No abstract

It has been widely accepted that there is a distance‐decay pattern in the soil microbiome. However, few studies have attempted to interpret the microbial distance‐decay pattern from the perspective of quantifying underlying processes. In this study, we examined the processes governing bacterial community assembly at multiple spatial scales in maize fields of Northeast China using Illumina MiSeq sequencing. Results showed that the processes governing spatial turnover in bacterial community composition shifted regularly with spatial scale, with homogenizing dispersal dominating at small spatial scales and variable selection dominating at larger scales, which in turn explained the distance‐decay pattern that closer located sites tended to have higher community similarity. Together, homogenizing dispersal and dispersal limitation resulting from geographic factors governed about 33% of spatial turnover in bacterial community composition. Deterministic selection processes had the strongest influence, at 57%, with biotic factors and abiotic environmental filtering (mainly imposed by soil pH) respectively contributing about 37% and 63% of variation. Our results provided a novel and comprehensive way to explain the distance‐decay pattern of soil microbiome via quantifying the assembly processes at multiple spatial scales, as well as the method to quantify the influence of abiotic, biotic, and geographic factors in shaping microbial community structure, thus enabling understanding of widely acknowledged microbial biogeographic patterns and microbial ecology.

Understanding the processes that regulate communities of microorganisms is a key issue and focus in microbial ecology. Although fungi play a critical role in soil biogeochemical cycling, their community assembly processes remain largely unknown, especially in agricultural soils. In this study, we investigated the relative importance of five community assembly processes (variable selection, homogeneous selection, homogeneous dispersal, dispersal limitation and an undominated process) in soil fungal communities under long‐term (28 years, 1990–2018) fertilization management consisting of 12 different treatments in triplicate field plots. Using Illumina MiSeq sequencing of the 18S rRNA eukaryotic gene, we observed that fungal communities in manure treatments were all structured primarily by homogeneous dispersal, whereas the communities in chemical fertilizer treatments were structured primarily by homogeneous dispersal and an undominated process. Soil calcium played an important role in shaping the soil fungal community, whereas soil organic matter concentrations had a considerable impact on the soil fungal phylogenetic community composition. Overall, our results suggest that fertilization management should be considered as a key factor driving microbial community assembly processes in farmed soils.Highlights Soil Ca played a key role in shaping eukaryotic microbial community Chemical fertilization resulted in homogenous selection and undominated processes. A combination of chemical and manure fostered homogenous selection processes.