Relative roles of spatial factors, environmental filtering and biotic interactions in fine-scale structuring of a soil mite community

• Rules that govern soil mite assemblages were identified at a scale of 5 m.
• Soil mite communities showed non-random structures.
• Both spatial factors and environmental filtering were important drivers.
• Biotic interactions were less influential in the observed pattern.

Community theories suggest that community structuring depends on dispersal limitation, environmental filtering and biotic interactions. However, the relative roles of these factors at fine scale are less well understood. In this study, we attempt to determine the relative roles of spatial factors, environmental filtering and biotic interactions in the fine-scale (5 m) structuring of a soil mite community from a temperate deciduous forest in the Maoershan Ecosystem Research Station in northeastern China. In August 2012, we established three plots and collected 100 samples from each plot in a 5 × 5 m2 area using a spatially delimited sampling design. To quantify the relative contributions of the spatial and environmental processes, Moran's eigenvector maps (MEMs), variation partitioning analysis and partial Mantel test were used. Null and neutral models were used to disentangle the effects of biotic interactions. Null mode analyses were conducted for non-random patterns of species co-existence and significant species-pairs in the assemblage of soil mites, and to determine whether the observed pattern was the result of biotic interactions. The neutral model was used to identify whether the community structure shows divergence, convergence or neutrality. The results indicated that the relatively large and significant variance was due to spatial factors in all plots. The contribution of environmental filtering was relatively low and non-significant in all plots based on variation partitioning, while it was significant in Plot II based on a partial Mantel test. Soil organic matter content, soil pH, and soil and litter water content explained a significant part of the variance observed in the distribution of the mite community. Furthermore, the null model revealed a non-random co-occurrence pattern in the soil mite community, and the environmental niche overlap indicated a weak contribution of biotic interactions. The observed mean dissimilarity implied significant divergence in communities based on neutral model analysis. Collectively, these results emphasize that both spatial and environmental processes were important drivers in the fine-scale structuring of soil mite communities in a temperate deciduous forest and that biotic interactions were less influential in the observed pattern.