Urbanization Intensification Enhances Soil Inorganic Carbon Accumulation but Divergently Impacts Its CO 2 Emissions

Abstract

Soil inorganic carbon (SIC) accounts for roughly 38% of the total carbon (C) stock in global soils. As a key component of urban ecosystems, parks are the hotspots of C cycling that are tightly linked with climate change. Compared with natural ecosystems, SIC in urban parks is often strongly altered by land management and construction activities. However, the SIC and its role as a potential source of carbon dioxide (CO 2 ) has often been overlooked in studies of urban parks. Here, we investigated the impact of different urbanization intensities on the SIC concentration of urban parks by a space‐for‐time substitution approach and explored whether urbanization affects the contribution of SIC‐derived CO 2 emissions by using δ 13 C stable isotope in Hangzhou, China. Our results showed that increasing urbanization intensity significantly increased SIC concentration, mainly driven by elevated mean annual temperature, soil pH, clay and fine silt content, mineral‐associated organic C, total nitrogen, exchange calcium and magnesium. Among these factors, the concentration of exchange calcium accounted for 16.8% of the variation in SIC. The SIC was positively correlated with mineral‐associated organic C, suggesting concurrent increase in both SIC and stable organic C component with increasing urbanization intensity. In contrast, SIC‐derived CO 2 emissions declined significantly with increasing urbanization intensity. Overall, these findings indicate that urbanization can simultaneously enhance SIC storage while suppressing SIC‐derived CO 2 emissions in urban park soils. Our study highlights the importance of incorporating SIC dynamics when evaluating soil C budgets and developing effective C management strategies in urban ecosystems.