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
Number of pages19
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