Nitrate is an important nitrogen source for Arctic tundra plants

Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to...

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Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 13; p. 3398
Main Authors: Liu, Xue-Yan, Koba, Keisuke, Koyama, Lina A, Hobbie, Sarah E, Weiss, Marissa S, Inagaki, Yoshiyuki, Shaver, Gaius R, Giblin, Anne E, Hobara, Satoru, Nadelhoffer, Knute J, Sommerkorn, Martin, Rastetter, Edward B, Kling, George W, Laundre, James A, Yano, Yuriko, Makabe, Akiko, Yano, Midori, Liu, Cong-Qiang
Format: Journal Article
Language:English
Published: United States 27.03.2018
Subjects:
Denitrification
Nitrates - metabolism
Nitrogen - analysis
Plant Leaves - growth & development
Plant Leaves - metabolism
Soil - chemistry
Tundra
plant nitrate
stable isotopes
Arctic tundra plants
nitrogen dynamics
soil nitrate
ISSN:1091-6490, 1091-6490
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Summary:Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO ) is a major N form used by plants worldwide, it is discounted as a N source for Arctic tundra plants because of extremely low NO concentrations in Arctic tundra soils, undetectable soil nitrification, and plant-tissue NO that is typically below detection limits. Here we reexamine NO use by tundra plants using a sensitive denitrifier method to analyze plant-tissue NO Soil-derived NO was detected in tundra plant tissues, and tundra plants took up soil NO at comparable rates to plants from relatively NO -rich ecosystems in other biomes. Nitrate assimilation determined by N enrichments of leaf NO relative to soil NO accounted for 4 to 52% (as estimated by a Bayesian isotope-mixing model) of species-specific total leaf N of Alaskan tundra plants. Our finding that in situ soil NO availability for tundra plants is high has important implications for Arctic ecosystems, not only in determining species compositions, but also in determining the loss of N from soils via leaching and denitrification. Plant N uptake and soil N losses can strongly influence C uptake and accumulation in tundra soils. Accordingly, this evidence of NO availability in tundra soils is crucial for predicting C storage in tundra.
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ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.1715382115