The nitrogen cycle: A review of isotope effects and isotope modeling approaches

Denk, Tobias; Mohn, Joachim; Decock, Charlotte; Lewicka‐Szczebak, Dominika; Harris, Eliza; Butterbach‐Bahl, Klaus; Kiese, Ralf; Wolf, Benjamin

doi:10.1016/j.soilbio.2016.11.015

Cited by 275 publications

(241 citation statements)

References 121 publications

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“…The increasing of soil δ 15 N under invasion supported increased NO 3 − losses compared to no invasion (Table , Figure g). Mechanically, NO 3 − is typically depleted in 15 N due to the strong 15 N discriminations during nitrification (Denk et al., ; Koba et al., ). Our results also suggest nitrification as a major process regulating δ 15 N signatures and the differences between NO 3 − and NH 4 + (Table ).…”

Section: Discussionmentioning

confidence: 99%

“…In soils, plant‐available N sources mainly include NH 4 + and NO 3 − (particularly in nonarctic and nonboreal ecosystems) (Chapin, Matson, & Vitousek, ; Craine et al., , ). The δ 15 N values of soil NH 4 + are often distinctly higher than that of NO 3 − because nitrification causes substantial 15 N enrichment in residual NH 4 + and 15 N depletion in newly produced NO 3 − (Denk et al., ; Koba et al., ). When plant‐available N is dominated by NH 4 + , plants may prefer NH 4 + over NO 3 − (McKane et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Lei

Tan

et al. 2018

Journal of Ecology

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Exotic plant invasion has been changing the vegetation composition and function of terrestrial ecosystems. Nitrogen (N) and phosphorus (P) are often the limiting nutrients for terrestrial plants. However, under invasive pressure, in situ plant N and P usage mechanisms remain poorly understood but are pivotal for a better understanding of plant invasion and coexistence in invaded ecosystems. Nitrogen and P concentrations, natural 15N abundance (δ15N values) were investigated in leaves and soils under different invasive pressures (here expressed as the biomass percentages of invasive plants in each plot) for two invasive species (Chromolaena odorata and Ageratina adenophora) in Xishuangbanna in tropical China. Soil N and P concentrations revealed the relatively N‐rich but P‐poor status of our study site. Under invasion, soil inorganic N (dominated by ammonium) and available P did not increase significantly. The leaf N and P of invasive plants increased, while leaf N increased but P decreased for native species. Natural δ15N mass balance between leaves and soil inorganic N sources revealed that ammonium dominated N utilization in both natives and invaders. Invasive plants showed ammonium utilization with increasing leaf N levels, while native plants under no invasion showed nitrate utilization with increasing leaf N levels. Synthesis. Increased soil ammonium availability contributed to preferential ammonium utilization by invasive plants and elevated ammonium utilization in natives, but the P competition of natives decreased in invaded ecosystems. These novel insights into nutrient dynamics in invaded ecosystems enhance our understanding of plant invasion and coexistence mechanisms.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Lei

Tan

et al. 2018

Journal of Ecology

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“…In this study, we compared the fractionation of two contrasting denitrifying bacteria: Pseudomonas fluorescens producing and reducing N 2 O, and Pseudomonas chlororaphis producing but not reducing N 2 O. Isotope effects during denitrification are diverse and species dependent (e.g., Denk et al, 2017). Our study demonstrates a new way to determine fractionation factors from continuous measurements of N 2 O.…”

Section: Introductionmentioning

confidence: 99%

Continuous measurements of nitrous oxide isotopomers during incubation experiments

et al. 2018

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Abstract. Nitrous oxide (N 2 O) is an important and strong greenhouse gas in the atmosphere. It is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N 2 O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. In the linear N=N=O molecule 15 N substitution is possible in two distinct positions: central and terminal. The respective molecules, 14 N 15 N 16 O and 15 N 14 N 16 O, are called isotopomers. It has been demonstrated that N 2 O produced by nitrifying or denitrifying microbes exhibits a different relative abundance of the isotopomers. Therefore, measurements of the site preference (difference in the abundance of the two isotopomers) in N 2 O can be used to determine the source of N 2 O, i.e., nitrification or denitrification. Recent instrument development allows for continuous positiondependent δ 15 N measurements at N 2 O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N 2 O) and Pseudomonas chlororaphis (only producing N 2 O). The continuous measurements of N 2 O isotopomers reveals the transient isotope exchange among KNO 3 , N 2 O, and N 2 . We find bulk isotopic fractionation of −5.01 ‰ ± 1.20 for P. chlororaphis, in line with previous results for production from denitrification. For P. fluorescens, the bulk isotopic fractionation during production of N 2 O is −52.21 ‰ ± 9.28 and 8.77 ‰ ± 4.49 during N 2 O reduction.The site preference (SP) isotopic fractionation for P. chlororaphis is −3.42 ‰ ± 1.69. For P. fluorescens, the calculations result in SP isotopic fractionation values of 5.73 ‰ ± 5.26 during production of N 2 O and 2.41 ‰ ± 3.04 during reduction of N 2 O. In summary, we implemented continuous measurements of N 2 O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better understanding of denitrifying bacteria and N 2 O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the globe.

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“…Apart from N 2 O emissions, the NO and N 2 emissions, plant uptake and microbial immobilization might be also stimulated by an increase in storms in the wet season of RD year (2014), causing greater N loss than in RW year (2013). Isotopic tracers should be considered in subsequent studies to quantify these pathways under the predicted precipitation scenarios (Denk et al, ). It was also possible that the lower N content in IPS plots was caused by lower inorganic N input from pond water because the average total inorganic N content was 4.85 mg/L in rainfall and 2.05 mg/L in pond water.…”

Section: Discussionmentioning

confidence: 99%

Intensified Precipitation Seasonality Reduces Soil Inorganic N Content in a Subtropical Forest: Greater Contribution of Leaching Loss Than N₂O Emissions

et al. 2019

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Soil nitrogen (N) loss has been predicted to intensify with increased global precipitation changes. However, the relative contributions of leaching and gaseous N emissions to intensified N losses are largely unknown. Thus, we simulated intensified precipitation seasonality in a subtropical forest by extending the dry season via rainfall exclusion and increasing the wet‐season storms via irrigation without changing the total annual precipitation. Extending the dry season length increased the monthly mean soil NO3− content by 25%–64%, net N mineralization rate by 32%–40%, and net nitrification rate by 25%–28%. After adding water in the wet season, the monthly NO3− leaching was enhanced by 43% in the relatively dry year (2013, 2,094‐mm annual rainfall), but reduced by 51% in the relatively wet year (2014, 1,551 mm). In contrast, the monthly mean N2O emissions were reduced by 24% in 2013 but increased by 78% in 2014. Overall, the annual inorganic N content was decreased significantly by the precipitation changes. Decrease of soil inorganic N might be linked to the enhanced NO3− leaching in 2013, and be linked to the increased N2O emissions in 2014. However, in both years the annual total amount of N lost through leaching was significantly greater than that through N2O emissions. The enhanced N2O emissions driven by wet‐season storms were correlated with an increase in nirS abundance. Our results suggest that increased frequency of droughts and storms will decrease soil inorganic N content in warm and humid subtropical forests mainly through enhanced leaching losses.

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The nitrogen cycle: A review of isotope effects and isotope modeling approaches

Cited by 275 publications

References 121 publications

Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Intensified Precipitation Seasonality Reduces Soil Inorganic N Content in a Subtropical Forest: Greater Contribution of Leaching Loss Than N₂O Emissions

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The nitrogen cycle: A review of isotope effects and isotope modeling approaches

Cited by 275 publications

References 121 publications

Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Plant nitrogen and phosphorus utilization under invasive pressure in a montane ecosystem of tropical China

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Intensified Precipitation Seasonality Reduces Soil Inorganic N Content in a Subtropical Forest: Greater Contribution of Leaching Loss Than N2O Emissions

Contact Info

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Intensified Precipitation Seasonality Reduces Soil Inorganic N Content in a Subtropical Forest: Greater Contribution of Leaching Loss Than N₂O Emissions