Cultivation enhances warming sensitivity of redox-driven carbon pulses in black soils: The overlooked role of anaerobic legacy effects

Abstract

Wetlands on the world’s most fertile black soil serve as critical yet vulnerable carbon reservoirs, yet their stability is threatened by redox fluctuations intensified by climate change and human activities. However, how cultivation modulates this process and its temperature sensitivity remains poorly understood. Here, we integrated field surveys of 10 black soils with mechanistic experiments on three contrasting soils along a cultivation gradient, including microbial inoculation, sterilization, radical quenching, and mineral chelation, to demonstrate that rice cultivation fundamentally reshaped the coupled biotic-abiotic process governing temperature sensitivity of carbon pulses under redox fluctuations. We found that rice cultivation enhanced iron-reducing capacity and shifted microbial metabolic pathways toward catabolism, establishing a persistent anaerobic legacy that amplified the warming sensitivity of aerobic carbon pulses. Mechanistically, ferrous mineral–catalyzed oxidation through both direct catalytic oxidation and • OH-mediated pathways dominated the aerobic pulse in cultivated soils (>44 to 61% of CO 2 yields). This pathway was dependent on anaerobic legacies, including activated mineral catalytic potential and accumulated dissolved organic carbon, and was further intensified by warming. Across 10 soils, paddies exhibited stronger ferrous mineral catalytic capacity for aerobic CO 2 pulses than natural wetlands, with warming further amplifying this divergence. These findings reveal a bio-abiotic coupling mechanism, where antecedent anaerobic microbial processes establish a functional legacy that governs subsequent abiotic mineral catalysis, that is currently underrepresented in ecosystem models.