Long-Term Fire History from Alluvial Fan Sediments: The Role of Drought and Climate Variability, and Implications for Management of Rocky Mountain Forests

Jennifer Pierce, Grant Meyer

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Alluvial fan deposits are widespread and preserve millennial-length records of fire. We used these records to examine changes in fire regimes over the last 2000 years in Yellowstone National Park mixed-conifer forests and drier central Idaho ponderosa pine forests. In Idaho, frequent, small, fire-related erosional events occurred within the Little Ice Age (∼1450?1800 AD), when greater effective moisture probably promoted grass growth and low-severity fires. This regime is consistent with tree-ring records showing generally wetter conditions and frequent fires before European settlement. At higher elevations in Yellowstone, cool conditions limited overall fire activity. Conversely, both Idaho and Yellowstone experienced a peak in fire-related debris flows between ∼950 and 1150 AD. During this generally warmer time, severe multidecadal droughts were interspersed with unusually wet intervals that probably increased forest densities, producing stand-replacing fires. Thus, severe fires are clearly within the natural range of variability in Idaho ponderosa pine forests over longer timescales. Historical records indicate that large burn areas in Idaho correspond with drought intervals within the past 100 years and that burn area has increased markedly since ∼1985. Recent stand-replacing fires in ponderosa pine forests are likely related to both changes in management and increasing temperatures and drought severity during the 20th century.

Original languageAmerican English
Pages (from-to)84-95
Number of pages12
JournalInternational Journal of Wildland Fire
Volume17
Issue number1
DOIs
StatePublished - 2008

Keywords

  • Debris flows
  • Idaho
  • Ponderosa pine
  • Yellowstone

EGS Disciplines

  • Earth Sciences
  • Geophysics and Seismology

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