Authors: Torppa, Kaisa; Engelbrecht Clemmensen, Karina ;Glimskär, Anders ;Skånes, Helle;Roslin, Tomas;Viketoft, Maria;Taylor, Astrid;Maaroufi, Nadia;

Old semi-natural grasslands are important for plant conservation in Sweden, but it is uncertain if they also benefit belowground biodiversity, such as earthworms. Traditional methods for earthworm species determination make use of morphological characteristics and therefore fail to determine juveniles that still lack certain morphological features and cryptic species that are morphologically similar. In this study, we describe the earthworm diversity, species composition and densities, determined by species barcoding, in 28 old semi-natural grasslands in Uppland, Sweden. We also characterize the drivers of earthworm community composition in these grasslands, by linking environmental variables to species densities using joint species distribution modelling. The environmental variables determined for each grassland include vegetation (diversity, plant functional group coverages, vegetation height), soil properties (texture, SOC, total N, total P, pH), management (fertilization, grazing intensity) and landscape heterogeneity around sampling locations.
We specifically ask the following questions: 1) Does DNA barcoding reveal patterns that are undetectable with traditional determination methods, such as higher species richness or differing patterns in adult and juvenile densities within a species? 2) Which environmental parameters best explain earthworm species richness and diversity in old grasslands? 3) Do earthworm species and ecological groups respond differently to environmental parameters?