Young growing forests store a lot of carbon, as the forest gets older the carbon sequestration capacity decreases. When trees are felled or burn down, there is a major release of carbon dioxide and it can take several years before this carbon loss is recovered.
“We cannot say that the carbon sequestration of newly planted trees is a ‘profit’ until the carbon emissions from previous felling have been compensated for by the new trees. How long that takes under various conditions is one of the things we study”, says Professor Natascha Kljun from the CEC.
Natascha Kljun and her colleagues measure the flow of greenhouse gases between the vegetation and the atmosphere, using instruments placed on tall masts. Researchers obtain data not only on greenhouse gases, but also on humidity, temperature, solar radiation and wind. There are now almost 600 such masts around the world, located in different climate zones and in different types of vegetation such as forests, grasslands, agricultural land, marshes and savannah.
“You have to take measurements for many years to obtain data which is representative of different conditions, and also to observe the effect of extreme weather events or climate change. The oldest towers have been in place since the early nineties, and they have provided very valuable data”, says Natascha Kljun.
The tower managed by the CEC in Norunda was one of the first towers established for greenhouse gas measurements. The forest in Norunda is now almost 100 years old and will soon be felled.
"As we have collected measurements from this forest for many years, this will be an excellent opportunity to study in detail what happens when old trees are felled and new trees are planted”, Natascha Kljun continues.
The resulting values are not only to be used to give advice on forest management in Sweden, but will also be used in regional and global ecosystem models, such as the EC-Earth model to improve the understanding of climate change on a global level.
Professor Natascha Kljun Natascha [dot] Kljun [at] cec [dot] lu [dot] se
Station Manager at Norunda measuring station, Anders Båth anders [dot] bath [at] cec [dot] lu [dot] se