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Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial r...

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Autores principales: Xia, Mengxue, Talhelm, Alan F., Pregitzer, Kurt S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6550334/
https://www.ncbi.nlm.nih.gov/pubmed/31178608
http://dx.doi.org/10.1016/j.soilbio.2017.04.011
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author Xia, Mengxue
Talhelm, Alan F.
Pregitzer, Kurt S.
author_facet Xia, Mengxue
Talhelm, Alan F.
Pregitzer, Kurt S.
author_sort Xia, Mengxue
collection PubMed
description Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methods to study effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry, such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.5% of the additional root mass retention. Nitrogen enrichment also slowed the loss of CTs and proteins in fine roots. Nitrogen additions initially slowed the loss of AIF, CTs, and proteins in leaf litter, which was comparatively low in AIF, but these effects disappeared at the later stage and did not affect leaf litter mass loss during the experiment. Our results suggest that decomposition of chemical classes subject to oxidative degradation, such as lignin and CTs, is generally inhibited by nitrogen enrichment; but whether this inhibition eventually slows litter mass loss and leads to organic matter accumulation depends on the initial quantities of these classes in litter.
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spelling pubmed-65503342019-06-05 Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition Xia, Mengxue Talhelm, Alan F. Pregitzer, Kurt S. Soil Biol Biochem Article Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methods to study effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry, such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.5% of the additional root mass retention. Nitrogen enrichment also slowed the loss of CTs and proteins in fine roots. Nitrogen additions initially slowed the loss of AIF, CTs, and proteins in leaf litter, which was comparatively low in AIF, but these effects disappeared at the later stage and did not affect leaf litter mass loss during the experiment. Our results suggest that decomposition of chemical classes subject to oxidative degradation, such as lignin and CTs, is generally inhibited by nitrogen enrichment; but whether this inhibition eventually slows litter mass loss and leads to organic matter accumulation depends on the initial quantities of these classes in litter. 2017 /pmc/articles/PMC6550334/ /pubmed/31178608 http://dx.doi.org/10.1016/j.soilbio.2017.04.011 Text en This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Article
Xia, Mengxue
Talhelm, Alan F.
Pregitzer, Kurt S.
Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title_full Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title_fullStr Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title_full_unstemmed Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title_short Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
title_sort chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6550334/
https://www.ncbi.nlm.nih.gov/pubmed/31178608
http://dx.doi.org/10.1016/j.soilbio.2017.04.011
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