Soil fauna, including mites, plays a central role in organic matter decomposition, microbial regulation or crumbly structure, and thus is considered central to soil ecosystem services. As changes in soil quality are directly reflected in changes in soil biodiversity, many soil invertebrates serve as effective bioindicators. The present, ongoing project investigates soil arthropod biodiversity across different soil types in Styria, Austria. In mites, it focuses on the two taxa most frequently used as soil bioindicators, Oribatida and Mesostigmata. Since they have different trophic roles and react differently to soil disturbances, assessing both groups concurrently may be best to monitor soil health. The project aims to generate national reference datasets for soil arthropod diversity in different habitat types and along stress gradients, offering a valuable foundation for future ecological assessments and methodological development Soil samples are collected twice annually (spring and autumn) at eight Styrian locations with different soil types. At each location, samples from undisturbed sites serve as ‘positive’ reference datasets and disturbed sites as ‘negative’ reference datasets. Five subsamples per site are collected using a soil corer. Soil arthropods are extracted with Berlese-Tullgren funnels and identified morphologically, and most representative taxa are also used for DNA barcode sequencing. Planned analyses include species diversity and species similarity, as well as distribution of higher taxa and functional groups. All resulting data will be uploaded to established public databases (e.g. EUdaphobase, NCBI GenBank). At the time of writing this abstract, two sampling events already took place (spring 2025 and autumn 2025). In spring 2025, a total of 14.870 arthropods were collected, 7.154 of them being oribatids and 1.492 mesostigmatids. The processing of the samples of the autumn 2026 collection is ongoing, presently 10.950 arthropods have been counted here, with 5.458 oribatids and 1.702 mesostigmatids. The initial results already indicate substantial mite diversity across sites and seasons.