Colours of the fall

Looking at the horizon now, I can see so many autumn colours on all the trees that surround our houses, parks and green spaces.  I am reminded of the rainbows of lockdown and how the bright colours were a symbol of hope in these uncertain days.  With another (sort-of!) of lockdown feeling imminent, it feels like the right time to take a moment to look at the colours and beauty around us and take ourselves into nature where it is calm, quiet and peaceful.  

I love nothing more than stepping out of the door and finding new woodland trails to explore in my local area.  Seeing the colours on the leaves turning shades of yellow, orange and red made me stop and think about how and why this happens. What is it that makes the leaves change colour and fall down, and why does it happen now?

Well it's all down to chemicals in the leaves called pigments. Chlorophyll is the most well-known pigment which makes the leaves a green colour. This helps the plant to make food using the sun's light. Another pigment is carotene which is a yellow colour, and anthocyanin which turns the leaves red and pink. 

The strength of these pigments is determined by different things.  When the nights start to get colder, the chlorophyll is destroyed by the colder temperatures and the leaf takes on a yellow colour.  If the weather stays dry, the sugars in the leaves become more concentrated and more anthocyanin is produced making the leaves turn red. Sunny days help the plant use up the remaining chlorophyll and produce sugars making it turn from green to red. 

As the days get shorter and darker, it signals to the tree to shed its leaves.  This is because there is not enough sunlight for the tree to keep producing energy and so the leaves are dropped and will be regrown in the spring. The shedded leaves fall to the ground and are decomposed by bacteria and fungi which releases nutrients ready to be taken up again. 

To find out more about the tree cycle, visit The Wildlife Trusts page on Autumn Leaves 🍁