Understanding ecological and evolutionary mechanisms that drive biodiversity patterns is important for comprehending biodiversity. Despite being critically important to the functioning of ecosystems, the mechanisms driving belowground biodiversity are little understood. We here investigated the radiation and trait diversity of soil oribatid mites from two mountain ranges, i.e. the Alps in Austria and Changbai Mountain in China, at similar latitude in the temperate zone differing in orogenesis and exposed to different climates. We collected and sequenced soil oribatid mites from forests at 950 to 1700 m at each mountain and embedded them into the chronogram of species from temperate Eurasia. We investigated the phylogenetic age of oribatid mites and compared the node age of species with the mountain uplift time of the Alps and Changbai Mountain. We then inspected trophic variation, geographical range size and reproductive mode, and identified traits that promote oribatid mite survival and evolution in montane forest ecosystems. We found that oribatid mites on Changbai Mountain are phylogenetically older than species in the Alps. All species on Changbai Mountain evolved long before the mountain uplift, but some species in the Alps evolved after the orogenesis. On Changbai Mountain more species possess broader trophic variation, have larger geographical range sizes and more often reproduce via parthenogenesis compared to species from the Alps. Species on Changbai Mountain survived the mountain uplift or colonized the mountain thereafter supporting the view that generalistic traits promote survival and evolution in phylogenetically old soil animal species. Collectively, our findings highlight that combining species traits and phylogeny allow deeper insight into the evolutionary forces shaping soil biodiversity in montane ecosystems.

Urbanization-induced environmental changes such as habitat fragmentation impacts arthropod assemblages and food web-related ecosystem functions, such as nutrient cycling, carbon storage and energy fluxes. Yet, we lack insight into how arthropod food webs are structured along urban fragmentation gradients. Here, we investigated the community composition and food web structure of litter-dwelling arthropods along fragmentation gradients (green median strip, urban park, urban forest and natural forest). We found the density of litter-dwelling arthropods in median strip and urban park to be two to four times higher than in urban and natural forests, with, as indicated by literature-based stable isotope values, 67% - 68% of the individuals comprising primary consumers (trophic level I) in median strip and urban park. Urban forests, reserved for biodiversity conservation, hosted the least arthropod density, taxa richness, biomass and body mass, but were colonized by a high number of specialist arthropods, e.g. Archaeognatha and Isoptera. Food webs were most simple in urban forest, but more complex in median strip and urban parks, i.e. open fragments, with abundant primary and secondary consumers including decomposers. Chilopoda and Araneae formed the apex predators in fragments and mostly consumed other predators of trophic level III. The biomass of decomposed litter on the soil surface as major resource of the soil animal community significantly correlated positively with the density of arthropods of trophic levels I, III and IV. Supporting the dominance of bottom-up forces, the density of adjacent trophic levels consistently correlated positively. Overall, our results suggest that small size urban fragments maintain a diverse community of arthropods forming complex food webs and thereby may contribute to conserving biodiversity and providing important ecosystem functions.