In 68 nations studied, forest area is expanding in 45 and density is also increasing in 45, said Pekka Kauppi of the University of Helsinki. "Changing area and density combined had a positive impact on the carbon stock in 51 countries." The point is that earlier forecasts of deforestation ignored density metrics. That trend has been underway since at least 2006. See http://news.nationalgeographic.com/news/2006/11/061113-forests.html. That 2006 study found that forests were growing, reversing an earlier trend of shrinking forests.
Previous studies on the world's forests have tended to focus solely on forest area, often measured by satellite, but according to the US and European researchers compiling the report this misses out on the fact that in many cases more tree mass is appearing as forests get denser, with taller trees and more of them.
'To speak of carbon, we must look beyond measurements of area and apply forestry methods traditionally used to measure timber volumes,” says forestry expert Paul Waggoner. 'Forests are like cities: they can grow both by spreading and by becoming denser,' says Iddo Wernick, another study author.
For example, according to US Forest Service figures, US timberland grew by only 1 per cent over the period 1953 to 2007. But this figure doesn't reflect the true story: the volume of growing stock increased by 51 per cent, and overall national forest density was well up.
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