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Letters to Nature

Nature 411, 469-472 (24 May 2001) | doi:10.1038/35078064; Received 6 February 2001; Accepted 22 March 2001

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Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere

Ram Oren1, David S. Ellsworth2,3, Kurt H. Johnsen4, Nathan Phillips5, Brent E. Ewers1, Chris Maier4, Karina V.R. Schäfer1, Heather McCarthy1, George Hendrey3, Steven G. McNulty6 & Gabriel G. Katul1

  1. Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA
  2. School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan 48109, USA
  3. Department of Environmental Sciences, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
  4. Southern Research Station, US Forest Service, Research Triangle Park, North Carolina 27709, USA
  5. Department of Geography, Boston University, Boston, Massachusetts 02215, USA
  6. Southern Global Climate Change Program, US Forest Service, Raleigh, North Carolina 27606, USA

Correspondence to: Ram Oren1 Correspondence and requests for materials should be addressed to R.O. (e-mail: Email: ramoren@duke.edu).

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Northern mid-latitude forests are a large terrestrial carbon sink1, 2, 3, 4. Ignoring nutrient limitations, large increases in carbon sequestration from carbon dioxide (CO2) fertilization are expected in these forests5. Yet, forests are usually relegated to sites of moderate to poor fertility, where tree growth is often limited by nutrient supply, in particular nitrogen6, 7. Here we present evidence that estimates of increases in carbon sequestration of forests, which is expected to partially compensate for increasing CO2 in the atmosphere, are unduly optimistic8. In two forest experiments on maturing pines exposed to elevated atmospheric CO2, the CO2-induced biomass carbon increment without added nutrients was undetectable at a nutritionally poor site, and the stimulation at a nutritionally moderate site was transient, stabilizing at a marginal gain after three years. However, a large synergistic gain from higher CO2 and nutrients was detected with nutrients added. This gain was even larger at the poor site (threefold higher than the expected additive effect) than at the moderate site (twofold higher). Thus, fertility can restrain the response of wood carbon sequestration to increased atmospheric CO2. Assessment of future carbon sequestration should consider the limitations imposed by soil fertility, as well as interactions with nitrogen deposition.

  1. Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA
  2. School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan 48109, USA
  3. Department of Environmental Sciences, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
  4. Southern Research Station, US Forest Service, Research Triangle Park, North Carolina 27709, USA
  5. Department of Geography, Boston University, Boston, Massachusetts 02215, USA
  6. Southern Global Climate Change Program, US Forest Service, Raleigh, North Carolina 27606, USA

Correspondence to: Ram Oren1 Correspondence and requests for materials should be addressed to R.O. (e-mail: Email: ramoren@duke.edu).