02670nas a2200205   4500008004100000245010700041210006900148300001300217490000800230520194400238653003302182653001602215653001402231653002402245653002202269100001602291700001902307700001702326856012102343       1999                        eng d00aInteracting influence of mycorrhizal symbiosis and competition on plant diversity in tallgrass prairie0 aInteracting influence of mycorrhizal symbiosis and competition o  a574 -5820 v1213 aIn tallgrass prairie, plant species interactions regulated by their associated mycorrhizal fungi may be important forces that influence species coexistence and community structure; however, the mechanisms and magnitude of these interactions remain unknown. The objective of this study was to determine how interspecific competition, mycorrhizal symbiosis, and their interactions influence plant community structure. We conducted a factorial experiment, which incorporated manipulations of abundance of dominant competitors, Andropogon gerardii and Sorghastrum nutans, and suppression of mycorrhizal symbiosis using the fungicide benomyl under two fire regimes (annual and 4-year burn intervals). Removal of the two dominant C4 grass species altered the community structure, increased plant species richness, diversity, and evenness, and increased abundance of subdominant graminoid and forb species. Suppression of mycorrhizal fungi resulted in smaller shifts in community structure, although plant species richness and diversity increased. Responses of individual plant species were associated with their degree of mycorrhizal responsiveness: highly mycorrhizal responsive species decreased in abundance and less mycorrhizal responsive species increased in abundance. The combination of dominant-grass removal and mycorrhizal suppression treatments interacted to increase synergistically the abundance of several species, indicating that both processes influence species interactions and community organization in tallgrass prairie. These results provide evidence that mycorrhizal fungi affect plant communities indirectly by influencing the pattern and strength of plant competitive interactions. Burning strongly influenced the outcome of these interactions, which suggests that plant species diversity in tallgrass prairie is influenced by a complex array of interacting processes, including both competition and mycorrhizal symbiosis.10aArbuscular mycorrhizal fungi10aCompetition10adiversity10aSpecies coexistence10atallgrass prairie1 aSmith, M.D.1 aHartnett, D.C.1 aWilson, G.T.  uhttp://knz.lternet.edu/content/interacting-influence-mycorrhizal-symbiosis-and-competition-plant-diversity-tallgrass