Functional Role of Mycorrhiza in the Competition for Water and Nitrogen

Beech trees form symbiotic associations with different species of ectomycorrhizal fungi. It is hypothetised that these fungi form characteristic communities, adapted to the prevailing environmental conditions improving the supply of nitrogen and water to the host tree. To test this hypothesis, mycorrhizal abundance and species composition in beech forests differing in nitrogen exposition and drought will be characterised and the role of mycorrhiza in nitrogen nutrition will be determined by measuring N-uptake of roots, hyphae and mycorrhizae using mesh bags and stable nitrogen isotopes under different field-experimental treatments. Shifts in mycorrhizal communities in response to changes in nitrogen and water supply to beech will be tested under controlled conditions in phytotrons and glasshouses. To the test the function of mycorrhizae for nitrogen nutrition and water supply to beech in comparison with other microorganisms, N-supply and water status of non-mycorrhizal and mycorrhizal beech will be investigated in growth boxes with separated root and hyphal compartments.

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Teilprojekt zu FOR 788:  Competitive Mechanisms of Water and Nitrogen Partitioning in Beech-Dominated Decidiuous Forests