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

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...

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Bibliographic Details
Published in:	Biogeochemistry Vol. 167; no. 9; pp. 1159 - 1174
Main Authors:	San Román, Atzín X., Srikanthan, Nivetha, Hamid, Andreia A., Muratore, Thomas J., Knorr, Melissa A., Frey, Serita D., Simpson, Myrna J.
Format:	Journal Article
Language:	English
Published:	Cham Springer International Publishing 01-09-2024 Springer Nature B.V
Subjects:	Availability Bacteria Biogeochemistry Biogeosciences Biomass Carbon cycle Climate change Climate prediction Community composition Composition effects Decomposition Earth and Environmental Science Earth Sciences Ecological research Ecosystems Environmental Chemistry Gas chromatography Gram-negative bacteria Gram-positive bacteria Life Sciences Magnetic resonance spectroscopy Mass spectrometry Mass spectroscopy Microbial activity Microbiomes Microorganisms NMR NMR spectroscopy Nuclear magnetic resonance Organic compounds Organic matter Organic soils Plants Roots Soil Soil chemistry Soil investigations Soil organic matter Soil temperature Soils Substrates Temperate forests Cutin Lignin Suberin Phospholipid fatty acids Soil warming Soil organic matter Nuclear magnetic resonance
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Summary:	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 13 C 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.
ISSN:	1573-515X 0168-2563 1573-515X
DOI:	10.1007/s10533-024-01165-9