Mite community composition across a European transect and its relationships to variation in other components of soil biodiversity

• Used extensive transect on which multiple aspects of soil biodiversity were measured.
• Composition of mite community varied with bio-climatic zone, land-use type.
• Mite community primarily related to extent of fungal dominance of microbial biomass.
• Composition of Mesostigmata community correlated with microbial activity (MSIR).
• At this spatial scale mites do not appear to be a good indicator of overall soil biodiversity.

The sustainable use of soils requires the protection of soil biodiversity because of its importance in the delivery of ecosystems services. However, no effective indicator exists which would allow assessment of the current state of biodiversity and is sensitive to change. This study, which is a component of the EcoFINDERS project, examines the use of mites (Acari) as a possible biological indicator of soil community composition. Thirty-six sites were sampled across 10 European countries spanning four bio-climatic zones (Alpine, Atlantic, Continental and Mediterranean) and 3 land uses (arable, grassland and forestry) for both biotic and abiotic variables. Results show a significant effect of bio-climatic zone on mite communities; in particular, the Mediterranean region had a rather distinct composition. Land use type significantly affected mite community composition and there was a distinct association with forestry. Cross-taxon congruence among soil taxa was variable and generally weak. Procrustes analysis showed that there was little similarity between the patterns of variation in mite community composition and those of other taxonomic groups (Collembola, Enchytraeidae, Nematoda and microbes). Mite and Collembola communities had the strongest correlation (r = 0.4316, p < 0.001). There was also variation in the indicator values of individual mite groups. Mesostigmata were correlated with soil microbial activity, as assessed using Multiple Substrate Induced Respiration, and Prostigmata with Collembola.