Determinants of Soil Microarthropod Community Biodiversity in the Svalbard High Arctic: Locality or Vegetation Community?

Arctic ecosystems, such as those in Svalbard, are facing diverse stressors, being at the forefront of global warming while also facing increasing anthropogenic impacts. This poses a variety of threats to biodiversity, including soil microarthropod communities, which play a crucial role in the functioning of the Arctic ecosystems. Monitoring these groups in Svalbard is challenging due to limited baseline knowledge, logistically demanding and costly sampling, and the difficult and time-consuming identification of soil microarthropod communities. In contrast, vegetation maps are relatively fast and easy to construct, often relying on remote sensing, and there are comprehensive vegetation maps available. These vegetation maps integrate numerous environmental characteristics into one vegetation community describing vegetation biodiversity. While relationships between soil microarthropod communities and vegetation communities have been documented in other regions, it remains unclear whether such patterns hold in the Arctic and whether existing vegetation maps could serve as proxies for soil microarthropod community composition and macroecology analyses. To address this question, we analyzed 172 soil samples collected from 33 localities across latitudinal and longitudinal gradients, representing 11 vegetation classes. In total, nearly 180,000 microarthropods were recorded, including approximately 63,000 Acari (87% Oribatida, 2% Mesostigmata, 10% Trombidiformes) and 116,000 Collembola. Oribatida and Mesostigmata were identified to family, while other groups were counted. Our analysis reveals that location is more important to soil microarthropod communities than vegetation community per se, indicating that these groups respond differently to local conditions. The variability of the Acari family abundances was mostly explained by Sørkapp, the southernmost and climatically harsh locality, followed by Fjortendejulibukta (northwestern Svalbard), which has a relatively mild climate but is subject to human disturbance. Locality also affected Oribatida diversity, mainly explained by Tjuvfjord in eastern Svalbard. At a larger scale, the approach of vegetation community classifications proved to be only weak proxies for the Acari and Collembola communities.