Functional diversity of beech (Fagus sylvatica L.) ectomycorrhizas with respect to nitrogen nutrition in response to plant carbon supply

European beech (Fagus sylvatica L.) is the dominant tree species of the potential natural vegetation
in Central Europe. In temperate forest ecosystems not affected by anthropogenic activities, nitrogen
is a growth-limiting factor. Beech trees form mutualistic associations with ectomycorrhizal (EM)
fungi, which have the ability to take up different inorganic and organic nitrogen-containing
compounds and to improve plant nitrogen-status. EM fungal communities and functions are therefore
of major interest for tree nutrition.
In this work, the functional diversity of beech ectomycorrhizas with respect to nitrogen (N) and
carbon (C) availability has been investigated. The following hypotheses were tested:
Mobilization of litter-derived nitrogen by EM fungi differs amongst fungal species in the first
phase of litter decomposition.
Long-distance EM exploration types accumulate more litter-derived N than short distance
ones, because of their higher accessibility to the litter.
Differences in litter-derived N accumulation between EM fungal species decrease over time
with the increasing availability of litter-released N via the soil.
Functional differences exist between EM fungal species with respect to nitrogen uptake and
processing.