Nature Nook Blog – The place for beautiful nature walks

Welcome to My Nature Nook Blog – The central hub of our nature walk and nature study tutorials.

Here you will find a host of mini-tutorials ready to help you with your nature walk thoughts and questions. If you have specific topics you would love to know more about, do feel free to leave a comment below this post. 

As I have just had a baby, the posts will probably be slow and few between for the next few months – two little explorers are hard work! But, do subscribe to keep up-to-date and receive all our blog posts straight to your inbox. Happy nature walking x

What Makes Leaves Change Their Colour In Autumn?

why do leaves change colour

Topic Overview

  • Leaves contain several different coloured pigments – green chlorophyll, red anthocyanin, yellow xanthophyll and orange carotenoid 
  • There is so much more chlorophyll compared to the other pigments, that the leaves appear green.
  • Autumn’s cold weather and reduced daylight hours prompt trees to enter a state of hibernation
  • Chlorophyll makes energy for the tree, but needs sunlight to function.
  • It also costs the tree a lot of energy to make its chlorophyll
  • So, they stop producing chlorophyll in order to save energy
  • Once the there is no more chlorophyll, we see the other pigments shine!

Are you ready to learn more? Let’s go!

Why do trees have leaves?

To understand why leaves change colour, we must first understand why trees have leaves in the first place.

Leaves are basically the kitchens of plants and trees. They take the main ingredients a tree needs to live (sunlight and carbon dioxide), combines them with water and minerals (absorbed by the trees’ roots), and uses sunlight to cook them up into oxygen and sugars. These sugars can then be used as an energy source by the tree.

Why are leaves green?

In order to acquire the sunlight it needs to cook its food, trees have a special pigment (called chlorophyll) inside their leaves. Chlorophyll absorbs the sunlight and uses it as a catalyst (a helper) in this energy-making process. (This process is called photosynthesis.)

Chlorophyll is green – and there is LOTS of it in every leaf. So, most leaves look green. But, chlorophyll is not the only pigment present inside leaves. There are actually several pigments, each with their own special function. The most important of these, are chlorophyll (green), carotenoids (orange), xanthophyll (yellow), tannins (brown) and anthocyanins (red). But there is so much chlorophyll compared to the others, that it completely masks them to the point that we cannot see the other colours. That is, until the arrival of autumn.

What makes leaves change colour in autumn?

As autumn sets in, the temperatures drop and the nights draw in, reducing daylight hours. This means less cooking or food-making time for the tree, which means less photosynthesis. The amount of energy created by the chlorophyll drops significantly – even though the tree is still using up energy to make it. (This change in temperature and daylight, is called photoperiodism). It makes no sense for the tree to be wasting energy in making chlorophyll if it is not getting anything back. So, it stops making chlorophyll.

(Remember, there is more than one pigment present in tree leaves. It is just the vast quantity of chlorophyll that makes us see leaves as green. So, it makes sense that once the tree stops producing chlorophyll, we will start to see the other pigments present in the leaves.)

But even these pigments compete with each other. Remember, xanthophyll is yellow, carotenoids are orange and anthocyanins are red. So, if there are more carotenoids and xanthophyll than anthocyanins, we see the leaves as orange or yellow. But if there are more anthocyanins than carotenoids, then the leaves appear red.

How does weather affect leaf colour?

Like chlorophyll, carotenoids and anthocyanin are also dependent on temperature and daylight hours – especially anthocyanin. So, sometimes, if the season is cold and bright, red leaves become much more vibrant (because the tree is producing lots of anthocyanin). Whereas, if the season is cloudy and overcast, the leaves look duller and not as bright (because it is not producing as much).

Do all trees lose their leaves in autumn?

Although photoperiodism will affect almost all trees, not all trees lose their leaves in response to it. Conifers are called evergreens because they do not shed their leaves in the autumn (although, larch does). Whereas deciduous trees almost always shed their leaves (although, holly and holly oak are exceptions).

Also, not all deciduous trees shed their leaves at the same time. Some trees, like ash, change colour and drop their leaves really early in the season. While others, such as oak, beech, sycamore and hornbeam take time to respond and hold on to their leaves for much, much longer.

Why are autumn trees different colours?

If you look around you in the autumn, you will notice a wide array of autumn shades. Some trees are red, some are yellow, some orange and others are brown. While the colour of each tree is dependent on the ratio of its pigments, certain trees tend to turn certain colours. For example, hornbeam and maple often turn red, while field maple and ash are usually yellow. Hawthorn often turns to orange and oak, with its tannins, turns a tan-brown colour.

Summary

So, what makes leaves change their colour in the autumn? It is all down to cooler weather, shorter daylight hours and pigments! Once the autumn kicks in and the days get shorter, the trees cannot justify wasting energy to produce chlorophyll, because it cannot help the tree make energy in return. So, they stop making it, allowing all the other pigments present in the leaf to step into the dimming light and shine!

Your Autumn Nature Walk Task

So, now it is your turn! Have a good look around while you are out and about this week.

  • What trees can you see?
  • What colours are they turning?
  • Are all trees of the same type turning the same colour?
  • Are the leaves within a single tree all the same colour?
  • Finally, did you enjoy this tutorial? If so, we would love 5 stars!
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Have fun with your nature walk x

P.S. If you would love to learn more, you can have a look at this BBC documentary about why leaves change colour in the autumn. You can also learn how to preserve your leaves for autumn crafts in our tutorial here x

Field Maples – Do you know how to find one?

how to identify a field maple

For this nature adventure, you will need: A natural hedgerow, your field journal and nature activity book, some pens or pencils, a crayon and a camera for any snapshots.

Your task for this adventure, is: to correctly identify a field maple tree, make an annotated sketch of the parts of this tree and find it in your activity book. Ready? Let’s go!

About The Field Maple (Acer campestre)

The field maple, or Acer campestre, is a very common tree. It is frequently found in wild hedgerows and woodlands. It may also be found growing in parks and country estates. Field maples can live to a ripe old age. There are some that are over 300 years old! 

It is a tree that at first glance looks very similar to the sycamore tree we looked at last week. But, if you remember, there are differences between them once you know what to look for.

Characteristics: Your clues for identifying field maples, are the leaves, flowers and seeds. In spring, the buds are a grey-brown colour, sometimes with darker lines or markings. During the summer, they have upright clusters of yellow-green, thin petal-ed flowers and small, dark green, rounded, star-shaped leaves. Finally, in the autumn, there it has lovely helicopter seeds.

Sometimes all the features of the tree may overlap – you might have buds, leaves, flowers and seeds all at the same time – or you my have only one clue to work with. Remember to use all available clues to help you. Also remember – not all clues might be on the tree itself – always have a look at the ground around the tree too.

How To Identify A Field Maple Tree

Buds – Unlike sycamore, the buds of this tree are not showy and easy to spot. They are a grey-brown colour, sometimes with black or darker brown markings. But, they can help you out when combined with other clues.

field maple buds

Leaves – Like sycamore, the leaves are star-shaped (palmate), but have 3-5 lobes, which are rounded and blunt at the ends – unlike the pointier, 5-lobed sycamore. They are also quite small. Much smaller than sycamore and Norway maple. (You can see all three leaves in our leaves field guide.)  During the summer, they are a plain old dark green. But in the autumn months, you will see them peeping out of the hedgerows with a glorious golden-yellow sheen.

field maple

Flowers – The flowers of the field maple, are a pale, lime-green in colour and stand upright in little clusters. Each flower has a round, green center, yellow stamens and thin, spaced-out green-coloured petals.

identifying field maple tree flowers

Seeds – The seeds are a ‘helicopter’ type seed, or samara. They have two broad wings, which stick out almost horizontally on either side. During the summer months, they are tinged with red or pink, making them easy to identify. But, beware, they also look similar to the sycamore and Norway maple. To get them right, remember that Sycamore seeds are the closest together, field maple seeds are the widest apart and Norway maple seeds are in the middle. (You can see them all here.)

field maple seeds

Your Nature Walk Activity

So, now we know how to spot a field maple, it is time for your nature adventure task!

Take a wild hedgerow or woodland nature walk and find a field maple tree. Once you have found it, look for landmarks to help you find it again, then note these down in your field diary.

Then, stand back and observe the tree. What shape is it? What is your overall impression of the tree? How does it move? How do the leaves move? What sound does it make when it blows in the wind?

Move in closer. Look at the bark. What colour is it? What texture? Is there any moss or lichen on it? If so, is it all the same type?

Glance at the twigs. Are they rigid and tough, or soft and bendy? Can you see any buds or leaf scars? Where are they? Along the main branches? Just on the twigs? All the way along the twigs? Or just at the tips?

Examine the leaves. How big are they? How do they feel? Rough or smooth, brittle or hairy? How prominent are the leaf veins?

Look at the flowers, if there are any – how big are they? Do they smell? Are they sticky? What types of insect are being attracted to them?

Notice any seeds – how big or small are the seeds? How far around the tree are they falling? Just beneath the tree or at a distance? Do they all spin the same way as they fall?

Now, take out your field books. Sketch in the outline of the tree and note down your observations on its overall impression, sounds and movement. Then make a rubbing of the bark. Note down or sketch any lichen types growing on it. Make a note of its colour.

Next, take a leaf rubbing, then sketch the leaf. Again, make a note of its colour and texture.

Then, draw any buds, flowers or seeds. Again, make sure to annotate them with colours, smells and textures etc, along with any other thought or observations.

Lastly, don’t forget to label the tree with its name, the date and where you found it. Remember, you may want to come back and re-examine the tree through its different seasons. You can also learn more about this lovely tree here

I hope you enjoyed this nature walk tutorial? If you have any thoughts, you can let us know by clicking a star and leaving us a note in the comments underneath. You can share snapshots of your nature walks with us too – just use #mynaturenook or tag us with @my.nature.nook on Instagram.

Have fun and happy nature walking x