Plant communities affect arbuscular mycorrhizal fungal diversity and community composition in grassland microcosms

Abstract

The diversity of arbuscular mycorrhizal (AM) fungi was investigated in an unfer- tilized limestone grassland soil supporting different synthesized vascular plant assem- blages that had developed for 3 yr. The experimental treatments comprised: bare soil; monocultures of the nonmy- cotrophic sedge Carex flacca ; monocultures of the mycotrophic grass Festuca ovina ; and a species-rich mixture of four forbs, four grasses and four sedges. The diversity of AM fungi was analysed in roots of Plantago lanceolata bioassay seedlings using terminal-restriction fragment length polymorphism (T-RFLP). The extent of AM col- onization, shoot biomass and nitrogen and phosphorus concentrations were also measured. The AM diversity was affected significantly by the floristic composition of the microcosms and shoot phosphorus concentration was positively correlated with AM diversity. The diversity of AM fungi in P. lanceolata decreased in the order: bare soil > C. flacca > 12 species > F. ovina . The unexpectedly high diversity in the bare soil and sedge monoculture likely reflects differences in the modes of colonization and sources of inoculum in these treatments compared with the assemblages containing established AM-compatible