Warming accelerates belowground litter turnover in salt marshes – insights from a Tea Bag Index study

Tang, Hao, Nolte, Stefanie ORCID: https://orcid.org/0000-0002-8570-241X, Jensen, Kai, Rich, Roy R., Mittmann-Goetsch, Julian and Mueller, Peter (2023) Warming accelerates belowground litter turnover in salt marshes – insights from a Tea Bag Index study. Biogeosciences, 20 (10). 1925–1935. ISSN 1726-4189

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Salt marshes play an important role in the global carbon cycle due to the large amount of organic carbon stored in their soils. Soil organic carbon formation in these coastal wetland ecosystems is strongly controlled by the plant primary production and initial decomposition rates of plant belowground biomass and litter. This study used a field warming experiment to investigate the response of belowground litter breakdown to rising temperature (+1.5 and +3.0◦C) across whole-soil profiles (0–60 cm soil depth) and the entire intertidal flooding gradient ranging from the pioneer zone via the low marsh to high marsh. We used standardized plant materials, following the Tea Bag Index approach, to assess the initial decomposition rate (k) and the stabilization factor (S) of labile organic matter inputs to the soil system. While k describes the initial pace at which labile (= hydrolyzable) organic matter decomposes, S describes the part of the labile fraction that does not decompose during deployment in the soil system and stabilizes due to biochemical transformation. We show that warming strongly increased k consistently throughout the entire soil profile and across the entire flooding gradient, suggesting that warming effects on the initial decomposition rate of labile plant materials are independent of the soil aeration (i.e., redox) status. By contrast, negative effects on litter stabilization were less consistent. Specifically, warming effects on S were restricted to the aerated topsoil in the frequently flooded pioneer zone, while the soil depth to which stabilization responded increased across the marsh elevation gradient via the low to high marsh. These findings suggest that reducing soil conditions can suppress the response of belowground litter stabilization to rising temperature. In conclusion, our study demonstrates marked differences in the response of initial decomposition rate vs. stabilization of labile plant litter to rising temperature in salt marshes. We argue that these differences are strongly mediated by the soil redox status along flooding and soil-depth gradients.

Item Type: Article
Additional Information: Financial support: Hao Tang received financial support from the China Scholarship council (grant no. CSC201606910043). Peter Mueller was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the Research Training Group (RTG) 2530 (Biota-mediated effects on carbon cycling in estuaries: project number 407270017). Julian Mittmann-Goetsch received funding from the Fischer Stiftung (Stifterverband für die Deutsche Wissenschaft) as part of the Seal-C project (a Stability Assessment of Wadden Sea Blue Carbon Stocks).
Uncontrolled Keywords: ecology, evolution, behavior and systematics,earth-surface processes ,/dk/atira/pure/subjectarea/asjc/1100/1105
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Collaborative Centre for Sustainable Use of the Seas
Faculty of Science > Research Groups > Environmental Biology
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Depositing User: LivePure Connector
Date Deposited: 13 Jul 2023 16:30
Last Modified: 21 Jul 2023 00:14
URI: https://ueaeprints.uea.ac.uk/id/eprint/92607
DOI: 10.5194/bg-20-1925-2023


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