Higher spatial than seasonal variation in floodplain soil eukaryotic microbial communities

Beta diversity is a key component of biodiversity with implications ranging from species dynamics to ecosystem functioning. However, beta-diversity and its drivers have received little attention, especially for micro-eukaryotes which play key roles in soil functioning. We studied the diversity of soil micro-eukaryotes in a Swiss lowland floodplain using high-throughput Illumina sequencing of soil DNA. We determined the temporal vs. spatial patterns of soil micro-eukaryotic alpha- and beta-diversity in six contrasted habitats sampled over one year. We identified the drivers of these patterns among soil conditions and functions and identified indicator taxa of habitats in each season. We found higher spatial than temporal variability and a strong space-time interaction in soil microeukaryotic diversity patterns as well as in their edaphic drivers, which contrasts with previous observation of bacterial diversity patterns. Our results show that, although soil micro-eukaryotic diversity indeed varies seasonally, it is correlated most strongly with edaphic variables and vegetation but the strength of correlations with individual drivers varied seasonally. Microbial diversity patterns and their drivers can thus differ quite substantially among seasons and taxa. Despite the dominance of spatial patterns, the temporal component of microbial diversity should not be ignored to accurately estimate the diversity and the complexity of soil microbial community assembly processes. Given the importance of soil microbial diversity for ecosystem functioning such knowledge is relevant for land management.