The effect of two arbuscular mycorrhizal inocula of contrasting richness and the same mycorrhizal potential on the growth and survival of wild plant species from La Gran Sabana, Venezuela

Diversity of arbuscular mycorrhizal fungi (AMF) is potentially important for the productivity and functioning of plant communities. However, from results published to date, it is unclear whether the increase in productivity and plant diversity obtained with increased AMF richness is a consequence of higher richness in itself or whether it is caused simply by an uncontrolled, higher mycorrhizal potential in the more diverse AMF inocula used. The aim of the present work was to evaluate the effect of AMF richness on the biomass and survival of several wild plant species from La Gran Sabana, Venezuela, comparing AMF inocula of varying richness but with similar mycorrhizal potential. We studied the effect of two inocula (containing two and five AMF species respectively, each with 600 propagules/100 g of soil) on growth and survival in a community composed of three woody species indigenous to La Gran Sabana. No differences were found in dry mass production or plant survival when the two inocula of contrasting richness were compared. Reasons for such results include the life history strategies of the AMF used in the present work.