke3 Tara W. Hudiburg et al.
  • 1Department of Forest, Rangeland, and Fire Sciences, University of Idaho, 875 Perimeter Dr., Moscow, ID 83844-1133, USA
  • 2Department of Ecosystem and Conservation Sciences, University of Montana, 32 Campus Dr., Missoula, MT 59812, USA
  • 3Department of Geography, University of Idaho, 875 Perimeter Dr., Moscow, ID 83844-3021, USA

Abstract. Wildfire is a dominant disturbance agent in forest ecosystems, shaping important biogeochemical processes including net carbon (C) balance. Long-term monitoring and chronosequence studies highlight a resilience of biogeochemical properties to large, stand-replacing, high-severity fire events. In contrast, the consequences of repeated fires or temporal variability in a fire regime (e.g., the characteristic timing or severity of fire) are largely unknown, yet theory suggests that such variability could strongly influence forest C trajectories (i.e., future states or directions) for millennia. Here we combine a 4500-year paleoecological record of fire activity with ecosystem modeling to investigate how fire-regime variability impacts soil C and net ecosystem carbon balance. We found that C trajectories in a paleo-informed scenario differed significantly from an equilibrium scenario (with a constant fire return interval), largely due to variability in the timing and severity of past fires. Paleo-informed scenarios contained multi-century periods of positive and negative net ecosystem C balance, with magnitudes significantly larger than observed under the equilibrium scenario. Further, this variability created legacies in soil C trajectories that lasted for millennia. Our results imply that fire-regime variability is a major driver of C trajectories in stand-replacing fire regimes. Predicting carbon balance in these systems, therefore, will depend strongly on the ability of ecosystem models to represent a realistic range of fire-regime variability over the past several centuries to millennia.

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Wildfire is a dominant disturbance agent in forest ecosystems, shaping important processes including net carbon (C) balance. Our results imply that fire-regime variability is a major driver of C trajectories in stand-replacing fire regimes. Predicting carbon balance in these systems, therefore, will depend strongly on the ability of ecosystem models to represent a realistic range of fire-regime variability over the past several centuries to millennia.
Wildfire is a dominant disturbance agent in forest ecosystems, shaping important processes...
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