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Anders Ahlström

Anders Ahlström

Senior lecturer

Anders Ahlström

The resilience of Amazon tree cover to past and present drying

Author

  • Tyler Kukla
  • Anders Ahlström
  • S. Yoshi Maezumi
  • Manuel Chevalier
  • Zhengyao Lu
  • Matthew J. Winnick
  • C. Page Chamberlain

Summary, in English

The Amazon forest is increasingly vulnerable to dieback and encroachment of grasslands and agricultural fields. Threats to these forested ecosystems include drying, deforestation, and fire, but feedbacks among these make it difficult to determine their relative importance. Here, we reconstruct the central and western Amazon tree cover response to aridity and fire in the mid-Holocene—a time of less intensive human land use and markedly drier conditions than today—to assess the resilience of tree cover to drying and the strength of vegetation-climate feedbacks. We use pollen, charcoal, and speleothem oxygen isotope proxy data to show that Amazon tree cover in the mid-Holocene was resilient to drying in excess of the driest bias-corrected future precipitation projections. Experiments with a dynamic global vegetation model (LPJ-GUESS) suggest tree cover resilience may be owed to weak feedbacks that act to amplify tree cover loss with drying. We also compare these results to observational data and find that, under limited human interference, modern tree cover is likely similarly resilient to mid-Holocene levels of aridification. Our results suggest human-driven fire and deforestation likely pose a greater threat to the future of Amazon ecosystems than drying alone.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • Middle Eastern Studies
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • MERGE: ModElling the Regional and Global Earth system

Publishing year

2021-07-01

Language

English

Publication/Series

Global and Planetary Change

Volume

202

Document type

Journal article

Publisher

Elsevier

Topic

  • Climate Research

Keywords

  • Amazon resilience
  • Dynamic global vegetation model
  • Fire
  • Mid-Holocene
  • Oxygen isotopes
  • Pollen

Status

Published

ISBN/ISSN/Other

  • ISSN: 0921-8181