Trees in Europe release their leaves up to a week earlier in the autumn when the amount of carbon dioxide in the air increases, shows a new study published in the scientific journal Science.
Research is an important piece of the puzzle in the overall knowledge of how trees' uptake of carbon dioxide can slow down the effect of global warming.
- This means that the calculations made now can overestimate how much the trees' production will increase as a result of climate change, says Johan Uddling Fredin, professor of plant physiology at the University of Gothenburg.
The growing season starts earlier
There is ample scientific evidence that the growing season starts earlier in the spring.
In the temperate zone, ie between the desert and the Arctic climate, it can be up to three weeks earlier than in the 60s, according to Johan Uddling Fredin.
-You have not had much knowledge about how trees are affected in the autumn.
But this study shows that there is some kind of saturation of how much trees can store during a growing season.
Did climate experiment
The researchers have made model calculations on data from Central European tree species between 1948 and 2015 and how they behaved with different types of conditions.
In addition, they have experimented with different climate scenarios on trees in Munich's botanical garden.
Several trees have been manipulated with shade, carbon dioxide and with heating.
- If you increase the carbon dioxide, photosynthesis increases and then the trees shed their leaves earlier and if you shade the tree, it keeps the leaves on later in the autumn, says Johan Uddling Fredin.
Applies to the "temperate zone"
But the observations only apply to Central European trees in the temperate zone.
- In dry ecosystems, the opposite is seen - that over time the season could have been longer, because more carbon dioxide means that the plants save water - especially in grass ecosystems, says Johan Uddling Fredin.