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.