Young forests fight climate crisis better says new study
YOUNG forests absorb one-quarter more carbon dioxide than tropical rainforests, a study has shown.
Dense rainforests near the Equator have traditionally been thought as the best at removing the greenhouse gas from the atmosphere.
But trees less than 140-years-old remove more than half of the carbon dioxide from the atmosphere, researchers at the University of Birmingham found. These forests have typically “regrown” on former agricultural or logging land or after forest fires and are found in middle and high latitudes.
Study author Dr Tom Pugh, of the Birmingham Institute of Forest Research (BIFOR), said a young forest could absorb up to 25 per cent more carbon than a comparable one that was older.
This finding went against conventional thinking that a forest’s “carbon sink” ability was overwhelming dependent on the fertilisation rates of its trees.
His research highlights the importance of forests in the world’s temperate zone for climate change mitigation. It also reveals how much carbon re-growing forests can be expected to take up in future.
Dr Pugh said the age-driven growth factor was important to take into account when calculating how much carbon a forest will absorb after reforestation schemes. He said: “It’s important to get a clear sense of where and why this carbon uptake is happening, because this helps us to make targeted and informed decisions about forest management.
“The amount of CO2 that can be taken up by forests is a finite amount: ultimately reforestation programmes will only be effective if we simultaneously work to reduce our emissions.”
Trees less than 140 years old have typically “regrown” on land previously used for agriculture, or cleared by fire or harvest and it is their young age that is one of the main drivers of this carbon uptake.
Forests are widely recognised as important carbon sinks - ecosystems capable of capturing and storing large amounts of carbon dioxide.
But dense tropical forests, close to the equator, such as the Amazon or Congo, have been assumed to be working the hardest to soak up these gases.
Dr Pugh’s team carried out fresh analysis of the global biosphere using a new combination of data and computer modelling.
They calculated the carbon uptake between 2001 and 2010 by old, established areas of forest using data sets of forest age including those deforested or suffering natural fires.
The study was published in the Proceedings of the National Academy of Sciences of the United States of America.