Lesson video

Hi, everyone, I'm Miss Reid, and welcome to our final lesson on biomes.

Let's have a look at our lesson question.

So our lesson question is, are biomes all equally fragile? Well, in this lesson, we're going to be learning about the threats and the outcomes of those threats that face the tundra, grasslands and desert biomes across the globe.

We'll also learn about the outcomes or consequences that these threats have on the biomes flora and fauna, as well as the impact on us as humans.

We'll conclude the lesson by considering which of these three biomes is most fragile and why.

In this lesson, you'll need an exercise book or a piece of paper.

You'll need a pencil, and you'll need your brain.

Please take a moment now to clear away any distractions, including turning off any notifications or apps or conversations you have running in the background if you know how to.

And finally if you can try and find a quiet place, where you won't be disturbed during this lesson.

Pause the video now so you can get the things you need and find a quiet place to work.

Now you have everything you need, let's carry on.

So we are of course geographers, and geographers are a type of scientists who study the earth.

And this includes the land.

That's the physical features and the people who live within it.

And that's the human features.

In today's lesson, we're going to be drawing a table.

And we're going to be looking at biome fragility, and then we'll be doing a writing task.

Here's the table.

Let's take a closer look.

So in this table, you have a column for the biome and its name.

You have a column for the threats that are facing the biome, and you have a column for the outcomes of those threats.

Each of the rows for the tundra, the grasslands, and the desert should be about eight to 10 lines so that you can fit all of the information that you're writing.

Pause the video now and draw that table.

Great.

Now you have your table, let's carry on.

Biome fragility.

Fragility is the quality of being easily broken or damaged.

We think of biomes as being fragile because slight variations in temperature can lead to huge climatic shifts that disrupt the natural balance of living and nonliving things within them.

The first biome we're going to think about is the tundra.

And we're going to think first about the threats that face this biome.

So the first thing is overfishing.

Humans are taking fish out of the water faster than fish can reproduce, and be replaced around the Tundra's in the oceans that are surrounding them.

Pollution.

Pollutants from human activities tend to make their way to polar regions transported by ocean currents, migratory birds and other means.

Marine debris such as ropes and nets are left in oceans, and they're often dumped or accidentally released from ships.

Toxic contaminants such as sewage or pesticides, also make their way into oceans when they're released into the environment upstream from coastlines.

They're eventually deposited into estuaries and bays and make their way into the wider ocean and up to the tundra through the ocean currents.

Oil and gas drilling and development is another threat that faces the tundra.

Oil and gas drilling development occurs because the northern tundras hold oil and gas reserves under the surface of the permafrost.

Getting to these reserves can be difficult and requires lots of equipment to be transported across the biome, meaning the creation of roads and drilling stations.

And this can be harmful to the habitats, or the living things.

Pause the video now so you can record the threats that face the tundra in your table.

Excellent work.

Now you've recorded the threats that face the tundra.

Let's have a look at the outcomes of these threats.

So, overfishing means a loss of species around the world, not simply just around the oceans or in the oceans that surround the tundra, including the oceans of the Arctic and the Southern Ocean surrounding Antarctica.

Humans are taking fish off the water faster than the fish can reproduce and be replaced.

In the Barents Sea, a relatively undisturbed area north of Norway and Russia.

That's above the tundra.

Overfishing has led to the decline of fish species, and they've threatened the future of important fisheries such as Cod.

Now I know that I have eaten Cod when I go for my fish and chips.

And it's good for me to think about the fact that this is a fish that is in decline.

Pollution.

Well, this has also led to the loss of species, but it's also led to toxin exposure.

Marine debris can entangle and therefore kill marine wildlife.

You can see in this image, there is an albatross there and it's been found dead on a beach.

And you can see that inside it, it has ingested plastic and other materials that it shouldn't be eating.

Now in addition, toxic contaminants either create dead zones where no marine life can survive.

Or the toxins are ingested and work their way up the food chain.

This does mean that the top predators, such as polar bears or even humans are exposed to high levels of toxins when eating fish and other marine animals.

Drilling for oil and gas.

This prevents vegetation.

Drilling wells can fill or melt the permafrost, and heavy vehicles and pipeline construction can damage soil and prevent vegetation from returning.

Pause the video now while you record the outcomes of overfishing, pollution and drilling on the tundra in your table.

Great work.

Now you've recorded the outcomes, we can move on.

So now we're thinking about grasslands and grasslands are called the savanna in Africa.

They have many different names depending on where you are and which continent you're looking at.

So the first threat to grasslands is the conversion of grasslands, from natural grasslands, to arable, and that's crops, or pastoral, and that's animal farmland.

To feed a growing human population, most of the world's grasslands including the American prairies have been converted from natural landscapes to fields of corn, wheat or other crops.

Grasslands that have remained largely intact until now, such as the East African savannas are at risk of being lost to agricultural farming.

Another threat is the changes in species.

Key species such as buffalo and prairie dogs in the American West, have been removed from grasslands.

And in some places, such as Northern Australia, invasive species like the Cane toad have been introduced.

Another threat is hunting.

Grasslands are home to some of the most magnificent animals on the planet, such as elephants, bison, lions, and hunters have found them enticing prey.

But when hunting is not controlled, or it's conducted illegally, species can be wiped out.

For example, it's legal to hunt elephants in Botswana.

Pause the video now and record the threats that face the grasslands in your table.

Now you've recorded the threats, let's have a look at the outcomes of these threats.

So the first is changes to the natural landscape.

Now when you convert natural grasslands to farmland, it means that animal species are lost.

But it also means that the plant species that kept the land intact are also lost.

In fact, early European settlers transformed the North American prairies to farmland, and when drought struck the region in the early 1930s, crops couldn't grow and bear fields were swept into powerful dust storms that destroyed farms and made the land uninhabitable for years.

So drought is essentially where there is no rain in the area for a prolonged period of time.

And that means that nothing can grow.

And that's what happened in the North American prairies.

Unbalanced ecosystems. Now the plants and animals that live in a grassland are connected through a vast web of interactions.

Cane toads are an invasive species that were introduced to Northern Australia.

They are poisonous to creatures that eat them, and they have therefore disrupted the natural balance in these ecosystems. They've damaged a host of other species such as fresh water crocodiles.

Loss of wildlife due to hunting.

Grasslands, as we've just said, are home to some of the most magnificent animals on earth.

But when hunting is not controlled, or is conducted illegally, species can be wiped out.

For example, there is a huge black market that deals illegally in the sale of elephant ivory, which is their tusks.

And this puts these great animals at risk of poaching in many countries across Africa and Asia.

Pause the video now so you can record the outcomes of these threats on the grasslands in your table.

Well done everyone.

Now you've recorded the outcomes of the threats to the grasslands.

Let's carry on.

So this is the final biome we're looking at today and it is the desert.

Plants, animals and other organisms that live in deserts have evolved to survive harsh conditions, scarce water and barren landscapes, as well as very little vegetation.

Many desert plants like cacti in the Americas, are able to absorb and store water, letting them survive long periods of drought.

That's time without rain.

Animals have adapted to get water from the food they eat, and to conserve what little they obtain.

They often come out only at night to avoid the worst of the heat.

And the deserts arid conditions mean that soils take a long time to recover when they're disturbed, and the lack of water makes desert landscapes vulnerable.

Threats that face the desert.

Population growth.

Over-farming in communities that border deserts put pressure on the land.

This can mean for example, that people living in grasslands, who are trying to farm the land, can over-farm it.

And it means that that fertile land, those grasslands actually turn into deserts.

It's the process of desertification, which means that deserts are getting bigger.

Desertification.

Let's think more about desertification.

Desertification is the process by which fertile land becomes desert.

And this is typically as a result of drought, deforestation or inappropriate farming.

Global warming is the main problem, or is the main impact of desertification.

Rather, desertification happens as a result of global warming.

So global warming is reducing snowpacks.

Snowpacks are a mass of snow, usually found in the mountains that provide water to deserts.

Global warming is also decreasing precipitation rates.

Global warming is also increasing dust source, dust storms. Now all of these things are putting pressure on deserts, but they're also putting pressure on surrounding landscapes, the surrounding biomes predominantly grasslands and that is why deserts are expanding into those areas.

This map indicates the places in the world that are most at risk of desertification.

Let's see them.

Desertification, as you know, is the process by which fertile land becomes desert, and is typically as a result of drought, deforestation or inappropriate agriculture.

The areas in red are the most high at risk of becoming deserts in the near future.

Once this process occurs, there's no coming back from it, and desertification puts millions of species of plant and animal life at risk.

Let's go back to the threats that face the desert.

I'd like you to pause the video and record the threats in your table.

Now you've recorded the threats.

Let's move forward and have a look at the outcomes of these threats.

Global warming.

When we talk about global warming, in the desert, we're mainly thinking about the depletion of water.

And global warming is leading to a depletion of water that is absolutely vital for the survival of desert biomes and the neighbouring grasslands.

Ice packs are melting, and freshwater stores underground are therefore not being restored.

On top of that, precipitation in deserts is decreasing.

And that means that the land in and around the deserts is becoming more dry.

And the species within these biomes cannot survive.

And that also means the deserts expand.

Deserts expanding.

This process is called? That's right, desertification.

Desertification is a huge risk, not simply for the plant and animal species within the deserts and the neighbouring biomes, but also for humans living in cities that border biomes.

For example, Las Vegas and Dubai are cities that border deserts.

And they are risk of this process of desertification.

Desertification also leads to a loss of wildlife.

For example, species like the great Indian bustard which only has about 150 of its population left, are critically endangered.

That means that they're facing extinction.

If land is not managed properly, desertification could be one of the reasons that they become extinct.

Pause the video now and record the outcomes of the threats to the desert in your table.

Excellent work everyone.

You should have a full table now with threats and outcomes to all three biomes.

We now have a writing task.

Let's take a closer look.

Use the information in your table to write about the threats and the outcomes to each biome.

Conclude by stating which of the three biomes you feel is most at risk.

Here are some sentence starters.

The threats to that____include.

The outcomes of these threats are.

In my opinion, the biome that is most at risk is.

because.

I'm now going to show you some paragraphs that I have written about the tundra.

I've outlined the threats and I've outlined the outcomes.

Let's have a read.

I'm going to read it out and you can read along with me at home.

The threats to the tundra include overfishing as humans are taking fish faster than species can reproduce and be replaced; pollution such as marine debris like ropes and nets, which are left in oceans and toxic contaminants such as sewage or pesticides, and oil and gas drilling and development, which encouraged the building of roads and drilling stations.

The outcomes of these threats are threefold.

overfishing has led to a decline of fish species and threatened the future of important fisheries such as Cod.

Pollution is threatening, because marine debris can entangle and therefore kill marine wildlife.

In addition, toxic contaminants either create dead-zones where no marine life can survive or are ingested and work their way up the food chain.

Drilling wells can thaw or melt permafrost, while heavy vehicles and pipeline construction can damaged soil and prevent vegetation from returning.

So you can see that I have paragraph on the threats that face the tundra, and I have the paragraph on the outcomes of those threats.

Your task is to write a threat and an outcomes paragraph for each three biomes.

And at the end, you need to state your opinion about which of those three biomes is most at risk.

You can use the sentence starter, In my opinion the biome that is most risk is.

and give your reasons using 'because.

' Pause the video now, so that you can complete that task.

Wow, I'm so impressed with the work you've done.

And you should be really proud of yourselves for getting to the end of this unit with an amazing written task to show everything that you've learned about these biomes.

That brings us to the end of this Geography unit.

And really big well done on all the fantastic learning that you've achieved throughout the unit.

If you're able to, please do take a picture of your work and ask a parent or carer to share it with your teacher so that they can see all of the amazing things that you've achieved throughout the unit.

If you'd like, ask your parent or carer to send a picture of your work to @OakNational on Twitter so I can see all of your work too That's all that's left for me to say.

Thank you.

Take care, and enjoy the rest of your learning for today.