Abstract: Glomalin-related soil protein (GRSP) secreted by arbuscular mycorrhizal fungi is an important component of soil organic carbon (SOC) and one of the important indicators of changes in soil carbon sequestration. The ability of GRSP to enhance soil carbon sequestration and its influencing mechanisms during rapid urbanization remains unclear. We selected 184 greenspace plots from the built-up area in Nanchang (505 km²) and categorized urbanization intensity based on the proportion of impervious surface area to total area. We then analyzed the effects of urbanization intensity on the contents of SOC, GRSP, and purified GRSP-containing carbon (GRSP-C), as well as their correlations with soil physicochemical properties, vegetation characteristics, and landscape patterns. The results showed that GRSP and GRSP-C contents were significantly higher in lowly urbanized areas than in highly urbanized areas by 19.35% and 13.21%, respectively (P<0.05). From lowly to highly urbanized areas, SOC content decreased from 18.64 mg·g^-1 to 15.02 mg·g^-1, accompanied by a decline in the contribution rate of GRSP-C to SOC from 3.89% to 2.04%, indicating that urbanization significantly weakened the roles of GRSP and GRSP-C in SOC sequestration. The redundancy analysis revealed that soil pH, soil total potassium, tree canopy size, and the total boundary length of greenspace patches were the main factors affecting the changes in the GRSP-related carbon sequestration during urbanization. A high soil total potassium content was not conducive to the accumulation of GRSP and GRSP-C. Soil pH was negatively correlated with the GRSP/SOC ratio and the contribution rate of the GRSP-C content to SOC, while larger tree canopy sizes and total boundary length increased the contribution rate of GRSP to SOC. By systematically investigating the role of GRSP in SOC sequestration, this study confirms that GRSP is a relatively novel pathway for contributing to soil carbon neutrality in urban greenspaces, even though its role could be influenced by urbanization.

Key words: glomalin-related soil protein, soil organic carbon, urbanization, urban greenspace