Land Use Change Alters Soil Organic Carbon Mineralization but Not Its Temperature Sensitivity in a Tropical Island of China

ABSTRACT Background and Aim Land use conversion from natural forests to plantations has significantly impacted soil organic carbon (SOC) dynamics, increasing uncertainty in assessing soil carbon sequestration under global change. Methods This study collected surface soils from natural secondary forests (NF) and rubber plantations (RPs) in southern China's tropics, conducting a laboratory incubation to investigate land use effects on SOC mineralization and temperature sensitivity ( Q 10 ). Results Results showed NF had significantly higher SOC (40.03 ± 1.04 g kg −1 ) than RP (12.91 ± 0.39 g kg −1 , p < 0.05), with greater total nitrogen, phosphorus, dissolved organic carbon, and microbial biomass. NF also exhibited significantly higher particulate and mineral‐associated organic carbon. NF soils had higher carbon mineralization rates at both 20°C and 30°C, with cumulative SOC mineralization reaching 74.30 ± 5.79 and 72.36 ± 3.75 mg C kg −1 in NF soils at 20°C and 30°C, respectively, compared with 29.59 ± 2.54 and 31.44 ± 1.74 mg C kg −1 in RP soils. Despite differences in mineralization, Q 10 values did not differ significantly between NF and RP (1.04 ± 0.06 vs. 1.14 ± 0.10, p > 0.05), indicating similar temperature responses. Correlation and principal component analyses revealed clear separation between NF and RP soils in soil physicochemical properties and SOC fractions, whereas Q 10 was not consistently correlated with most soil variables. Conclusion These results suggest that land use conversion alters soil properties and SOC distribution, ultimately affecting mineralization potential. Overall, land‐use conversion influenced the absolute magnitude of SOC mineralization more strongly than its relative temperature sensitivity.