Plant dominated ecosystem respiration of alpine meadow in permafrost region under experimental warming

Ecosystem carbon emissions induced by climate warming exert a positive feedback on global climate change. However, our understanding of how ecosystem respiration responds to long-term warming and its drivers remains limited in alpine grassland of permafrost regions. Here, a decade-long experimental warming was conducted to investigate the dynamics of ecosystem respiration, soil organic carbon (SOC), and plant functional traits in an alpine meadow of the northeastern Qinghai–Tibetan Plateau permafrost region. A decade of experimental warming elevated soil temperature by 0.55 °C and stimulated ecosystem respiration by 56.75%. However, the variation in ecosystem respiration was not significantly correlated with soil temperature. Warming significantly increased aboveground biomass by 25.25% ( p < 0.05), with a particularly dramatic increase in legume biomass (approximately 30-fold). Contrasted with its short- and medium-term enhancements, warming suppressed both SOC and root biomass in the tenth year. The SOC loss was strongly linked to the reduction in root biomass and was primarily derived from more labile carbon fractions. Ecosystem respiration was significantly correlated with aboveground biomass ( p < 0.05), and sedge and legume biomass contributed substantially to the enhancement of ecosystem respiration. These findings indicated that the increase in ecosystem carbon emissions under warming was largely driven by plant biomass rather than SOC decomposition. This highlights that accurate projections of the permafrost carbon feedback must incorporate the impacts of warming-induced shifts in plant functional traits.