It’s Autumn | What Happens To Trees At This Time Of Year?
After receiving some good feedback on my tree geek blog it’s now time for 1.2 – Its Autumn!
Autumn is here and it’s all around us but what actually happens to trees at this time of year? If you’re actually interested to see why the leaves change colour then keep on reading.
I love autumn, I really do, probably more than spring in fact and this is because everything is starting to wind down and get ready for life in the slow lane. The baby birds have fledged their nests and have gone on to build their own lives, the tree leaves are preparing to be abscised so they are showing some beautiful colours in the low autumn sun and with Christmas appearing on the horizon we are coming into a beautiful time of the year.
Colours of Leaves
As the trees start to wind down the first thing you will notice is the trees leaves starting to change colour from green to probably yellow then maybe orange, or red before they are finally abscised.
The reason that leaves are actually green is because they absorb all of the colours of the light spectrum and it is the green light that is least useful to the tree so it is bounced back by the chloroplasts.
The other colours have been there all year but you won’t have seen them as the leaf is using them to fund internal processes.
As we start to experience less sunlight the tree will know that the cold season is coming and it would cost more energy to keep a leaf alive than it can produce which is not cost effective, hence leaf fall.
Less sunlight means that the chloroplasts will start to break down so the leaves will start to change colour, revealing new pigments underneath treating us to the beautiful colours that follow.
The science part
In some species and in certain special years, you will see another stage, the fiery reds! These are caused by another chemical called anthocyanins, which also act as a natural antifreeze to stop the inside of the tree from freezing.
The reds are produced in years when lots of sunlight and dry weather have increased the amount of sugar in the trees sap, which triggers the tree to release anthocyanins in an attempt to utilise the last of the energy from its leaves. Giving it an extra power boost to help it through dormancy in the winter and to help fund budburst in the spring.
So when you are walking around your local park in awe of the low autumn sun on the magnificent colours of the autumn trees leaves or if this pops up in the pub quiz you can impress your friend’s with a bit of knowledge.