Article

Plant and Soil

, Volume 281, Issue 1, pp 15-24

Mycorrhizal Hyphal Turnover as a Dominant Process for Carbon Input into Soil Organic Matter

  • Douglas L. GodboldAffiliated withSchool of Agricultural and Forest Sciences, University of Wales Email author 
  • , Marcel R. HoosbeekAffiliated withLaboratory of Soil Science and Geology, Department of Environmental Sciences, Wageningen University
  • , Martin LukacAffiliated withSchool of Agricultural and Forest Sciences, University of Wales
  • , M. Francesca CotrufoAffiliated withDipartimento di Scienze Ambientali, Seconda Università degli Studi di Napoli
  • , Ivan A. JanssensAffiliated withDepartment of Biology, University of Antwerpen (UA)
  • , Reinhart CeulemansAffiliated withDepartment of Biology, University of Antwerpen (UA)
  • , Andrea PolleAffiliated withInstitut für Forstbotanik, Universität Göttingen
  • , Eef J. VelthorstAffiliated withLaboratory of Soil Science and Geology, Department of Environmental Sciences, Wageningen University
  • , Giuseppe Scarascia-MugnozzaAffiliated withDi.S.A.F.Ri., Università degli Studi della Tuscia
    • , Paolo De  AngelisAffiliated withDi.S.A.F.Ri., Università degli Studi della Tuscia
    • , Franco MigliettaAffiliated withInsitute of Biometeorology, IBIMET-CNR
    • , Alessandro PeressottiAffiliated withDipartimento Produzione Vegetale eTechnologie Ambientali, Università di Udine 208

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Abstract

The atmospheric concentration of CO2 is predicted to reach double current levels by 2075. Detritus from aboveground and belowground plant parts constitutes the primary source of C for soil organic matter (SOM), and accumulation of SOM in forests may provide a significant mechanism to mitigate increasing atmospheric CO2 concentrations. In a poplar (three species) plantation exposed to ambient (380 ppm) and elevated (580 ppm) atmospheric CO2 concentrations using a Free Air Carbon Dioxide Enrichment (FACE) system, the relative importance of leaf litter decomposition, fine root and fungal turnover for C incorporation into SOM was investigated. A technique using cores of soil in which a C4 crop has been grown (δ13C −18.1‰) inserted into the plantation and detritus from C3 trees (δ13C −27 to −30‰) was used to distinguish between old (native soil) and new (tree derived) soil C. In-growth cores using a fine mesh (39 μm) to prevent in-growth of roots, but allow in-growth of fungal hyphae were used to assess contribution of fine roots and the mycorrhizal external mycelium to soil C during a period of three growing seasons (1999–2001). Across all species and treatments, the mycorrhizal external mycelium was the dominant pathway (62%) through which carbon entered the SOM pool, exceeding the input via leaf litter and fine root turnover. The input via the mycorrhizal external mycelium was not influenced by elevated CO2, but elevated atmospheric CO2 enhanced soil C inputs via fine root turnover. The turnover of the mycorrhizal external mycelium may be a fundamental mechanism for the transfer of root-derived C to SOM.

Keywords

δ13C abundance C sequestration EuroFACE mycorrhiza poplar SOM