| Summary: | on the effects of vegetation and associated changes on above and below-ground processes in tundra soils. In a sub-arctic alpine tundra heath, vegetation composition was manipulated by removing plant species with certain mycorrhizal associations. The experiment will follow the effects of this manipulation on above and below-ground biogeochemical and ecological processes over the next decades. This thesis explores the links between fungal community composition and plant mycorrhizal type, plant community composition and soil chemistry. Analysis of soil and root-associated fungal DNA was used to relate the fungal community composition at the onset of the experiment (i.e. undisturbed baseline) to the fungal community composition one year after the first plant removal, as well as to soil chemical properties and vegetation observations. We found a strong relationship between plant mycorrhizal association type and root-associated fungal community composition of 28 plant species from the study site. Moreover, vegetation community composition explained a considerable part of soil fungal community composition (42 %), suggesting a systematic link between the two. Vegetation changes simulated by plant functional group removal, however, did not significantly affect the fungal community composition after one year. Changes could be expected in the longer term but there was no evidence for a quick turnover below-ground after rapid above-ground changes.
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