Autumn Leaves: The science behind one of the most beautiful seasons

Hi everyone!

We know that at the time this post is being published it will still be August, and the height of summer here in the Northern Hemisphere, but within the next two months or so, autumn will well and truly be upon us. So, today, we thought we could talk a bit about the science behind this beautiful season.

Thinking of autumn automatically brings to mind images of crisp mornings, cosy evenings, and of the picturesque falling leaves with their hues of red, orange, yellow and gold. The change of colour of these leaves marks a change of seasons, and the decreasing temperature and light levels that goes along with that. But why do these leaves lose their greenness and fall from the trees?

Trees' leaves contain a chemical called chlorophyll which allows them to convert water and carbon dioxide into glucose, or sugars, through a process called photosynthesis. This is how they gain energy from sunlight. Chlorophyll is green in colour, giving the summer months, when trees photosynthesise the most, that beautiful fresh, green backdrop. However, as the light levels start to fade throughout the months of September and October, the tree receives less and less sunlight in order to gain energy from. During the summer, chlorophyll naturally breaks down and is replenished, but now this process slows down, meaning the chlorophyll isn't replaced as quickly or as much. This causes the green colour to start to disappear.

The chemicals that cause the classic orange and yellow shades associated with autumn, are actually always contained within the leaves, but are hidden by the stronger green colour produced by the chlorophyll. So, as the chlorophyll breaks down, these orange and yellow colours are revealed. Interestingly, each species of tree has slightly different colouring of leaf, giving a stunning wide array of shades. Not all species will produce red leaves, and the ones that do require specific conditions, in particular, an extremely dry and sunny year.

The next stage is 'the fall'. This is when the leaves die and drop off of the branches, allowing space for new growth in the spring. But, the trees' use for them is not over. The leaves coating the ground around the tree improve the soil's drainage and ability to retain moisture. They also host a variety of species of insects and fungi which decompose them.

The ideal conditions for this process is a long 'Indian' summer, which allows the leaves to keep producing energy for the tree through photosynthesis for as long as possible, followed by a short burst of cold temperatures which speed up the changing of colours and the fall, giving us the maximum amount of yellow and orange leaves. If we have a wet autumn, the process is slowed down, meaning many of the leaves will turn completely brown before falling off.

We hope you found this post interesting and helpful, and will see you again next week with another post,

Your Green World Blog Team💚

Sources:
https://www.kew.org/read-and-watch/why-do-leaves-change-colour
https://www.forestryengland.uk/blog/why-do-leaves-change-colour-autumn

Images:
Autumn Leaves, owned by Hideo (on flickr.com), is licensed under CC BY-NC-ND 2.0.
Autmn Beech Leaves, owned by Jonas Strömtedt (on flickr.com), is licensed under CC BY 2.0.

Comments

Animals 36-40 in our '50 incredible animals' series

Hi, As you probably noticed, we took a break from this series, mostly due to having just too much to do. But we're back now with the last three posts. 36. The Pinocchio frog The Pinocchio frog can be found in the Foja Mountains in Indonesia. They mainly eat insects, although little is known about them. They are named because the males have a spike on their noses. They were only discovered in 2008, and this was completely by accident! It remained unnamed scientifically until over ten years later when it was given the name " Litoria pinocchio " . There is very little information about them but Wikipedia states that "the male Pinocchio frog inflates its nose when calling, and the nose decreases in size when the frog is calm and quiet," which I think is hilarious and so interesting! 37. Snub-nosed monkey Especially noticeable due to their curious looks, the snub-nosed monkeys can be found in the forests of central China and northern...

Overfishing- An Introduction

When writing the article on the Yangtze Finless Porpoise, I briefly touched on the topic of overfishing. Many of you have probably heard about it, and know it is a massive problem threatening our seas and their inhabitants. Overfishing is so destructive, it can kill all life in the ocean, and many of you might be part of it every day. So I read through many articles from international organisations, and they all say pretty much the same things. It's a highly complex topic, with so many things to say and do, so this is just an introduction to the broadest points. It's very interesting (and sad) but when you look into it further you realize there is actually a lot you can do! This is very important, especially for ocean lovers and seafood people. What is overfishing? By definition, overfishing is so intense fishing, people catch fish quicker than the stocks can reproduce. Leading to a massive decrease in stocks that can peak in the extinction of a s...

Photo Essay | dolphin spotting boat ride

Hi Everyone! Quite a while ago now, me and my family went on a dolphin spotting boat ride, and I've been meaning to share some photos for ages now! We saw so many dolphins very close up and we managed to get some good shots, although it can never be as magical as in person! All photos in this post were taken by me or my family. They were so close to the boat! This photo is stunning! It's under the water! Again - under the water! It was so hard to capture them jumping! This was the boat.... ...

Deforestation and why it’s a problem

Hi everyone, Welcome back to another post. Today we’ll be talking about deforestation and its impacts on our earth. Deforestation, the widespread clearance of natural forests, has been happening for thousands of years. One example is Western Europe, where, two millennia ago, 80% of the land was cloaked in dense forest cover. However, over time, a significant portion of this green expanse was sacrificed to create room for crops, livestock grazing, and as a source of fuel and building materials. Presently, a mere 34% of Western Europe retains its woodland. Today, the tropics deal with the brunt of deforestation. Activities such as mining, agriculture, road construction, and the establishment of vast cattle ranches drive the mass clearance of tropical rainforests. This results in the release of huge amounts of carbon dioxide into the atmosphere, exacerbating the global climate crisis. The consequences come in two waves: first, the reduced number of...

Animals 41 - 45 in our '50 incredible animals' series

Hi everyone, 41. Ghost shark So first of all, this is a real animal and not a horror movie! Ghost sharks, often referred to as chimaeras, include around 50 species. They mostly live in the deep ocean and are seldom seen, hence the name. They can be found all over the world. Some species have a large range, for example, the rabbit fish which inhabits the entire northern Atlantic Ocean, or a small range, like the Galapagos Ghost shark which only lives in the waters around the Galapagos . Not much is known considering their population status however they are currently not considered threatened. It is assumed that they reproduce in the same way as most sharks. Not much else is known about ghost sharks. They are as mysterious as their name suggests! 42. Sea pig Again, this is a real animal! But it is not in any way like a pig (I have no idea why they called it a sea pig ). It is a type of sea cucumber, that lives in the ocean depths. Their bodies are fille...

National parks - how do they help the environment?

Hello National parks are a place of immense beauty. They are know as tourist attractions and are best recognised by their incredible landscapes. Today we are talking about their effects on the natural world! Yosemite National Park, United States National parks are normally created and protected by governments. In most cases, they have public access, meaning that visitors can walk around in them and admire them. The IUCN defines what is a national park and what isn't. In 2006, over 6 500 areas met the criteria and are defined as a national park. However, there are many areas called National Park, that aren't a national park according to IUCN and there are places that the IUCN defines as a national park but the government doesn't. So some countries have their own definitions. In the UK and some other countries, a national park referes to an u...

Coral reefs

Hello! We would love to introduce you to the topic of coral reefs and especially coral reef bleaching, as it is a greatly ignored but certainly significant topic. Have fun! 5 coral reef facts 1. The Great Barrier Reef is the largest living structure on the planet and is 2300 km long! 2. Less than 0.1% of the world's ocean surface is covered in coral reefs. 3. At least 25% of all marine animals live there. 4. Coral reefs are often known as the rainforests of the ocean. 5. In 1 square kilometre of coral reef, up to 35 tons of fish can be 'produced'. The 5 biggest coral reefs in the world 1. Great Barrier Reef (near Australia) 2. Red Sea Coral Reef (near Egypt, Israel and Djibouti) 3. New Caledonia Reef (Pacific Ocean near New Caledonia) 4. The Mesoamerican Barrier Reef (near Mexico, Belize, Guatemala and Honduras) 5. Florida Reef (Atlantic Ocean/Gulf of Mexico near Florida) What is coral? Coral is actually made up of small anim...

How does plastic affect the environment?

Hello, I wanted to clarify exactly how plastic affects the environment. I hope this will explain. When plastic breaks, it releases toxic gasses that poison animals. Also, if plastic is swallowed it could cut or damage the inside of the animal. Many animals such as turtles and dolphins mistake the small plastic fragments for food. Even if the plastic is too small to cut into the insides of the animal or cause choking, too many micro plastics inside an animal will eventually block the digestive tracts and they will starve to death. Recent research proves that plastic has entered the human body. This is because plankton eats microplastics and small fish eat plankton. Bigger fish eat smaller fish and we eat the bigger fish. So inside us is plastic. Plastic also blocks waterways and sewers. This leads to the perfect breading grounds for disease carrying animals such as mosquitos. When plastic is burned it releases those toxic gas...

Animals 46-50 in our '50 incredible animals' series

Hi everyone! Welcome to the final part in our '50 Incredible Animal series' where you can find out about animals 46-50. We started this series almost a year ago to celebrate our 50th post and it feels crazy to think that we are now nearing our 100th. To read all of the previous posts from this series, click here . Hope you enjoy it! 46. Spiny bush viper Spiny bush vipers, Atheris hispida, are a species of venomous snake native to Central and East Africa in tropical forests and shrubland. They are mostly solitary creatures but can climb trees, which is where they find the majority of their prey. Spiny bush vipers are carnivorous and feed on mammals, frogs and lizards, as well as birds. Independent from birth, Spiny bush vipers can have up to 12 'snakelets' at a time and are 15cm in length. Currently, there are no known threats to Spiny bush vipers, and they are categorized as Not Evaluated on the IUCN Red List. 47. Leafy sea dragon ...

Energy comparison: Hydroelectricity

Hello everyone, Welcome back to another energy comparison post. Today we're talking about hydroelectricity. This is basically just using the power of moving water for our own uses. This idea has been around for thousands of years. The ancient Greeks and Romans used watermills to grind grains for making bread. Watermills were used up until the Industrial Revolution. What is hydroelectricity? There are three types of hydroelectric power plants. Impoundment facilities are the most common. The water is stored in a pool or reservoir normally located at a higher elevation. The dam uses gates or valves to control the water flow. When there is demand for electricity, the water is released. It falls downwards and turns turbines that turn the kinetic energy of the water (movement energy) into electric energy. Diversion facilities don't have a dam. They channel the water towards the turbines using a system of canals. Pumped-storage facilities are...

Green World

Search This Blog