Increasing Soil Microbial Necromass Carbon Under Climate Change in Chinese Terrestrial Ecosystems: A Meta-Analysis

Soil necromass carbon (C) has significant potential for C sequestration in combination with minerals. Global warming and nitrogen (N) deposition affect necromass C, but these effects vary greatly across different climate conditions, land uses, and soil properties, and the role of regional specificity remains poorly understood. We synthesized 197 paired observations from 50 climate change studies to investigate these effects in China. Our results indicate that warming and N addition significantly increase necromass C accumulation by 17% and 9%, respectively. Warming strongly enhanced necromass C incroplands (+44%), cool (+16%) and semi-arid regions (+15%), and soils rich in soil organic carbon (SOC) (+17%) or loam (+22%), whereas N addition further promoted sequestration in croplands (+12%), forests (+10%) SOC-rich soils (+16%), and clay (+7%) or clay–loam (+12%) soils. In the context of climate change, soil C management requires attention to land use, climate, and soil properties. However, heterogeneous responses of microbial necromass C to global warming and N addition are still poorly understood. In the future, global warming is projected to enhance necromass C in croplands, cool or semiarid regions, SOC-rich and loam soils, whereas N addition is expected to further promote its sequestration in croplands, forests, SOC-rich, and clay-based soils. These findings demonstrate the targeted management of necromass C, particularly through optimized nitrogen application in clay-rich croplands and conservation tillage in cool and semiarid regions, offering a nature-based solution to complement global climate mitigation.