Old trees make the best carbon sinksA new study published in last week’s issue of Nature shows

Old trees make the best carbon sinksA new study published in last week’s issue of Nature shows that, contrary to popular assumptions, it is old trees rather than young that convert the most carbon into biomass. The work has important implications for understanding the global carbon cycle, underlines the vitality of conservation of the remaining old growth forests worldwide and for developing forestry management strategies to mitigate climate change through systems such as carbon offsetting.Previously, young fast growing species were thought to transform the most carbon into biomass, with growth rated believed to slow and eventually stop as the trees aged. The new global study by a team of 38 scientists overturned this belief, demonstrating that the larger older trees accounted for a third of annual mass growth in forests while amounting to a mere 6% of the trees. They showed that large old trees could add as much as the volume of a whole medium tree to their biomass yearly, and that their growth rate increased with age. The work was based on an analysis of nearly 675,000 trees of 400 species spread worldwide, and confirms another paper published in 2010 that focussed on eucalypts and sequoias. Another study in 2012The latest study is wider ranging, and confirms that preservation of these rare and important trees is important for more than merely aesthetic reasons. As well as planting many young trees, middle aged ones should not be cut, and the cycle of using fast growing commercial trees such as pine as carbon offsets will not yield as high benefits as preserving existing forests and allowing the continued growth of older trees. Sadly, old trees are disappearing fast all over the world, mostly due to pressure on habitats and the increase in commercial forestry and deforestation in areas such as the Amazon and Borneo.LozImage credit of General Sherman, the largest specimen in Sequoia National Forest: Jim Bahnhttp://www.theguardian.com/environment/2014/jan/15/trees-grow-more-older-carbonhttp://www.smh.com.au/environment/climate-change/oldgrowth-forests-seen-more-valuable-as-carbon-sinks-study-20140116-30vvc.htmlhttp://www.foresteurope.org/es/node/499Original paper, paywall access: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12914.html2010 study: http://www.sciencedirect.com/science/article/pii/S037811270900872X -- source link

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