Distinct patterns suggest that assembly processes differ for dominant arthropods in above-ground and below-ground ecosystems

Depiction of the patterns and underlying processes within communities is a key topic in community ecology. However, we still know relatively little about these patterns and processes for the dominant arthropod communities living in above-ground (AG) and below-ground (BG) ecosystems. To test whether the community patterns for AG communities are consistent with those of BG communities and to inform whether the underlying processes are congruous, samples of ground carabid and soil collembolan communities were collected from a primary mixed forest in Northeastern China. Within a 9-ha permanent forest plot, 225 carabid samples were captured using pitfall traps in August 2015, and 768 collembolan samples were collected using soil augers in September 2014. Vegetative, topographic, soil and spatial variables were also measured. Geostatistics, null models and variation partitioning were used to evaluate the spatial distributions, co-occurrence patterns and contributions of environmental and spatial factors, respectively. The carabid community did not show obvious spatial autocorrelation, while the collembolan community showed significant spatial autocorrelation and aggregation on multiple spatial scales. Both communities showed non-random co-occurrence patterns, but of different types. The carabid community was driven by weak and insignificant topographic filtering, while the collembolan community was driven by strong and significant topographic filtering. The two communities were each shaped by spatial factors, but the carabid community’s spatial distribution may be regulated by their high dispersal ability, which allowed the beetles to overcome topographic constraints. On the other hand, the collembolan community’s spatial distribution may be regulated by their dispersal limitations, which combine with topographic constraints to create an aggregation pattern. Finally, we conclude that the dominant AG and BG arthropod communities exhibit different community structure patterns controlled different spatial processes.