I did a quick search, and found a few articles, but that is not publicized much.
Global warming makes trees grow at fastest rate for 200 years
2 Feb 2010
Forests in the northern hemisphere could be growing faster now than they were 200 years ago as a result of climate change, according to a study of trees in eastern America.
Higher concentrations of carbon dioxide and extended growing seasons could be favourable for agriculture in some parts of the world, mainly in the northern hemisphere. The study in Maryland suggests that the extra growth in trees could help to act as a more efficient carbon “sink”, which could offset the carbon dioxide being added to the atmosphere by the burning of fossil fuels.
And more...
Fifth of world carbon emissions soaked up by extra forest growth, scientists find
Trees in the tropics are getting bigger, which means they are soaking up an extra 5bn tonnes of CO2 a year
http://www.guardian.co.uk/environment/2009/feb/18/trees-tropics-climate-change
Trees across the tropics are getting bigger and offering unexpected help in the fight against climate change, scientists have discovered.
A laborious study of the girth of 70,000 trees across Africa has shown that tropical forests are soaking up more carbon dioxide pollution that anybody realised. Almost one-fifth of our fossil fuel emissions are absorbed by forests across Africa, Amazonia and Asia, the research suggests.