Warming promotes loss of subsoil carbon through accelerated degradation of plant-derived organic matter

Ofiti, Nicholas O. E.; Zosso, Cyrill U.; Soong, Jennifer L.; Solly, Emily F.; Torn, M. S.; Wiesenberg, Guido L. B.; Schmidt, Michael W.

doi:10.1016/j.soilbio.2021.108185

Cited by 49 publications

(48 citation statements)

References 59 publications

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“…Soil organic carbon concentrations were lower in warmed plots compared to control plots below 20 cm (LME; p < 0.01; F = 15.17) in the soil cores analyzed here and as described in more detail on replicated cores in Soong et al (2021). Fine root concentrations did not change with depth but were lower in warmed plots compared to control plots, as described in Ofiti et al (2021; Table 1).…”

Section: Bulk Parametersmentioning

confidence: 65%

“…We reported results as significant at a level of p < 0.05. Ofiti et al, 2021), and fine root mass (g m −2 , Ofiti et al, 2021) in control and warmed plots (mean ± SE, n = 3). More details on carbon concentrations on replicated cores can be found in Soong et al (2021 3 Results…”

Section: Discussionmentioning

confidence: 99%

“…Second, we hypothesized that microbial necromass, as assessed by brGDGTs, will decrease despite the expectation that the microbial biomass will increase. This hypothesis is based on the observation that microorganism-derived fatty acids were less abundant in warmed plots at our study site and that soil organic carbon was more decomposed (Ofiti et al, 2021). Thus, warming might accelerate microbial necromass turnover.…”

Section: Our Research Was Guided By the Following Three Hypothesesmentioning

confidence: 93%

“…Due to the higher persistence of brGDGTs in soils, there might be a lag in response as compared to PLFAs (Weijers et al, 2010). Nevertheless, accelerated decomposition at soil depths below 50 cm, as observed by Ofiti et al (2021), likely combined with lower microbial biomass inputs cause a decrease in concentrations of brGDGTs. Microbial biomass carbon, on the other hand, was not affected by warming at any depth (Fig.…”

Section: Less Microbial Biomass With Warming In Subsoil But Not Topsoilmentioning

confidence: 96%

“…brGDGTs generally have a longer turnover time compared to the faster cycling PLFAs (Kindler et al, 2009;Weijers et al, 2010), giving a more time-integrated signal of microbial abundance. Our first observations from the study site indicate that there might be less microbial necromass in warmed plots but relatively more microorganism-derived fatty acids compared to plant-derived fatty acids, especially in the subsoil below 50 cm (Ofiti et al, 2021). Thus, we used brGDGTs as a complementary proxy to explore potential changes in microbial necromass.…”

Section: Introductionmentioning

confidence: 99%

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Whole-soil warming decreases abundance and modifies the community structure of microorganisms in the subsoil but not in surface soil

Zosso

Ofiti

Soong

et al. 2021

SOIL

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Abstract. The microbial community composition in subsoils remains understudied, and it is largely unknown whether subsoil microorganisms show a similar response to global warming as microorganisms at the soil surface do. Since microorganisms are the key drivers of soil organic carbon decomposition, this knowledge gap causes uncertainty in the predictions of future carbon cycling in the subsoil carbon pool (> 50 % of the soil organic carbon stocks are below 30 cm soil depth). In the Blodgett Forest field warming experiment (California, USA) we investigated how +4 ∘C warming in the whole-soil profile to 100 cm soil depth for 4.5 years has affected the abundance and community structure of microorganisms. We used proxies for bulk microbial biomass carbon (MBC) and functional microbial groups based on lipid biomarkers, such as phospholipid fatty acids (PLFAs) and branched glycerol dialkyl glycerol tetraethers (brGDGTs). With depth, the microbial biomass decreased and the community composition changed. Our results show that the concentration of PLFAs decreased with warming in the subsoil (below 30 cm) by 28 % but was not affected in the topsoil. Phospholipid fatty acid concentrations changed in concert with soil organic carbon. The microbial community response to warming was depth dependent. The relative abundance of Actinobacteria increased in warmed subsoil, and Gram+ bacteria in subsoils adapted their cell membrane structure to warming-induced stress, as indicated by the ratio of anteiso to iso branched PLFAs. Our results show for the first time that subsoil microorganisms can be more affected by warming compared to topsoil microorganisms. These microbial responses could be explained by the observed decrease in subsoil organic carbon concentrations in the warmed plots. A decrease in microbial abundance in warmed subsoils might reduce the magnitude of the respiration response over time. The shift in the subsoil microbial community towards more Actinobacteria might disproportionately enhance the degradation of previously stable subsoil carbon, as this group is able to metabolize complex carbon sources.

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Section: Bulk Parametersmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Our Research Was Guided By the Following Three Hypothesesmentioning

confidence: 93%

Section: Less Microbial Biomass With Warming In Subsoil But Not Topsoilmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Whole-soil warming decreases abundance and modifies the community structure of microorganisms in the subsoil but not in surface soil

Zosso

Ofiti

Soong

et al. 2021

SOIL

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Long-term warming in a temperate forest accelerates soil organic matter decomposition despite increased plant-derived inputs

San Román,

Srikanthan,

Hamid

et al. 2024

Biogeochemistry

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Climate change may alter soil microbial communities and soil organic matter (SOM) composition. Soil carbon (C) cycling takes place over multiple time scales; therefore, long-term studies are essential to better understand the factors influencing C storage and help predict responses to climate change. To investigate this further, soils that were heated by 5 °C above ambient soil temperatures for 18 years were collected from the Barre Woods Soil Warming Study at the Harvard Forest Long-term Ecological Research site. This site consists of large 30 × 30 m plots (control or heated) where entire root systems are exposed to sustained warming conditions. Measurements included soil C and nitrogen concentrations, microbial biomass, and SOM chemistry using gas chromatography–mass spectrometry and solid-state 13C nuclear magnetic resonance spectroscopy. These complementary techniques provide a holistic overview of all SOM components and a comprehensive understanding of SOM composition at the molecular-level. Our results showed that soil C concentrations were not significantly altered with warming; however, various molecular-level alterations to SOM chemistry were observed. We found evidence for both enhanced SOM decomposition and increased above-ground plant inputs with long-term warming. We also noted shifts in microbial community composition while microbial biomass remained largely unchanged. These findings suggest that prolonged warming induced increased availability of preferred substrates, leading to shifts in the microbial community and SOM biogeochemistry. The observed increase in gram-positive bacteria indicated changes in substrate availability as gram-positive bacteria are often associated with the decomposition of complex organic matter, while gram-negative bacteria preferentially break down simpler organic compounds altering SOM composition over time. Our results also highlight that additional plant inputs do not effectively offset chronic warming-induced SOM decomposition in temperate forests.

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Responses of soil microbial carbon use efficiency to warming: Review and prospects

et al. 2022

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Warming promotes loss of subsoil carbon through accelerated degradation of plant-derived organic matter

Cited by 49 publications

References 59 publications

Whole-soil warming decreases abundance and modifies the community structure of microorganisms in the subsoil but not in surface soil

Whole-soil warming decreases abundance and modifies the community structure of microorganisms in the subsoil but not in surface soil

Long-term warming in a temperate forest accelerates soil organic matter decomposition despite increased plant-derived inputs

Responses of soil microbial carbon use efficiency to warming: Review and prospects

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