Lesson video

Hello, My name's Mrs. Harking.

Today we're going to be exploring the Boreal forest biome.

This is actually the largest land-based biome on the planet and in a very harsh environment, so it's going to be interesting to find out how the trees here have adapted to be able to survive and thrive in environments like this.

Today's lesson is the Boreal forest biome.

It is taken from the forest biomes unit.

Why are forest so important? Our outcome today is to locate Boreal forest and explain the climate and adaptations.

Here are some keywords that are useful to know before we start the lesson.

Please feel free to pause the video at any point if you feel that you would like to record any of these.

First keyword we've got here is biome, which is a large region of the world with places that have similar climates, vegetation and animals that have adapted to living there.

So our biome that we are looking at in particular today is the boreal forest.

Then we have latitude.

So these are imaginary lines on earth showing the position north or south of the equator measured in degrees.

Hemisphere is half of the earth, so the earth is divided into the northern and southern hemispheres by the equator and the eastern and western hemispheres by the prime meridian.

Solar radiation is energy radiated from the sun via electromagnetic waves.

So this is the heat and light coming through sun.

Photosynthesis is a last key word, and this is the process by which green plants and certain bacteria can create glucose from sunlight, water and carbon dioxide.

We have three parts to our lesson today.

Firstly, where are boreal forests then why are boreal forest cold and dry? And finally, how have trees adapted in Boreal forests? So our first section, where are boreal forests? The Boreal forest, also known as taiga, is the world's largest land-based biome.

We can see it on the map here shown by the blue shading.

It is between the tundra to the north and then to the south, the majority of the biomes to the south are the Temperate deciduous for us, at least on the border with the boreal forest, some regions we've got Savannah.

Can we do a quick check for understanding now, fill in the blanks for each sentence.

Taiga is another word for the forest.

Boreal forest are the world's land-based biome.

Well done.

So you've got taiga is another word for the Boreal forest and Boreal forest are the world's largest land-based biome.

Boreal forest are located at high latitudes in the cold northern reaches of Europe, Asia, and North America.

Andeep's wondering why are none in the southern hemisphere.

Well the reason for that is because there's just not enough land in the right climate zone.

There's a lot of ocean in that climate zone and obviously trees can't grow in the ocean, in the middle of the ocean, at least.

Time for a quick check for understanding which continents contain Boreal forest? Is it A, Europe, Asia, and North America, B, Europe, Antarctica and North America, or C, Europe, Asia and Africa.

Well done, it is Europe, Asia, and North America.

Right, time for our practise task.

So we've got four questions here.

I would like you to answer each.

Name the world's largest land-based biome.

It's question one, question two, are boreal forest located at high, mid or low latitudes? Three, which hemisphere are the boreal forests located in? And four, name three continents that Boreal forests are located in.

I would like you to pause the video now to give you time to do this.

Well done, excellent effort.

Here are my answers, let's compare them to yours.

So the world's largest land-based biome is the boreal forest, are boreal forest located in high, middle or low altitudes.

They're high latitudes.

Which hemisphere are the boreal forests located in? It's the northern hemisphere and name three continents that Boreal Forest are located in.

So we've got Europe, Asia, and North America.

Well done everyone, great effort.

Let's have a look at my answers and compare them to yours.

So firstly, name the world's largest land-based biome.

That's Boreal forests, number two are Boreal Forests located at high bids or low latitudes? So Boreal forests are located at high latitudes.

Which hemisphere are boreal forests located in? That's the northern hemisphere and name three continents that Boreal forests are located in.

So you should have Europe, Asia and North America.

Did you get those all right, well done.

If there's anything you need to tweak, feel free to edit now.

Now we're onto the second part of our lesson, why are boreal forests cold and dry? Temperatures are often below freezing in boreal forests.

We can see that on the climate graph here to the right.

Lucas says he remembers that the red line shows temperature and the blue bars show precipitation on a climate graph.

And this is a really good point.

It's really easy to read a climate graph off incorrectly by reading off the bars against the temperature axis instead of the line for temperature.

Okay, so the line shows temperature should be read off against the temperature axis, which is on the right hand side here, and the bars show rainfall and they should be read off against the left hand side axis here.

So what we can see on the graph here is that actually the temperatures are often below freezing.

January, February, March and December, so four months of the year, the temperatures are on average below freezing in boreal forests.

That is very cold.

Don't be fooled by the fact that the temperature line does go to the top of the graph.

Graphs tend to be formatted so that the data goes to the top of the graph.

That doesn't mean that the boreal forests are hot.

Okay, so the maximum temperature the boreal forest gets you on this graph is 18 degrees Celsius on average for the month of July.

That's not that hot when we compare it to other forests.

Temperatures are lower at higher latitudes as the solar radiation has to heat a greater area due to the curvature of the earth.

Let's have a look at this diagram to understand that a bit further.

The diagram is not to scale.

The sun would be a lot larger and further away in reality, the orange lines represent solar radiation going from the sun to the earth's surface.

At A, that solar radiation is spread over a greater surface area than at B where the solar radiation is concentrated more and therefore will heat that area more.

So A is going to be cooler and B will be warmer.

Right, time for a quick check for understanding.

Can you select the correct statement? Is it A, the same amount of solar radiation has to heat a larger area at higher latitudes.

Is it B, at higher latitudes there is less solar radiation than at the equator or is it C, solar radiation is less concentrated at the equator.

Well done.

It's A, the same amount of solar radiation has to heat a larger area at higher latitudes and because it's spread over that larger area, it means that area is a lot cooler than it would be closer to the equator.

Just to confirm, B is not correct because there's the same amount of solar radiation.

It isn't less solar radiation and C says solar radiation is less concentrated at the equator, whereas actually it's more concentrated at the equator.

Okay, so A is our correct answer.

Now we're going to have a look at the rainfall.

So there's relatively little rainfall in the boreal biome.

The average monthly rainfall range in the boreal biome shown here is 42 to 78 millimetres.

I'm going to pop some lines on the graph just so you can see that.

Remember we're looking at the bars for rainfall and we're reading off against the left hand axis.

So in comparison, the average rainfall range in the tropical rainforest biome is 50 to 350 millimetres.

So way more, students can be misled by the fact that for most climate graphs, the data will go to the top of the graphs.

That is because the axes are just made long enough to take the data.

So on this graph, the rainfall does go to the top of the graph.

That does not mean there's a lot of rainfall in the boreal forest.

There actually isn't that much rainfall at all.

We've just shown that there's a lot less than the tropical rainforests might have.

So we must remember that that boreal forests are dry.

So average temperatures and rainfall show that boreal forest biome has a cold, dry climate.

Can we just do a quick check for understanding now, boreal forests are, is it A rainy and warm, B, wet and cold or C, dry and cold? Well done, it is dry and cold.

A suitable temperature is required to create moist air needed for rain.

So if we wanted rain to happen, we would require first of all, warm air, which evaporates water.

Then that warm, moist air needs to rise, the water vapour within the air would then cool and as it cools, the water vapour condenses to form water droplets and cloud which rain.

Now if this doesn't happen, if we don't have the warm air evaporating to start with, then the whole process of rain formation isn't going to happen as often and that's what happens in boreal forests.

So in boreal forest it is cold, meaning there's less warmer air to start the process of rain creation.

Can you fill in the blank of this sentence for me as our quick check for understanding? In Boreal forest there is little rain as there is less moist air to rise and kickstart the process of rain creation.

Fantastic.

You've been paying attention, that's great.

So it's in boreal forests there is little rain as there is less warm, moist air to rise and kickstart the process of rain creation.

Right, we're onto our practise task now.

I would like you to read this answer through and correct its mistakes.

So the question asked was, describe and explain the climates in boreal forests shown in the climate graph.

You've got this climate graph on the right here and a student has actually described and explained this climate, but they've made quite a few mistakes.

So temperatures vary between 42 degrees C and 76 degrees C.

Now 42 and 76 are highlighted in different colour.

Massive hint, there's an error here.

Can you work out what that error is and write it correctly? Right, let's read through the rest.

Temperatures are high as the solar radiation has a heated greater area at higher latitudes.

This is due to the curvature of earth.

The rainfall does not rise higher than 18.

6 millimetres per month as it is warm.

This means there is less cold air to start the process of rain creation.

So could you edit that answer for me? Feel free to pause the video now.

Well done.

Let's compare Your answer to mine.

So I have, temperatures vary between minus 6.

3 degrees C and 18.

6 degrees C.

So the student we saw had made an error, they'd read off the rainfall data, they'd read off the bars against the temperature axis instead of reading the red line for temperature.

So making sure you don't do that in future, it's a good one to look out for.

It's easily done.

Temperatures are low, not high, as solar radiation has to heat a greater area at higher latitudes.

This is due to the curvature of earth.

The rainfall does not rise higher than 76 millimetres.

Again, they'd read off the wrong symbol in the graph, per month.

As it is cold, this means there is less warm air to start the process of rain creation.

How did you do, did you get all of those? So five different corrections should have been made there.

Well done, feel free to pause the video now if you need to tweak your answer.

We are now on the third section of our lesson.

So how have trees adapted in boreal forests? Boreal forests contain many coniferous trees which produce cones, for example, pines and furs.

This makes sense because the word cone is almost in coniferous trees, right? Coniferous trees are normally evergreen.

This means that trees don't lose their leaves.

Again, this word makes sense.

Evergreen, always green, don't lose their leaves.

There are very few deciduous trees in boreal forests.

Deciduous trees do lose their leaves in winter.

It is worth noting that conifers and evergreen shouldn't be used interchangeably.

Many coniferous trees are evergreen, but there are also other evergreen trees.

For example, holly trees don't loose their leaves in winter.

So we just need to be a little bit careful about how we use those two terms. Let's have a quick check for understanding to see if you really understand those three key terms we've just introduced.

So for each of the following trees, state whether they are deciduous, evergreen or coniferous.

Now it could be that some of these examples are more than one of the key terms. A is an oak tree, there are no leaves on this tree here.

B is a fur tree.

We can see that cone has been labelled on and C is a holy tree and C we've labelled on here.

Leaves remain in the winter.

Just in case you didn't pick that.

Well done, let's take a look at your answers.

So an oak tree is deciduous, A fur tree is an evergreen and coniferous.

So we should have used two key terms there, evergreen and coniferous tree and a holly tree is evergreen.

So B are evergreen, coniferous trees, those are the ones that we see in the majority in Boreal forests.

coniferous trees adapt to the dry conditions by using their waxy, needle-like leaves to prevent water loss.

They adapt to their short growing season by not shedding needles.

This means that they can conserve energy as new leaves don't need to be regrown each year.

And also it allows some photosynthesis to occur even during the winter.

The coniferous trees also adapt the snowfall and they do this by growing into a conical shape to shed snow easily and prevent branches breaking under the weight of the snow.

You can see here circled on the photograph is a perfect example of a conical shaped tree.

It's almost like an ice cream cone turned upside down and it just protects the branches from the potential to be broken by heavy snow on them.

Quick check for understanding now.

How do trees in Boreal forest adapt to dry conditions? How do trees in Boreal forest adapt to short growing seasons? Well done, so they adapt to the dry conditions by having these waxy needle-like leaves and they adapt to the short growing season by not shedding their needles.

Right, our practise task now.

Going to look at all three of these different challenges that they need to adapt to.

So dry conditions, short growing season and snowfall.

And I would like you to match the challenge to the correct adaptation.

So on the right hand side we've got our adaptations.

Trees don't shed needles.

This conserves energy as leaves don't need to be regrown each year and it also allows some photosynthesis to occur during the winter.

Waxy needle-like leaves, prevent water loss and conical shape to shed snow easily and prevent branches breaking under the weight.

The second part of the task is to explain how trees in Boreal forests have adapted to the harsh climates.

I would like you to do this in paragraphs and I would like you to include the words coniferous, so trees that produce cones and evergreen, trees that don't lose their leaves in autumn.

Then I would like you to include the challenging conditions that the trees face as well as the adaptations and how these help the trees to survive.

You can pause the video now.

Well done everyone.

Let's have a look at some answers.

So we should have the challenges and adaptations matched up as we've got below.

So dry conditions mean that they've adapted by creating these waxy needle-like leaves that prevent water loss.

The short growing season has been adapted to by trees not shedding their needles.

This conserves energy as new leaves don't need to be regrown each year and also allows some photosynthesis to occur during the winter.

Because of the snowfall, the trees have adapted by having a conical shape to shed snow easily and prevent branches breaking under the weight to the snow.

Did you get those right? Well done, that's fantastic.

Feel free to pause the video now if you need to tweak anything.

So on to answer two, we've got explain how trees in Boreal forest have adapted to the harsh climate.

So your answer might include, boreal forest contain many coniferous trees which produce cones, for example, pines and furs.

Coniferous trees are normally evergreen.

This means trees that don't lose their leaves.

Coniferous trees adapt to the conditions that high latitudes by growing waxy needle-like leaves to prevent water loss to survive in the dry climate, the trees don't shed leaves.

This conserves energy as new leaves don't need to be regrown each year and also allows them to photosynthesize a little during the winter.

The trees have a conical shape to shed snow easily and prevent branches breaking under the weight.

Did you remember to include those key terms or did you cover that explanation well enough? Feel free to pause the video now if you need to tweak your answer.

Well done everyone.

We've reached the end of our lesson today.

Great effort, our summary is as follows, the Boreal forest is the world's largest land-based biome.

The Boreal Forest is also known as the taiga, they're found at high latitudes.

There is little rainfall in the Boreal biome due to the high latitudes and temperature.

Boreal forests contain many coniferous trees, which are normally evergreen, and so don't drop their leaves.

I hope you found today's lesson interesting.

I'm looking forward to seeing you next time.