Environmental drivers of litter- and soil-dwelling springtail communities across European forests, assessed by morphotaxonomy and soil DNA metabarcoding

Springtails are abundant in forest litter and soils, where they play a crucial role in the transformation and decomposition of organic matter. However, most data on springtail communities originates from studies at the local and regional levels, while larger-scale studies are lacking. To address this gap, we applied standardized methods to investigate springtail communities in forests from a Europe-wide study, covering a pedo-climatic gradient across 25 sites in 17 countries. We evaluated which environmental factors influence springtail density, alpha-diversity, and community structure. We sampled forest litter and underlying soil separately and applied both morphological identification and soil DNA metabarcoding. On average, we recorded approximately 2,500 individuals m-2 for litter-dwelling and 10,500 individuals m-2 for soil-dwelling springtails, with the highest values recorded in the Arctic and Boreal regions and the lowest in the Mediterranean region. Species richness averaged 5.2 in the litter and 7.0 in the soil applying morphotaxonomy, whereas using metabarcoding indicated a higher richness of 10.2 in the soil. Using morphotaxonomy, the key factor influencing density and alpha-diversity of litter-dwelling springtails positively was litter dry mass, whereas mean annual temperature had a negative effect, and the key factors positively influencing the density of soil-dwelling springtail were soil pH and clay content, whereas mean annual precipitation had a negative effect. When data from metabarcoding were used, similar key factors emerged. Our results demonstrate that metabarcoding represents a promising approach for future large-scale studies when simple and reliable methods are needed to rapidly assess shifts in springtail community profiles.