Nitrogen deposition and temperature structure fungal communities associated with alpine moss-sedge heath in the UK

Moss-sedge heath, an important habitat of oceanic alpine regions, is under threat from elevated nitrogen (N) deposition and rising temperatures increasing decomposition rates and fragmentation of the extensive, thick moss mats of Racomitrium lanuginosum which characterise this habitat. Here, we examine the potential effects of N deposition and temperature on fungal communities associated with R. lanuginosum mats. Fungal community composition in both green moss shoots and underlying soil were significantly influenced by mat temperatures and green moss shoot N contents. Total OTU, Ascomycota, Basidiomycota and saprotrophic fungal richness in shoots were all positively related to temperature, while in soil, the richness of all groups, except Basidiomycota, was positively related to moss tissue N. The observed community changes suggest that increased N loading and increasing temperatures are ameliorating growing conditions for fungi associated with moss-sedge heath. Further study is required to determine if the observed changes in fungal communities contribute to accelerated decomposition of moss mats and degradation of the habitat.