Spatial and environmental factors are minor structuring forces in a soil Collembola metacommunity in a maize agroecosystem

Understanding the processes underlying species richness across multiple sites is a major challenge in ecology. Metacommunity theory assumes that local community assemblages are largely structured by spatial and environmental factors. However, the relative importance of these factors is not clear and has varied between studies. Most studies were conducted at sampling intervals that were short (< 10 m), or long (> 1 km). In this study, to address a dearth of data at intermediate sampling intervals, we examined the pattern of the soil Collembola metacommunity in an agroecosystem by sampling at 40m intervals to try to disentangle the relative influence of spatial-environmental interactions on community composition. The soil Collembola community was sampled at 121 locations arranged regularly within a 400m x 400m corn field, over three months (August, September, and October 2015). We used standard geospatial analysis of metacommunity structure analytical framework to identify the pattern of soil Collembola metacommunity, with three essential elements (coherence, species turnover, and boundary clumping), to provide clues to the processes driving community assembly. We used variance partitioning analysis to determine the relative contributions of spatial and environmental factors (e.g., soil pH value, soil organic matter, soil total nitrogen and soil water content). From the results of the analysis, the soil Collembola metacommunity showed a nested pattern (rather than random, checkerboards, nested subsets, evenly spaced, Clementsian and Gleasonian patterns) on all three sampling dates. Soil Collembola metacommunities have a less restricted distribution along the environmental gradient, and connectivity may be important in shaping the community composition at this intermediate sampling interval. Based on the results of the variance partitioning analysis, spatial factors only explained 7.03-14.4% of the soil Collembola community variance, while the environmental factors were not significant at this scale. Our results suggest that both spatial and environmental factors are minor drivers of soil Collembola communities at an intermediate sampling frequency, compared to other studies conducted at shorter or longer sampling intervals.