Stoichiometry controls asymbiotic nitrogen fixation and its response to nitrogen inputs in a nitrogen-saturated forest

Ecology ◽  
2018 ◽  
Vol 99 (9) ◽  
pp. 2037-2046 ◽  
Author(s):  
Mianhai Zheng ◽  
Wei Zhang ◽  
Yiqi Luo ◽  
Dejun Li ◽  
Senhao Wang ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Asymbiotic Nitrogen Fixation ◽  
Nitrogen Inputs

Asymbiotic nitrogen fixation and denitrification in a mature forest in coastal British Columbia

1989 ◽  
Vol 19 (9) ◽  
pp. 1194-1200 ◽  
Author(s):  
G. H. Cushon ◽  
M. C. Feller
Keyword(s):  
British Columbia ◽  
Nitrogen Fixation ◽  
Forest Floor ◽  
Mineral Soil ◽  
Gaseous Nitrogen ◽  
Blue Green Algae ◽  
Asymbiotic Nitrogen Fixation ◽  
Nitrogen Inputs ◽  
Decaying Wood ◽  
Floor Material

Gaseous nitrogen inputs due to asymbiotic nitrogen fixation and outputs due to biological denitrification were estimated for a mature mid-successional Pseudotsugamenziesii (Mirb.) Franco–Thujaplicata Donn–Tsugaheterophylla (Raf.) Sarg. forest in southwestern British Columbia. Forest floor material, mineral soil, decaying wood, foliage, and bark were incubated in an atmosphere of 10 kPa C2H2 to allow the simultaneous measurement of N2O production by denitrifying bacteria and C2H2 reduction by free-living bacteria and blue-green algae. Forest floor material accounted for 70% of an estimated total annual nitrogen fixation of 0.3 kg N•ha−1•year −1.•Relatively small amounts of nitrogen were fixed in mineral soil, decaying wood, and foliage, and no indication of nitrogen fixation activity in bark was detected. Some denitrification was found; it was essentially negligible, although possibly underestimated. The net gaseous nitrogen input into the mid-successional forests of the study area is likely to be < 5% of the total net nitrogen inputs, which are primarily from precipitation.

Glucose Influence on the Asymbiotic Nitrogen Fixation During Lignocellulsic Waste Composting

1996 ◽  
pp. 137-148
Author(s):  
K. Ezelin ◽  
G. Brun ◽  
M. Kaemmerer ◽  
J. C. Revel
Keyword(s):  
Nitrogen Fixation ◽  
Asymbiotic Nitrogen Fixation

Asymbiotic nitrogen fixation

1958 ◽  
pp. 9-47 ◽  
Author(s):  
P. W. Wilson
Keyword(s):  
Nitrogen Fixation ◽  
Asymbiotic Nitrogen Fixation

scholarly journals Asymbiotic Nitrogen Fixation is Greater in Soils under Long‐Term No‐Till Versus Conventional Tillage

2019 ◽  
Vol 83 (4) ◽  
pp. 1148-1152
Author(s):  
David W. Franzen ◽  
Patrick Inglett ◽  
Caley K. Gasch
Keyword(s):  
Nitrogen Fixation ◽  
Conventional Tillage ◽  
No Till ◽  
Asymbiotic Nitrogen Fixation

scholarly journals Nutrient-ColimitedTrichodesmiumas a Nitrogen Source or Sink in a Future Ocean

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Nathan G. Walworth ◽  
Fei-Xue Fu ◽  
Michael D. Lee ◽  
Xiaoni Cai ◽  
Mak A. Saito ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Source ◽  
Nitrogen Metabolism ◽  
Organic Nitrogen ◽  
Open Ocean ◽  
Nitrogen Fixing ◽  
Content Type ◽  
Nitrogen Inputs ◽  
Ocean Conditions ◽  
Nitrogen Scavenging

ABSTRACTNitrogen-fixing (N2) cyanobacteria provide bioavailable nitrogen to vast ocean regions but are in turn limited by iron (Fe) and/or phosphorus (P), which may force them to employ alternative nitrogen acquisition strategies. The adaptive responses of nitrogen fixers to global-change drivers under nutrient-limited conditions could profoundly alter the current ocean nitrogen and carbon cycles. Here, we show that the globally important N2fixerTrichodesmiumfundamentally shifts nitrogen metabolism toward organic-nitrogen scavenging following long-term high-CO2adaptation under iron and/or phosphorus (co)limitation. Global shifts in transcripts and proteins under high-CO2/Fe-limited and/or P-limited conditions include decreases in the N2-fixing nitrogenase enzyme, coupled with major increases in enzymes that oxidize trimethylamine (TMA). TMA is an abundant, biogeochemically important organic nitrogen compound that supports rapidTrichodesmiumgrowth while inhibiting N2fixation. In a future high-CO2ocean, this whole-cell energetic reallocation toward organic nitrogen scavenging and away from N2fixation may reduce new-nitrogen inputs byTrichodesmiumwhile simultaneously depleting the scarce fixed-nitrogen supplies of nitrogen-limited open-ocean ecosystems.IMPORTANCETrichodesmiumis among the most biogeochemically significant microorganisms in the ocean, since it supplies up to 50% of the new nitrogen supporting open-ocean food webs. We usedTrichodesmiumcultures adapted to high-CO2conditions for 7 years, followed by additional exposure to iron and/or phosphorus (co)limitation. We show that “future ocean” conditions of high CO2and concurrent nutrient limitation(s) fundamentally shift nitrogen metabolism away from nitrogen fixation and instead toward upregulation of organic nitrogen-scavenging pathways. We show that the responses ofTrichodesmiumto projected future ocean conditions include decreases in the nitrogen-fixing nitrogenase enzymes coupled with major increases in enzymes that oxidize the abundant organic nitrogen source trimethylamine (TMA). Such a shift toward organic nitrogen uptake and away from nitrogen fixation may substantially reduce new-nitrogen inputs byTrichodesmiumto the rest of the microbial community in the future high-CO2ocean, with potential global implications for ocean carbon and nitrogen cycling.

Molybdenum and phosphorus limitation of asymbiotic nitrogen fixation in forests of Eastern Canada: Influence of vegetative cover and seasonal variability

2013 ◽  
Vol 67 ◽  
pp. 140-146 ◽  
Author(s):  
Marie-Eve Jean ◽  
Karine Phalyvong ◽  
Julie Forest-Drolet ◽  
Jean-Philippe Bellenger
Keyword(s):  
Nitrogen Fixation ◽  
Seasonal Variability ◽  
Phosphorus Limitation ◽  
Vegetative Cover ◽  
Eastern Canada ◽  
Asymbiotic Nitrogen Fixation

scholarly journals Negligible isotopic fractionation of nitrogen within temperate <i>Zostera</i> spp. meadows

2018 ◽  
Author(s):  
Douglas G. Russell ◽  
Wei Wen Wong ◽  
Perran L. M. Cook
Keyword(s):  
Nitrogen Fixation ◽  
Coastal Zone ◽  
Solid Phase ◽  
Isotopic Fractionation ◽  
Nitrogen Isotope ◽  
Small Contribution ◽  
Seagrass Beds ◽  
Seagrass Meadows ◽  
Nitrogen Inputs ◽  
External Sources

Abstract. Seagrass meadows form an ecologically important ecosystem in the coastal zone. Excessive nitrogen inputs to the coastal zone pose a key threat to seagrass through eutrophication and associated algal overgrowth. The 15N / 14N ratio of seagrass is commonly used to assess extent to which sewage derived nitrogen may be influencing seagrass beds. There have however, been no studies comparing the 15N / 14N ratios of seagrass beds, their associated sediments and of critical importance, the porewater NH4+ pool, which is most bioavailable. Here, we undertook a study of the 15N / 14N ratios of seagrass tissue, sediment porewater NH4+ pool and the sediment solid phase to elucidate the extent of any fractionating processes taking place during organic matter mineralisation and nitrogen assimilation. The study was undertaken within two coastal embayments known to receive nitrogen from a range of sources including marine, urban and sewage sources. The δ15N of porewater ammonium was strongly correlated with the δ15N of both the sediment solid phase and seagrass tissue (r2 of 0.89 and 0.85) respectively. The δ15N porewater NH4+ minus the δ15N seagrass tissue ranged between −1.4 and 7 ‰ with an average 1.6 ‰. We suggest the most likely explanation for this was fractionation during assimilation as a consequence of diffusion limitation, although the magnitude of this change was relatively small. Nitrogen fixation may have also contributed a small amount to the observed isotopic depletion of the plants relative to the sediment porewater NH4+ pool. A consideration of the nitrogen isotope values of the seagrass bed nitrogen pools compared to external sources suggest the dominant source of nitrogen to seagrass is recycling from within the bed, with a relatively small contribution from water column assimilation, particulate trapping and nitrogen fixation.

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