Elevated CO2 influences microbial carbon and nitrogen cycling

Liyou Wu,Jizhong Zhou,Joy D van Nostrand,Sarah E Hobbie,Ye Deng,Peter B Reich,Meiying Xu,Zhili He

doi:10.1186/1471-2180-13-124

Abstract

BackgroundElevated atmospheric CO2 (eCO2) has been shown to have significant effects on terrestrial ecosystems. However, little is known about its influence on the structure, composition, and functional potential of soil microbial communities, especially carbon (C) and nitrogen (N) cycling. A high-throughput functional gene array (GeoChip 3.0) was used to examine the composition, structure, and metabolic potential of soil microbial communities from a grassland field experiment after ten-year field exposure to ambient and elevated CO2 concentrations.ResultsDistinct microbial communities were established under eCO2. The abundance of three key C fixation genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), carbon monoxide dehydrogenase (CODH) and propionyl-CoA/acetyl-CoA carboxylase (PCC/ACC), significantly increased under eCO2, and so did some C degrading genes involved in starch, cellulose, and hemicellulose. Also, nifH and nirS involved in N cycling were significantly stimulated. In addition, based on variation partitioning analysis (VPA), the soil microbial community structure was largely shaped by direct and indirect eCO2-driven factors.ConclusionsThese findings suggest that the soil microbial community structure and their ecosystem functioning for C and N cycling were altered dramatically at eCO2. This study provides new insights into our understanding of the feedback response of soil microbial communities to elevated CO2 and global change.

Highlights

Elevated atmospheric CO2 has been shown to have significant effects on terrestrial ecosystems
Overall responses of microbial C and N cycling genes under CO2 Based on the number of functional genes, Shannon diversity, evenness and dominance, no significant differences were detected in the overall microbial diversity (Additional file 1)
Significant (p < 0.05) differences were observed in the abundance of C and N cycling genes between ambient CO2 and Elevated atmospheric CO2 (eCO2) microbial communities by detrended correspondence analysis (DCA) together with analysis of similarities (ANOSIM), nonparametric multivariate analysis of variance (Adonis) and Multi-Response Permutation Procedure (MRPP)

Summary

Introduction

Elevated atmospheric CO2 (eCO2) has been shown to have significant effects on terrestrial ecosystems. Little is known about its influence on the structure, composition, and functional potential of soil microbial communities, especially carbon (C) and nitrogen (N) cycling. A high-throughput functional gene array (GeoChip 3.0) was used to examine the composition, structure, and metabolic potential of soil microbial communities from a grassland field experiment after ten-year field exposure to ambient and elevated CO2 concentrations. Studies of ecosystem responses to elevated CO2 have shown that eCO2 can have major effects on terrestrial ecosystems by enhancing plant photosynthetic CO2 fixation and primary. Since microorganisms mediate important biogeochemical processes such as soil C and N cycling, and are expected to influence future atmospheric CO2 concentrations, functional understanding of how eCO2 affects soil microbial community composition and structure will be necessary for robust prediction of atmospheric CO2 concentrations in the future. Distinctly different results of the soil microbial diversity and activity under eCO2 have been obtained in different studies [11,14,15,16,17], and the possible relationships between the microbial community functional structure and the plant and soil parameters are still not clear

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Discussion

Conclusion