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Communication Dans Un Congrès Année : 2017

Unravelling complexity of biophysical interactions in soil: linking fungal traits, pore geometry and distribution of soil organic matter hotspots to explain evolution of CO2

Résumé

Soil structure provides a home to large numbers of microorganisms offering them a food base, support, access to water, air and nutrients and protection from predators. To be able to function, soils need to deliver these essential requirements for life, at micro-habitat scales. Soil structure is the soil characteristic that makes this possible. Therefore, soil structure holds the key to life in soil, regulates many ecosystem services and ultimately underpins sustainable life on Earth. Despite this, the exact way in which soil structure exerts its control is not fully understood and considered to be too complex to be explicitly included in modelling of key processes such as SOM dynamics. In this study we ask: can we develop a predictive framework for fungal ecology in heterogeneous soil that bridges scales, and what benefits would it bring? To address this question we developed a model that considers fungal interactions at scales directly relevant to the organisms (micro-meters) in order to predict ecosystem services, such as the evolution of CO2, as an emergent property of these interactions. The model is based on fungal traits, and explores through scenario modelling how these impact upon exploration of pore networks as determined by X-ray CT, and how this is affected by the location of particulate organic matter and the distribution of water within the pore space. The model predicted two important behaviours that are not captured by other models: (i) the evolution of CO2 increases in a non-linear way with increasing organic matter content. This response suggests a critical behaviour could be expected in microbial processes involved in the decomposition of SOM; (ii) the same amount of SOM in a soil sample (e.g. represented as a bulk property) can lead to substantial different CO2 evolutions, predicted to differing by a factor 200, depending on the spatial distribution and accessibility within the soil structure. This is the first modelling framework that is capable of combining fungal dynamics in structured soil with SOM dynamics and evolution of CO2. The advantage of the modelling approach is that scenarios can be rapidly explored beyond what is experimentally tractable, and as such can explore parameter spaces where soil functioning and biodiversity may be resilient to change, and can guide further experimental testing.
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hal-01607082 , version 1 (05-06-2020)

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  • HAL Id : hal-01607082 , version 1
  • PRODINRA : 408188

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Wilfred Otten, Ruth Falconer, Xavier Portell-Canal, Philippe Baveye, Patricia Garnier, et al.. Unravelling complexity of biophysical interactions in soil: linking fungal traits, pore geometry and distribution of soil organic matter hotspots to explain evolution of CO2. 6th International Symposium on Soil Organic Matter, Sep 2017, Harpenden, United Kingdom. pp.30. ⟨hal-01607082⟩
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