Drainage enhances modern soil carbon contribution but reduces old soil carbon contribution to ecosystem respiration in tundra ecosystems. (25th February 2019)

• Record Type: Journal Article
• Authors: Kwon, Min Jung; Natali, Susan M.; Hicks Pries, Caitlin E.; Schuur, Edward A. G.; Steinhof, Axel; Crummer, K. Grace; Zimov, Nikita; Zimov, Sergey A.; Heimann, Martin; Kolle, Olaf; Göckede, Mathias
• Is Part Of: Global change biology. Volume 25:Number 4(2019)
• Page Start: 1315
• Page End: 1325
• Publication Date: 2019-02-25
• Subjects: carbon source partitioning -- drying experiment -- ecosystem respiration -- permafrost -- radiocarbon -- soil hydrology; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.14578
• Languages: English
• ISSNs: 1354-1013

Abstract

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 CO2 from two drying manipulation experiments: one in moist and the other in wet tundra. We demonstrate that higher contributions of CO2 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. Abstract : Warming thaws permafrost and the subsequent geomorphological changes re‐distribute surface water in the Arctic. Drying of tundra ecosystems increased autotrophic respiration and decomposition of modern soil carbon in shallow layers but decreased that of old soil carbon in deeper layers. These changes can be attributed to more aerobic soil conditions, but also soil temperature increases in shallow layers but decreases in deep layers, as well as shifts in plant communities.