Fungal endophyte symbiosis and plant diversity in successional fields

Increasing evidence suggests that microbial interactions are important dete rminants of plant biodiversity. The hypothesis that fungal endophyte symbio sis reduces diversity in successional fields was tested by manipulating inf ection of tall fescue, the most abundant perennial grass in the eastern Uni ted States. Over a 4-year period. species richness declined and tall fescue dominance increased in infected plots relative to uninfected plots without differences in total productivity. A host-specific endophyte, with negligi ble biomass, altered plant community structure in this Long-term field expe riment and may be reducing plant diversity throughout its expanding range.