The landscape that surrounds us in this period is colored bymaples, beeches, chestnutsand other trees that lose their leaves in autumn. The trees prepare for winter rest by recovering reserves.
The chlorophyll contained in the leaves degrades. Thus the carotenoids (yellow/orange pigments) contained in the leaf are no longer masked by the intense green of the chlorophyll and theleaves appear yellow and orange to us.
The color red or purpleof some trees in autumn is instead due to the presence of anthocyanins, which are produced by the plant in response to night frosts.Finally, the color brownof the leaves now close to falling is given by the tannins.
Why do deciduous trees lose their leaves in autumn?
Leaves are the main organ for chlorophyll photosynthesis (transformation of solar energy into chemical energy) and for this reason, in general,They have a large surface area.
A lot of water evaporates from the surface.On warm winter days, the leaves would lose a lot of water through evaporation, butthe tree would have no way of recovering it from the cold and often frozen ground.
Furthermore, leaves are very fragile organs and would not be able to resist the cold.Once the leaves have fallen, the tree can slow its metabolismand save energy while waiting for spring!
