Arbuscular mycorrhizal mycelial respiration in a moist tropical forest
Author for correspondence:
Andrew T. Nottingham
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- •Arbuscular mycorrhizal fungi (AMF) are widespread in tropical forests and represent a major sink of photosynthate, yet their contribution to soil respiration in such ecosystems remains unknown.
- •Using in-growth mesocosms we measured AMF mycelial respiration in two separate experiments: (1) an experiment in a semi-evergreen moist tropical forest, and (2) an experiment with 6-m-tall Pseudobombax septenatum in 4.5-m3 containers, for which we also determined the dependence of AMF mycelial respiration on the supply of carbon from the plant using girdling and root-cutting treatments.
- •In the forest, AMF mycelia respired carbon at a rate of 1.4 t ha−1 yr−1, which accounted for 14 ± 6% of total soil respiration and 26 ± 12% of root-derived respiration. For P. septenatum, 40 ± 6% of root-derived respiration originated from AMF mycelia and carbon was respired < 4 h after its supply from roots.
- •We conclude that arbuscular mycorrhizal mycelial respiration can be substantial in lowland tropical forests. As it is highly dependent on the recent supply of carbon from roots, a function of aboveground fixation, AMF mycelial respiration is therefore an important pathway of carbon flux from tropical forest trees to the atmosphere.