Soil minerals regulate soil organic carbon accumulation through glomalin-related soil protein along an elevation...

Soil minerals and glomalin-related soil protein (GRSP), as key soil binding agents, play a crucial role in enhancing soil organic carbon (SOC) sequestration. However, the key driving mechanisms of SOC accumulation process mediated by soil minerals and GRSP remain poorly understood in the arid elevation gradients. This study aimed to evaluate how soil minerals and GRSP affect SOC accumulation across an elevation gradient ranging from 1707 to 3548 m a.s.l on the northern slope of the Central Kunlun Mountains. We collected soil samples from two depths (0-10 cm and 10-30 cm) across the elevation gradient. Bulk soil organic carbon (OC), aggregate-associated OC content, Al/Fe oxides, Ca²⁺, and GRSP all increased along the elevational gradient at both soil depths of 0-10 cm and 10-30 cm. Specifically, microaggregate OC constituted the larger proportion and played a crucial role in promoting SOC accumulation. Random forest analysis revealed that soil minerals (41.63-60.75%) were the dominant factors driving SOC accumulation. Partial least squares path modelling revealed that SOC accumulation was directly influenced by GRSP, climate, and elevation; indirectly influenced by soil minerals and physiochemical factors. Soil minerals regulated SOC accumulation primarily through GRSP. Overall, the contribution of soil minerals to SOC accumulation processes in mountain ecosystems was considerably greater than that of climate and vegetation. These findings highlight the critical of soil minerals and GRSP factors in regulating SOC accumulation in arid mountain ecosystem, providing valuable insights for climate change mitigation strategies.