Age group 5 to 8 years
Rainforests cover just over 6% of the Earth's land surface.
The major areas of rainforest are found in South America, Africa and South-eastern Asia. The largest of them is called the Amazon and is in South America. It grows across 8 countries and covers 2 million square miles.
Read all about rainforests below or use the list below to jump to a topic:
Geography
Tropical rainforests need high temperatures (an average of 25c all year) and lots of rain (an average rainfall of at least 2m although some get up to 10m of rain per year compared to an average of 50cm in the wettest parts of the UK) and up to 100% humidity (humidity means how much water is in the air). Rainforests lie very near the equator.
Despite only covering up to 6% of the Earth's land surface these rainforests are thought to contain over half of the Earth's species of animals and plants. They hold within them lots of things that are useful to us and also have an effect on our weather and climate.
Ecology
The rainforest has four layers
Layer 1: A layer of small plants on the floor- here it is still and dark. With only two percent of light making it here, plants find it difficult to grow; there are lots of animals though.
Layer 2: The understorey- a cool dark area where it is still difficult for plants to grow so most of it is short and leafy, again there are lots of animals including insects snakes and spiders.
Layer 3: An evergreen canopy in the middle - 25-45 m above the ground and 6-7m thick this area acts as a roof and shields the ground from light, rain and wind.
Layer 4: Scattered tall trees which tower above the canopy- known as emergent's, they have straight trunks and the tops are shaped like cauliflowers. At heights of up to 60-70m it is very hot and dry.
There are different types of rainforest
Lowland - this covers the greatest area and are found where the ground is low lying, warm and wet. In these areas there is little or no dry season so unlike at home where we have spring, summer, autumn, and winter, it is the same weather all year round.
Seasonal - this is also called monsoon rainforest. Here there is a dry season which lasts about three months and during this time the trees shed their leaves.
Winding their way through the rainforests are mazes of streams and other water features. One of the most well known is the Amazon River which is said to hold 2/3 of the worlds fresh water.
Biodiversity
Rainforests are filled with all sorts of different animals and plants. This is known as their biodiversity. All the rainforests in the world may contain between two-thirds and a half of all the world's wildlife species. Remember that rainforests only cover 6% of the world's surface. Scientists believe that there is a great diversity because rainforests are the oldest ecosystems on earth. Some have been around for at least 100 million years.
Did you know that 100 hectares of the Amazon rainforest can contain as many different plant species as in the whole of the UK (that's 1500 species)?
Many plants live on trees so that they can reach the light. One example are called Epiphytes or air plants. They have a thick, waxy waterproof layer to trap the water they catch. Another plant which uses the tree branches to reach the light is a climber or liana.
On the ground are lots of roots and small plants that like the dark and damp. One example would be ferns, we get some types of ferns here in UK too and like those in the rainforest they like to grow in the dark and damp areas.
The flowers that grow in the rainforest have to attract insects, birds and animals that help them to spread their seeds. In order to do this they are often brightly coloured and smell very nice and sweet.
There are other ways of getting seeds spread. Most seeds are encased in a shell or wall. Some float away on the wind and some entice animals to eat them by having a juicy, tasty flesh, just like all the fruits that you eat at home. These seeds get moved around when they are left after the flesh has been eaten.
The variety of animals in the rainforest is amazing. In the trees there are insects, frogs, snakes, spiders, birds and lots of mammals like monkeys and jaguars. There are lots more in the water too. The Amazon River is said to hold 2000 different types (or species) of fish. Some fish that you might have heard of include piranhas; these fish have very sharp teeth which they use for eating fish and fruits. You also find some big snakes called Anacondas who as well like to swim in the water and sometimes climb trees and the big crocodiles called caimans.
There are probably lots of animals that you already know that live in the rainforest. Look at the pictures below and see what makes these animals and plants special.
The Wealth of the Rainforest
So who else lives in the rainforest? Well people do, it is estimated that about 50 million indigenous (meaning they have always lived there) forest people live in the rainforests. The people in the rainforest live in tribes, each with their own way of living or culture.
The indigenous people are very good at hunting, agriculture (farming), fishing and gathering. They know how to use the things growing in the forest (known as resources) to make food, medicines, building materials, clothes, string, glue and oil. They have a very good knowledge of not only the other plants and animals living in the rainforest but also how they can best use them without using them all up. This is very important as it means that they can be used for lots of generations to come. This practice is known as sustainability.
Having all of this knowledge means that the indigenous people are very important, we have a lot to learn from them.
How many things do you know that come from the rainforest?
The first major one is wood. The UK gets a lot of its wood from Canada, Russia, the US and Scandinavia. However we also still get wood from the rainforests. Some examples include mahogany, sapele, teak, mernati, greenheart and ramin. Wood is used to make furniture, window sills, doorframes and toys to name just a few.
Lots of ingredients used to make our medicines also came originally from the rainforests. It is estimated that one in four medicines sold in Britain contain ingredients derived originally from species from the rainforest. Some examples include cough mixtures and antibiotics.
In addition to medicines and wood are food products. These include spices (black pepper, chilli, cinnamon, cloves, ginger, nutmeg and vanilla), nuts (brazil nuts, macademia, cashew and peanuts), fruit and vegetables (avocado, papaya, limes, mangoes, passion fruit, pineapple, coconuts, sweet potatoes and grapefruit).
Some other products such as oils are used in shampoo, soaps, perfumes, make-up and drinks. There are also gums that are used in chewing gum, Wellington boots, paints and varnish.
Finally there are other products that originate from the rainforest and these include dyes, bamboo, and natural fibres all of which are used to make products such as furniture, floor coverings, bags and clothing.
Why is the rainforest being destroyed?
Well the rainforests have lots of things in them that people like to have. Some examples are wood and ingredients for medicines and shampoos, make-up, soaps and perfumes, and things that we eat including spices (black pepper and chilli), nuts (brazil nuts and peanuts), fruit and vegetables (limes, mangoes, passion fruit, pineapple and grapefruit).
Unfortunately when some of these things are taken away from the rainforests, it is not done in a way that makes it easy for things to grow back.
It is estimated that, every year, 150,000 square kilometres of tropical rainforest is destroyed. That is the size of England and Wales. On top of this the same amount of area is being damaged.
When people go to the rainforests to cut down trees they often cut down more that they need to make roads so it is easier to get there. This makes it easier for other people to get into the rainforests and clear it (by burning it) for farming. But these farmers often don't understand the area and so use up the nutrients in the ground very quickly and have to move on and clear more land.
Removing all this land means the indigenous people lose their homes. Cutting down the rainforests removes them from their homes and destroys their societies. We still have much to learn from the indigenous people and by displacing them we are perhaps losing all of that knowledge. The decline of indigenous people has been massive. It is said that in 1942 when Christopher Columbus first got to the Americas there was 1.5-2 million indigenous people, now there are just 940,000.
It is estimated that up to 50,000 species a year may be coming extinct through the destruction of the rainforest. Some species facing extinction include chimpanzees, giant ant eaters, giant otters and mountain gorillas. The rainforest in Madagascar has 10,000 species of plants and of these 80% are found no where else in the world. An example of this is the Lemur. Unfortunately 90% of Madagascar's rainforest has already been destroyed. There are still thousands of species that we still haven't discovered. We are losing them before we have even seen them.
What effect does this have?
The rainforests have an effect on our weather and our climate. The difference between climate and weather is time. Weather is what it is doing today and tomorrow, climate is what we expect it to do over the year. We expect it to be warm is the summer and cold in the winter. Both the weather and the climate can change.
Weather
What our weather is like depends on lots of things from all over the world. Heat and rain are the more important factors. Our heat comes from the sun. It sends it down in rays and the areas that get most of the heat are around the equator as these are closest to the sun. When the heat hits the earth some is absorbed and some will bounce back. The heat that is trapped in gets moved around the earth in currents creating the warm (or cold) weather.
Coupled with this is water. Water moves around the world in a great big cycle. There is a limited amount of water in the world so we can't get more if we run out. The cycle starts in the ground with the water table. This is where all the water collects when its hits and sinks into the ground. From here its goes into the streams and rivers (where some of its gets taken away for us to use), into ponds and also gets sucked up by trees and plants. The water that flows in the streams and rivers eventually gets into the sea. Once in the sea, large amounts of it gets evaporated by the sun and when there is enough of it in the atmosphere it forms clouds that get moved around in the air currents. From here the cycle starts again as these clouds will rain and the water will fall back to earth.
The rainforest plays a very important part in the water cycle. The trees remove water from the water table to use during photosynthesis. The heat from the sun evaporates lots of this water into the air where it forms clouds and rains. Without the trees the water would stayed locked in the ground and there would be less rain in the rainforests and the rest of the world. This is a problem because when it does rain the soil on the ground gets washed away into streams and rivers (making it difficult for things to live) and without the forests to soak up the rain, there is more chance of floods.
So by cutting down the trees there is less soil and less rain. This makes is very difficult for anything to grow back. The remaining forest becomes hotter and drier and at more risk of fire.
Climate
There are gases in our atmosphere that trap heat in. These are called greenhouse gases and examples are carbon dioxide and methane. The more of these gases that are in the air - the more heat gets trapped. This makes the earth a hotter place which can cause all sorts of problems for everybody across the world. This is known as global warming. The rainforests play an important part in helping the world from getting too hot.
1. Trees store up lots of carbon by taking it out of the atmosphere to use to make energy (photosynthesis). But when the trees are cut down they are no longer able to take the carbon dioxide out of the air.
2. Burning down the rainforests releases all the carbon dioxide that had been stored back into the atmosphere.
This contributes more greenhouse gases to trap the heat in and make the earth even hotter. Global warming is being caused as too many greenhouse gases are getting released into the atmosphere. It is estimated that up to one third of the carbon dioxide being released is from rainforest fires, the rest is released from burning fossil fuels (coal, oil and gas).
Increasing the temperature of the world can lead to changes in our weather, melting of the icecaps and causing the sea levels to rise.
But all is not lost Cool Earth is working to keep carbon where it belongs.
