Response to nitrogen addition reveals metabolic and ecological strategies of soil bacteria

Samad, Sainur; Johns, Charlotte; Richards, Karl G.; Lanigan, Gary; Klein, Cecile A. M. de; Clough, Timothy J.; Morales, Sergio E.

doi:10.1101/107961

Cited by 2 publications

(1 citation statement)

References 71 publications

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“…S4). The rRNA operon copy number correlates with bacterial reproduction rate and response rate to resource availability (Roller et al 2016, Wu et al 2017), thus reflects the ecological strategies of bacteria, as higher rRNA operon copy number is associated with the faster‐growing copiotrophic bacteria (Roller et al 2016, Samad et al 2017). The increased abundance‐weighted average rRNA operon copy number under N addition thus provided another line of evidence that elevated N input favored copiotrophic taxa.…”

Section: Discussionmentioning

confidence: 99%

Critical transition of soil bacterial diversity and composition triggered by nitrogen enrichment

Liu

Jiang

Yang

et al. 2020

Ecology

128

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Soil bacterial communities are pivotal in regulating terrestrial biogeochemical cycles and ecosystem functions. The increase in global nitrogen (N) deposition has impacted various aspects of terrestrial ecosystems, but we still have a rudimentary understanding of whether there is a threshold for N input level beyond which soil bacterial communities will experience critical transitions. Using high-throughput sequencing of the 16S rRNA gene, we examined soil bacterial responses to a long-term (13 yr), multi-level, N addition experiment in a temperate steppe of northern China. We found that plant diversity decreased in a linear fashion with increasing N addition. However, bacterial diversity responded nonlinearly to N addition, such that it was unaffected by N input below 16 g NÁm À2 Áyr À1 , but decreased substantially when N input exceeded 32 g NÁm À2 Áyr À1. A meta-analysis across four N addition experiments in the same study region further confirmed this nonlinear response of bacterial diversity to N inputs. Substantial changes in soil bacterial community structure also occurred between N input levels of 16 to 32 g NÁm À2 Áyr À1. Further analysis revealed that the loss of soil bacterial diversity was primarily attributed to the reduction in soil pH, whereas changes in soil bacterial community were driven by the combination of increased N availability, reduced soil pH, and changes in plant community structure. In addition, we found that N addition shifted bacterial communities toward more putatively copiotrophic taxa. Overall, our study identified a threshold of N input level for bacterial diversity and community composition. The nonlinear response of bacterial diversity to N input observed in our study indicates that although bacterial communities are resistant to low levels of N input, further increase in N input could trigger a critical transition, shifting bacterial communities to a low-diversity state.

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Section: Discussionmentioning

confidence: 99%

Critical transition of soil bacterial diversity and composition triggered by nitrogen enrichment

Liu

Jiang

Yang

et al. 2020

Ecology

128

View full text Add to dashboard Cite

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Influence of soil moisture on codenitrification fluxes from a urea-affected pasture soil

Clough

Lanigan

Klein

et al. 2017

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Intensively managed agricultural pastures contribute to N2O and N2 fluxes resulting in detrimental environmental outcomes and poor N use efficiency, respectively. Besides nitrification, nitrifier-denitrification and heterotrophic denitrification, alternative pathways such as codenitrification also contribute to emissions under ruminant urine-affected soil. However, information on codenitrification is sparse. The objectives of this experiment were to assess the effects of soil moisture and soil inorganic-N dynamics on the relative contributions of codenitrification and denitrification (heterotrophic denitrification) to the N2O and N2 fluxes under a simulated ruminant urine event. Repacked soil cores were treated with 15N enriched urea and maintained at near saturation (−1 kPa) or field capacity (−10 kPa). Soil inorganic-N, pH, dissolved organic carbon, N2O and N2 fluxes were measured over 63 days. Fluxes of N2, attributable to codenitrification, were at a maximum when soil nitrite (NO2−) concentrations were elevated. Cumulative codenitrification was higher (P = 0.043) at −1 kPa. However, the ratio of codenitrification to denitrification did not differ significantly with soil moisture, 25.5 ± 15.8 and 12.9 ± 4.8% (stdev) at −1 and −10 kPa, respectively. Elevated soil NO2− concentrations are shown to contribute to codenitrification, particularly at −1 kPa.

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Response to nitrogen addition reveals metabolic and ecological strategies of soil bacteria

Abstract: Running head: Community successions in N treated soils

Cited by 2 publications

References 71 publications

Critical transition of soil bacterial diversity and composition triggered by nitrogen enrichment

Critical transition of soil bacterial diversity and composition triggered by nitrogen enrichment

Influence of soil moisture on codenitrification fluxes from a urea-affected pasture soil

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