Modulation of hydrothermal conditions on the inhibiting and promoting effects of cumulative drought on vegetation productivity in southwest China

•Not all drought events impart identical damage effects on terrestrial ecosystems.•Inhibiting and promoting effects of cumulative drought on GPP was distinguished.•The effects show large discrepancies in different geomorphic settings and vegetation.•Hydrothermal conditions play a vital role in modulating the effects. Southwest China, characterized by its climate sensitivity and ecological fragility, is experiencing heightened vulnerability to recurrent extreme drought due to climate change. However, not all drought events impart identical damage effects on terrestrial ecosystems. The ecosystem’s response to drought becomes intricately diverse and is remain poorly understood in this region. Here, we comprehensively distinguish the inhibiting and promoting effects of cumulative drought on vegetation productivity and the modulation of hydrothermal conditions using various remote-sensing data and meteorological observations. Our results show that cumulative drought exerts pronounced inhibiting and promoting effects on vegetation productivity in 57.3% and 25.0% of vegetated area in southwest China, respectively, and shows large discrepancies in different geomorphic settings and different vegetation types. Particularly, vegetation productivity is more easily inhibited by cumulative drought in the karst landform with inadequate water-holding capacity. The croplands suffer the most inhibited effects and hardly benefit from the cumulative drought because that most of croplands are mainly distributed on the karst landform. Productivity for much of the grasslands is most strongly promoted by cumulative drought with relatively low temperature over western Sichuan and northwestern Yunnan, where with rich solar radiation can compensate energy for vegetation growth and less precipitation prevents prolonged waterlogging of plant roots owing to soil water saturation. Forests have well-developed deep root systems and can draw deep groundwater to compensate for water shortages during prolonged droughts, making them the least inhibited by cumulative drought. Savannas are the second weakly inhibited by cumulative drought, ranking below forests owing to their intermediate ecological character, straddling the boundaries between grasslands and forests. Overall, this study significantly advances our knowledge of the effects of cumulative drought on vegetation productivity and the role of hydrothermal conditions, providing valuable insights for efforts to mitigate cumulative drough