I mentioned recently how we have had probably our best autumn colours here in France since we arrived. Why is it though, that some autumns are wonderful and others are rather drab? It's all down to 2 factors, the weather and the tree species affecting the colour pigments in leaves.
Autumn colours are caused by 2 groups of pigments in the leaves, carotenoids and anthocyanins. Throughout the year a third pigment, the more well know chlorophyll used in photosynthesis, masks other pigments and so the leaves appear predominantly green. As the tree prepares for leaf fall in autumn less chlorophyll is produced and other pigments can show their colours. Carotenoids are present in the leaf all year round and they give leaves their yellow, gold and orange colour.
|Carotenoid pigments in beech leaves|
|Anthocyanin pigments in Virginia Creeper leaves|
Not all trees are the same though and some contain more of these colour-giving pigments than others. Maples, dogwoods, cherries and some oaks contain the most and these are the predominant tree species in New England, a region famous for it's autumn colours. In Great Britain (and probably Normandy) only about 10% of the trees have these high levels of pigments so we can never really compete with New England. That said this year has been wonderful. The weather earlier will have helped to produce some of the colours but a long calm autumn (except for the day the boys and yours truly decided to take a ferry to England in the tail end of a hurricane!) has meant that the leaves have not been blown off early and so the colours have had the time to develop and shine through.
|Oak tree bathed in the light of an autumn sunset|
Are you having a good autumn where you live? What colours are the best?