Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland

Hough, Moira; McCabe, Samantha; Vining, S. Rose; Pedersen, Emily Pickering; Wilson, Rachel M.; Lawrence, R. D.; Chang, Kuang-Yu; Bohrer, Gil; Riley, William J.; Crill, Patrick; Varner, Ruth K.; Blazewicz, Steven J.; Dorrepaal, Ellen; Tfaily, Malak M.; Saleska, S. R.; Rich, V. I.

doi:10.1111/gcb.15970

Cited by 14 publications

(6 citation statements)

References 73 publications

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“…For example, through field, lab, and mechanistic modeling, thermodynamic properties of OM have been shown to influence microbial respiration in both aerobic and anaerobic river corridor settings (Boye et al, 2017;Graham et al, 2018;Garayburu-Caruso et al, 2020a;Song et al, 2020;Sengupta et al, 2021). This has also recently been shown in soil systems as well (Hough et al, 2022). Other attributes of OM chemistry, such as the carbon-to-nitrogen ratio, also have strong influences over river corridor rates and fluxes (Bauer et al, 2013;Liu et al, 2020).…”

Section: Introductionmentioning

confidence: 96%

Organic matter transformations are disconnected between surface water and the hyporheic zone

et al. 2022

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Abstract. Biochemical transformations of organic matter (OM) are a primary driver of river corridor biogeochemistry, thereby modulating ecosystem processes at local to global scales. OM transformations are driven by diverse biotic and abiotic processes, but we lack knowledge of how the diversity of those processes varies across river corridors and across surface and subsurface components of river corridors. To fill this gap we quantified the number of putative biotic and abiotic transformations of organic molecules across diverse river corridors using ultra-high-resolution mass spectrometry. The number of unique transformations is used here as a proxy for the diversity of biochemical processes underlying observed profiles of organic molecules. For this, we use public data spanning the contiguous United States (ConUS) from the Worldwide Hydrobiogeochemical Observation Network for Dynamic River Systems (WHONDRS) consortium. Our results show that surface water OM had more biotic and abiotic transformations than OM from shallow hyporheic zone sediments (1–3 cm depth). We observed substantially more biotic than abiotic transformations, and the numbers of biotic and abiotic transformations were highly correlated with each other. We found no relationship between the number of transformations in surface water and sediments and no meaningful relationships with latitude, longitude, or climate. We also found that the composition of transformations in sediments was not linked with transformation composition in adjacent surface waters. We infer that OM transformations represented in surface water are an integrated signal of diverse processes occurring throughout the upstream catchment. In contrast, OM transformations in sediments likely reflect a narrower range of processes within the sampled volume. This indicates decoupling between the processes influencing surface water and sediment OM, despite the potential for hydrologic exchange to homogenize OM. We infer that the processes influencing OM transformations and the scales at which they operate diverge between surface water and sediments.

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Section: Introductionmentioning

confidence: 96%

Organic matter transformations are disconnected between surface water and the hyporheic zone

et al. 2022

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“…5). We observed habitat-and depth-specific metabolite and gene expression patterns, probably due to differences in plant and microbial community species between habitats 5,31 . Importantly, unlike PO alone (Fig.…”

Section: Articlementioning

confidence: 87%

Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle

McGivern,

Cronin,

Ellenbogen

et al. 2024

Nat Microbiol

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With rising global temperatures, permafrost carbon stores are vulnerable to microbial degradation. The enzyme latch theory states that polyphenols should accumulate in saturated peatlands due to diminished phenol oxidase activity, inhibiting resident microbes and promoting carbon stabilization. Pairing microbiome and geochemical measurements along a permafrost thaw-induced saturation gradient in Stordalen Mire, a model Arctic peatland, we confirmed a negative relationship between phenol oxidase expression and saturation but failed to support other trends predicted by the enzyme latch. To inventory alternative polyphenol removal strategies, we built CAMPER, a gene annotation tool leveraging polyphenol enzyme knowledge gleaned across microbial ecosystems. Applying CAMPER to genome-resolved metatranscriptomes, we identified genes for diverse polyphenol-active enzymes expressed by various microbial lineages under a range of redox conditions. This shifts the paradigm that polyphenols stabilize carbon in saturated soils and highlights the need to consider both oxic and anoxic polyphenol metabolisms to understand carbon cycling in changing ecosystems.

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“…It is commonly reported that litter decomposition responds to climate warming and its underlying mechanisms when litter is located on the soil surface (Hough et al, 2022;Yang et al, 2022; Frontiers in Ecology and Evolution 08 frontiersin.org . However, this is not always the case.…”

Section: Discussionmentioning

confidence: 99%

Effects of warming and litter positions on litter decomposition in a boreal peatland

Wang

Sun

et al. 2022

Front. Ecol. Evol.

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Litter decomposition is an important source of carbon accumulation in the permafrost peatlands. Climate warming has led to shrub expansions and accelerated litter mixing with soils and fluctuations in the water table. However, little is known about how changes in the position of the litter will affect litter decomposition under climate warming. To reveal the mechanisms of response of the location of litter in the soil and climate warming to litter decomposition in permafrost peatlands. Here, we selected the evergreen shrub, Chamaedaphne calyculata, and the deciduous shrub, Vaccinium uliginosum, from the permafrost peatlands of the Greater Hing’an Mountains, China. The leaf litter was placed on the soil surface (no-mixing) and mixed with the soil (soil-litter mixing), and then it was incubated for 124 days at 15°C (control) and 20°C (warming). Our results showed that warming significantly increased the CO2 emission rates of C. calyculata and V. uliginosum by 19.9 and 17.4%, respectively. When compared to no-mixing, the CO2 emission rates were reduced (not significantly) by 1.5 (C. calyculata) and increased 13.6% (V. uliginosum) with soil-litter mixing. Interestingly, soil-litter mixing suppressed the positive effect of warming on the CO2 emission rates relative to no-mixing, and the suppressing effects in the V. uliginosum subplot were stronger than those in the C. calyculata subplot. Specifically, warming significantly increased the CO2 emissions of C. calyculata by 27.4% under no-mixing but the increase decreased to 13.1% under soil-litter mixing. Similarly, warming induced significant increases in the CO2 emissions of V. uliginosum, with an increase of 38.8% under no-mixing but non-significant increases (1.9%) were observed under soil-litter mixing. The combination of the enzyme activities of β-1,4-glucosidase, β-1,4-xylosidase and β-D-1,4-cellobiosidase and laccase and phenolics explained more than 60.0% of the variability in the CO2 emissions of C. calyculata and V. uliginosum, respectively. Our study highlights the importance of litter positions in mediating the responses of litter decomposition to climate warming and shrub expansions in the northern peatlands.

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Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Cited by 14 publications

References 73 publications

Organic matter transformations are disconnected between surface water and the hyporheic zone

Organic matter transformations are disconnected between surface water and the hyporheic zone

Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle

Effects of warming and litter positions on litter decomposition in a boreal peatland

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