Bark-beetle-attacked trees produced more charcoal than unattacked trees during a forest fire on the Kenai Peninsula, Southern Alaska

Abstract

Alaskan boreal forests frequently suffer from outbreaks of bark beetles and fires, factors that appear to combine to alter charcoal production. Charcoal (black carbon) production in forest ecosystems is an important pathway to clarify for a more complete understanding of the effects of fire on carbon cycling in boreal forests. In this study, we aimed to clarify the effects of prevalent outbreaks of the spruce beetle, Dendroctonus rufipennis (Kirby), on charcoal production during forest fires in boreal forests. Snags with prefire damage by the spruce beetle (infested snags) have significantly more charcoal than those undamaged before fire (noninfested snags). This increased amount of charcoal in spruce beetle-damaged trees was probably the result of dried biomass in the canopies of these trees. The results of this study suggest that with changing environmental conditions, the proliferation of insect damage in the boreal forest can modify the effects of fire on carbon sink via a change in the amount of charcoal production.

Keywords:

• Climate change
• charcoal
• disturbances interaction
• forest fire
• spruce beetle

Acknowledgements

B. Oskolkoff (Ninilchik Natives Associations, Inc.) and D. Buesseler, landowners of our research site, kindly allow us to conduct our research in their personal property. We express our sincere thanks to them. We deeply acknowledge Prof. L. Hinzman, Dr K. Nakau, and Prof. M. Fukuda for their information and support during the investigation in Alaska. We deeply thank Dr Y. Matsuura for his invaluable advice during the project. We also greatly thank the member of Silviculture and Forest Ecological Studies of Hokkaido University for their kind support for the sample processing. This study was funded by the JAXA-IARC Information System (2007–2010) and JSPS doctoral fellowship to Makoto, K. (No. 192105).