Mycorrhizal and rhizobial interactions influence model grassland plant community structure and productivity

Arbuscular mycorrhizal (AM) fungi and rhizobium are likely important drivers of plant coexistence and grassland productivity due to complementary roles in supplying limiting nutrients. However, the interactive effects of mycorrhizal and rhizobial associations on plant community productivity and competitive dynamics remain unclear. To address this, we conducted a greenhouse experiment to determine the influences of these key microbial functional groups on communities comprising three plant species by comparing plant communities grown with or without each symbiont. We also utilized N-fertilization and clipping treatments to explore potential shifts in mycorrhizal and rhizobial benefits across abiotic and biotic conditions. Our research suggests AM fungi and rhizobium co-inoculation was strongly facilitative for plant community productivity and legume (Medicago sativa) growth and nodulation. Plant competitiveness shifted in the presence of AM fungi and rhizobium, favoring M. sativa over a neighboring C