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Rising atmospheric CO2 reduces nitrogen availability in boreal forests

  • Galloway, J. N. et al. Transformation of the nitrogen cycle: recent trends, questions, and potential solutions. Science 320, 889–892 (2008).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Craine, J. M. et al. Isotopic evidence for oligotrophication of terrestrial ecosystems. Nat. Ecol. Evol. 2, 1735–1744 (2018).

    Article 
    PubMed 

    Google Scholar
     

  • Hiltbrunner, E., Körner, C., Meier, R., Braun, S. & Kahmen, A. Data do not support large-scale oligotrophication of terrestrial ecosystems. Nat. Ecol. Evol. 3, 1285–1286 (2019).

    Article 
    PubMed 

    Google Scholar
     

  • Mason, R. E. et al. Evidence, causes, and consequences of declining nitrogen availability in terrestrial ecosystems. Science 376, eabh3767 (2022).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Mason, R. E. et al. Explanations for nitrogen decline: response. Science 376, 1170–1170 (2022).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Olff, H. et al. Explanations for nitrogen decline. Science 376, 1169–1170 (2022).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Norby, R. J. et al. Enhanced woody biomass production in a mature temperate forest under elevated CO2. Nat. Clim. Change 14, 983–988 (2024).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Terrer, C. et al. Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass. Nat. Clim. Change 9, 684–689 (2019).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Norby, R. J., Warren, J. M., Iversen, C. M., Medlyn, B. E. & McMurtrie, R. E. CO2 enhancement of forest productivity constrained by limited nitrogen availability. Proc. Natl Acad. Sci. USA 107, 19368–19373 (2010).

    Article 
    ADS 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Rockström, J. et al. Planetary boundaries: exploring the safe operating space for humanity. Ecol. Soc. 14, 32 (2009).

  • Galloway, J. N. et al. Nitrogen cycles: past, present, and future. Biogeochemistry 70, 153–226 (2004).

    Article 
    CAS 

    Google Scholar
     

  • Ackerman, D., Millet, D. B. & Chen, X. Global estimates of inorganic nitrogen deposition across four decades. Glob. Biogeochem. Cycles 33, 100–107 (2019).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Galloway, J. N., Bleeker, A. & Erisman, J. W. The human creation and use of reactive nitrogen: a global and regional perspective. Annu. Rev. Environ. Resour. 46, 255–288 (2021).

    Article 

    Google Scholar
     

  • Lan, X. & Keeling, R. Trends in atmospheric CO2. Global Monitoring Laboratory https://gml.noaa.gov/ccgg/trends (2025).

  • Yue, K. et al. Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis. Sci. Rep. 6, 19895 (2016).

    Article 
    ADS 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Luo, Y. et al. Progressive nitrogen limitation of ecosystem responses to rising atmospheric CO2. Bioscience 54, 731–739 (2004).

    Article 

    Google Scholar
     

  • Hungate, B. A., Dukes, J. S., Shaw, M. R., Luo, Y. Q. & Field, C. B. Nitrogen and climate change. Science 302, 1512–1513 (2003).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Canadell, J. G. in Climate Change 2021: The Physical Science Basis (eds Masson-Delmotte, V. et al.) 673–816 (Cambridge Univ. Press, 2021).

  • Robinson, D. δ15N as an integrator of the nitrogen cycle. Trends Ecol. Evol. 16, 153–162 (2001).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Hobbie, E. A. & Högberg, P. Nitrogen isotopes link mycorrhizal fungi and plants to nitrogen dynamics. New Phytol. 196, 367–382 (2012).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Gerhart, L. M. & McLauchlan, K. K. Reconstructing terrestrial nutrient cycling using stable nitrogen isotopes in wood. Biogeochemistry 120, 1–21 (2014).

    Article 
    CAS 

    Google Scholar
     

  • Craine, J. M. et al. Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils. Plant Soil 396, 1–26 (2015).

    Article 
    CAS 

    Google Scholar
     

  • Craine, J. M. et al. Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability. New Phytol. 183, 980–992 (2009).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Chen, Q. et al. Global mycorrhizal status drives leaf δ15N patterns. J. Ecol. 113, 1150–1163 (2025).

    Article 
    CAS 

    Google Scholar
     

  • McLauchlan, K. K. et al. Centennial-scale reductions in nitrogen availability in temperate forests of the United States. Sci. Rep. 7, 7856 (2017).

    Article 
    ADS 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Peñuelas, J. et al. Increasing atmospheric CO2 concentrations correlate with declining nutritional status of European forests. Commun. Biol. 3, 125 (2020).

    Article 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Vitousek, P. M., Cen, X. Y. & Groffman, P. M. Has nitrogen availability decreased over much of the land surface in the past century? A model-based analysis. Biogeochemistry 167, 793–806 (2024).

  • Doucet, A., Savard, M. M., Bégin, C. & Smirnoff, A. Is wood pre-treatment essential for tree-ring nitrogen concentration and isotope analysis? Rapid Commun. Mass Spectom. 25, 469–475 (2011).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Bukata, A. R. & Kyser, T. K. Response of the nitrogen isotopic composition of tree-rings following tree-clearing and land-use change. Environ. Sci. Technol. 39, 7777–7783 (2005).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Poulson, S. R., Chamberlain, C. P. & Friedland, A. J. Nitrogen isotope variation of tree rings as a potential indicator of environmental change. Chem. Geol. 125, 307–315 (1995).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Thurner, M. et al. Nitrogen concentrations in boreal and temperate tree tissues vary with tree age/size, growth rate and climate. Biogeosciences 22, 1475–1493 (2025).

    Article 
    ADS 

    Google Scholar
     

  • United Nations Economic Commission for Europe. 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone to the Convention on Long-range Transboundary Air Pollution. Protocol to Abate Acidification, Eutrophication and Ground-level Ozone (UNECE, 1999).

  • Pihl Karlsson, G., Akselsson, C., Hellsten, S. & Karlsson, P. E. Atmospheric deposition and soil water chemistry in Swedish forests since 1985—effects of reduced emissions of sulphur and nitrogen. Sci. Total Environ. 913, 169734 (2024).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Hakkarainen, J., Ialongo, I., Maksyutov, S. & Crisp, D. Analysis of four years of global XCO2 anomalies as seen by Orbiting Carbon Observatory-2. Remote Sens. 11, 850 (2019).

    Article 
    ADS 

    Google Scholar
     

  • Mead, D. J. & Preston, C. M. Distribution and retranslocation of 15N lodgepole pine over eight growing seasons. Tree Physiol. 14, 389–402 (1994).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Nömmik, H. The Uptake and Translocation of Fertilizer N15 in Young Trees of Scots Pine and Norway Spruce (Predecessors to SLU, Royal School of Forestry, Sveriges lantbruksuniversitet, 1966).

  • Tomlinson, G. et al. The mobility of nitrogen across tree-rings of Norway spruce (Picea abies L.) and the effect of extraction method on tree-ring δ15N and δ13C values. Rapid Commun. Mass Spectrom. 28, 1258–1264 (2014).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Bassett, K. R., Östlund, L., Gundale, M. J., Fridman, J. & Jämtgård, S. Forest inventory tree core archive reveals changes in boreal wood traits over seven decades. Sci. Total Environ. 900, 165795 (2023).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Michaud, T. J., Cline, L. C., Hobbie, E. A., Gutknecht, J. L. M. & Kennedy, P. G. Herbarium specimens reveal that mycorrhizal type does not mediate declining temperate tree nitrogen status over a century of environmental change. New Phytol. 242, 1717–1724 (2024).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Ferm, M. et al. Wet deposition of ammonium, nitrate and non-sea-salt sulphate in Sweden 1955 through 2017. Atmos. Environ. X 2, 100015 (2019).

    CAS 

    Google Scholar
     

  • Kranabetter, J. M., Saunders, S., MacKinnon, J. A., Klassen, H. & Spittlehouse, D. L. An assessment of contemporary and historic nitrogen availability in contrasting coastal Douglas-Fir forests through δ15N of tree rings. Ecosystems 16, 111–122 (2013).

    Article 
    CAS 

    Google Scholar
     

  • Oulehle, F. et al. Changes in forest nitrogen cycling across deposition gradient revealed by δ15N in tree rings. Environ. Pollut. 304, 119104 (2022).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Ťupek, B. et al. Foliar turnover rates in Finland—comparing estimates from needle-cohort and litterfall-biomass methods. Boreal Environ. Res. 20, 283–304 (2015).


    Google Scholar
     

  • Hu, C. C. et al. Global distribution and drivers of relative contributions among soil nitrogen sources to terrestrial plants. Nat. Commun. 15, 6407 (2024).

    Article 
    ADS 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Balderas Torres, A. & Lovett, J. C. Using basal area to estimate aboveground carbon stocks in forests: La Primavera Biosphere’s Reserve, Mexico. Forestry 86, 267–281 (2013).

    Article 

    Google Scholar
     

  • Gauthier, S., Bernier, P., Kuuluvainen, T., Shvidenko, A. Z. & Schepaschenko, D. G. Boreal forest health and global change. Science 349, 819–822 (2015).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Bergh, J., Linder, S., Lundmark, T. & Elfving, B. The effect of water and nutrient availability on the productivity of Norway spruce in northern and southern Sweden. Forest Ecol. Manag. 119, 51–62 (1999).

    Article 

    Google Scholar
     

  • Elmore, A. J., Nelson, D. M. & Craine, J. M. Earlier springs are causing reduced nitrogen availability in North American eastern deciduous forests. Nat. Plants 2, 16133 (2016).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • McLauchlan, K. K., Craine, J. M., Oswald, W. W., Leavitt, P. R. & Likens, G. E. Changes in nitrogen cycling during the past century in a northern hardwood forest. Proc. Natl Acad. Sci. USA 104, 7466–7470 (2007).

    Article 
    ADS 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • BassiriRad, H. et al. Widespread foliage δ15N depletion under elevated CO2: inferences for the nitrogen cycle. Glob. Change Biol. 9, 1582–1590 (2003).

    Article 
    ADS 

    Google Scholar
     

  • Sabo, R. D. et al. Positive correlation between wood δ15N and stream nitrate concentrations in two temperate deciduous forests. Environ. Res. Commun. 2, 025003 (2020).

    Article 

    Google Scholar
     

  • Isles, P. D. F., Creed, I. F. & Bergström, A. K. Recent synchronous declines in DIN:TP in Swedish lakes. Glob. Biogeochem. Cycles 32, 208–225 (2018).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Lucas, R. W. et al. Long-term declines in stream and river inorganic nitrogen (N) export correspond to forest change. Ecol. Appl. 26, 545–556 (2016).

    Article 
    PubMed 

    Google Scholar
     

  • Goedkoop, W., Adler, S., Huser, B., Gardfjell, H. & Lau, D. C. P. Climate change-induced landscape alterations increase nutrient sequestration and cause severe oligotrophication of subarctic lakes. Glob. Change Biol. 31, e70314 (2025).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Nilsson, J. L., Camiolo, S., Huser, B., Agstam-Norlin, O. & Futter, M. Widespread and persistent oligotrophication of northern rivers. Sci. Total Environ. 955, 177261 (2024).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Pan, Y. et al. A large and persistent carbon sink in the world’s forests. Science 333, 988–993 (2011).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Stocker, B. D. et al. Empirical evidence and theoretical understanding of ecosystem carbon and nitrogen cycle interactions. New Phytol. 245, 49–68 (2025).

    Article 
    PubMed 

    Google Scholar
     

  • Norby, R. J. & Zak, D. R. Ecological lessons from Free-Air CO2 Enrichment (FACE) experiments. Annu. Rev. Ecol. Evol. Syst. 42, 181–203 (2011).

    Article 

    Google Scholar
     

  • Reich, P. B. & Hobbie, S. E. Decade-long soil nitrogen constraint on the CO2 fertilization of plant biomass. Nat. Clim. Change 3, 278–282 (2013).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Bassiouni, M., Smith, N. G., Reu, J. C., Peñuelas, J. & Keenan, T. F. Observed declines in leaf nitrogen explained by photosynthetic acclimation to CO2. Proc. Natl Acad. Sci. USA 122, e2501958122 (2025).

    Article 
    CAS 
    PubMed 
    PubMed Central 

    Google Scholar
     

  • Thomas, R. Q., Brookshire, E. N. J. & Gerber, S. Nitrogen limitation on land: how can it occur in Earth system models? Glob. Change Biol. 21, 1777–1793 (2015).

    Article 
    ADS 

    Google Scholar
     

  • Davies-Barnard, T. et al. Nitrogen cycling in CMIP6 land surface models: progress and limitations. Biogeosciences 17, 5129–5148 (2020).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Gerber, S., Hedin, L. O., Oppenheimer, M., Pacala, S. W. & Shevliakova, E. Nitrogen cycling and feedbacks in a global dynamic land model. Glob. Biogeochem. Cycles 24, GB1001 (2010).

    Article 
    ADS 

    Google Scholar
     

  • Sigurdsson, B. D., Medhurst, J. L., Wallin, G., Eggertsson, O. & Linder, S. Growth of mature boreal Norway spruce was not affected by elevated [CO2] and/or air temperature unless nutrient availability was improved. Tree Physiol. 33, 1192–1205 (2013).

    Article 
    CAS 
    PubMed 

    Google Scholar
     

  • Read, D. J. Mycorrhizas in ecosystems. Experientia 47, 376–391 (1991).

    Article 

    Google Scholar
     

  • Gundale, M. J. et al. The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: a review. Glob. Change Biol. 30, e17276 (2024).

    Article 
    CAS 

    Google Scholar
     

  • Cambron, T. W. et al. Plant nutrient acquisition under elevated CO2 and implications for the land carbon sink. Nat. Clim. Change 15, 935–946 (2025).

    Article 
    ADS 
    CAS 

    Google Scholar
     

  • Bunn, R. A. et al. What determines transfer of carbon from plants to mycorrhizal fungi? New Phytol. 244, 1199–1215 (2024).

    Article 
    PubMed 

    Google Scholar
     

  • Lindahl, B. D. et al. A group of ectomycorrhizal fungi restricts organic matter accumulation in boreal forest. Ecol. Lett. 24, 1341–1351 (2021).

    Article 
    PubMed 

    Google Scholar
     

  • Terrer, C. et al. A trade-off between plant and soil carbon storage under elevated CO2. Nature 591, 599–603 (2021).

    Article 
    ADS 
    CAS 
    PubMed 

    Google Scholar
     

  • Palmroth, S. et al. Increased leaf area index and efficiency drive enhanced production under elevated atmospheric CO2 in a pine-dominated stand showing no progressive nitrogen limitation. Glob. Change Biol. 30, e17190 (2024).

    Article 
    CAS 

    Google Scholar
     

  • Fridman, J. et al. Adapting National Forest Inventories to changing requirements—the case of the Swedish National Forest Inventory at the turn of the 20th century. Silva Fenn 48, 1095 (2014).

    Article 

    Google Scholar
     

  • Hedwall, P.-O., Gong, P., Ingerslev, M. & Bergh, J. Fertilization in northern forests—biological, economic and environmental constraints and possibilities. Scand. J. For. Res. 29, 301–311 (2014).

    Article 

    Google Scholar
     

  • Harris, I., Osborn, T. J., Jones, P. & Lister, D. Version 4 of the CRU TS monthly high-resolution gridded multivariate climate dataset. Sci. Data 7, 1–18 (2020).

    Article 

    Google Scholar
     

  • McCarroll, D. & Loader, N. J. Stable isotopes in tree rings. Q. Sci. Rev. 23, 771–801 (2004).

    Article 
    ADS 

    Google Scholar
     

  • Lan, X., Tans, P. & Thonin, K. W. Atmospheric carbon dioxide dry air mole fractions from the NOAA GML Carbon Cycle Cooperative Global Air Sampling Network, 1968–2023, version: 2024-07-30. Global Monitoring Laboratory https://doi.org/10.15138/wkgj-f215 (2024).

  • Yang, J. & Tian, H. ISIMIP3a N-deposition input data (v1.3). ISIMIP https://doi.org/10.48364/ISIMIP.759077.3 (2023).

  • Elfving, B. & Tegnhammar, L. Trends of tree growth in Swedish forests 1953–1992: an analysis based on sample trees from the National Forest Inventory. Scand. J. For. Res. 11, 26–37 (1996).

    Article 

    Google Scholar
     

  • Östlund, L., Zackrisson, O. & Axelsson, A. L. The history and transformation of a Scandinavian boreal forest landscape since the 19th century. Can. J. For. Res. 27, 1198–1206 (1997).

    Article 
    ADS 

    Google Scholar
     

  • Fridman, J. & Westerlund, B. in National Forest Inventories: Assessment of Wood Availability and Use (ed. Vidal, C.) 769–782 (Springer, 2016).

  • R Core Team. R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, 2023).

  • Pinheiro, J. C. & Bates, D. M. Mixed-Effects Models in S and S-PLUS (Springer, 2000).

  • Pinheiro, J. et al. nlme: linear and nonlinear mixed effects models. R package v.3.1-166 (CRAN, 2024).

  • Bartoń, K. MuMIn: multi-model inference. R package v.1.47.5 (2023).

  • Lenth, R. V. emmeans: estimated marginal means, aka least-squares means. R package v.1.9.0 (CRAN, 2023).

  • Wickham, H. ggplot2: Elegant Graphics for Data Analysis (Springer, 2009).

  • Lê, S., Josse, J. & Husson, F. FactoMineR: a package for multivariate analysis. J. Stat. Softw. 25, 1–8 (2008).

    Article 

    Google Scholar
     

  • Bassett, K. Reduces nitrogen availability in boreal forests (dataset). figshare https://doi.org/10.6084/m9.figshare.30675002 (2026).

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