Description of the continuous nature of organic matter in models of soil carbon dynamics

Abstract

The understanding of soil organic matter (SOM) dynamics has considerably advanced in recent years. It was previously assumed that most SOM consisted of recalcitrant compounds, whereas the emerging view considers SOM as a range of polymers continuously processed into smaller molecules by decomposer enzymes.Mainstreaming these new insights in current models is challenging because of their ill-adapted framework.We propose the C-STABILITY model to resolve this issue. Its innovative framework combines compartmental and continuous modelling approaches to accurately reproduce SOM cycling processes. Model theoretical simulations highlight the role of SOM accessibility on its turnover. They reveal how enzyme depolymerization, decomposer community succession and carbon use efficiency are key drivers of SOM composition and quantity during decomposition and at steady-state.The mathematical structure of C-STABILITY may be tailored to different scales and is open to alternative formulations, thus offering a promising foundation for enhancing carbon cycling predictions.

Uniting the scales of microbial biogeochemistry with trait‐based modelling

“…From a more theoretical perspective, Bosatta and Ågren (1985) applied an integrodifference model with carbon ‘quality’ as a continuous spectrum to demonstrate the importance of substrate quality for microbial stoichiometry, an approach later extended e.g. to vertical spatial structure (Bosatta & Ågren, 1996) and microbial physiology (Sainte‐Marie et al., 2020). In another demonstration that the stoichiometry of soil biogeochemical cycles varies according to microscale processes, Kaiser et al.…”

“…ogy(Sainte-Marie et al, 2020). In another demonstration that the stoichiometry of soil biogeochemical cycles varies according to microscale processes,Kaiser et al (2014) used an individual-based model to show that microscale interactions between microbial functional groups can overcome the effects of nitrogen limitation.Recent research has also shown the importance of social dynamics between competing microbes that can only be explicitly modelled using a spatial framework.…”