Production and consumption of NH 4 + and NH3 in trees

Pearson, Jennifer; Woodall, J.; Elisabeth, Clough; Nielsen, Kent Høier; Schjørring, Jan K.

doi:10.1007/978-94-015-9856-9_3

Cited by 9 publications

(5 citation statements)

References 61 publications

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“…As a fast growing pioneer, S. nigra transports nitrate to the shoot for assimilation. By this strategy, pioneers have more closely linked C and N acquisition in the leaf, when compared with climax species that carry out most of their N assimilation in their roots (Pearson et al, 2002). A preference for shoot N assimilation, high NR activity and a closer coupling between N and C metabolism in the leaf may give pioneer species such as S. nigra a greater buffering capacity against atmospheric inputs when compared with climax species like C. monogyna .…”

Section: Resultsmentioning

confidence: 99%

Tree leaf biomarkers for atmospheric nitrogen deposition

Marsh

Miller

Zhang

et al. 2005

Water Air Soil Pollut: Focus

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The aim of this paper was to investigate the effects of nitrogen (N) deposition on tree N cycling and identify potential biomarkers for N deposition. Between April and October 2002 extensive fieldwork was undertaken at Mardley Heath in Hertfordshire. This woodland, located adjacent to the A1(M) motorway, is exposed to high levels of atmospheric nitrogen oxides from the traffic. Measurements of δ 15 N, in vivo nitrate reductase (NR) activity, tissue, xylem and surface nitrate concentrations as well as N concentration and growth were made along a 700-m transect at 90 • to the motorway. The δ 15 N data show that oxidised N from the road traffic is taken up by nearby trees and is incorporated into plant tissues. Our measurements of NR activities suggest elevated rates close to the motorway. However, xylem sap, leaf tissue and leaf surface nitrate concentrations showed no differences between the roadside location and the most distant sampling point from the motorway. Taken together the δ 15 N and nitrate reductase data suggest uptake and assimilation of N through the foliage. We conclude that for this lowland deciduous woodland, tissue, xylem and surface measurements of nitrate are unreliable biomarkers for N deposition whereas δ 15 N, growth measurements and integrated seasonal NR might be useful. The results also point to the benefit of roadside tree planting to screen pollution from motor vehicles.

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Section: Resultsmentioning

confidence: 99%

Tree leaf biomarkers for atmospheric nitrogen deposition

Marsh

Miller

Zhang

et al. 2005

Water Air Soil Pollut: Focus

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“…Glutamine synthetase catalyzes assimilation of NH4 + into glutamine and is therefore important in regulating the pool of NH4 + available for exchange as NH3 between the leaf and atmosphere and remobilizing 575 organic N for storage during senescence. A decline in GS activity can thus result in increased leaf NH4 + concentrations (Pearson et al, 2002;Wang et al, 2011). Senescent leaves were similar to green leaves with respect to median tissue pH but showed distinctly higher concentrations of tissue NH4 + .…”

Section: Biogeochemistrymentioning

confidence: 94%

“…Senescence marks the translocation of N in leaves to storage tissues (Schneider et al, 1996). Along with a decline in photosynthetic activity, degradation of chlorophyll, and other metabolic changes, glutamine synthetase (GS) activity also declines (Pearson et al, 2002). Glutamine synthetase catalyzes assimilation of NH4 + into glutamine and is therefore important in regulating the pool of NH4 + available for exchange as NH3 between the leaf and atmosphere and remobilizing 575 organic N for storage during senescence.…”

Section: Biogeochemistrymentioning

confidence: 99%

Atmospheric Deposition of Reactive Nitrogen to a Deciduous Forest in the Southern Appalachian Mountains

Walker

Chen

et al. 2022

Preprint

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Abstract. Assessing nutrient critical load exceedances requires complete and accurate atmospheric deposition budgets for reactive nitrogen (Nr). The exceedance is the total amount of Nr deposited to the ecosystem in excess of the critical load, which is the amount of Nr input below which harmful effects do not occur. Total deposition includes all forms of Nr (i.e., organic and inorganic) deposited to the ecosystem by wet and dry pathways. Here we present results from the Southern Appalachian Nitrogen Deposition Study (SANDS), in which a combination of measurements and field-scale modeling were used to develop a complete annual Nr deposition budget for a deciduous forest at the Coweeta Hydrologic Laboratory. Wet deposition of ammonium, nitrate, nitrite, and bulk organic N were measured directly. The dry deposited Nr fraction was estimated using a bidirectional resistance-based model driven with speciated measurements of Nr air concentrations (e.g., ammonia, ammonium aerosol, nitric acid, nitrate aerosol, bulk organic N in aerosol, total alkyl nitrates, and total peroxy nitrates), micrometeorology, canopy structure, and biogeochemistry. Total annual deposition was 6.6 kg N ha-1 yr-1, which is on the upper end of Nr critical load estimates recently developed for similar ecosystems in nearby Great Smoky Mountains National Park. Of the total (wet + dry) budget, 50.7 % was contributed by reduced forms of Nr (NHx = ammonia + ammonium), with oxidized and organic forms contributing 41.6 % and 7.7 %, respectively. Our results indicate that reductions in NHx deposition would be needed to achieve the lowest estimates (3.0 kg N ha-1 yr-1) of Nr critical loads in southern Appalachian forests.

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“…Glutamine synthetase catalyzes assimilation of NH + 4 into glutamine and is therefore important in regulating the pool of NH + 4 available for exchange as NH 3 between the leaf and atmosphere as well as remobilizing organic N for storage during senescence. A decline in GS activity can thus result in increased leaf NH + 4 concentrations (Pearson et al, 2002;Wang et al, 2011). Senescent leaves were similar to green leaves with respect to median tissue pH but showed higher concentrations of tissue NH + 4 .…”

Section: Biogeochemistrymentioning

confidence: 95%

“…Senescence marks the translocation of N in leaves to storage tissues (Schneider et al, 1996). Along with a decline in photosynthetic activity, degradation of chlorophyll, and other metabolic changes, glutamine synthetase (GS) activity also declines (Pearson et al, 2002). Glutamine synthetase catalyzes assimilation of NH + 4 into glutamine and is therefore important in regulating the pool of NH + 4 available for exchange as NH 3 between the leaf and atmosphere as well as remobilizing organic N for storage during senescence.…”

Section: Biogeochemistrymentioning

confidence: 99%

Atmospheric deposition of reactive nitrogen to a deciduous forest in the southern Appalachian Mountains

Walker

Chen

et al. 2023

Biogeosciences

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Abstract. Assessing nutrient critical load exceedances requires complete and accurate atmospheric deposition budgets for reactive nitrogen (Nr). The exceedance is the total amount of Nr deposited to the ecosystem in excess of the critical load, which is the amount of Nr input below which harmful effects do not occur. Total deposition includes all forms of Nr (i.e., organic and inorganic) deposited to the ecosystem by wet and dry pathways. Here we present results from the Southern Appalachian Nitrogen Deposition Study (SANDS), in which a combination of measurements and field-scale modeling was used to develop a complete annual Nr deposition budget for a deciduous forest at the Coweeta Hydrologic Laboratory. Wet deposition of ammonium, nitrate, nitrite, and bulk organic N were measured directly. The dry deposited Nr fraction was estimated using a bidirectional resistance-based model driven with speciated measurements of Nr air concentrations (e.g., ammonia, ammonium aerosol, nitric acid, nitrate aerosol, bulk organic N in aerosol, total alkyl nitrates, and total peroxy nitrates), micrometeorology, canopy structure, and biogeochemistry. Total annual deposition was ∼ 6.7 kg N ha−1 yr−1, which is on the upper end of Nr critical load estimates recently developed for similar ecosystems in the nearby Great Smoky Mountains National Park. Of the total (wet + dry) budget, 51.1 % was contributed by reduced forms of Nr (NHx = ammonia + ammonium), with oxidized and organic forms contributing ∼ 41.3 % and 7.6 %, respectively. Our results indicate that reductions in NHx deposition would be needed to achieve the lowest estimates (∼ 3.0 kg N ha−1 yr−1) of Nr critical loads in southern Appalachian forests.

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Production and consumption of NH 4 + and NH3 in trees

Cited by 9 publications

References 61 publications

Tree leaf biomarkers for atmospheric nitrogen deposition

Tree leaf biomarkers for atmospheric nitrogen deposition

Atmospheric Deposition of Reactive Nitrogen to a Deciduous Forest in the Southern Appalachian Mountains

Atmospheric deposition of reactive nitrogen to a deciduous forest in the southern Appalachian Mountains

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