Lesson video

Hello and welcome.

My name is Ms. Harrison.

I'm so excited to be learning with you today.

Today's lesson is called Characteristics of the Tropical Rainforest.

Grab everything you might need for today's lesson, and let's begin out learning.

By the end of today's lesson, you'll be able to describe key abiotic and biotic characteristics of the tropical rainforest.

Before we begin this learning, we need to define the keywords that we'll be using throughout today's lesson.

The keywords in today's lesson are biome, climate, biotic, and abiotic.

Biome, this is a large scale ecosystem with specific climate, plants, and animals.

Climate, this is the average weather conditions in a region over a long period of time.

Biotic, these are the living components of the environment, such as plants, animals, and microorganisms. Abiotic, these are the non-living components, such as temperature, rainfall, humidity, soil quality, and sunlight.

Fantastic.

Now that we've defined these keywords, we can begin our learning.

The first question we are going to explore in today's lesson is, where are tropical rainforests located? A biome is a large scale ecosystem with specific plants, animals, and climate.

Tropical rainforests are one of the most biodiverse biomes on Earth, providing a home for over 50% of known species, despite only covering 6% of planet Earth's land surface.

How much of Earth's land surface do tropical rainforests cover? Is it, A, 3%, B, 6%, C, 12%? Pause the video here whilst you to attempt this task, and press play when you're ready to continue.

Excellent.

The answer is B.

Well done if you managed to identify that correctly.

The map shows the distribution of the tropical rainforest biome.

How would you describe this distribution? Aisha has said that she would describe it by saying tropical rainforests are mainly found between the tropics of cancer and the tropics of Capricorn.

Almost all of the countries along the equator have a tropical rainforest.

And that's right.

We can extend this answer by saying that tropical rainforests are located 25 degrees north and south of the equator.

Well done.

There are five major tropical rainforests in the world, and these are the Central American, the Amazon Basin, the Congo Basin, Madagascan, and the Southeast Asian.

The Amazon rainforest is the largest tropical rainforest, and it's located mainly in Brazil.

It contains around 10% of all known species, and is home to 47 million people, including 2 million indigenous people.

It also stores vast amounts of carbon, playing a really important role in regulating the global climate.

True or false.

the Amazon rainforest located in Central America is one of the smallest rainforests in the world.

Pause the video here whilst you have a think, and press play When you're ready to check your answers.

Excellent.

The answer is false.

I would now like you to explain why this statement is false.

Pause the video here and press play when you're ready to check your answer.

Excellent.

The reason why this statement is false is because Amazon Rainforest is located in South America and is the world's largest rainforest.

It is home to 10% of the world's known species and 47 million people, including 2 million indigenous people.

Well done if you managed to explain that correctly, I would now like you to label the missing tropical rainforest on the map below.

Pause the video here whilst you take a closer look at the map, and press play when you're ready to check your answers.

Fantastic work.

Let's see if you managed to identify them correctly.

We have the Central American, the Southeast Asian, and the Amazon Basin.

Fantastic work on that task.

Well done.

I would now like you to describe the distribution of the tropical rainforests.

Laura has cleverly noted that the equator runs through many tropical rainforests.

Take a closer look at the map on your screen, and then pause the video here whilst you describe the distribution of tropical rainforests, Press play When you're ready to check your answers.

Great work.

Let's check our answers.

Your answer may have included the following points.

Tropical rainforests covers 6% of Earth's land surface.

They're found 25 degrees north and south of the equator, between the Tropic of cancer and the Tropic of Capricorn.

The Amazon rainforest in South America is the largest rainforest in the world.

Well done if you managed to include any of those points in your answer.

We're now going to explore the second question in today's lesson.

What is the climate like in the tropical rainforests? Tropical rainforest ecosystems, like all ecosystems, consist of biotic, which are living things, and abiotic, which are non-living things.

Examples of biotic characteristics are plants, humans, and animals, and examples of abiotic characteristics are soil, temperature, and rainfall.

Rainfall and temperature are a key abiotic characteristic of the tropical rainforest biome and the tropical rainforest climate.

What is the difference between biotic and abiotic characteristics of an ecosystem? Is it A, biotic characteristics of non-living things, while abiotic characteristics are living organisms like animals and plants, B, biotic characteristics are living organisms or abiotic characteristics are non-living things like temperature, C, biotic characteristics are only found in ecosystems with very high biodiversity.

Pause the video here whilst you identify the difference, and press play when you're ready to check your answer.

Great work.

The difference between biotic and abiotic characteristics is B, biotic characteristics are living organisms while abiotic are non-living things like temperature.

Well done.

The tropical rainforest biome has an equatorial climate.

This means that it's high annual rainfall and little variation in temperature.

These near perfect growing conditions for plants result in the dense evergreen rainforest forming.

Now, let's talk about how the curvature of the Earth's surface affects the amount of solar energy received in different regions.

This is a really important factor in explaining why tropical rainforests are so warm and humid all year round.

As you can see, the Sun's rays do not hit every part of the Earth in the same intensity.

Near the equator, the Sun's race strike the Earth almost directly.

This means that their energy is more concentrated in a smaller area, making the climate warmer.

What do you think happens to solar energy as we move further away from the equator? Exactly.

As you move further towards the poles, the Sun's rays hit the Earth at a slanted angle.

This spreads the solar energy over a large area, making it much less intense.

As a result, these regions are much cooler than the tropics.

This concentrated solar energy at the equator is a key reason why tropical rainforests have consistently high temperatures, creating the perfect conditions for dense plant growth and high biodiversity.

Can you think of any other factors besides solar energy that might influence the climate and tropical rainforests? Fantastic.

Well done.

The Earth has tilted at an angle of 23.

5 degrees.

This tilt is what causes the seasons.

As the Earth orbits the Sun, different parts of the planet receive more or less direct sunlight at different times of the year.

This is why we experience summer, winter, spring, and autumn in places like the UK.

But what about the equator? Does it experience same seasonal change? Not quite.

At the equator, the Sun is directly overhead all year round.

This means that the amount of solar radiation received doesn't change much throughout the year.

As a result, the climate stays consistently warm with little variation in temperature.

Imagine holding a flashlight directly above a piece of paper.

The light is focused on one spot and stays concentrated.

That's what happens at the equator.

Now, if you tilt the flashlight at an angle, the light spreads out over a larger area, and this is similar to what happens at higher latitudes where seasons occur due to the Earth's tilt.

Since the equator receives high consistent solar energy, tropical rainforests remain warm and wet throughout the year, making them an ideal environment for dense plant growth and high biodiversity.

Why do tropical rainforests have high temperatures all year round? There are two correct answers here.

Is it A, the Sun's rays hit Earth directly at the equator, so solar energy is concentrated here.

B, the amount of solar radiation received at the equator does not change throughout the year, or C, the Sun's rays are blocked by convection clouds, keeping the temperature low in the tropical rainforest.

Pause the video here whilst you attempt this task and press play when you're ready to continue.

Excellent.

The answer is A and B.

The Sun's rays hits Earth directly at the equator, so solar energy is concentrated here.

And the amount of solar radiation received at the equator does not change throughout the year.

Well done on this task.

We'll now begin to discuss the intertropical convergence zone and its impact on the equatorial climate.

The ITCZ is a belt of low pressure near the equator where warm, moist air converges and rises leading to significant rainfall.

The rising air cools and condenses and forms clouds resulting in heavy rainfall.

This is why tropical rainforest, such as the Amazon, receives substantial precipitation.

The ITCZ shifts north and south during the year due to the movement of the Sun.

This causes some tropical regions to experience wet and dry seasons, depending on the ITCZ's position.

The ITCZ plays a really important role in determining seasonal rainfall patterns in tropical climates.

Understanding the movement helps in predicting weather patterns and climate variations.

This knowledge is essential for understanding the global climate system.

Climate graphs are used to analyse the climate of a location.

To read monthly temperatures, you use the scale labelled temperature, and a line is used to display temperature.

To read monthly rainfall, You see the scale labelled rainfall, and a bar is used to display rainfall.

So when we look at this, we can see the temperature in tropical rainforest usually stays between 25 to 30 degrees all year round.

The range between high low temperatures is really, really low.

Andeep has cleverly said that heat can see that the temperature does not really change much at all throughout the year.

Tropical rainforests receive a huge amount of rainfall, often more than 2,000 millilitres per year, but have you ever wondered why it rains so much and in such short, intense bursts? The main reason for this is convectional rainfall, which happens because of the intense heat near the equator.

The Sun's heat warms the ground and water in the rainforest.

This heat is then transferred to the air above, making it warm and moist.

Warm air is lighter than cold air, so it rises.

As the warm moist air rises higher into the atmosphere, it starts to cool down.

Cool air can't hold as much moisture, so the water vapour and the dense air condenses into tiny droplets forming clouds.

Eventually, these droplets combine to form heavy rain, which falls in short intense bursts.

This process happens almost every day in tropical rainforests, which is why they're so wet and humid.

The heat causes continuous evaporation and cloud formation, leading to heavy rainfall in short, heavy bursts.

As we know, rainforests receive more than 2,000 millilitres of rain annually with some areas getting up to 4,000 millilitres annually.

Some rainforests experience changes in rainfall throughout the year, like you can see in the image on your screen.

This is because of the movement of the ITCZ, which brings more rain when it is overhead and less when it moves away from an area.

True or false.

Tropical rainforests typically have a cold season and a warm season.

Pause the video here whilst you attempt this task and press play when you're ready to check your answers, Fantastic.

The answer is false.

I would now like you to explain why this answer is false.

Pause the video here and press play when you're ready to continue.

Great work.

The reason why this answer is false is because the temperature typically does not vary much throughout the year in tropical rainforest.

It stays in a range of 25 to 30 degrees.

Some rainforests do have changes in precipitation though.

While rainfall is typically high all year, there may be a wet season which is even wetter.

How does the intertropical convergence zone impact tropical rainforests? Is it A, the ITCZ causes dry conditions and low rainfall all year, which limits the growth of tropical rainforests, B, the ITCZ creates a low pressure zone near the equator, leading to high rainfall levels or C, movement of the ITCZ means a tropical rainforest receive similar amounts of rainfall each month.

Pause the video here whilst you attempt this task, and press play when you're ready to check your answer.

Excellent.

The answer is B.

The ITCZ creates a low pressure zone near the equator, leading to high rainfall levels.

Well done if you manage to identify that correctly.

I would now like you to describe the climate graph of Manaus in Brazil.

You can see the climate graph on the screen.

Remember, temperature is used in lines and rainfall is measured in bars.

Izzy has said that she can see that the temperature in Manaus does not change much.

Pause the video here whilst you take a closer look at this graph and describe the climate graph of Manaus in Brazil, and press play when you're ready to continue.

Fantastic work on this task.

Let's check your answer.

Your answer could include the following points.

The rainfall in Manaus Brazil shows a clear pattern of high and consistent precipitation throughout the year.

According to the climate graph, the rainfall peaks between December and January, with the wettest months being January to April, receiving over 250 millilitres of rainfall each month.

The drier season occurs from June to November with rainfall amounts dropping slightly, but still remaining relatively high, typically around 150 to 200 millilitres per month.

Temperatures remain consistently high, ranging from 25 degrees to 30 degrees with little variation.

Well done if you included any of the following points in your answer.

We're now going to explore our final question of today's lesson.

What are the different layers of the rainforest? The tropical rainforest has a perfect climate for plant growth, warm temperatures, high humidity, and lots of rainfall.

These are all abiotic factors, non-living parts of an ecosystem.

But because plants thrive in these conditions, they face intense competition for sunlight.

Plants need sunlight for photosynthesis, the process that allows them to make their own food.

But in the rainforest, the tallest trees block most of the sunlight, leaving little for plants below.

What do you think happens to plants that don't get enough sunlight? Pause the video here whilst you have a think, and press play when you're ready to continue.

Exactly.

They struggle to grow or they must develop special adaptations.

This intense competition has led to the rainforest developing a layered structure, and each layer has different conditions and plant types.

The climates of the rainforest allows plants to grow well, but this leads to intense competition.

As a result, plants need to adapt and organise themselves into layers to survive.

The tropical rainforest has four distinct layers, the emergent layer, the canopy layer, the under canopy layer, and the forest floor.

The emergent layer.

The emergent layer has trees that can reach between 30 to 50 metres.

They're isolated trees which stick out above the canopy and they receive the most sunlight and are exposed to really strong winds.

The animals that can be found here include parrots and eagles.

The canopy layer, the trees here grow between 20 to 30 metres, and this is where most rainforest plants and animals are found.

The foliage are closely packed together and they form a continuous layer of leaves, which blocks sunlight from reaching lower layers, and animals that can be found here include monkeys, toucans, sloths, and many insects.

The under canopy, the trees here grow between 10 to 20 metres, and it's very dark and humid with smaller trees and shrubs and ferns.

It receives very little sunlight, and this makes it really hard for the trees to grow.

There are small mammals that are found here that include snakes, frogs, and spiders.

The forest floor, this is where plants grow between zero to 10 metres, and receives the least amount of sunlight, between one to 2% of sunlight reaches its layer.

It's really dark and damp, and it's covered with lots of decaying plant matter.

Nutrients are recycled really quickly in this slayer.

And in this layer, we can find animals like jaguars, tapirs, ants, and decomposers like fungi.

Which parts of the rainforest is this? The continuous layer of branches and leaves located 20 to 30 metres above the forest floor.

Pause the video here whilst you decide, and press play when you're ready to continue.

Fantastic.

The answer is C, the canopy layer.

True or false.

The forest floor layer receives most sunlight, meaning that plants growing reach heights of 30 to 50 metres.

Pause the video here whilst you attempt this task, and press play when you're ready to check your answers.

Excellent.

The answer is false.

I would like you to explain why this answer is false.

Pause the video here and press play when you're ready to check your answers.

Fantastic.

This forest floor is the darkest layer of the rainforest.

It receives between one to 2% of all sunlight because all the rest is blocked by the layers above the forest floor, especially in the canopy layer.

Well done if you managed to explain that correctly.

I would now like you to describe the difference between a canopy layer and the forest floor.

Alex has cleverly noted that the forest floor receives very little sunlight because it is mostly blocked by the canopy layer.

Pause the video here whilst you attempt to answer this question, and press play when you're ready to continue.

Excellent.

Let's check our answers.

Your answers should look a little bit like this.

Canopy layer is located 20 to 30 metres above the ground, and is formed by the leaves and branches of trees forming continuous canopy.

It receives plenty of sunlight, and most of the plants and animals of the tropical rainforest are found here.

The forest floor is the layer from zero to 10 metres.

Only one to 2% of light filters through the canopy and under canopy to reach the forest floor, so it is very dark and damp.

It's covered in decaying plant matter which decomposes quickly due to the humid conditions, and decomposers such as fungi are found here.

Well done if you manage to include any of those points in your answer.

Well done.

We've come to the end of our lesson on characteristics of the tropical rainforest.

Before we end this lesson, let's summarise what we've learned in today's lesson.

Tropical rainforests are one of the most important biomes on Earth.

They're mainly found between the Tropic of Cancer and Tropic of Capricorn near the equator.

But what makes them so unique? Their climate.

Tropical rainforests have warm temperatures and high rainfall all year round, and temperatures rarely drop below 25 degrees or rise above 30 degrees, and the annual rainfall often exceeds 2,000 millilitres.

How do you think this constant warmth and moisture affect plant growth? That's right.

These perfect conditions allow plants to grow quickly and densely, making rainforest one of the most biodiverse places on Earth.

We can divide rainforest characteristics into two categories, abiotic factors, which are non-living, things like temperature, rainfall, and sunlight, and biotic factors that are living, like plants, animals, and microorganisms. The abiotic factors in rainforest create ideal conditions for plants to grow, but they also lead to intense competition for sunlight, and this is why the rainforests have laid structures with different plants adapted to different levels of light.

The warm and wet conditions in tropical rainforests influence everything, from the types of plants that grow to the animals that live there.

Without this unique climate, the rainforest rich biodiversity would not exist.

Well done in today's lesson.

You've done brilliantly, and I look forward to learning with you again very soon.