MYCORRHIZAL FUNGAL DIVERSITY DETERMINES PLANT BIODIVERSITY, ECOSYSTEMVARIABILITY AND PRODUCTIVITY

The functioning and stability of terrestrial ecosystems are determined by plant biodiversity and species composition(1-5). However. the ecol ogical mechanisms by which plant biodiversity and species composition are regulated and maintained are not well understood. These mechanisms need to be identified to ensure successful management for conservatio n and restoration of diverse natural ecosystems. Here we show,by using two-independent, but complementary, ecological experiments, that belo w-ground diversity of arbuscular mycorrhizal fungi (AMF) is a major fa ctor contributing to the maintenance of plant biodiversity and to ecos ystem functioning. At low AMF diversity, the plant species composition and overall structure of microcosms that simulate European calcareous grassland fluctuate greatly when the AMF taxa that are present are ch anged. Plant biodiversity, nutrient capture and productivity in macroc osms that simulate North American old-fields increase significantly wi th increasing AMF-species richness. These results emphasize the need t o protect AMF and to consider these fungi in future management practic es in order to maintain diverse ecosystems. Our results also show that microbial interactions can drive ecosystem functions such as plant bi odiversity, productivity and variability.