Disentangling the drivers of ground-dwelling macro-arthropod metacommunity structure at two different spatial scales

Abstract

Research on factors determining soil metacommunity patterns across multiple spatial scales is quite rare. In this study, we aimed to compare the mechanisms that drive species co-occurrence and consequently form the ground-dwelling macro-arthropod metacommunity structure at local (104 m) and regional (106 m) scales. For the comparison, we used three distant (approximately 200 km from each other) locations within the northeast black soil region of China. At each location, we had five sampling plots (at a distance of 500 m from each other), and at each plot, we had five sampling sites within agrolandscapes (10 m away from each other). At each site, we set three pitfall traps. Animals were collected three times: in May, July and September 2015. The analysis of the elements of metacommunity structure showed that the regional level of the metacommunity always demonstrated a Clementsian structure (a grouped distribution of species along environmental gradients), while the local scale metacommunity structure was dependent on sampling month and varied between Clementsian, random and nested distributions. Based on the results of a variance partitioning analysis, including pure environmental (environmental filtering) and pure spatial predictors (dispersal), as well as the interaction of environmental and spatial factors (shared fraction), we observed that the shared fraction at the regional scale was 30% larger than at the local scale. A species co-occurrence analysis further demonstrated that the observed C-scores were not significantly higher than simulated indices for each guild separately at the local scale. Our results suggest that biotic interactions are not the key drivers of metacommunity structure at the local scale in agriculture, while environmental filtering and dispersal appear to be key drivers of metacommunity structure at the regional scale.