Roles of environmental and spatial factors in structuring assemblages of forest-floor Mesostigmata in the boreal region of Northern Alberta, Canada

Mesostigmatid mites (Arachnida: Parasitiformes) are a diverse, abundant group of soil predators; however, in comparison to some other groups of soil fauna (e.g. oribatid mites), little is known about environmental and spatial processes that influence local species richness and abundance. The main objective of our study was to identify factors strongly correlated with assemblages of Mesostigmata from boreal forests in northern Alberta, Canada. Soil and litter samples came from 62 sites with up to 4 samples per site (216 samples total), with a north–south range of ~800 km between sites. Environmental variables included ground cover type (e.g. moss, lichen, grass), disturbance intensity, precipitation, and temperature. From 3021 individual adult Mesostigmata, we identified 101 species/morphospecies from 21 families, the most species-rich being Ascidae, Zerconidae, and Digamasellidae. Redundancy analysis determined that the environmental variables that correlated most strongly with mite assemblages were precipitation, moss cover, and disturbance intensity. Spatial distance between sites had almost the same explanatory power, as environmental factors. Assemblages became more dissimilar with increasing spatial distance. This study showed the importance that particular environmental and spatial factors likely have on Mesostigmata composition in Canadian boreal forests; however, manipulative studies are required to be able to attribute causation to these correlations.