Long-term pattern and magnitude of soil carbon feedback to the climate system in a warming world

In a 26-year soil warming experiment in a mid-latitude hardwood forest, we documented changes in soil carbon cycling to investigate the potential consequences for the climate system. We found that soil warming results in a four-phase pattern of soil organic matter decay and carbon dioxide fluxes to the atmosphere, with phases of substantial soil carbon loss alternating with phases of no detectable loss. Several factors combine to affect the timing, magnitude, and thermal acclimation of soil carbon loss. These include depletion of microbially accessible carbon pools, reductions in microbial biomass, a shift in microbial carbon use efficiency, and changes in microbial community composition. Our results support projections of a long-term, self-reinforcing carbon feedback from mid-latitude forests to the climate system as the world warms.

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Organic Amendments Alter Long-Term Turnover and Stability of Soil Carbon: Perspectives from a Data-Model Integration

Agronomy ◽

10.3390/agronomy11112134 ◽

2021 ◽

Vol 11 (11) ◽

pp. 2134

Author(s):

Guocheng Wang ◽

Zhongkui Luo

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Agricultural Soils ◽

Organic Amendments ◽

Climate Conditions ◽

Local Soil ◽

Microbial Carbon ◽

Use Efficiency

Organic amendment (OA) additions may profoundly regulate the turnover behaviours of soil organic carbon (SOC). Explicit understanding of such role of OA is crucial for accurately assessing the potential of carbon sequestration in agricultural soils. To explore the effects of OA additions on the detailed SOC stabilization and destabilization processes, we collected SOC measurements from 29 trials with experimental duration ranging from 14 to 85 years across the globe. Using these datasets, we constrained a soil carbon model to analyse SOC turnover and built-up processes as impacted by OA additions. We found that OA generally decreases microbial carbon use efficiency (CUE) and the fraction of inert SOC that is resistant to decomposition (finert), but has divergent effects on the decay rate of humic SOC (khum). Across the sites, there was great variability in the effects of OA on CUE, khum, and finert, which can be largely explained by local soil and climate conditions and the quantity and quality of OA. Long-term simulations suggested that, without considering the effects of OA on CUE, khum, and finert, the effectiveness of OA additions for carbon sequestration could be largely overestimated. Our results suggest that the strong site-specific regulations of OA on SOC dynamics as demonstrated in this study must be properly considered and better constrained by observational data when assessing SOC sequestration in agricultural soils under the management of OA additions.

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Assessment of depth‐dependent microbial carbon‐use efficiency in long‐term fertilized paddy soil using an 18 O–H 2 O approach

Land Degradation and Development ◽

10.1002/ldr.3708 ◽

2020 ◽

Vol 32 (1) ◽

pp. 199-207 ◽

Cited By ~ 2

Author(s):

Mostafa Zhran ◽

Tida Ge ◽

Yaoyao Tong ◽

Yangwu Deng ◽

Xiaomeng Wei ◽

...

Keyword(s):

Paddy Soil ◽

Carbon Use Efficiency ◽

Microbial Carbon ◽

Use Efficiency ◽

Microbial Carbon Use Efficiency

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Changes in Soil Carbon Dynamics in Response to Long-Term Soil Warming - Integration Across Scales from Cells to Ecosystems

10.2172/1502957 ◽

2019 ◽

Author(s):

Jerry Melillo

Keyword(s):

Soil Carbon ◽

Carbon Dynamics ◽

Soil Warming ◽

Soil Carbon Dynamics

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Soil carbon loss in warmed subarctic grasslands is rapid and restricted to topsoil

10.5194/bg-2021-338 ◽

2022 ◽

Author(s):

Niel Verbrigghe ◽

Niki I. W. Leblans ◽

Bjarni D. Sigurdsson ◽

Sara Vicca ◽

Chao Fang ◽

...

Keyword(s):

Soil Carbon ◽

Critical Role ◽

Aggregate Size ◽

Climate Feedbacks ◽

Soil Warming ◽

Soil C ◽

Soc Stock ◽

Mate System ◽

Soc Stocks

Abstract. Global warming may lead to carbon transfers from soils to the atmosphere, yet this positive feedback to the cli- mate system remains highly uncertain, especially in subsoils (Ilyina and Friedlingstein, 2016; Shi et al., 2018). Using natural geothermal soil warming gradients of up to +6.4 °C in subarctic grasslands (Sigurdsson et al., 2016), we show that soil organic carbon (SOC) stocks decline strongly and linearly with warming (−2.8 ton ha−1 °C−1). Comparison of SOC stock changes following medium-term (5 and 10 years) and long-term (> 50 years) warming revealed that all SOC loss occurred within the first five years of warming, after which continued warming no longer reduced SOC stocks. This rapid equilibration of SOC observed in Andosol suggests a critical role for ecosystem adaptations to warming and could imply short-lived soil carbon-climate feedbacks. Our data further revealed that the soil C loss occurred in all aggregate size fractions, and that SOC losses only occurred in topsoil (0–10 cm). SOC stocks in subsoil (10–30 cm), where plant roots were absent, remained unaltered, even after > 50 years of warming. The observed depth-dependent warming responses indicate that explicit vertical resolution is a prerequisite for global models to accurately project future SOC stocks for this soil type and should be investigated for soils with other mineralogies.

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