Autumn Colours

The teddy bears were sadly watching the dried leaves falling from the trees. This seemed to happen every Autumn until most of the trees were just bare branches. "I like the leaves on the trees changing colour from green to yellow, red and orange - they're very pretty," said Henry "but why don't the trees keep their leaves on all year round? Why do they have to fall off?"

"Well, there's a reason why leaves change colour in Autumn," said Scary "and also why all the leaves fall off certain trees."

He explained that when leaves are green in Spring and Summer they are working hard to turn sunlight into energy so that the tree can grow. A chemical called 'chlorophyll' is what gives the leaves their green colour.

But, when the days get shorter (and there are much less hours of sunshine) and the weather gets colder (as it does in Autumn) then it is harder for the chlorophyll to make the food needed to keep the leaves green. The green colour disappears, leaving behind other colours that you normally can't see. This is when the yellow and orange colours magically become visible and give the leaves their beautiful new look.

However, trees then shed their leaves in the Autumn season to survive the harsh cold conditions of Winter. By the way, Autumn is often called Fall in the United States simply because leaves fall from the trees at that time. Shedding their leaves helps trees to conserve water and energy. If the leaves remained on the trees, the water in the leaves would freeze and burst in the Winter as the water turned to ice, and by the time Summer rolled round, the tree would have no working leaves left, so no means to create food. But with the old leaves fallen, there is room for new ones to grow in the Spring.

This leaf falling doesn't affect every tree. It happens to deciduous trees such as ash, beech, elm, cherry, oak, maple, willow and poplar.

Still, there are some trees which are known as 'evergreens.' As the name suggests, that means that their leaves are green all the time and they don't fall off. The reason for this is trees such as firs have a thick, waxy coating called a resin that protects their leaves. This means they don't freeze and rupture like other trees' leaves would when they get cold, so they don't need all of them to fall off and re-grow in time for Summer.

"But, but, but" interrupted Lizzie. "I'm constantly cleaning up needles from our Christmas tree inside in December. So they do fall off!"

"Well, they wouldn't if we didn't cut them down and bring them indoors" said Scary. "Trees that are cut down cannot take up water any more. As the tree loses water, the needles are unable to make food any more, so they fall off."

"I don't think we should cut down a tree this year then," said Lizzie. "Maybe we could decorate a tree out in the garden instead. One that would stay living and still look Christmassy. We could dress it with lights and decorations, and maybe some gifts for the birds," she continued thoughtfully.

Well, now you know about trees in Autumn, and maybe you will decide to have a living Christmas tree outside rather than a cut one inside. Perhaps we'll get to see Lizzie's version, to give you some ideas, later in the year.