Recovery time patterns of vegetation productivity following anomalies preceding abrupt declines.

Increasing abrupt declines in vegetation productivity threaten ecosystem structure, functioning, and services under accelerating global change. Compared with widely used indirect resilience indicators, direct indicators such as recovery time capture actual resilience dynamics and may provide reliable early warning signals of abrupt declines. However, recovery time patterns preceding abrupt declines remain poorly understood. Here, we quantified recovery time following negative and positive vegetation productivity anomalies preceding abrupt declines using long-term observations across global natural terrestrial ecosystems. We found that, in more than 75% of abrupt declines, the longest or second-longest historical recovery time occurred within the two anomalies preceding the decline, averaging 19 months. The most prevalent recovery pattern was a coupled response, characterized by prolonged recovery from negative anomalies and shortened recovery from positive anomalies, consistent with the "ball-in-cup" model. Incomplete recovery, rather than extreme anomalies, was the primary contributor to the longest recovery time. Among water balance-related factors, variability, rather than the mean state or long-term trend, emerged as the dominant driver of prolonged recovery and incomplete recovery. These findings quantify recovery dynamics preceding abrupt declines that are not captured by indirect resilience indicators, providing insights for ecological risk assessment and timely intervention.