Forests strongly affect climate through the exchange of large amounts of atmospheric CO2 (ref. 1). The main drivers of spatial variability in net ecosystem production (NEP) on a global scale are, however, poorly known. As increasing nutrient availability increases the production of biomass per unit of photosynthesis2 and reduces heterotrophic3 respiration in forests, we expected nutrients to determine carbon sequestration in forests. Our synthesis study of 92 forests in different climate zones revealed that nutrient availability indeed plays a crucial role in determining NEP and ecosystem carbon-use efficiency (CUEe; that is, the ratio of NEP to gross primary production (GPP)). Forests with high GPP exhibited high NEP only in nutrient-rich forests (CUEe = 33 ± 4%; mean ± s.e.m.). In nutrient-poor forests, a much larger proportion of GPP was released through ecosystem respiration, resulting in lower CUEe (6 ± 4%). Our finding that nutrient availability exerts a stronger control on NEP than on carbon input (GPP) conflicts with assumptions of nearly all global coupled carbon cycle–climate models, which assume that carbon inputs through photosynthesis drive biomass production and carbon sequestration. An improved global understanding of nutrient availability would therefore greatly improve carbon cycle modelling and should become a critical focus for future research.
Subscribe to Journal
Get full journal access for 1 year
only $17.75 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Dixon, R. K. et al. Carbon pools and flux of global forest ecosystems. Science 263, 185–90 (1994).
Vicca, S. et al. Fertile forests produce biomass more efficiently. Ecol. Lett. 15, 520–526 (2012).
Janssens, I. A. et al. Reduction of forest soil respiration in response to nitrogen deposition. Nature Geosci. 3, 315–322 (2010).
Valentini, R. et al. Respiration as the main determinant of carbon balance in European forests. Nature 404, 861–865 (2000).
Kato, T. & Tang, Y. Spatial variability and major controlling factors of CO2 sink strength in Asian terrestrial ecosystems: Evidence from eddy covariance data. Glob. Chang. Biol. 14, 2333–2348 (2008).
Piao, S. et al. Footprint of temperature changes in the temperate and boreal forest carbon balance. Geophys. Res. Lett. 36, L07404 (2009).
De Vries, W. et al. The impact of nitrogen deposition on carbon sequestration by European forests and heathlands. For. Ecol. Manage. 258, 1814–1823 (2009).
Fernández-Martínez, M. et al. Spatial variability and controls over biomass stocks, carbon fluxes and resource-use efficiencies in forest ecosystems. Trees Struct. Funct. 28, 597–611 (2014).
Luyssaert, S. et al. CO2 balance of boreal, temperate, and tropical forests derived from a global database. Glob. Chang. Biol. 13, 2509–2537 (2007).
Hijmans, R. J., Cameron, S. E., Parra, J. L., Jones, P. G. & Jarvis, A. Very high resolution interpolated climate surfaces for global land areas. Int. J. Climatol. 25, 1965–1978 (2005).
Reichstein, M. et al. On the separation of net ecosystem exchange into assimilation and ecosystem respiration: Review and improved algorithm. Glob. Chang. Biol. 11, 1424–1439 (2005).
Vickers, D., Thomas, C. K., Martin, J. G. & Law, B. Self-correlation between assimilation and respiration resulting from flux partitioning of eddy-covariance CO2 fluxes. Agric. For. Meteorol. 149, 1552–1555 (2009).
Lasslop, G., Reichstein, M., Detto, M., Richardson, A. D. & Baldocchi, D. D. Comment on Vickers et al: Self-correlation between assimilation and respiration resulting from flux partitioning of eddy-covariance CO2 fluxes. Agric. For. Meteorol. 150, 312–314 (2010).
Litton, C. M., Raich, J. W. & Ryan, M. G. Carbon allocation in forest ecosystems. Glob. Chang. Biol. 13, 2089–2109 (2007).
Manzoni, S., Taylor, P., Richter, A., Porporato, A. & Agren, G. I. Environmental and stoichiometric controls on microbial carbon-use efficiency in soils. New Phytol. 196, 79–91 (2012).
Shan, J., Morris, L. A. & Hendrick, R. L. The effects of management on soil and plant carbon sequestration in slash pine plantations. J. Appl. Ecol. 38, 932–941 (2002).
Goulden, M. L. et al. Patterns of NPP, GPP, respiration, and NEP during boreal forest succession. Glob. Chang. Biol. 17, 855–871 (2011).
Chapin, F. S. The mineral nutrition of wild plants. Annu. Rev. Ecol. Syst. 11, 233–260 (1980).
Burton, A., Pregitzer, K., Ruess, R., Hendrick, R. & Allen, M. Root respiration in North American forests: Effects of nitrogen concentration and temperature across biomes. Oecologia 131, 559–568 (2002).
Lee, S. C. et al. A protein phosphorylation/dephosphorylation network regulates a plant potassium channel. Proc. Natl Acad. Sci. USA 104, 15959–15964 (2007).
Keith, H., Mackey, B. G. & Lindenmayer, D. B. Re-evaluation of forest biomass carbon stocks and lessons from the world’s most carbon-dense forests. Proc. Natl Acad. Sci. USA 106, 11635–11640 (2009).
Cotrufo, M. F., Wallenstein, M. D., Boot, C. M., Denef, K. & Paul, E. The Microbial Efficiency-Matrix Stabilization (MEMS) framework integrates plant litter decomposition with soil organic matter stabilization: Do labile plant inputs form stable soil organic matter? Glob. Chang. Biol. 19, 988–995 (2013).
Peñuelas, J., Sardans, J., Rivas-ubach, A. & Janssens, I. A. The human-induced imbalance between C, N and P in earth’s life system. Glob. Chang. Biol. 18, 3–6 (2012).
Peñuelas, J. et al. Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe. Nature Commun. 4, 2934 (2013).
Zaehle, S. & Friend, A. D. Carbon and nitrogen cycle dynamics in the O-CN land surface model: 1 model description, site-scale evaluation, and sensitivity to parameter estimates. Glob. Biogeochem. Cycles 24, GB1005 (2010).
Zaehle, S., Friedlingstein, P. & Friend, A. D. Terrestrial nitrogen feedbacks may accelerate future climate change. Geophys. Res. Lett. 37, L01401 (2010).
Piao, S. et al. Evaluation of terrestrial carbon cycle models for their response to climate variability and to CO2 trends. Glob. Chang. Biol. 19, 2117–2132 (2013).
R Core Team R: A language and environment for statistical computing. R Found. Stat. Comput. 1, 409 (2013).
Grömping, U. Relative importance for linear regression in R: The package relaimpo. J. Stat. Softw. 17, 1–27 (2006).
This research was supported by the Spanish Government projects CGL2010-17172 and Consolider Ingenio Montes (CSD2008-00040), by the Catalan Government Grants SGR 2009-458 and FI-2013 and by the European Research Council Synergy grant 610028, P-IMBALANCE. S.V. and M.C. are postdoctoral fellows of the Research Foundation - Flanders (FWO). S.L. was financially supported by ERC Starting Grant 242564 and received additional financial support from FWO Vlaanderen. We appreciate the financial support of the GHG-Europe project. We also thank all site investigators, their funding agencies, the various regional flux networks (Afriflux, AmeriFlux, AsiaFlux, CarboAfrica, CarboEurope-IP, ChinaFlux, Fluxnet-Canada, KoFlux, LBA, NECC, OzFlux, TCOS-Siberia, USCCC), the Office of Science (BER) and US Department of Energy (for funding the development of measurement and data submission protocols), and the Fluxnet project, whose work and support is essential for obtaining the measurements without which the type of integrated analyses conducted in this study would not be possible.
The authors declare no competing financial interests.
About this article
Cite this article
Fernández-Martínez, M., Vicca, S., Janssens, I. et al. Nutrient availability as the key regulator of global forest carbon balance. Nature Clim Change 4, 471–476 (2014) doi:10.1038/nclimate2177
Long-term impact of nitrogen fertilization on carbon and water fluxes in a Douglas-fir stand in the Pacific Northwest
Forest Ecology and Management (2020)
Effects of nitrogen deposition on water use efficiency of global terrestrial ecosystems simulated using the IBIS model
Ecological Indicators (2019)
Soil respiration and organic matter decomposition dynamics respond to legacy fertilizer and weed control treatments in loblolly pine stands
Soil Biology and Biochemistry (2019)
Nature Reviews Microbiology (2019)