Abstract

Extramatrical mycelia (EMM) of ectomycorrhizal fungi are important in carbon (C) and nitrogen (N) cycling in forests, but poor knowledge about EMM biomass and necromass turnovers makes the quantification of their role problematic. We studied the impacts of elevated CO2 and N fertilization on EMM production and turnover in a Pinus taeda forest. EMM C was determined by the analysis of ergosterol (biomass), chitin (total bio- and necromass) and total organic C (TOC) of sand-filled mycelium in-growth bags. The production and turnover of EMM bio- and necromass and total C were estimated by modelling. N fertilization reduced the standing EMM biomass C to 57% and its production to 51% of the control (from 238 to 122kgCha(-1)yr(-1)), whereas elevated CO2 had no detectable effects. Biomass turnover was high (13yr(-1)) and unchanged by the treatments. Necromass turnover was slow and was reduced from 1.5yr(-1) in the control to 0.65yr(-1) in the N-fertilized treatment. However, TOC data did not support an N effect on necromass turnover. An estimated EMM production ranging from 2.5 to 6% of net primary production stresses the importance of its inclusion in C models. A slow EMM necromass turnover indicates an importance in building up forest humus.

Keywords

Duke Forest free-air CO2 enrichment (FACE); ectomycorrhiza; elevated CO2; extramatrical mycelium; fungal biomass; nitrogen (N) fertilization; stable isotopes; turnover

Published in

New Phytologist
2016, Volume: 211, number: 3, pages: 874-885

SLU Authors

• Ågren, Göran

  • Department of Ecology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Environmental Sciences
Microbiology
Ecology


Publication identifier

DOI: https://doi.org/10.1111/nph.13961

Permanent link to this page (URI)

https://res.slu.se/id/publ/81079