Increasing carbon storage in intact African tropical forests (from this week's Nature)

[jpak]

http://www.nature.com/nature/journal/v457/n7232/abs/nature07771.html

Absract

The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide1, 2. The role of tropical forests is critical because they are carbon-dense and highly productive3, 4. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades5, 6, 7, but the response of one-third of the world's tropical forests in Africa8 is largely unknown owing to an absence of spatially extensive observation networks9, 10. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha-1 yr-1 between 1968 and 2007 (95% confidence interval (CI), 0.22–0.94; mean interval, 1987–96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr-1 (CI, 0.15–0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area6, 7, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia5, 6, 11 together yields a comparable figure of 0.49 Mg C ha-1 yr-1 (n = 156; 562 ha; CI, 0.29–0.66; mean interval, 1987–97). This indicates a carbon sink of 1.3 Pg C yr-1 (CI, 0.8–1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data12 suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks13, as some theory14 and models2, 10, 15 predict.

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Editor's Summary

19 February 2009

Tropical forests grab carbon

Tropical forests store and process large amounts of carbon, affecting the amount of CO2 in the atmosphere, and hence the rate and magnitude of climate change. The extent of the contribution of tropical forests in this role is uncertain, largely because of a lack of monitoring. An international collaboration has now collected and analysed data from a ten-country network of 79 long-term monitoring plots across the largest tropical continent - Africa. Their findings reveal that above-ground carbon storage in live trees increased by 0.63 tonnes of carbon per hectare per year between 1968 and 2007. Extrapolation to unmeasured forest components and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 340 million tonnes a year. These results provide evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon.

[OKIsItJustMe]

1. One-fifth of fossil-fuel emissions absorbed by threatened forests

http://www.leeds.ac.uk/media/press_releases/current09/rainforest.htm

18 February 2009

One-fifth of fossil-fuel emissions absorbed by threatened forests

An international team of scientists have discovered that rainforest trees are getting bigger. They are storing more carbon from the atmosphere in their trunks, which has significantly reduced the rate of climate change.

Globally, tropical trees in undisturbed forest are absorbing nearly a fifth of the CO2 released by burning fossil fuels.

The researchers show that remaining tropical forests remove a massive 4.8 billion tonnes of CO2 emissions from the atmosphere each year. This includes a previously unknown carbon sink in Africa, mopping up 1.2 billion tonnes of CO2 each year.

Published today in Nature, the 40 year study of African tropical forests–one third of the world’s total tropical forest–shows that for at least the last few decades each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon per year.

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