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Dry Periods Amplify the Amazon and Congo Forests' Rainfall Self-Reliance
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  • Lan Wang-Erlandsson,
  • Ruud J. van der Ent,
  • Arie Staal,
  • Patrick Keys,
  • Delphine Clara Zemp,
  • Ingo Fetzer,
  • Makoto Taniguchi,
  • Line Gordon
Lan Wang-Erlandsson
Stockholm Resilience Centre, Stockholm University

Corresponding Author:lan.wang@su.se

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Ruud J. van der Ent
Delft University of Technology
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Arie Staal
Utrecht University
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Patrick Keys
Department of Atmospheric Science, Colorado State University
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Delphine Clara Zemp
University of Neuchâtel
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Ingo Fetzer
Stockholm Resilience Centre, Stockholm University
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Makoto Taniguchi
Research Institute for Humanity and Nature
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Line Gordon
Stockholm Resilience Centre, Stockholm University
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A substantial amount of the tropical forests of South America and Africa is generated through moisture recycling (i.e., forest rainfall self-reliance). Thus, deforestation that reduces evaporation and dampens the water cycle can further increase the risk of water-stress-induced forest loss in downwind areas, particularly during water scarce periods. However, few studies have investigated dry period forest rainfall self-reliance over longer records and consistently compared the rainforest moisture recycling in both continents. Here, we analyze dry-season anomalies of moisture recycling for mean-years and dry-years, in the South American (Amazon) and African (Congo) rainforests over the years 1980-2013. We find that, in the dry seasons, the reliance of forest rainfall on their own moisture supply (ρfor) increases by 7% (from a mean annual value of 26% to 28%) in the Amazon and up to 30% (from 28% to 36%) in the Congo. Dry years further amplify dry season ρfor in both regions by 4-5%. In both the Amazon and Congo, dry season amplification of ρfor is strongest in regions with a high mean annual ρfor. In the Amazon, forest rainfall self-reliance has declined over time. At the country scale, dry season ρfor can differ drastically from mean annual ρfor. In for example Bolivia and Gabon, mean annual ρfor is ~30% while dry season ρfor is ~50%. The dry period amplification of forest rainfall self-reliance further highlights the role of forests for sustaining their own resilience, and for maintaining downwind rainfall at both regional and national scales.
03 Apr 2023Submitted to ESS Open Archive
03 Apr 2023Published in ESS Open Archive