Permanent land use and microbial contributions shape soil organic carbon stabilization in lake floodplains
Abstract
Floodplain ecosystems play a key role in soil organic carbon (SOC) storage, as they integrate inputs from both vegetation and deposited sediments. Promoting land uses with low anthropogenic disturbances helps maintain the function of these ecosystems as soil carbon (C) sinks. However, the tipping points along a disturbance gradient where land use transitions generate the largest SOC losses or gains remain unclear, though they are key for effective land use management and climate change mitigation. Because flood events can mobilize and enhance the loss of labile C, determining the main origin of stable SOC, whether from plants or soil microorganisms, is also important to identify the optimal combination of land use, vegetation, and soil type for SOC stabilization in floodplains. We examined how SOC stabilization and origin vary in the floodplain of Lake Saint-Pierre, Québec, Canada along an anthropogenic disturbance gradient of six land uses: conventional and improved croplands, temporary and permanent meadows, marshes, and forested swamps. In all 6 land uses at the same elevation, we quantified SOC stocks, mineral-associated organic matter - C (MAOM-C), soil δ13C and sugar biomarkers. Driven by land use change, variations in plant inputs were associated with changes in topsoil SOC storage. Forested swamps had the highest MAOM-C due to greater plant biomass inputs that increased both microbial- and plant-derived C. Across all land uses, microbial-derived sugars, particularly of fungal origin, were more abundant in MAOM than plant-derived sugars. Notably, MAOM remained below its saturation capacity. Soil C pools, including MAOM-C, and both microbial- and plant-derived C, increased nonlinearly with decreasing disturbance, with a tipping point occurring at the transition from temporary to permanent meadows. Our results highlight the importance of increasing both microbial- and plant-derived C inputs to promote SOC stabilization, while emphasizing the persistent key role of fungal metabolism in floodplain soils.
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BibTeX
@article{rabearison2026permanent,
title = {{Permanent land use and microbial contributions shape soil organic carbon stabilization in lake floodplains}},
author = {Toky Jeriniaina Rabearison and Jim Félix-Faure and François Guillemette and Michelle Garneau and Christine Martineau and Louis Astorg and Martin Chantigny and Virginie Favreau and Jessika Malko and Alexandre Roy and Vincent Maire},
journal = {Soil Biology and Biochemistry},
year = {2026},
month = may,
doi = {10.1016/j.soilbio.2026.110199},
url = {https://hal.science/hal-05768438v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Permanent land use and microbial contributions shape soil organic carbon stabilization in lake floodplains
AU - Toky Jeriniaina Rabearison
AU - Jim Félix-Faure
AU - François Guillemette
AU - Michelle Garneau
AU - Christine Martineau
AU - Louis Astorg
AU - Martin Chantigny
AU - Virginie Favreau
AU - Jessika Malko
AU - Alexandre Roy
AU - Vincent Maire
PY - 2026
DA - 2026/05/17
JO - Soil Biology and Biochemistry
DO - 10.1016/j.soilbio.2026.110199
UR - https://hal.science/hal-05768438v1
AB - Floodplain ecosystems play a key role in soil organic carbon (SOC) storage, as they integrate inputs from both vegetation and deposited sediments. Promoting land uses with low anthropogenic disturbances helps maintain the function of these ecosystems as soil carbon (C) sinks. However, the tipping points along a disturbance gradient where land use transitions generate the largest SOC losses or gains remain unclear, though they are key for effective land use management and climate change mitigation. Because flood events can mobilize and enhance the loss of labile C, determining the main origin of stable SOC, whether from plants or soil microorganisms, is also important to identify the optimal combination of land use, vegetation, and soil type for SOC stabilization in floodplains. We examined how SOC stabilization and origin vary in the floodplain of Lake Saint-Pierre, Québec, Canada along an anthropogenic disturbance gradient of six land uses: conventional and improved croplands, temporary and permanent meadows, marshes, and forested swamps. In all 6 land uses at the same elevation, we quantified SOC stocks, mineral-associated organic matter - C (MAOM-C), soil δ13C and sugar biomarkers. Driven by land use change, variations in plant inputs were associated with changes in topsoil SOC storage. Forested swamps had the highest MAOM-C due to greater plant biomass inputs that increased both microbial- and plant-derived C. Across all land uses, microbial-derived sugars, particularly of fungal origin, were more abundant in MAOM than plant-derived sugars. Notably, MAOM remained below its saturation capacity. Soil C pools, including MAOM-C, and both microbial- and plant-derived C, increased nonlinearly with decreasing disturbance, with a tipping point occurring at the transition from temporary to permanent meadows. Our results highlight the importance of increasing both microbial- and plant-derived C inputs to promote SOC stabilization, while emphasizing the persistent key role of fungal metabolism in floodplain soils.
SN - 0038-0717
ER -