Controls on organic matter degradation in thawing permafrost peatlands and subsequent greenhouse gas emissions
Abstract
Northern peatlands store globally important amount of soil organic carbon. However, global temperature rise promotes periods of thaw in discontinuous permafrost zone, resulting in the shifts in vegetation and water table level and subsequently, change in carbon accumulation rate in peat profiles. This in return would directly impact the organic carbon (OC) pool composition by triggering the microbial activity and metabolic transformations in these regions. Given that the breakdown of soil organic matter (SOM) is often a major pathway for decomposition in peatlands, knowledge of organic matter reactivity under different permafrost regimes is critical for determining future climate feedbacks. Here in this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was utilized to examine the SOM composition gathered from bog and fen sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. In this study, we tested the hypotheses that organic matter reactivity increases with permafrost thaw due to thaw-induced subsidence and associated shifts in hydrology and plant community which highly affect the organic C sequestration and decomposition rate/processes. Transition from Sphagnum-dominated bogs to more waterlogged, sedge-dominated rich fens shifts the anaerobically produced CO2 and CH4 towards higher production potentials and different mechanisms, indicating a major role of plant communities on the available OC via changes in organic matter chemical composition (commonly referred to as organic matter "quality") in a thawing peatland complex.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B23M2569A
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0702 Permafrost;
- CRYOSPHERE;
- 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE