Long-term nitrogen addition affects the phylogenetic turnover of soil microbial community responding to moisture pulse

Chi Liu,Jiabao Li,James C Stegen,Xiangzhen Li,Junpeng Rui,Minjie Yao

doi:10.1038/s41598-017-17736-w

Abstract

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. We started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightly increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.

Highlights

The processes shaping the composition and structure of communities are central topics in ecological research
The P-value for λ is calculated with a likelihood ratio test, where the observed λ is compared to a trait distribution without phylogenetic signal
We first investigated the phylogenetic structure and turnover of prokaryotic communities along the N gradient based on the 16S rDNA sequencing

Summary

Introduction

The processes shaping the composition and structure of communities are central topics in ecological research. Soil microbial communities are highly diverse, and they can change rapidly in compositions at different timescales[2,3]. Because of highly diversified physiologic and genomic properties of microorganisms, it is difficult to understand the detailed processes shaping soil microbial community structure under different environments. By extending Vellend’s theoretical framework[21] at the scale of a metacommunity, Stegen et al.[19] propose a comprehensive null modeling approach that estimates the relative influences of ecological processes on community assembly. Homogeneous selection usually causes low compositional turnover. Variable selection usually causes high compositional turnover. When selection is not the primary cause of compositional turnover, low levels of dispersal coupled with ecological drift can result in large differences in community composition; this scenario is referred to as dispersal limitation. It is not clear to what extent the spatial phylogenetic turnover shifts along N addition gradients, and whether the N addition history alters the microbial response to moisture pulse

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