Why do leaves change colour in autumn?
At the end of the growing season, as winter approaches, trees stop producing sap in order to protect themselves. Without sap, photosynthesis can no longer take place and the chlorophyll breaks down and eventually disappears. In the absence of chlorophyll, the other pigments present in the leaves become visible. These pigments—anthocyanins (pink, red and purple) and carotenoids (yellow and orange)—are also present in common fruits and vegetables such as corn, carrots, turnips, tomatoes and red peppers. Have you ever stopped to think about how our forests, when arrayed in their fall colours, are like a basket of fruits or vegetables? As for conifers, their foliage is more cold resistant because they are smaller and covered by a protective layer of wax. They therefore do not lose their chlorophyll and they remain green throughout the winter, with the exception of tamarack (larch).
