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

Author(s): Tara W. Hudiberg, Philip E. Higuera, Jeffrey A. Hicke
Year Published: 2017
Description:

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.

Citation: Hudiburg, Tara W.; Higuera, Philip E.; Hicke, Jeffrey A. 2017. Fire-regime variability impacts forest carbon dynamics for centuries to millennia. Biogeosciences 14(17):3873-3882.
Topic(s): Fire History, Frequency
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 15548
FRAMES RCS number: 24779
Record updated: Oct 9, 2017