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Title: Long-term nitrogen deposition enhances microbial capacities in soil carbon stabilization but reduces network complexity
Abstract Background

Anthropogenic activities have increased the inputs of atmospheric reactive nitrogen (N) into terrestrial ecosystems, affecting soil carbon stability and microbial communities. Previous studies have primarily examined the effects of nitrogen deposition on microbial taxonomy, enzymatic activities, and functional processes. Here, we examined various functional traits of soil microbial communities and how these traits are interrelated in a Mediterranean-type grassland administrated with 14 years of 7 g m−2year−1of N amendment, based on estimated atmospheric N deposition in areas within California, USA, by the end of the twenty-first century.

Results

Soil microbial communities were significantly altered by N deposition. Consistent with higher aboveground plant biomass and litter, fast-growing bacteria, assessed by abundance-weighted average rRNA operon copy number, were favored in N deposited soils. The relative abundances of genes associated with labile carbon (C) degradation (e.g.,amyAandcda) were also increased. In contrast, the relative abundances of functional genes associated with the degradation of more recalcitrant C (e.g.,mannanaseandchitinase) were either unchanged or decreased. Compared with the ambient control, N deposition significantly reduced network complexity, such as average degree and connectedness. The network for N deposited samples contained only genes associated with C degradation, suggesting that C degradation genes became more intensely connected under N deposition.

Conclusions

We propose a conceptual model to summarize the mechanisms of how changes in above- and belowground ecosystems by long-term N deposition collectively lead to more soil C accumulation.

 
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Award ID(s):
2129235 2129332
NSF-PAR ID:
10370445
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Springer Science + Business Media
Date Published:
Journal Name:
Microbiome
Volume:
10
Issue:
1
ISSN:
2049-2618
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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