Autumn is just about reaching us here in East Berkshire this weekend. The Maples especially in the fields near us are now in the full colours of autumn.
Each year in autumn some of these forests, put on one of the greatest shows on earth. We look on, in wonder at the colour and spectacle as our forests and woodlands transform into a riot of colour. But what makes deciduous trees shed their leaves?
Trees have evolved so that each leaf it grows catches some sunlight every day. The sunlight falling onto the leaves is vital for the trees survival. It is how it makes its food. A chemical called Chlorophyll is pumped into the leaves. This green Chlorophyll has the ability to take the energy provided by the sun, combined with water from the roots and carbon dioxide from the air and produce simple sugars which are the basis of the trees nourishment. During this process the chlorophyll breaks down and is used up, during high summer new supplies from the roots will replace it.
But as summer gives way to autumn, days shorten; temperatures cool and less sunlight reaches each leaf and therefore reduces the amount of food produced. As autumn progresses the imbalance, between maintaining the leaves and the amounts of food produced, becomes more one sided. To stop this imbalance, at some point trees will stop supplying chlorophyll to their leaves.
The withdrawal of Chlorophyll means that the leaves no longer convert sunlight into food. Without a constant re-supply the leaves lose their green colour. It is now, chemicals like Carotenoids and Anthocyanins present all year, get trapped in the old leaves. You may not know the chemical names but you will know their colours. Without the overwhelming green Chlorophyll the leaf colour changes and we get to see the orange, yellow, red and purples of autumn. Carotenoids are orange and yellow, while Anthocyanins are red and purple.
Get out into our woods with your camera and capture one of the greatest spectacles in nature.