Drainage enhances modern soil carbon contribution but reduces old soil carbon contribution to ecosystem respiration in tundra ecosystems

Min Jung Kwon, Susan M. Natali, Caitlin E. Hicks Pries, Edward A.G. Schuur, Axel Steinhof, K. Grace Crummer, Nikita Zimov, Sergey A. Zimov, Martin Heimann, Olaf Kolle, Mathias Göckede

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Warming temperatures are likely to accelerate permafrost thaw in the Arctic, potentially leading to the release of old carbon previously stored in deep frozen soil layers. Deeper thaw depths in combination with geomorphological changes due to the loss of ice structures in permafrost, may modify soil water distribution, creating wetter or drier soil conditions. Previous studies revealed higher ecosystem respiration rates under drier conditions, and this study investigated the cause of the increased ecosystem respiration rates using radiocarbon signatures of respired CO 2 from two drying manipulation experiments: one in moist and the other in wet tundra. We demonstrate that higher contributions of CO 2 from shallow soil layers (0–15 cm; modern soil carbon) drive the increased ecosystem respiration rates, while contributions from deeper soil (below 15 cm from surface and down to the permafrost table; old soil carbon) decreased. These changes can be attributed to more aerobic conditions in shallow soil layers, but also the soil temperature increases in shallow layers but decreases in deep layers, due to the altered thermal properties of organic soils. Decreased abundance of aerenchymatous plant species following drainage in wet tundra reduced old carbon release but increased aboveground plant biomass elevated contributions of autotrophic respiration to ecosystem respiration. The results of this study suggest that drier soils following drainage may accelerate decomposition of modern soil carbon in shallow layers but slow down decomposition of old soil carbon in deep layers, which may offset some of the old soil carbon loss from thawing permafrost.

Original languageEnglish (US)
Pages (from-to)1315-1325
Number of pages11
JournalGlobal change biology
Volume25
Issue number4
DOIs
StatePublished - Apr 2019

Keywords

  • carbon source partitioning
  • drying experiment
  • ecosystem respiration
  • permafrost
  • radiocarbon
  • soil hydrology

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

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