Resilience of lake biogeochemistry to boreal-forest wildfires during the late Holocene

Melissa L. Chipman, Feng Sheng Hu

Research output: Contribution to journalArticle

Abstract

Novel fire regimes are expected in many boreal regions, and it is unclear how biogeochemical cycles will respond. We leverage fire and vegetation records from a highly flammable ecoregion in Alaska and present new lake-sediment analyses to examine biogeochemical responses to fire over the past 5300 years. No significant difference exists in δ13C, %C, %N, C: N, or magnetic susceptibility between pre-fire, post-fire, and fire samples. However, δ15N is related to the timing relative to fire (χ2 = 19.73, p < 0.0001), with higher values for fire-decade samples (3.2 ± 0.3) than pre-fire (2.4 ± 0.2) and post-fire (2.2 ± 0.1) samples. Sediment δ15N increased gradually from 1.8 ± 0.6 to 3.2 ± 0.2 over the late Holocene, probably as a result of terrestrial-ecosystem development. Elevated δ15N in fire decades likely reflects enhanced terrestrial nitrification and/or deeper permafrost thaw depths immediately following fire. Similar δ15N values before and after fire decades suggest that N cycling in this lowland-boreal watershed was resilient to fire disturbance. However, this resilience may diminish as boreal ecosystems approach climate-driven thresholds of vegetation structure, permafrost thaw and fire.

Original languageEnglish (US)
Article number20190390
JournalBiology letters
Volume15
Issue number8
DOIs
StatePublished - Aug 1 2019

Keywords

  • Boreal fires
  • C: N
  • Carbon
  • Ecological resilience
  • Nitrogen
  • δC
  • δN

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Agricultural and Biological Sciences(all)

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