The older they are, the better they get. This is true not only for wines but also for trees, at least when it comes to their ability to remove carbon from the air. Until now, most scientists believed that the growth of trees slows down as they age but a new study published in Nature finds just the opposite. Researchers recently discovered that the growth rate of trees increases continuously with age.
A group of researchers conducted a large-scale study in which they measured the diameters of 403 tropical and temperate tree species worldwide, totaling two-thirds of a million trees, to estimate their biomass growth rate.
They found that although the total productivity of a forest declines as trees age, older trees continue to grow and actively fix carbon from the atmosphere. In fact, just one massive tree can accumulate same amount of carbon in a year as that contained in a middle sized tree. However, a large number of young trees may offset the carbon removed by a few large trees.
Since larger trees are more potent at sequestering carbon from the atmosphere, they can have a huge impact in mitigating climate change. Thus, saving older growth forests – which are declining at an alarming rate particularly in Southeast Asia – should be the focus of conservation efforts.
Planting trees helps but so does saving the larger trees.
Stephenson, N.L., Das, A.J., Condit, R., Russo, S.E., Baker, P.J., Bechman N.G., Coomes, D.A.,…Zavala, M.A. (2014). Rate of tree carbon accumulation increases continuously with tree size. Nature. Published online 15 January 2014. DOI:10.1038/nature12914.