Decadal-scale observations are key to detecting the stabilizing effects of plant diversity in natural ecosystems

Extensive experimental and theoretical evidence demonstrates the positive effects of plant diversity on the temporal stability of productivity, yet how the diversity-stability relationship varies across timescales and different diversity dimensions in natural ecosystems remains unclear. By integrating a comprehensive regional vegetation survey conducted in Tibetan alpine grasslands with the global plant diversity and productivity databases, we revealed a consistent temporal pattern at regional and global scales: the stabilizing effect of plant diversity on productivity strengthened over time, approaching saturation at 10 to 13 years. Notably, plant phylogenetic diversity emerged as the dominant biotic driver of long-term stability. In contrast, plant community height exerted a stronger positive influence on short-term stability. These findings highlight the critical role of timescales in shaping diversity-stability relationships and underscore the necessity of decadal-scale studies. Our results further support integrating phylogenetic diversity into conservation and management strategies to sustain ecosystem functioning under global change.