Warming alters microplastic-induced soil carbon priming across diverse terrestrial ecosystems

• Microplastic-induced soil carbon PE is sensitive to soil nitrogen availability. • Soil DOM chemodiversity responds divergently to warming across ecosystems. • Warming shifts MP-induced PE from positive to negative in forest and grassland soil. Microplastics threaten terrestrial ecosystems, with biodegradable types potentially amplifying soil organic carbon losses through the priming effect. However, the response of microplastic-induced priming effect to global warming across ecosystems remains largely unknown. Here, we collected soils from farmland, grassland, and forest ecosystems across 1200 km in northeastern China, and explored the polybutylene succinate (PBS)-induced priming effect under two temperature conditions (25 ℃ and 29.5 ℃). We found that the input of PBS significantly increased soil CO 2 emission irrespective of ecosystem type and temperature, accompanied by an increase lability of soil dissolved organic matter (DOM). At 25°C, PBS induced a positive priming effect across all ecosystems—the strongest in grassland soils, followed by farmland and forest, and this effect was closely linked to changes in soil nitrogen transformation potential and availability. Warming slightly increased the intensity of cumulative priming effect in farmland soils (22–32 %) but significantly decreased it from 19 % to –32 % in forest soils and from 51 % to −21 % in grassland soils. These differences may be attributed to the varying responses of soil DOM chemodiversity to warming, with newly formed DOM molecules increasing in farmland soils after PBS addition but not in forest or grassland soils. Together, these findings advance our understanding of the mechanisms driving microplastic-induced priming effect and provide insights into how microplastic pollution may alter soil carbon cycling under global warming.