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

Cercozoa 和 Oomycota 包含巨大的生物多样性和林木和其他植被的重要病原体。我们使用空气采样器分析了这些原生动物门在 3 月份（在叶前) 和 May (叶子展开后) 2019 年，采用独立于培养的高通量元条形码方法。我们在空气样本中分别发现了具有 122 和 81 个 OTU 的高多样性 Cercozoa 和 Oomycota。特别是卵菌在两个采样日期之间显示出群落组成的显着差异。然而，树冠和靠近地面的空气样本之间的群落组成差异可以忽略不计，而且树种特性也不影响空气样本中的群落，表明原生生物通过空气传播的分布在森林生态系统中不受空间限制。寄主物种不在森林中的植物病原体的 OTU 表明繁殖体从森林生物群落外扩散。总体而言，我们的研究结果有助于更好地了解原生生物和原生生物病原体在空气中传播的随机过程，这是了解它们在森林生态系统中群落组装机制的先决条件。