Global Change Impacts on Mineral-Associated Organic Matter: Consequences for Soil Carbon Persistence

Mineral-associated organic matter (MAOM) in soils constitutes the largest terrestrial carbon pool and the primary reservoir of soil nitrogen. Mineral protection, by encapsulating and binding organic matter to restrict microbial accessibility, is expected to buffer MAOM against decomposition and reduce its sensitivity to global changes. Yet this assumed stability is increasingly questioned by empirical observations. Increasing evidence indicates that MAOM comprises a multi-pool continuum, with a substantial fraction rapidly cycling and some fraction being sensitive to biotic or abiotic perturbations under global changes. This review synthesizes current knowledge on how global change factors may alter MAOM dynamics, including MAOM formation and destabilization, as well as the implications of altered MAOM dynamics for soil carbon persistence. We highlight future research directions and propose strategies to balance the stabilization of slow-cycling MAOM and the maintenance of a viable fast-cycling MAOM pool to support nutrient cycling and plant productivity. Advancing this knowledge requires recognizing MAOM dynamics in soil management and developing mechanistic frameworks that integrate rhizosphere interactions, alongside biological and mineral controls, to better predict MAOM variations under global changes.