Are old forests underestimated as global carbon sinks?
Article first published online: 21 DEC 2001
Global Change Biology
Volume 7, Issue 4, pages 339–344, April 2001
How to Cite
Carey, E. V., Sala, A., Keane, R. and Callaway, R. M. (2001), Are old forests underestimated as global carbon sinks?. Global Change Biology, 7: 339–344. doi: 10.1046/j.1365-2486.2001.00418.x
- Issue published online: 21 DEC 2001
- Article first published online: 21 DEC 2001
- Received 20 April 2000; revised version received 30 October and accepted 7 November 2000
- carbon sequestration;
- carbon sink;
- coniferous forests;
- missing carbon;
- net primary productivity;
- old-growth forests
Old forests are important carbon pools, but are thought to be insignificant as current atmospheric carbon sinks. This perception is based on the assumption that changes in productivity with age in complex, multiaged, multispecies natural forests can be modelled simply as scaled-up versions of individual trees or even-aged stands. This assumption was tested by measuring the net primary productivity (NPP) of natural subalpine forests in the Northern Rocky Mountains, where NPP is from 50% to 100% higher than predicted by a model of an even-age forest composed of a single species. If process-based terrestrial carbon models underestimate NPP by 50% in just one quarter of the temperate coniferous forests throughout the world, then global NPP is being underestimated by 145 Tg of carbon annually. This is equivalent to 4.3–7.6% of the missing atmospheric carbon sink. These results emphasize the need to account for multiple-aged, species-diverse, mature forests in models of terrestrial carbon dynamics to approximate the global carbon budget.