Combined effects of multifactorial drivers on soil organic carbon retention: the underestimated role of reactive minerals in arid ecosystems

Abstract

Background and aims

Soil organic carbon (SOC) content is regulated by the combined effects of multifactorial drivers. However, the interactions between SOC and these drivers, as well as the potential networks linking them, have rarely been quantitatively assessed.

Methods

Based on a large-scale soil survey from 260 sites across the Mongolian Plateau, we examined the direct and indirect effects of climatic, edaphic, ecological, and mineral factors (a total of 11 variables) on SOC, and assessed the sensitivity of SOC and reactive minerals (amorphous, free forms of Fe/Al-(hydr) oxides) to the aridity index (AI) through meta-analysis (n = 2405).

Results

The mineral-associated organic carbon (MAOC) increased linearly with SOC accumulation across the Mongolian Plateau. Boosted regression trees (BRT) analysis indicated that the mineral factor exhibited the greatest impact on SOC, accounting for 35.4% of the variance, followed by soil properties (23.6%), ecological (22.8%), and climatic factor (18.2%). Path analysis and variance partitioning analysis (VPA) revealed the distinguishing role of reactive minerals in SOC retention and the smaller direct effect of climate compared to its indirect effects.

Conclusion

SOC and reactive minerals exhibited a positive responded to AI on a global scale, with a higher sensitivity to AI in arid regions. On the Mongolian Plateau, AI promoted substantial accumulation of metal-bound organic carbon (OC) and enhanced metal–organic associations. These findings revealed the complex interactions between climate, soil, mineral, and ecological factors in regulating SOC and highlighted the critical role of reactive minerals in SOC preservation in arid regions.

Graphical Abstract