The abundance of extramatrical vesicular-arbuscular mycorrhizal hyphae was determined in soil samples collected from the upper 10 cm directly beneath grasses during the wet season when plants were actively growing. Total extramatrical hyphae length ranged from 0.03-6.95 m g-1 soil (arithmetic mean 1.86 m g-1, geometric mean 1.29 m g-1). Hyphal length was negatively correlated with organic matter content and total soil mineral nutrient concentration, as well as concentrations of many individual minerals. Hyphal length was positively correlated with the ratio of plant to soil nutrient contents. Results suggest that mycorrhizal associations act to stabilize ecosystem nutrient fluxes, helping to maintain plant concentrations within narrow levels compared with soil variation, and thereby ameliorating potential nutritional stress in both plants and herbivores. -from Authors