Drought duration outweighs intensity in governing ecosystem recovery time

Frequent and severe droughts pose growing threats to ecosystem stability. However, our knowledge of how ecosystem recovery after drought varies with different drought characteristics and across ecosystems remains limited. Here, we utilize solar-induced chlorophyll fluorescence-based gross primary production (GOSIF-GPP) to systematically investigate drought recovery time and drought legacy effects across diverse ecosystems from 2001 to 2020, employing a random forest model to identify the main drivers of drought recovery. We find that drought recovery time exhibits pronounced spatial heterogeneity, with the majority of ecosystems (80.5 %) recovering within 2 to 5 months following drought events. Recovery time increases with both drought duration and severity, whereas prolonged moderate-intensity droughts cause about 1.74 ± 0.06 months longer recovery time than short, severe-intensity droughts, reflecting the greater influence of duration than intensity. Gross Primary Productivity loss emerges as the most critical factor influencing recovery time, accounting for 24.8 % of the relative importance, followed by temperature during the recovery period (11.7 %) and solar radiation (11.2 %). Across different biomes, woody plants display stronger drought legacy effects compared to herbaceous plants, as evidenced by a lower recovery proportion by the third year after drought ended in woody plants (46.2 %) compared to herbaceous plants (53.1 %). Arid ecosystems show longer and stronger legacy effects likely due to limited water resources. These findings enhance our understanding of ecosystem drought responses and underscore the need to integrate recovery dynamics into process-based models to improve estimates of the terrestrial carbon sink.