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| Quantification of ectomycorrhizal mycelium |
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S. Raidl
Section Mykologie, Institut für Systematische Botanik, LMU München, Menzinger Straße 67, D-80638 München, Germany
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Ectomycorrhizae are generally accepted to be the primary nutrient and water absorbing organs of the common forest trees of boreal and temperate forests. In most species of ectomycorrhizal fungi, nutrient uptake is performed by the extramatrical mycelium consisting of single hyphae or strands of bundled hyphae usually called rhizomorphs. Depending on the organisation of the rhizomorphs, several morphotypes or exploration types of ectomycorrhizal mycelia can be distinguished, which may differ strongly in structure and extension as well as in biomass.
In rhizotrone experiments, spruce seedlings inoculated with the ectomycorrhizal fungi Piloderma croceum and Tomentellopsis submollis were exposed to different CO2 concentrations and nitrogen fertilization. Elevated CO2 combined with N-amendment showed in both the fungal species an increase in their biomass: In Piloderma the biomass of the mycorrhizal mantle (measured by the length of the mycorrhizal systems) increased nearly 25 % and the biomass of the extramatrical mycelium (measured by the total hyphal length) about 50 %; in Tomentellopsis the mantle biomass increased about 60 %.The possible conversion of mycorrhizal and hyphal length into real biomass data (fungal dry weight in mg) may allow a rough estimation about the carbon need of symbiontic ectomycorrhizal fungi.
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