Lesson video

Hello, my name is Ms. Gileadite, and I'm your geography teacher for today.

In today's lesson, we are going to be learning about the human impact on ecosystems. So let's get started.

So our lesson outcome for today is that you can explain how human activity changes ecosystems and reduces biodiversity.

We've got four keywords for today's lesson.

So the first one is deforestation, which is the complete removal of trees.

Invasive species are plants, animals, or other organisms that are brought into a new environment, usually by humans, where they don't naturally belong.

Biodiversity is all the living things in an ecosystem or area.

And an ecosystem is a natural environment where the plants and animals interact with it.

We've got two learning cycles.

So first of all, we're going to look at deforestation and pollution, and then we're going to look at climate change and invasive species.

Okay, so let's get going with the first learning cycle.

Now, human activities can have an effect on the biosphere.

Okay, so quick recap.

The biosphere is all the living things on earth.

So that includes plants, animals, insects, even bacteria, and ecosystems. Okay, so let's have a look at some of the different human impacts on the biosphere.

So deforestation is a big one, so the cutting down of trees, overfishing, human-induced climate change, pollution from industry, introducing invasive species, and farming.

Okay, so all of these things have a massive impact on our natural world.

Okay, let's have a look at some of these in a bit more detail.

Now, deforestation is when large areas of trees are cut down, and this usually happens because of these reasons.

So trees may be cut down to make space for cattle grazing, farming.

Okay, so the slide there, the picture on the slide there is of a palm oil plantation.

So sometimes they'll chop the trees down, but they'll plant other crops that they want to use for farming.

For building cities or roads, so chopping down to make space, or for logging.

Okay, so using the wood, using the logs for wood or paper.

Now let's have a look at how deforestation can affect ecosystems. So if the trees are removed from an area, the animal habitats are destroyed, so they've not got anywhere to live anymore.

That means there's a reduction in the animal, okay, because if there isn't space for it to have its nest or to hunt, okay, eventually some of these animals will die.

So there's a loss in that biodiversity.

This can lead to an extinction of species.

Okay, so that means that that species of plant or animal eventually dies out.

So as a quick reminder, so biodiversity loss means the decline or disappearance of different species of plants, animals, fungi, and microorganisms in an ecosystems. Okay.

Now, deforestation can also affect the local climate and therefore the ecosystem as well.

So let's have a look how this happens.

So the trees are removed.

This can mean that there is less transpiration.

Okay, so transpiration is the evaporation of water from plant leaves.

If there's less transpiration, that means that there is less water vapour in the atmosphere, okay, and therefore there is less rainfall.

If there is less rainfall, that eventually leads to a drier climate in the area.

Okay.

If there's less rainfall, therefore a drier climate.

That can mean that plants find it harder to grow, and eventually there is biodiversity loss as well, okay, because the plants will eventually die as they're not able to grow from the lack of rain.

Okay, so deforestation not only affects ecosystems in the terms of it destroys habitats and therefore leads to biodiversity loss, it also affects the climate that can lead to biodiversity loss as well.

Okay, let's check our understanding.

So what two ways can deforestation affect ecosystems? Have a quick chat with your partner or write your ideas down.

Okay, so first of all, deforestation can destroy habitats.

This can lead to a reduction in biodiversity and even an extinction of species.

And deforestation can cause there to be less transpiration, therefore less rainfall.

A drier climate makes it harder for plants to grow and can reduce biodiversity.

Well done if you've got both of those.

Okay, let's have a look at a case study of where this is happening.

Okay, so in Indonesia, forests are being cut and burned to make room for palm oil plantations.

Okay.

So sometimes they chop forest down to use the wood, but if they just want to make space for cattle grazing or for plantations, they actually burn the forest because it's easier and it is quicker.

Okay, however, there is a big problem with that in that it releases a lot of CO2 into the atmosphere.

Okay.

Now, palm oil is used in chocolate, shampoo, cookies, and many other day-to-day items. So it is used in a lot of things.

However, that is leading to many negative effects.

There's a loss of habitat for endangered species like the orangutan.

So there's a picture of the orangutans on the slide here.

Tigers, elephants, and rhinos lose space and food, and fewer plants and animals leads to biodiversity loss.

Okay, so if you want to look at this as an example, it might be worth doing a little bit of research on the effect of palm oil plantations.

Okay, so we're gonna have a look at how farming can affect ecosystems as well.

So farmers use chemicals called fertilisers and pesticides to help grow crops and kill pests.

Okay, so fertiliser gives the plants extra nutrients which helps them grow bigger and quicker, and pesticides are used to kill pests that might eat the plants.

Now, pesticides can kill helpful insects like bees and butterflies.

Okay, so even though they do kill some of the unwanted insects, they also can kill some of the wanted ones as well.

Okay, so we need things like bees to help pollinate plants.

Chemicals can poison birds, frogs, and fish, disrupting food chains, and chemicals can damage the soil, which becomes less fertile over time.

Okay, so farmers need to be really, really careful when they are using pesticides and fertilisers that this isn't having a large impact on the surrounding ecosystem.

Because actually if they use too much of it, then their soil becomes less fertile, and they can't use it in the future.

It is not sustainable.

Okay, so as I just said, farmers can use chemical fertilisers which help the plants grow.

Now, what can happen is that these can run off and through the soil into rivers and lakes during rainfall.

Okay, so if you've got rainfall over a field that's got lots of these fertilisers in, it can basically wash the fertiliser out, which can enter the local waterways.

Now, if this fertiliser gets into some of the local waterways, it can create something called algae blooms. So what happens is, because there's more fertiliser in the water, it means that the algae can grow.

Okay, so good for algae because it means that they can grow lots of it.

However, that is really bad for the other plants in the area because algae blocks sunlight.

If you have a look at the picture on the slide here, you can see that the whole pond is just covered in algae, and that means that other plants in the in the water can't get any sunlight to grow.

They also use up oxygen, which is vital for plants to grow, and also other fish and marine life can die.

Okay, so even though you might think, "Oh, well great, that's lots of algae growing," actually, it's really, really bad because it causes the other plants in the environment to deteriorate.

Okay, we'll look at an example of this.

So the Mississippi River in the Gulf of Mexico.

So along this river, it's a very fertile farmland.

Okay.

Now, farmers along the river use large amounts of fertiliser to help the crops grow.

Okay.

However, when it rains, fertiliser washes into the rivers, which eventually flow into the Gulf of Mexico.

Okay, so on the slide here, there's a map of the Gulf of Mexico.

Okay, so it's just to the east of Mexico and to the south of that part of the United States.

Now, this is having many negative effects.

So the fertiliser cause algae to grow quickly, and that's called an algal bloom like we've just looked at.

Now the algae uses up all the oxygen in the water, and this is creating a dead zone, an area with so little oxygen that fish and other animals can't survive.

Okay, so in the Gulf of Mexico, there's an area now called the dead zone, where basically very few animals are able to live because the algae has used up all of the oxygen.

Okay, let's check our understanding.

So have a look at that picture there.

So what does it show and what causes it? Have a quick chat with your partner? Okay, so the picture shows an algal bloom, which is caused by fertiliser entering the water system, leading to algae growing, which can kill other life in the area.

Well done if you got that right.

Okay, next one.

So factories from industry can release harmful chemicals into the air, but also the water and the soil.

Okay.

In the world now, we are seeing a lot more of this.

Okay.

Now, water pollution, so if that chemical gets into the local water supplies, can kill fish, insects, and plants in the rivers and the oceans.

Soil pollution can make it hard for plants to grow, and air pollution can cause acidic rainfall, which damages forests, lakes, and crops.

Okay, so if there's too much carbon in the atmosphere, it means that the water, the rain water turns into slightly acidic, so a carbonic acid.

If that falls on vegetation, it can be very damaging for it.

Okay, true or false.

Industrial factories only release harmful chemicals into the atmosphere.

That is false, and can you tell me why? Industrial factories can release harmful chemicals into the air, water, and the soil.

Well done if you got that right.

Okay, we're onto our first task for this lesson.

What I would like you to do is put the statements into the correct order in the flow diagram to show how deforestation can affect ecosystems. So pause the video and have a go at this first task.

Okay, second, what I would like you to do is complete the sentences to explain how farming can affect ecosystems, so the use of fertilisers can, and the use of pesticides can.

Okay, let's check our understanding, okay, or just check the answers.

So first of all, the trees are removed.

This can lead to destroy animal habitats, reduces biodiversity, and that can lead to an extinction of species.

Well done if you've got those right.

Okay, and here we've got example answers for the second task.

So the use of fertilisers can lead to the chemicals going through the soil and into rivers and lakes during rainfall.

Excess fertiliser causes algal blooms, so too much algae grows.

Algae blocks, sunlight and uses oxygen.

So fish and other life may die.

The use of pesticides can kill helpful insects like bees and butterflies.

Chemicals can also damage the soil, which becomes less fertile over time.

Don't worry if you didn't get an exact answer from that, but hopefully your answer should look similar to mine.

Okay, we're onto our second learning cycle now, looking at climate change and invasive species.

Now, invasive species are plants, animals, or organisms that humans bring to places where they don't naturally belong.

They often spread quickly and harm native species and ecosystems. So there's different ways that humans might spread them.

So it can happen accidentally, but also it can happen on purpose.

So they can be spread through travel and trade.

They can be spread on ships, and they can also be spread through pets or garden plants that escape.

Now, how invasive species affect ecosystems. Now, they can outcompete native species for food or space.

So that means that the ones that naturally occur in that area die out because the invasive species is taking over that area.

They can reduce biodiversity by pushing some of the native species to extinction.

So if the native species runs out of space, eventually it can just die out because of the new organism.

The invasive species can also bring disease that local species can't fight off, and also they can change habitats like invasive species, invasive plants taking over.

Okay, true or false.

Invasive species are plants, animals, or organisms that naturally occur in an area and thrive in certain months of the year.

That is false, and can you tell me why? Invasive species are plants, animals, or organisms that humans bring to places where they don't naturally belong.

Well done if you got that right.

So in the UK, there's a real problem with Japanese knotweed.

Okay.

Now, Japanese knotweed is a fast-growing plant that was brought to the UK from Asia in the 1800s as a garden plant, and it's having quite a lot of negative impacts on the local ecosystems. So it's taking over natural areas, pushing out native plants.

They can form thick walls of stems, stopping light from reaching other species.

They reduce the amount of food and space for insects, birds, and other animals, and they can damage property, and is difficult and expensive to remove.

It costs the UK millions every year.

Okay, so we're now going to look at the impact of climate change on local ecosystems. So climate change is the long-term changes in the earth's temperature, rainfall, and weather patterns, which is mostly caused by human activities like burning fossil fuels.

Okay, so when we burn fossil fuels, it releases carbon dioxide into the atmosphere, which is meaning that more of the sun's heat is getting trapped.

Okay.

Now, how do you think that climate change, the earth getting hotter and also more extreme weather, could affect ecosystems? Have a quick chat with your partner.

Okay, let's have a look.

So how climate change is affecting ecosystems? Now, melting ice and rising seas destroy habitats.

So for example, polar regions.

So one of the most affected places by climate change is at the very north and south of our planet.

Okay, so these areas are naturally very, very cold.

But because of the increase in temperature, these areas are melting, which is meaning that the animals that live there are struggling to survive.

So for example, polar bears that live on the ice are finding that there's less and less ice to live on.

Changing rainfall affects where plants can grow and animals can live.

So some areas are seeing less and less rainfall, and in some places they are turning into deserts, which is called desertification.

So here on the slide, you can see an area of land that was grassland which is slowly turning into a desert.

Warmer temperatures can make some places too hot for native species.

So they're having to migrate and leave an area because it's too hot to survive there, and there's more wildfires, droughts, and storms which can damage natural environments.

So as I said, we are seeing more extreme weather, which has a big impact on the ecosystem.

So wildfires can burn forests, droughts can mean that plants just can't grow, and storms can damage vegetation and destroy animal habitats.

Okay, let's check our understanding.

How can climate change affect ecosystems? Can you name the impact on A, B, and C? Okay, so it can destroy habitats, it can cause drought, and it can also cause wildfires.

Well done if you got that right.

Okay, let's have a look at an example.

So the golden toad was a bright orange amphibian that lived only in the Monteverde Cloud Forest in Costa Rica.

Now what happened? Climate change caused dry hot conditions in their cloud forest.

The toad's breeding ponds dried up so the eggs couldn't survive.

A fungal disease, possibly worsened by climate change, also spread in the area.

And the last golden toad was seen in 1989.

Now, sadly, this is becoming more common in lots of different animals around the world where climate change is leading to their numbers becoming endangered or even extinct.

Now, fewer species means a weaker ecosystem and can lead to less resilience.

Okay, so if you've got less biodiversity, your ecosystem isn't as strong, so it's less resilient, and these are the things it's less resilient to.

So if there's a disease spreading in the area, if you've got less of different types of plants, then they're not as well able to fight the disease off.

They're less resilient to drought, less resilient to invasive species, and less resilient to climate change.

So unfortunately, it kind of has a knock on effect.

If one thing can mean it becomes less resilient, then the problem can get worse and worse.

Now, I want you to have a think.

Why do you think it is important for us to look after ecosystems? So why, us as humans, do you think that is important? Have a quick chat with your partner.

Okay, let's have a look.

So it is important that we protect ecosystems from biodiversity loss because they provide us with food, clean water, clean air, and medicines, and they regulate the climate.

That's absolutely spot on.

Now, all of these things here, these benefits are called ecosystem services, which are the benefits that nature provides us, to people, for free.

Okay, so we need these things.

These services keep the planet healthy and they support human life.

Okay.

So let's check our understanding.

Which of the following is not an ecosystem service? That is coal.

Well done if you got that right.

Okay, we're on to our final task for this lesson.

What I'd like you to do, first of all, is annotate the photograph to explain how climate change can affect ecosystems. So pause the video and annotate the picture.

Okay.

Now I'd like you to have a go at filling in the bullet points.

So biodiversity loss can lead to ecosystems being less resilient to, and can you name the four things they are less resilient to? Okay.

And finally, I'd like you to read the speech bubble and highlight ecosystem services that Andeep mentions in a colour.

Okay.

So read the paragraph from Andeep and highlight any of the ecosystem services.

Okay, let's have a look at the answers.

So first of all, for this picture, I have put warmer temperatures make some places too hot for native species.

Changing rainfall patterns affect where plants can grow and animals can live.

And more wildfires, droughts, and storms damage natural environments.

Well done if you got those.

Okay.

Biodiversity loss can lead to ecosystems being less resilient to disease, drought, invasive species, and climate change.

Well done if you've got those.

Okay, and let's have a look at these ecosystem services from Andeep.

So Andeep says, "I love going to the woods near my house.

The trees give us clean air to breathe." That is an ecosystem service.

"And the bees help the plants grow by pollinating them." Another one.

"We get fresh water from the river," spot on, "and that runs through the forest.

It's also a peaceful place where I can relax and feel happy." Okay, and that's also an ecosystem service too.

We can use the natural environment for leisure, and also it is really beneficial to our mental health.

Okay, here we've got a summary for today's lesson.

Now deforestation reduces habitats and threatened species survival.

Pollution from agriculture and industry harms, ecosystems, climate change alters ecosystems and species distributions, and invasive species introduced by humans disrupt native ecosystems. Biodiversity loss reduces ecosystem resilience and services.

Now, well done.

There's a lot of content in that lesson, so a fantastic job from you.

Right, that's it from me, and I'll see you next time.

Bye.