OTU count was positively correlated with read count (Pearson’s r = 0.90), thus we avoided single sample based richness estimates. For richness estimates of the habitats we applied a shared corrected Chao index (Chiu et al. 2014).More specifically, we provided a range for the Chao estimates based on a lower conservative OTU filtering and an upper overestimate based on unfiltered OTUs. In the former case all OTUs that occurred only in one sample of the dataset (independent of the absolute OTU frequency) were removed while in the latter case all OTUs including singletons were kept. Supporting rarefaction curves displaying the sampling effort for Eukarya and Fungi based on a singleton filtered OTU matrix are provided in the Suppl. material 5).