Vertically Divergent Responses of SOC Decomposition to Soil Moisture in a Changing Climate

Pallandt, Marleen; Ahrens, Bernhard; Koirala, Sujan; Lange, Holger; Reichstein, Markus; Schrumpf, Marion; Zaehle, Sönke

doi:10.1029/2021jg006684

Cited by 5 publications

(6 citation statements)

References 79 publications

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“…From a plant perspective, soil organic matter helps hold water, maintaining turgor pressure between rainfall events (Libohova et al., 2018). Similar sensitivity of modeled decompositions rates to OCS and initial soil moisture was found in a depth‐explicit decomposition model (Pallandt et al., 2022). Our results indicate that ‐P soils with intermediate OCS are buffered against changes in precipitation, and thus had effect sizes near zero, in contrast to −P soils with the highest OCS, where high water‐retention may facilitate stimulation of root‐growth and associated microbial and autotrophic respiration (Maurel & Nacry, 2020).…”

Section: Discussionsupporting

confidence: 73%

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Soil Respiration Response to Simulated Precipitation Change Depends on Ecosystem Type and Study Duration

et al. 2022

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Section: Discussionsupporting

confidence: 73%

“…From a plant perspective, soil organic matter helps hold water, maintaining turgor pressure between rainfall events (Libohova et al, 2018). Similar sensitivity of modeled decompositions rates to OCS and initial soil moisture was found in a depth-explicit decomposition model (Pallandt et al, 2022).…”

Section: Soil Characteristics As Modifiers Of Respiration Changesupporting

confidence: 57%

Soil Respiration Response to Simulated Precipitation Change Depends on Ecosystem Type and Study Duration

et al. 2022

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“…However, it is now understood that soil carbon depends on a number of other mechanistic relationships with soil type, microbial communities, as well as species composition. Taken together, soil carbon uncertainties need to be addressed in the next generation of ESMs with greater emphasis of the modeling community by basing more off mechanistic science of the relationships driving soil and rhizospheric processes (Pallandt et al 2022).…”

Section: Discussionmentioning

confidence: 99%

Tipping point in North American Arctic-Boreal carbon sink persists in new generation Earth system models despite reduced uncertainty

Braghiere

Fisher

Miner

et al. 2023

Environ. Res. Lett.

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Estimating the impacts of climate change on the global carbon cycle relies on projections from Earth system models (ESMs). While ESMs currently project large warming in the high northern latitudes, the magnitude and sign of the future carbon balance of Arctic-Boreal ecosystems are highly uncertain. The new generation of increased complexity ESMs in the Intergovernmental Panel on Climate Change Sixth Assessment Report (IPCC AR6) is intended to improve future climate projections. Here, we benchmark the Coupled Model Intercomparison Project (CMIP) 5 and 6 (8 CMIP5 members and 12 CMIP6 members) with the International Land Model Benchmarking (ILAMB) tool over the region of NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) in North America. We show that the projected average Net Biome Production (NBP) in 2100 from CMIP6 is higher than that from CMIP5 in the ABoVE domain, despite the model spread being slightly narrower. Overall, CMIP6 shows better agreement with contemporary observed carbon cycle variables (photosynthesis, respiration, biomass, soil carbon) than CMIP5, except for soil carbon and turnover time. Although both CMIP ensemble members project the ABoVE domain will become a carbon sink by the end of the 21st century, the sink strength in CMIP6 increases with CO2 emissions. CMIP5 and CMIP6 ensembles indicate a tipping point defined here as a negative inflection point in the NBP curve by 2050-2080 independently of the Shared Socioeconomic Pathway (SSP) for CMIP6 or Representative Concentration Pathway (RCP) for CMIP5. This model ensemble therefore suggests that, if the carbon sink strength keeps declining throughout the 21st, the arctic-boreal ecosystems in North America may become a carbon source over the next century.

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“…This could be likely attributed to factors beyond temperature that also influence the rate of SOC decomposition. For instance, soil moisture is a critical factor directly modulating SOC decomposition rate in the model (Pallandt et al., 2022; Wang, Huang, et al., 2019; Wang, Zhao, et al., 2019). The heating of the soil due to SOC decomposition exacerbates water loss from the upper soil layers, exerting a negative effect on SOC decomposition.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of effects of heat released from SOC decomposition on soil carbon stock and temperature

Huang,

Qiu

et al. 2024

Global Change Biology

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Heat released from soil organic carbon (SOC) decomposition (referred to as microbial heat hereafter) could alter the soil's thermal and hydrological conditions, subsequently modulate SOC decomposition and its feedback with climate. While understanding this feedback is crucial for shaping policy to achieve specific climate goal, it has not been comprehensively assessed. This study employs the ORCHIDEE‐MICT model to investigate the effects of microbial heat, referred to as heating effect, focusing on their impacts on SOC accumulation, soil temperature and net primary productivity (NPP), as well as implication on land‐climate feedback under two CO2 emissions scenarios (RCP2.6 and RCP8.5). The findings reveal that the microbial heat decreases soil carbon stock, predominantly in upper layers, and elevates soil temperatures, especially in deeper layers. This results in a marginal reduction in global SOC stocks due to accelerated SOC decomposition. Altered seasonal cycles of SOC decomposition and soil temperature are simulated, with the most significant temperature increase per unit of microbial heat (0.31 K J−1) occurring at around 273.15 K (median value of all grid cells where air temperature is around 273.15 K). The heating effect leads to the earlier loss of permafrost area under RCP8.5 and hinders its restoration under RCP2.6 after peak warming. Although elevated soil temperature under climate warming aligns with expectation, the anticipated accelerated SOC decomposition and large amplifying feedback on climate warming were not observed, mainly because of reduced modeled initial SOC stock and limited NPP with heating effect. These underscores the multifaceted impacts of microbial heat. Comprehensive understanding of these effects would be vital for devising effective climate change mitigation strategies in a warming world.

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Vertically Divergent Responses of SOC Decomposition to Soil Moisture in a Changing Climate

Cited by 5 publications

References 79 publications

Soil Respiration Response to Simulated Precipitation Change Depends on Ecosystem Type and Study Duration

Soil Respiration Response to Simulated Precipitation Change Depends on Ecosystem Type and Study Duration

Tipping point in North American Arctic-Boreal carbon sink persists in new generation Earth system models despite reduced uncertainty

Evaluation of effects of heat released from SOC decomposition on soil carbon stock and temperature

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