To the canopy and beyond: Air dispersal as a mechanism of ubiquitous protistan pathogen assembly in tree canopies

• We analysed air dispersal of Cercozoa and Oomycota with an sampler in tree crowns. Oomycete community assembly is driven by random factors neutral processes. Distribution protistan propagules through the was not spatially restricted. Our results demonstrate pathogens from outside biome. Air may explain ubiquitous presence forests. contain a huge biodiversity important forest trees other vegetation. analyzed these phyla near-ground (~2 m) crowns (~25 three species (oak, linden ash) temperate floodplain March (before leafing) May (after leaf unfolding) 2019 cultivation-independent high-throughput metabarcoding approach. found high diversity samples 122 81 OTUs, respectively. Especially oomycetes showed significant difference composition between both sampling dates. Differences canopies close to ground were however negligible, also identity did affect communities samples, indicating that distribution restricted ecosystem. OTUs plant pathogens, whose host occur forest, Overall, our lead better understanding stochastic processes protists prerequisite understand mechanisms their ecosystems.