We observed an extremely high abundance and diversity of AM fungi.

Support for the Functional Equilibrium Model was nuanced and expands our understanding of AM fungal ecology.

There was little response to grazing. This suggests that either AM fungi are stable in regards to large ungulate grazing, or that responses are ephemeral.

Responses to the phosphorous (P) gradient suggest that P limitation influences AM fungal structures across the gradient. Although new production of AM fungal hyphae is greatest in low-P sites, the standing crop of hyphae is greatest in the dry, high-P sites.

There was a very tight inverse relationship between soil P and annual rainfall. Our models suggest that AM fungal biomass is directly influenced by P and indirectly influenced by rainfall.

The community of AM fungal spores was responsive to numerous environmental factors. Responses by individual families were varied, suggesting that niche partitioning occurs in response to environmental gradients.

Within the family of Gigasporaceae, we observed evidence for temporal partitioning between auxiliary cells and spores. Previously, this has only been documented in laboratory cultures. Our study provides the first field evidence that auxiliary cells may function as P storage units and are precursors to spores.