Using glomalin as an indicator for arbuscular mycorrhizal hyphal growth: an example from a tropical rain forest soil

Glomalin concentrations of extra-radical arbuscular mycorrhizal (AM) hyphae were estimated by deploying hyphal in-growth cores containing glomalin-free sand in field soils in a tropical forest and in pot cultures. In field soils, glomalin was 0.044±0.013 μg m⁻¹ hyphae. In pot cultures glomalin concentrations were lower (range 0.0068-0.036 μg m⁻¹), and varied significantly among species. Using this technique, preliminary estimates of extraradical AM hyphal production on Inceptisols were 1.91 Mg ha⁻¹yr⁻¹ and on Oxisol were 1.47 Mg ha⁻¹ yr⁻¹, but they could range between 0.9-5.7 Mg ha⁻¹ yr⁻¹. These rates of hyphal production are approximately 10% (range 5-33%) of estimated above ground primary production of the forest.