VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI - A DETERMINANT OF PLANT COMMUNITY STRUCTURE IN EARLY SUCCESSION

1. Infection of plants by vesicular-arbuscular mycorrhizas (VAM) was reduced by application of the contact fungicide iprodione in two early successional plant communities. 2. One community was initiated in 1988 and monitored for four years, the other started in 1990 and monitored for 18 months. 3. In both communities reduction in fungal infection resulted in a lower plant species richness, with a number of species occurring in untreated (control) plots but absent in fungicide-treated plots. These were mostly perennial forbs. 4. It is suggested that VAM fungi are important in structuring early successional communities and that this is brought about by enhanced seedling establishment of forbs when fungi are present.