Production and turnover of ectomycorrhizal extramatrical mycelial biomass and necromass under elevated CO2 and nitrogen fertilization.
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 122 kg C ha(-1)  yr(-1) ), whereas elevated CO2 had no detectable effects. Biomass turnover was high (˜13 yr(-1) ) and unchanged by the treatments. Necromass turnover was slow and was reduced from 1.5 yr(-1) in the control to 0.65 yr(-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.
School of Science & Technology, Örebro University, Örebro, SE-701 82, Sweden.
Alf
A
Ekblad
School of Science & Technology, Örebro University, Örebro, SE-701 82, Sweden.
Anna
A
Mikusinska
Department of Ecology, Swedish University of Agricultural Sciences, PO Box 7044, Uppsala, SE-750 07, Sweden.
Göran I
GI
Ågren
Agroscope, Reckenholzstrasse 191, Zürich, 8046, Switzerland.
Lorenzo
L
Menichetti
Department of Biology, Microbial Ecology, Lund University, Lund, SE-223 62, Sweden.
Håkan
H
Wallander
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Rytas
R
Vilgalys
Department of Biology, Microbial Ecology, Lund University, Lund, SE-223 62, Sweden.
Adam
A
Bahr
School of Science & Technology, Örebro University, Örebro, SE-701 82, Sweden.
Ulrika
U
Eriksson
D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D002247:Carbon Isotopes; D002686:Chitin / Q000378:metabolism; D004875:Ergosterol / Q000378:metabolism; D005308:Fertilizers; D065928:Forests; D008954:Models, Biological; D025282:Mycelium / Q000187:drug effects / Q000254:growth & development*; D009584:Nitrogen / Q000494:pharmacology*; D041603:Pinus taeda / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D002247:Carbon Isotopes; D005308:Fertilizers; D002686:Chitin; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen; D004875:Ergosterol
Duke Forest free-air CO2 enrichment (FACE); ectomycorrhiza; elevated CO2; extramatrical mycelium; fungal biomass; nitrogen (N) fertilization; stable isotopes; turnover