Biotic degradation at night, abiotic degradation at day: positive feedbacks on litter decomposition in drylands

Daniel Gliksman*, Ana Rey, Ron Seligmann, Rita Dumbur, Or Sperling, Yael Navon, Sabine Haenel, Paolo De Angelis, John A. Arnone, José M. Grünzweig

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

The arid and semi-arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO2) uptake, which depends largely on plant litter decomposition and the subsequent release of CO2 back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO2 efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO2 efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long-term trend of global carbon sequestration.

Original languageAmerican English
Pages (from-to)1564-1574
Number of pages11
JournalGlobal Change Biology
Volume23
Issue number4
DOIs
StatePublished - 1 Apr 2017

Bibliographical note

Publisher Copyright:
© 2016 John Wiley & Sons Ltd

Keywords

  • dew
  • facilitation
  • litter CO flux
  • litter decomposition
  • litter moisture-content
  • microbial degradation
  • microbial priming
  • photodegradation
  • relative humidity
  • semi-arid ecosystems

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