Holocene development of Boreal forests and fire regimes on the Kenai Lowlands of Alaska

R. S. Anderson, D. J. Hallett, E. Berg, R. B. Jass, J. L. Toney, C. S. De Fontaine, A. DeVolder

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Several studies have noted a relationship between vegetation type and fire frequency, yet despite the importance of ecosystem processes such as fire the long-term relationships between disturbance, climate and vegetation type are incompletely understood. We analysed pollen, plant macrofossils and sedimentary charcoal from three lakes within the Kenai lowlands to determine postglacial relationships between disturbance, climate and vegetation for the Boreal forest of southwest Alaska. An herb tundra was established in the lowlands following deglaciation by 13000 cal. BP. Salix, Alnus and probably Betula kenaica, expanded in the area after 10 700 cal. BP, followed by Picea glauca by 8500 cal. BP. Picea mariana became established by 4600 cal. BP. The early Holocene was probably the driest time during the postglacial, as determined by aquatic plant macrofossils and climate models. Lake levels reached near-modern conditions by at least 8000 cal. BP. Mean Fire Intervals (MFI) were longest during the shrub-herb tundra phase (138 ± 65 yr), decreased after expansion of B. kenaica, Salix and Populus (77 ± 49 yr) and Picea glauca (81 ± 41 yr), and increased again with the arrival of P. mariana (130 ± 66 yr). Unlike previous studies, our data demonstrate the highest fire frequencies during the early to mid-Holocene and less frequent fire during the late Holocene when P. mariana forests dominated the lowlands. Early Holocene forests of P. glauca and B. kenaica existed in summers that were longer and drier than today, while the increasingly wetter and cooler climates of the late Holocene probably hindered forest fire around Paradox Lake, perhaps because of less frequent summer drought.

Original languageEnglish (US)
Pages (from-to)790-803
Number of pages14
JournalHolocene
Volume16
Issue number6
DOIs
StatePublished - Sep 1 2006

Keywords

  • Alaska
  • Boreal forest
  • Charcoal analysis
  • Climate change
  • Fire history
  • Holocene
  • Vegetation history

ASJC Scopus subject areas

  • Global and Planetary Change
  • Archaeology
  • Ecology
  • Earth-Surface Processes
  • Palaeontology

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    Anderson, R. S., Hallett, D. J., Berg, E., Jass, R. B., Toney, J. L., De Fontaine, C. S., & DeVolder, A. (2006). Holocene development of Boreal forests and fire regimes on the Kenai Lowlands of Alaska. Holocene, 16(6), 790-803. https://doi.org/10.1191/0959683606hol966rp