Root-induced fungal growth triggers macroaggregation in forest subsoils

Baumert, Vera; Forstner, Stefan J.; Zethof, Jeroen; Vogel, Cordula; Heitkötter, Julian; Schulz, Stefanie; Kögel‐Knabner, Ingrid; Mueller, Carsten W.

doi:10.1016/j.soilbio.2021.108244

Cited by 36 publications

(12 citation statements)

References 77 publications

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“…This approach may even allow the characterization of priming effects in different aggregate size classes in the rhizosphere based on microbial stoichiometry (Mo et al, 2021;Wang et al, 2020). Molecular marker analyses including a suite of exudate-, bacteria-and fungi-specific substances has high potential to shed more light on rhizosphere gradients and hot spots of OM enrichment (time-integrated signals/stable on medium-term in contrast to microbiological parameters) (Baumert et al, 2021). As a first step 13 C labelled carbon fraction which can be imaged in 2D with NanoSims or LA-IRMS is used to represent the soluble root derived carbon pool (exudates) and complement the C initialisation described and/or to assist validation of experimental results, especially in view of stoichiometric constraints for plant and microbial processes (Clode et al, 2009;Gorka et al, 2019;Vidal et al, 2018).…”

Section: Resultsmentioning

confidence: 99%

Linking rhizosphere processes across scales: Opinion

Schnepf

Carminati

Ahmed

et al. 2021

Preprint

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PurposeSimultaneously interacting small-scale rhizosphere processes determine emergent plant-scale behaviour, including growth, transpiration, nutrient uptake, soil carbon storage and transformation by microorganisms. Current advances in modelling and experimental methods open the path to unravel and link those processes.MethodsWe present a series of examples of state-of-the art simulations addressing this multi-scale, multi-process problem from a modelling point of view, as well as from the point of view of integrating newly available rhizosphere data and images.ResultsEach example includes a model that links scales and experimental data to set-up simulations that explain and predict spatial and temporal distribution of rhizodeposition as driven by root architecture development, soil structure, presence of root hairs, soil water content and distribution of soil water. Furthermore, two models explicitly simulate the impact of the rhizodeposits on plant nutrient uptake and soil microbial activity, respectively. This exemplifies the currently available state of the art modelling tools in this field: image-based modelling, pore-scale modelling, continuum scale modelling and functional-structural plant modelling. We further show how to link the pore scale to the continuum scale by homogenisation or by deriving effective physical parameters like viscosity from nano-scale chemical properties.ConclusionModelling allows to integrate and make use of new experimental data across different rhizosphere processes (and thus across different disciplines) and scales. Described models are tools to test hypotheses and consequently improve our mechanistic understanding of how rhizosphere processes impact plant-scale behaviour. Linking multiple scales and processes is the logical next step for future research.

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Section: Resultsmentioning

confidence: 99%

Linking rhizosphere processes across scales: Opinion

Schnepf

Carminati

Ahmed

et al. 2021

Preprint

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“…Further differentiation of DOM into specific root exudates, microbial biomass, microbial necromass and POM (Angst et al 2016;Baumert et al 2021) can be envisaged and tackled with the same modelling approach for an increased accuracy of the model outputs. This approach may even allow the characterization of priming effects in different aggregate size classes in the rhizosphere based on microbial stoichiometry (Mo et al 2021;Wang et al 2020).…”

Section: Challenges and Open Questionsmentioning

confidence: 99%

“…This approach may even allow the characterization of priming effects in different aggregate size classes in the rhizosphere based on microbial stoichiometry (Mo et al 2021;Wang et al 2020). Molecular marker analyses including a suite of exudate-, bacteria-and fungi-specific substances has high potential to shed more light on rhizosphere gradients and hot spots of OM enrichment (time-integrated signals/stable on medium-term in contrast to microbiological parameters) (Baumert et al 2021). As a first step 13 C labelled carbon fraction which can be imaged in 2D with Nano-Sims or LA-IRMS is used to represent the soluble root derived carbon pool (exudates) and complement the C initialisation described and/or to assist validation of experimental results, especially in view of stoichiometric constraints for plant and microbial processes (Clode et al 2009;Gorka et al 2019;Vidal et al 2018).…”

Section: Challenges and Open Questionsmentioning

confidence: 99%

Linking rhizosphere processes across scales: Opinion

et al. 2022

Self Cite

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Purpose Simultaneously interacting rhizosphere processes determine emergent plant behaviour, including growth, transpiration, nutrient uptake, soil carbon storage and transformation by microorganisms. However, these processes occur on multiple scales, challenging modelling of rhizosphere and plant behaviour. Current advances in modelling and experimental methods open the path to unravel the importance and interconnectedness of those processes across scales. Methods We present a series of case studies of state-of-the art simulations addressing this multi-scale, multi-process problem from a modelling point of view, as well as from the point of view of integrating newly available rhizosphere data and images. Results Each case study includes a model that links scales and experimental data to explain and predict spatial and temporal distribution of rhizosphere components. We exemplify the state-of-the-art modelling tools in this field: image-based modelling, pore-scale modelling, continuum scale modelling, and functional-structural plant modelling. We show how to link the pore scale to the continuum scale by homogenisation or by deriving effective physical parameters like viscosity from nano-scale chemical properties. Furthermore, we demonstrate ways of modelling the links between rhizodeposition and plant nutrient uptake or soil microbial activity. Conclusion Modelling allows to integrate new experimental data across different rhizosphere processes and scales and to explore more variables than is possible with experiments. Described models are tools to test hypotheses and consequently improve our mechanistic understanding of how rhizosphere processes impact plant-scale behaviour. Linking multiple scales and processes including the dynamics of root growth is the logical next step for future research.

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“…However, this effect may also be partially offset by absorptive roots by fostering the formation of mineral–organic associations and soil aggregates via exudates (e.g. carbohydrates) and hyphae releasing mineral surface‐bound reactive metabolites (Baumert et al, 2021; Keiluweit et al, 2015; Lehmann et al, 2017; Zak et al, 2019). These interactive processes also further exacerbate the uncertainty about the magnitude and direction of the microbial necromass contribution to rhizosphere SOC sequestration between the two root functional modules.…”

Section: Introductionmentioning

confidence: 99%

Absorptive roots drive a larger microbial carbon pump efficacy than transport roots in alpine coniferous forests

et al. 2022

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1. Root activity creates a unique microbial hotspot in the rhizosphere and profoundly regulates soil carbon (C) dynamics, but empirical assessments of the soil microbial carbon pump (MCP, the iterative accumulation of necromass after microbial anabolism) and associated ecological consequences on soil C storage based on insight of the rhizosphere are still neglected, especially for different root functional modules.2. We assessed the soil MCP efficacy (i.e. the contribution of microbial necromass to SOC) by investigating the divergent contribution of microbial necromass based on amino sugar extrapolations to soil organic C (SOC) in the rhizosphere of two root functional modules (i.e. absorptive roots and transport roots) and the bulk soil in an alpine coniferous forest.3. The results showed that the MCP efficacy in both rhizosphere and bulk soil was more than 50%, suggesting that microbial necromass plays a key role in SOC formation. More importantly, absorptive roots drove a greater rhizosphere MCP efficacy (56%) than transport roots (51%). 4. Synthesis. These observations suggest that the microbial necromass is a major contributor to SOC storage in both rhizosphere and bulk soil in alpine coniferous forests. The magnitude of the contribution of microbial necromass to rhizosphere SOC depends on root functional differentiation. Our study provides novel and direct empirical evidence for the active soil MCP functions in SOC sequestration from the perspective of the rhizosphere.

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Root-induced fungal growth triggers macroaggregation in forest subsoils

Cited by 36 publications

References 77 publications

Linking rhizosphere processes across scales: Opinion

Linking rhizosphere processes across scales: Opinion

Linking rhizosphere processes across scales: Opinion

Absorptive roots drive a larger microbial carbon pump efficacy than transport roots in alpine coniferous forests

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