Eutrophication asynchronized species due to abundance-specific responses

Nitrogen eutrophication rapidly reduces species diversity, yet its impacts on the stable provision of ecosystem functions remain poorly understood. To address this gap, we applied an extended diversity–stability framework to a globally distributed grassland nitrogen addition experiment and partitioned ecosystem stability and its components, i.e., population stability and species asynchrony, into dominant and subordinate groups. We found that ecosystem stability was primarily driven by dominant species and exhibited an abundance-specific response. This response arose because nitrogen addition promoted the growth of dominant species, which in turn suppressed subordinate species. Consequently, asynchronized dynamics between the two groups coincided with reduced species diversity, and declines in population stability were confined to subordinate species. These findings indicate that, in natural ecosystems, uneven species abundances can obscure the positive effects of species diversity on species asynchronous and ecosystem stability, as predicted by theoretical and experimental studies under relatively even species-abundance distributions.