Both drought and heavy precipitation events have significant impacts on terrestrial carbon sequestration. While extensive research has focused on the adverse impacts of droughts on terrestrial carbon sinks, the effects of extreme precipitation events remain underexplored. Here we investigated the carbon sink dynamics induced by a record-breaking heavy precipitation event over the Yangtze River Valley (YRV) in June-July (JJ) 2020, using OCO-2 v10 MIP posterior data and simulations from two terrestrial biosphere models (VEGAS and LPJwsl). Our results show that extreme precipitation in JJ caused a significant decline in net biome productivity (NBP), with reductions of approximately −16.75 Tg C by OCO-2 v10 MIP, −23.50 Tg C by VEGAS, and −16.88 Tg C by LPJwsl, predominantly driven by substantial decreases in gross primary production (GPP). Following the cessation of precipitation in August, negative NBP anomalies persisted due to stronger total ecosystem respiration (TER*), but rapid recovery was observed, with recovery rates of 55.40%, 83.58%, and 86.85%, respectively, driven by a resurgence in GPP. Extreme precipitation also triggered significant variations in temperature, soil moisture, surface downward solar radiation (RAD), and vapor pressure deficit (VPD), all of which influenced NBP. Attribution analysis revealed reduced RAD as the primary factor behind negative NBP anomalies during JJ, with contributions of approximately −19.36 Tg C in VEGAS and −8.54 Tg C in LPJwsl. In August, VEGAS emphasized negative legacy effects from JJ, while LPJwsl pointed to the suppressive role of high temperatures. Furthermore, both models consistently underscored the pivotal role of RAD in carbon sink recovery. Considering the increasing frequency and intensity of heavy precipitation under global warming, our study emphasized the negative effects of extreme precipitation on the terrestrial carbon sequestration, providing the further understanding on interactions of extreme climatic events and terrestrial ecosystems.

Terrestrial carbon sinks,loss and recovery,2020 extreme precipitation,Yangtze River Valley