Iterative effects: a new paradigm for root dynamics.

Roots profoundly influence soil carbon storage through root production, turnover, and decomposition over time. While root-derived carbon stabilization in aggregates and minerals is known, the role of slowly decomposing root fragments has been largely overlooked. We propose a new paradigm, 'iterative effects', integrating multigenerational root production and turnover with multistage root decomposition to address the build-up of moderately stable soil carbon forms. To inspire future studies, we develop several heuristic scenarios that differentiate root iterative effects on carbon cycling within branching root systems, across steady-state and non-steady-state ecosystems, under natural and anthropogenic disturbances, and shaped by intra- and intergenerational interactions among root processes. This theoretical framework provides novel insights into soil carbon cycling and ecosystem responses to global changes.