Nitrogen deposition reduces grassland phyllosphere microbial diversity and network stability along a precipitation gradient

Phyllosphere microbiomes are crucial for maintaining plant growth and health, but their responses to global change remain largely unclear. Based on a precipitation gradient and N addition experiment in a semiarid grassland on the Mongolian Plateau, this study explored phyllosphere microbial diversity and stability. Across the two host plant species (Artemisia frigida, Leymus chinensis), decreased precipitation altered phyllosphere microbial community composition only. Increased precipitation reduced bacterial diversity and affected bacterial and fungal community composition. However, N addition significantly decreased bacterial, fungal, and protistan diversity, altered their community composition, and weakened phyllosphere microbiome network complexity and stability in both host plant species, suggesting that N addition had a stronger influence on phyllosphere microbial communities than changing precipitation. Our findings of strong sensitivity of phyllosphere microbial diversity and stability to N enrichment provide mechanistic understanding of changes in phyllosphere microbiomes and consequent plant growth and productivity under future global change scenarios. Nitrogen enrichment reduces phyllosphere microbial diversity and network stability in grasslands and exerts a stronger effect than changing precipitation, based on precipitation gradient and nitrogen addition experiments on the Mongolian Plateau.