Holocene fire dynamics and their climatic controls on the southern Cape coast of South Africa - A 7.2 ka multi-proxy record from the peatland Vankervelsvlei

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Paul Strobel - , Friedrich Schiller University Jena (Author)
  • Theresa Henning - , Friedrich Schiller University Jena (Author)
  • Marcel Bliedtner - , Friedrich Schiller University Jena (Author)
  • Stella G. Mosher - , University of Utah (Author)
  • Humay Rahimova - , University of Bayreuth, Helmholtz Zentrum München - German Research Center for Environmental Health (Author)
  • Torsten Haberzettl - , University of Greifswald (Author)
  • Kelly L. Kirsten - , University of Cape Town (Author)
  • Eva Lehndorff - , University of Bayreuth (Author)
  • Mitchell J. Power - , University of Utah, Natural History Museum of Utah (Author)
  • Michael Zech - , Heisenberg Chair of Physical Geography with a Focus on Paleoenvironmental Research (Author)
  • Roland Zech - , Friedrich Schiller University Jena (Author)

Abstract

Fire is a natural phenomenon along South Africa's southern Cape coast, but identifying its climatic drivers has been a subject of considerable debate. This study investigates the hydroclimatic and fire dynamics from a 9.6 m sediment core from Vankervelsvlei covering the past 7.2 ka. The fen is located near the southern Cape coast within the year-round rainfall zone of South Africa. A reconstruction of hydroclimatic variability through time applies oxygen isotopes from hemicellulose-derived sugars and hydrogen isotopes from leaf wax-derived n-alkanes. Coupling both isotopes enables a reconstruction of the atmospheric source and seasonality of precipitation as well as estimating local relative humidity. Past trends in fire activity are inferred from macro-charcoal and polycyclic aromatic hydrocarbon (PAH) analyses, the latter serving as fire biomarkers. Results indicate high fire activity at Vankervelsvlei accompanied by generally moist conditions and a year-round rainfall regime linked to both Westerly-derived winter precipitation and Easterly- and locally-derived summer precipitation from 7.2+0.2/−0.2 to 4.5+0.3/−0.3 cal ka BP. From 4.5+0.3/−0.3 to 1.5+0.4/−0.2 cal ka BP, a shift to a Westerly-derived winter rainfall regime is identified. This variation features alongside reduced fire activity and persistent drought conditions as Easterly- and locally-derived summer precipitation decreased. From 1.5+0.4/−0.2 cal ka BP until present day, macro-charcoal and PAH accumulation rates show high fire activity. Paleoclimate evidence from the last two millennia suggests a variable climate with an overall increase in total moisture availability as contributions from both Westerly-derived winter precipitation and Easterly- and locally-derived summer precipitation support the year-round rainfall regime present today. Results from Vankervelsvlei support previous evidence from regional paleo-reconstructions, refining our understanding of the interplay between hydroclimatic variability and fire activity along South Africa's southern Cape coast. Our study discusses the role of large-scale climate modes, specifically the intensity of El Niño, as a potential driver of short-term hydroclimatic variability, which in turn drives fuel availability and fire activity at Vankervelsvlei during the Holocene.

Details

Original languageEnglish
Article number108464
JournalQuaternary science reviews
Volume325
Publication statusPublished - 1 Feb 2024
Peer-reviewedYes

External IDs

ORCID /0000-0002-9586-0390/work/170107129

Keywords

Sustainable Development Goals

Keywords

  • Charcoal, Paleoclimate, Paleofire, Polycyclic aromatic hydrocarbons, Precipitation, Relative humidity, Stable isotopes