Extramatrical ectomycorrhizal mycelium contributes one-third of microbial biomass and produces, together with associated roots, half the dissolved organic carbon in a forest soil

Mona N Högberg; Peter Högberg

doi:10.1046/j.1469-8137.2002.00417.x

Extramatrical ectomycorrhizal mycelium contributes one-third of microbial biomass and produces, together with associated roots, half the dissolved organic carbon in a forest soil

New Phytol. 2002 Jun;154(3):791-795. doi: 10.1046/j.1469-8137.2002.00417.x.

Authors

Mona N Högberg¹, Peter Högberg¹

Affiliation

¹ Department of Forest Ecology, Section of Soil Science, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.

PMID: 33873454
DOI: 10.1046/j.1469-8137.2002.00417.x

Abstract

• A large-scale tree-girdling experiment enabled estimates in the field of the contribution of extramatrical mycelium of ectomycorrhizal (ECM) fungi to soil microbial biomass and by ECM roots and fungi to production of dissolved organic carbon (DOC). • Tree-girdling was made early (EG) or late (LG) during the summer to terminate the flow of photosynthate to roots and ECM fungi. Determination of microbial C (C_micr ) and microbial N in root-free organic soil was performed by using the fumigation-extraction technique; extractable DOC was determined on unfumigated soil. • Soil C_micr was 41% lower on LG than on control plots 1 month after LG, whereas at the same time (that is, 3 months after EG), the C_micr was 23% lower on EG than on control plots. Extractable DOC was 45% lower on girdled plots than control plots. • Our results, which are of particular interest as they were obtained directly in the field, clearly demonstrate the important contribution by extramatrical ECM mycelium to soil microbial biomass and by ECM roots to the production of DOC, a carbon source for other microbes.

Keywords: ectomycorrhizal fungi; ectomycorrhizal mycelium; extractable dissolved organic carbon (DOC); forest soil; fumigation-extraction; microbial N; soil microbial biomass.