Temporal Decoupling of Biodiversity Effects on Grassland Productivity and Stability.

One key unresolved question in ecology is what drives temporal trends in biodiversity-stability relationships and how these trends link to ecosystem functioning. This knowledge gap reflects a limited understanding of interspecific interactions in biodiversity-stability relationships. Using plant productivity data from a 20-year grassland biodiversity experiment, complemented by a paired 5-year experiment that controlled for legacy effects, we disentangled the contributions of species-specific dynamics and interaction-dependent processes to plant community stability. Over 20 years, the stabilising effects of biodiversity strengthened, driven mainly by increasing asynchrony in species-specific dynamics rather than shifts in interaction-dependent effects. While biodiversity's stabilising effect initially increased alongside productivity, this coupling weakened over time as interaction-dependent effects on productivity and stability became decoupled. Our findings reveal the dynamic nature of biodiversity effects on plant community stability, underscoring the importance of understanding long-term ecosystem trajectories.