Old-growth forests as global carbon sinks

Sebastiaan Luyssaert*, Ernst Detlef Schulze, Annett Börner, Alexander Knohl, Dominik Hessenmöller, Beverly E. Law, Philippe Ciais, John Grace

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Old-growth forests remove carbon dioxide from the atmosphere at rates that vary with climate and nitrogen deposition. The sequestered carbon dioxide is stored in live woody tissues and slowly decomposing organic matter in litter and soil. Old-growth forests therefore serve as a global carbon dioxide sink, but they are not protected by international treaties, because it is generally thought that ageing forests cease to accumulate carbon. Here we report a search of literature and databases for forest carbon-flux estimates. We find that in forests between 15 and 800 years of age, net ecosystem productivity (the net carbon balance of the forest including soils) is usually positive. Our results demonstrate that old-growth forests can continue to accumulate carbon, contrary to the long-standing view that they are carbon neutral. Over 30 per cent of the global forest area is unmanaged primary forest, and this area contains the remaining old-growth forests. Half of the primary forests (6 × 10 8 hectares) are located in the boreal and temperate regions of the Northern Hemisphere. On the basis of our analysis, these forests alone sequester about 1.3 ± 0.5 gigatonnes of carbon per year. Thus, our findings suggest that 15 per cent of the global forest area, which is currently not considered when offsetting increasing atmospheric carbon dioxide concentrations, provides at least 10 per cent of the global net ecosystem productivity. Old-growth forests accumulate carbon for centuries and contain large quantities of it. We expect, however, that much of this carbon, even soil carbon, will move back to the atmosphere if these forests are disturbed.

Original languageEnglish
Pages (from-to)213-215
Number of pages3
JournalNature
Volume455
Issue number7210
Early online date11 Sep 2008
DOIs
Publication statusPublished - 2008

Keywords

  • Analysis
  • Nitrogen
  • Organic Matter
  • Primary
  • Soils
  • age
  • ageing
  • atmosphere
  • carbon
  • carbon sink
  • climate
  • ecosystem
  • ecosystem productivity
  • estimates
  • forest
  • forests
  • litter
  • old growth forests
  • primary forest
  • productivity
  • rates
  • sink
  • soil
  • will

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