Nitrate is an important nitrogen source for Arctic tundra plants

Xue Yan Liu, Keisuke Koba, Lina A. Koyama, Sarah E. Hobbie, Marissa S. Weiss, Yoshiyuki Inagaki, Gaius R. Shaver, Anne E. Giblin, Satoru Hobara, Knute J. Nadelhoffer, Martin Sommerkorn, Edward B. Rastetter, George W. Kling, James A. Laundre, Yuriko Yano, Akiko Makabe, Midori Yano, Cong Qiang Liu

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

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 (NO3 ) is a major N form used by plants worldwide, it is discounted as a N source for Arctic tundra plants because of extremely low NO3 concentrations in Arctic tundra soils, undetectable soil nitrification, and plant-tissue NO3 that is typically below detection limits. Here we reexamine NO3 use by tundra plants using a sensitive denitrifier method to analyze plant-tissue NO3 . Soil-derived NO3 was detected in tundra plant tissues, and tundra plants took up soil NO3 at comparable rates to plants from relatively NO3 -rich ecosystems in other biomes. Nitrate assimilation determined by15N enrichments of leaf NO3 relative to soil NO3 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 NO3 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 NO3 availability in tundra soils is crucial for predicting C storage in tundra.

Original languageEnglish (US)
Pages (from-to)3398-3403
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number13
DOIs
StatePublished - Mar 27 2018

Bibliographical note

Funding Information:
We thank Laura Gough, Andrew J. Schauer, Muneoki Yoh, Nozomi Suzuki, Naohiro Yoshida, Yanbao Lei, Xiaodong Li, Erica Steve, Marshall Otter, Asami Nakanishi, Takahiro Hayashi, Ryo Kobayashi, Chieko Takahashi, Syuichiro Matsushima, Hiroyu Katoh, Azusa A. Hokari, Tomoko Makita, and colleagues and staff at TFS, TUAT, Center for Ecological Research, and the Institute of Geochemistry, Chinese Academy of Sciences for their assistance in the field and laboratory. We also thank Hideo Yamasaki for fruitful discussions on NO3− production by plants, and Erik Hobbie for helpful comments during the revision. This study was supported by the Kyoto University Foundation, the Sumitomo Foundation, Program for Next Generation World-Leading Researcher (Grant GS008) and Grant-in-Aid for Scientific Research (KAKENHI Grants 26252020, 26550004, 17H06297, and P09316) from the Japan Society for Promotion of Science, the National Natural Science Foundation of China (Grants 41730855, 41522301, and 41473081), the National Key Research and Development Program of China (Grants 2016YFA0600802 and 2017YFC0210101), and the 11th Recruitment Program of Global Experts (the Thousand Talents Plan) for Young Professionals granted by the central budget of China. Logistical support at Toolik Lake was provided by the US National Science Foundation Office of Polar Programs. Site selection, site maintenance, site descriptions, and field data were provided by the Arctic Long-Term Ecological Research program, funded by the US National Science Foundation Division of Environmental Biology (Grants 1026843, 1504006, and 1637459).

Funding Information:
ACKNOWLEDGMENTS. We thank Laura Gough, Andrew J. Schauer, Muneoki Yoh, Nozomi Suzuki, Naohiro Yoshida, Yanbao Lei, Xiaodong Li, Erica Steve, Marshall Otter, Asami Nakanishi, Takahiro Hayashi, Ryo Kobayashi, Chieko Takahashi, Syuichiro Matsushima, Hiroyu Katoh, Azusa A. Hokari, Tomoko Makita, and colleagues and staff at TFS, TUAT, Center for Ecological Research, and the Institute of Geochemistry, Chinese Academy of Sciences for their assistance in the field and laboratory. We also thank Hideo Yamasaki for fruitful discussions on NO3− production by plants, and Erik Hobbie for helpful comments during the revision. This study was supported by the Kyoto University Foundation, the Sumitomo Foundation, Program for Next Generation World-Leading Researcher (Grant GS008) and Grant-in-Aid for Scientific Research (KAKENHI Grants 26252020, 26550004, 17H06297, and P09316) from the Japan Society for Promotion of Science, the National Natural Science Foundation of China (Grants 41730855, 41522301, and 41473081), the National Key Research and Development Program of China (Grants 2016YFA0600802 and 2017YFC0210101), and the 11th Recruitment Program of Global Experts (the Thousand Talents Plan) for Young Professionals granted by the central budget of China. Logistical support at Toolik Lake was provided by the US National Science Foundation Office of Polar Programs. Site selection, site maintenance, site descriptions, and field data were provided by the Arctic Long-Term Ecological Research program, funded by the US National Science Foundation Division of Environmental Biology (Grants 1026843, 1504006, and 1637459).

Publisher Copyright:
© 2018 National Academy of Sciences. All Rights Reserved.

Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.

Keywords

  • Arctic tundra plants
  • Nitrogen dynamics
  • Plant nitrate
  • Soil nitrate
  • Stable isotopes

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