Mature Trees Are Poor Carbon Sponges
Mature Trees Are Poor Carbon Sponges
Mature trees have all the carbon dioxide they need.
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Many carbon offsetting projects offer to either plant new trees or to protect existing woodlands which will then act as carbon sponges absorbing excess CO2 from the atmosphere and reducing climate change. With the Government now getting involved in setting guidelines for carbon offset projects, scientists are now analysing more closely the claims made by the carbon offset suppliers.
Some carbon offset projects in the UK offer to protect some existing woodland which will then act like a carbon sink absorbing carbon dioxide (CO2) which would otherwise have contributed to global warming in the atmosphere. However, scientific evidence showed as early as 2003 that mature trees already have all the carbon dioxide that they need.
Unlike humans who need to breath continuously in order to receive the oxygen we need to survive, trees keep stores of carbon taken from the CO2 which they breathe. Measuring the carbon stores of trees in a 100 year old forest near Basel, Switzerland, Gunter Hoch found that only 35-40% of the stores are used during each year. Therefore it can be assumed that trees are already very well supplied with CO2 and therefore will not absorb more even as CO2 concentrations in the atmosphere increase.
Although increasing the percentage of CO2 in the atmosphere means that there is potential for the trees to stage a growth spurt, fixed supplies of vital nutrients such as Nitrogen prevent this from happening. In addition the space above and below ground is limited so trees do not absorb much of the extra CO2.
Old Trees Poor Carbon Sponges - taken by Minnesotans For Sustainability from an article published in Nature in July 2003.
Article Last Modified: 15:19, 18th Jan 2007Comment on this Article
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