Abstract
DarkDivNet is a global research collaboration which explores dark diversity - the set of species that are absent from a site despite being suitable under the site conditions and present in the region. Participants of the network survey vascular plant diversity both at local (10 m x 10 m) and regional scales (radius 10 km) using a standardized approach. They also measure simple plant traits and collect soil samples. Observed and dark diversity together form the site-specific species pool, and the ratio of observed diversity and dark diversity describes community completeness. We shall explore how observed and dark diversity, site-specific species pool and community completeness vary across natural and anthropogenic gradients. We link plant diversity measures to the information obtained from environmental DNA: soil biota and plant taxa that occurred at the site before. We will refine existing dark diversity methods and use large vegetation databases to infer species habitat suitability. We expand the dark diversity concept from a purely taxonomy-based approach to include the functional and phylogenetic aspects of diversity. DarkDivNet currently includes 161 planned sampling areas globally, but new participants are welcome. The main vegetation sampling period is scheduled until September 2020, with the first research papers being produced after that.