The objective of the project is to investigate the responses of the peat microbial communities to long-term effects of warming and increased precipitation of nitrogen and sulfur compounds, using an 18-year in-situ peatland experiment simulating these perturbations. The field experiment, which has been running since 1995, has so far shown dramatic changes in vegetation distribution, groundwater level depths and concomitant exchange of carbon between the mire and the atmosphere as well as changes in methane formation, oxidation and, thus, methane emissions. In the present study 16S amplicon sequencing and shotgun metagenomics and metatranscriptomics are used to investigate the taxonomic and functional composition of microbial communities, respectively. The 16S amplicon data and the functional potential of the community (i.e. shotgun metagenomics) have been analysed and a manuscript is ongoing. The results indicate that increased N deposition is the most important factor modulating the microbial community, and that the impacts of these perturbations (nitrogen, sulfur, warming) on the microbial community either multiply or counteract one another. However, while the long-term perturbations resulted in a substantial shift in the taxonomic composition of microbial communities, only minor changes occurred in genome-encoded functional traits, indicating a functional redundancy. Thus, the analysis of the metatranscriptome will provide better insights on the effect of climate change on the peat microbial function.