Legacy effects of altered precipitation on clonal traits and ecosystem productivity recovery in a semi–arid typical steppe

The increasing frequency and intensity of extreme precipitation events exert profound impacts on the structure and function of semi–arid grassland ecosystems. However, the mechanisms through which plant communities recover via clonal strategies after precipitation anomalies cease remain poorly understood. Using a long–term precipitation manipulation experiment conducted in a typical semi–arid steppe at Yunwu Mountain, Ningxia, China, we imposed drought and increased–precipitation treatments and quantified changes in belowground bud density, aboveground shoot density, and the bud:shoot ratio during the recovery phase after precipitation manipulations were removed. We further assessed how precipitation legacy effects regulate these clonal traits and their relationships with ecosystem productivity recovery. Our results showed that drought legacy effects significantly reduced belowground bud density, aboveground shoot density, and species richness, with a particularly strong suppression of clonal regeneration potential in forbs. Conversely, increased–precipitation legacy effects enhanced community–level clonal renewal capacity by promoting the replenishment of forb bud banks and shoots. Community composition analyses revealed that historical precipitation regimes substantially reshaped the functional group structure of both belowground buds and aboveground shoots, and that these effects persisted throughout the recovery period. Further analyses indicated that under drought recovery scenarios, both belowground bud density and aboveground shoot density significantly promoted the recovery of aboveground net primary productivity (ANPP), whereas under increased precipitation recovery conditions, these trait–resilience relationships weakened and became non–significant. These findings demonstrate that clonal traits play a critical role in supporting grassland recovery under resource–limited conditions, whereas their influence may be overridden by other ecological processes when resources are relatively abundant. Our study provides novel insights into the mechanisms underlying grassland ecosystem recovery amidst increasingly frequent extreme precipitation events.