Arbuscular mycorrhizal mycelial respiration in a moist tropical forest

Authors

  • Andrew T. Nottingham,

    1. Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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  • Benjamin L. Turner,

    1. Smithsonian Tropical Research Institute, 0843-03092 Balboa, Ancon, Panama
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  • Klaus Winter,

    1. Smithsonian Tropical Research Institute, 0843-03092 Balboa, Ancon, Panama
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  • Marcel G. A. van der Heijden,

    1. Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
    2. Ecological Farming Systems, Research Station ART, Swiss Federal Research Institute Agroscope, Zurich, Switzerland
    3. Plant–Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, 3508 TB, Utrecht, the Netherlands
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  • Edmund V. J. Tanner

    1. Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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Author for correspondence:
Andrew T. Nottingham
Tel: +44 (0) 1223 333900
Email: atn24@cam.ac.uk

Summary

  • 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.

Ancillary