Study shows increase in CO2 has not stimulated growth of tropical trees

Posted by ap507 at Dec 23, 2014 01:10 PM |
Study involving Dr Arnoud Boom featured as cover story in Nature Geoscience journal

The work of a University of Leicester geographer features as the cover story of the January issue of the journal Nature Geoscience.

Dr Arnoud Boom (pictured) in the Department of Geography is one of the collaborating authors in the international study that examined the relationship between the growth of tropical trees and rise in CO2 levels.

Since the start of the industrial revolution in 1850, atmospheric CO2 levels have increased by about 40%. However,  the growth of tropical trees has not increased as a result. The prediction that tropical forests would help to slow down climate change therefore appears to be too optimistic.

Experiments have shown us that CO2 can boost the growth of trees due to changes in the leaves. To measure such changes in tropical rainforests the team analysed stable carbon isotopes present in the wood of trees growing in Bolivia, Cameroon and Thailand. The big question was whether this improved water supply had also resulted in increased tree growth.

With the aid of annual rings, it is possible to investigate the whole period throughout which CO2 levels in the atmosphere have been increasing. Studies are uncovering more and more tropical tree species that have annual rings: a wonderful source of information on the growth, physiology and environment of trees.

Almost all models made so far assume that CO2 stimulates tree growth in the tropics. In this way, tropical forests can function as carbon sinks. They intercept a part of the extra CO2. The study demonstrates that this assumption is probably too optimistic and that increased CO2 did not lead to the expected extra growth in existing forests.

The story has been chosen by Nature Geoscience as the cover story for its January issue, which also features the work of Dr Sue Page, Head of the Department of Geography, on Global vulnerability of peatlands to fire and carbon loss.

You can access the articles here. 

 Press Release

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