African tropical forests playing key role in mitigating global warming

February 20th, 2009 - 4:02 pm ICT by ANI  

Washington, Feb 20 (ANI): A new report in the journal Nature has shown that trees in intact African tropical forests hold more carbon now than they did 40 years ago, which is a hopeful sign that tropical forests could help to mitigate global warming.

Growing trees absorb carbon. Dead, decomposing trees release carbon.

Researchers expect growth and death to approximately balance each other out in mature, undisturbed forests, and thus for total tree carbon stocks, the carbon held by the trees, to remain approximately constant.

Yet, scientists discovered that on average each hectare (100 x 100 meters, or 2.2 acres) of apparently mature, undisturbed African forest was increasing in tree carbon stocks by an amount equal to the weight of a small car each year.

Previous studies have shown that Amazonian forests also take up carbon, although at somewhat lower rates.

According to Helene Muller-Landau, staff scientist at the Smithsonian Tropical Research Institute, If you assume that these forests should be in equilibrium, then the best way to explain why trees are growing bigger is anthropogenic global change the extra carbon dioxide in the atmosphere could essentially be acting as fertilizer.

But, its also possible that tropical forests are still growing back following past clearing or fire or other disturbance. Given increasing evidence that tropical forests have a long history of human occupation, recovery from past disturbance is almost certainly part of the reason these forests are taking up carbon today, she added.

Muller-Landau advises that this newfound sink shouldnt be taken for granted, or presumed to continue indefinitely.

While we still cant explain exactly what is behind this carbon sink, one thing we know for sure is that it cant be a sink forever. Trees and forests just cant keep getting bigger, she said.

Tropical forests are buying us a bit more time right now, but we cant count on them to continue to offset our carbon emissions in the future, she added. (ANI)

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