Ghost species form an important component of the epiphytic biota in temperate forests

Sequencing of environmental samples has great potential for biodiversity research, but its application is limited by the lack of reliable DNA barcode databases for species identifications. Such a database has been created for epiphytic lichens of Europe, allowing us to compare the results of environmental sequencing with standard taxonomic surveys. The species undetected by taxonomic surveys (what we term the ghost component) amount to about half of the species actually present in hectare plots of Central European forests. Some of these, which currently occur only as diaspores or weakly developed thalli, are likely to be favoured in the course of global change. The ghost component usually represents a larger fraction in managed forests than in old growth unmanaged forests. The total species composition of different plots is much more similar than suggested by taxonomic surveys alone. On a regional scale, this supports the well-known statement that \"everything is everywhere, but, the env..., , , # Ghost species form an important component of the epiphytic biota in temperate forests

[https://doi.org/10.5061/dryad.fqz612k0g](https://doi.org/10.5061/dryad.fqz612k0g)

The dataset contains Illumina amplicon sequencing of three barcode loci: nuclear ribosomal region ITS1, nuclear ribosomal region ITS2, and mitochondrial ribosomal SSU. The three barcoding loci were PCR-amplified from environmental samples of epiphytic lichen biomass. Sample pools of individual barcoding loci were sent for Illumina library preparation and sequencing (250 bp paired-end, two independent runs). The resulting reads were BLAST identified with the sequences of lichen taxa from Martin7 database (Vondrák J. et al., 2023: Martin7: a reference database of DNA barcodes for European epiphytic lichens and its taxonomic implications. Preslia 95: 311-345.)

## Description of the data and file structure

The two independent Illumina sequencing runs (I2 and I3) yielded following fastq data:

I2_A: ITS2 barcode amplifi...