WEBVTT
00:00:00.160 --> 00:00:02.000
Ooh, it's fall.
00:00:02.160 --> 00:00:08.640
That means pumpkin spice, cooler weather, and in some areas of the world, changing leaves.
00:00:08.800 --> 00:00:12.560
But what causes these gorgeous, incredible changes?
00:00:12.720 --> 00:00:17.679
Well, I'm Mimi Fotz, and that's what we're talking about today on Hello from the Van.
00:00:21.679 --> 00:00:25.280
Science, chemicals, photosynthesis.
00:00:25.440 --> 00:00:28.640
These are the voyages of the incredible tree.
00:00:28.879 --> 00:00:37.759
To understand what happens in the fall, we need to go back, back to the beginnings of spring and when those leaves first got their start.
00:00:38.000 --> 00:00:41.039
I feel like we should personify the trees a little bit.
00:00:41.119 --> 00:00:45.840
It's hard for me to think about things if I don't think about them as living, breathing, and alive.
00:00:45.920 --> 00:00:48.240
And an easy way to do that is to just give it a name.
00:00:48.399 --> 00:00:49.600
So here goes nothing.
00:00:49.759 --> 00:00:53.280
One of the most common species of tree in the world is a red maple.
00:00:53.359 --> 00:00:57.600
So let's say that we're going to talk about a red maple named Jack.
00:00:57.759 --> 00:00:59.920
In the winter, Jack is sleeping.
00:01:00.079 --> 00:01:05.519
He's sleeping because it's cold, days are shorter and dark, and sleep helps with the hunger.
00:01:05.680 --> 00:01:08.799
Jack's metabolism, like all trees, slows down.
00:01:08.959 --> 00:01:14.879
In the spring, when things start to warm up, the days get longer and the sun shines brighter.
00:01:15.120 --> 00:01:18.000
And our red maple friend starts to wake up too.
00:01:18.159 --> 00:01:21.680
And Jack, after all that sleep, is hungry.
00:01:21.920 --> 00:01:23.439
Much like I am in the morning.
00:01:23.599 --> 00:01:29.040
But deciduous trees, that's the fancy name for trees with leaves, deciduous.
00:01:29.200 --> 00:01:30.400
You can try saying it with me.
00:01:30.640 --> 00:01:31.680
Deciduous.
00:01:31.840 --> 00:01:33.120
Yeah, it's a great word, isn't it?
00:01:33.280 --> 00:01:36.400
Deciduous trees aren't like birds or humans.
00:01:36.560 --> 00:01:40.560
They can't just go catch breakfast and then suddenly feel full and energized.
00:01:40.719 --> 00:01:46.319
Leaves are required to breathe, to grow, and to make food.
00:01:46.480 --> 00:01:52.480
As the days warm up and get longer, Jack's first priority is then making these leaves.
00:01:52.640 --> 00:01:54.959
And make the leaves does he ever.
00:01:55.200 --> 00:02:02.480
As the leaves grow, they go from a bud to then having a blade, that's the leafy part, with a vein system and a stem.
00:02:02.719 --> 00:02:04.799
That's how the leaf connects to the tree.
00:02:04.959 --> 00:02:09.439
The blade is made up of hundreds, if not thousands, of tiny cells.
00:02:09.520 --> 00:02:13.520
And in these cells is a critical substance called chlorophyll.
00:02:13.680 --> 00:02:20.719
Chlorophyll is what gives the leaves their green color and is also required for a process called photosynthesis.
00:02:20.879 --> 00:02:21.840
So it's a lot of big words.
00:02:22.000 --> 00:02:23.599
Chlorophyll, that's the green stuff.
00:02:23.759 --> 00:02:26.400
Photosynthesis, that's what the green stuff does.
00:02:26.560 --> 00:02:35.840
Photosynthesis is where the tree takes carbon dioxide and water and combines them with sunlight and chlorophyll.
00:02:36.080 --> 00:02:37.759
Hang with me, it's a little sciencey.
00:02:38.080 --> 00:02:46.879
The chemical reaction of the carbon dioxide and water with the chlorophyll results in the production of sugars, which provide energy to the tree.
00:02:47.039 --> 00:02:56.080
Now the leaves do use a little bit of this energy, but the majority of it is transported in the form of a sugar solution to other parts of the tree that require it.
00:02:56.319 --> 00:02:58.080
Think the trunk and the roots.
00:02:58.319 --> 00:02:59.680
But that's not all.
00:02:59.919 --> 00:03:03.919
There are other substances also running around in those green leaves.
00:03:04.080 --> 00:03:07.120
They're called flavonoids and carotenoids.
00:03:07.280 --> 00:03:12.240
Flavonoids are yellow and carotenoids are orange, like carrots.
00:03:12.400 --> 00:03:14.159
Carotenoid, orange carrot.
00:03:14.319 --> 00:03:15.599
It's a correlation thing.
00:03:15.759 --> 00:03:20.560
These chemicals and their corresponding colors are present in the leaves all year long.
00:03:20.719 --> 00:03:26.319
We just can't see them because they're overpowered by the abundance of chlorophyll.
00:03:26.400 --> 00:03:32.879
But again, where do trees like our friend Jack get this chlorophyll, flavonoids, and carotenoids?
00:03:33.039 --> 00:03:36.159
It starts in the roots, but it ends in the leaves.
00:03:36.319 --> 00:03:39.360
You see, the roots and the trunk of the tree hold the sap.
00:03:39.680 --> 00:03:44.240
It is brought through the roots and trunk to the stem of the leaf and into the veins.
00:03:44.319 --> 00:03:47.919
But it can only do this with the help of sunshine.
00:03:48.080 --> 00:03:52.159
The sun acts as the fuel for this photosynthesis.
00:03:52.319 --> 00:03:58.080
Much like a traditional car can't go without gas, a tree can't grow without the sun.
00:03:58.240 --> 00:04:01.599
Without the sun, trees like Jack couldn't make chlorophyll.
00:04:01.759 --> 00:04:06.639
Remember, we need chlorophyll, sunshine, air, water for trees to grow?
00:04:06.800 --> 00:04:07.439
Let's go back.
00:04:07.599 --> 00:04:08.319
It's spring.
00:04:08.479 --> 00:04:12.719
The world is warming up, and the days of sun are getting longer.
00:04:13.039 --> 00:04:20.240
Jack is starting to grow leaves, and in those leaves, Jack begins to harvest carbon dioxide and sunshine.
00:04:20.319 --> 00:04:25.199
And through this chemical reaction of the leaf, he produces a sugary starch-like syrup.
00:04:25.439 --> 00:04:32.160
This starchy, sugary food is sent to every part of the tree where it is used in building bark and tissue.
00:04:32.480 --> 00:04:36.720
We humans also sometimes partake of this deliciousness.
00:04:36.879 --> 00:04:38.560
Have you ever had maple syrup?
00:04:38.800 --> 00:04:39.279
Yep.
00:04:39.439 --> 00:04:46.800
That comes from the process of photosynthesis in the leaves that then goes into the trunk as part of that sugary, starchy syrup.
00:04:46.959 --> 00:04:51.360
We then harvest it, boil it down, and it becomes Canadian deliciousness.
00:04:51.600 --> 00:04:55.120
But let's get back to Jack and off the maple syrup train here for a little bit.
00:04:55.279 --> 00:04:59.120
As the tree grows and summer is plentiful, life is good.
00:04:59.360 --> 00:05:04.000
Sunshine abounds, the days are long, and chlorophyll is all the rage.
00:05:04.160 --> 00:05:05.120
The leaves are green.
00:05:05.279 --> 00:05:07.279
But remember how chlorophyll is green?
00:05:07.519 --> 00:05:10.480
In the summer, there's a lot of chlorophyll, so everything is green.
00:05:10.560 --> 00:05:11.600
It's a sign of summer.
00:05:11.680 --> 00:05:12.720
We see it all the time.
00:05:12.879 --> 00:05:15.279
Food, sunshine, water are also available.
00:05:15.439 --> 00:05:18.800
This is how trees like Jack are able to grow and thrive in the summer.
00:05:19.040 --> 00:05:22.560
Everything that they require to grow, it's all plentiful.
00:05:22.720 --> 00:05:25.279
But before you know it, another season has changed.
00:05:25.439 --> 00:05:30.480
The days start to get shorter, it gets colder, and food is less plentiful.
00:05:30.639 --> 00:05:36.959
This change causes trees like our friend Jack to produce a stress hormone called abscissic acid.
00:05:37.120 --> 00:05:38.720
Try saying that three times fast.
00:05:38.879 --> 00:05:40.399
Oh my goodness, trying to do this today.
00:05:40.560 --> 00:05:42.160
Whew! Absissic acid.
00:05:42.319 --> 00:05:43.519
Absissific acid.
00:05:43.759 --> 00:05:45.439
Absisic acid.
00:05:45.680 --> 00:05:56.160
As the tree's stress goes up from a lack of food and an increase in colder weather, this abscic acid begins to close the connection between the leaves and the stems.
00:05:56.399 --> 00:06:06.399
This is why a fallen tree stem usually looks thinner and almost dried out compared to a healthy, strong stem in the spring or summer, because of the abscisic acid.
00:06:06.480 --> 00:06:13.439
As the stem dries out from this acid, it also stops receiving water and nutrients from the tree.
00:06:13.600 --> 00:06:17.360
This is critical because one of those things is chlorophyll.
00:06:17.680 --> 00:06:27.439
As this highway from root to leaf closes up, so does the access to chlorophyll and the green color lessens.
00:06:27.600 --> 00:06:32.319
We are then left with flavonoids and carotenoids that have always been there.
00:06:32.480 --> 00:06:38.480
We've just not been able to see them because they have been overpowered by the chlorophyll.
00:06:38.720 --> 00:06:47.199
And after a few weeks of cold and stress and absystic acid, Jack and his deciduous tree friends enter a state called dormancy.
00:06:47.360 --> 00:06:49.040
This is similar to hibernation.
00:06:49.199 --> 00:06:51.600
It helps the trees to conserve energy.
00:06:51.759 --> 00:06:56.639
As most of the world understands it, in the mid-bleak winter, trees are not actively growing.
00:06:56.800 --> 00:07:03.839
It's hard to grow when sunshine is your fuel for photosynthesis and there's not much of that sunshine to go around.
00:07:04.000 --> 00:07:10.560
So trees hibernate and they stay in that state until the world starts to warm and the days get longer again.
00:07:10.639 --> 00:07:13.759
And the cycle goes round and round and round.
00:07:13.920 --> 00:07:26.959
So what we see in the fall when the air gets crisp and cool and the leaves start to change color is actually those trees getting ready to go into hibernation, to go into a state of dormancy.
00:07:27.199 --> 00:07:32.879
You know, it is incredible to me that chlorophyll masks the incredibleness that is fall.
00:07:32.959 --> 00:07:36.720
The reds and the yellows and the oranges and the golds have been there all along.
00:07:36.959 --> 00:07:39.600
We just couldn't see them for the abundance.
00:07:39.839 --> 00:07:45.759
In the words of LM Montgomery, I'm so glad I live in a world where there are Octobers.
00:07:45.920 --> 00:07:49.199
I'm Mimi Fotz, and this has been Hello from the Van.
00:00:00.160 --> 00:00:02.000
Ooh, it's fall.
00:00:02.160 --> 00:00:08.640
That means pumpkin spice, cooler weather, and in some areas of the world, changing leaves.
00:00:08.800 --> 00:00:12.560
But what causes these gorgeous, incredible changes?
00:00:12.720 --> 00:00:17.679
Well, I'm Mimi Fotz, and that's what we're talking about today on Hello from the Van.
00:00:21.679 --> 00:00:25.280
Science, chemicals, photosynthesis.
00:00:25.440 --> 00:00:28.640
These are the voyages of the incredible tree.
00:00:28.879 --> 00:00:37.759
To understand what happens in the fall, we need to go back, back to the beginnings of spring and when those leaves first got their start.
00:00:38.000 --> 00:00:41.039
I feel like we should personify the trees a little bit.
00:00:41.119 --> 00:00:45.840
It's hard for me to think about things if I don't think about them as living, breathing, and alive.
00:00:45.920 --> 00:00:48.240
And an easy way to do that is to just give it a name.
00:00:48.399 --> 00:00:49.600
So here goes nothing.
00:00:49.759 --> 00:00:53.280
One of the most common species of tree in the world is a red maple.
00:00:53.359 --> 00:00:57.600
So let's say that we're going to talk about a red maple named Jack.
00:00:57.759 --> 00:00:59.920
In the winter, Jack is sleeping.
00:01:00.079 --> 00:01:05.519
He's sleeping because it's cold, days are shorter and dark, and sleep helps with the hunger.
00:01:05.680 --> 00:01:08.799
Jack's metabolism, like all trees, slows down.
00:01:08.959 --> 00:01:14.879
In the spring, when things start to warm up, the days get longer and the sun shines brighter.
00:01:15.120 --> 00:01:18.000
And our red maple friend starts to wake up too.
00:01:18.159 --> 00:01:21.680
And Jack, after all that sleep, is hungry.
00:01:21.920 --> 00:01:23.439
Much like I am in the morning.
00:01:23.599 --> 00:01:29.040
But deciduous trees, that's the fancy name for trees with leaves, deciduous.
00:01:29.200 --> 00:01:30.400
You can try saying it with me.
00:01:30.640 --> 00:01:31.680
Deciduous.
00:01:31.840 --> 00:01:33.120
Yeah, it's a great word, isn't it?
00:01:33.280 --> 00:01:36.400
Deciduous trees aren't like birds or humans.
00:01:36.560 --> 00:01:40.560
They can't just go catch breakfast and then suddenly feel full and energized.
00:01:40.719 --> 00:01:46.319
Leaves are required to breathe, to grow, and to make food.
00:01:46.480 --> 00:01:52.480
As the days warm up and get longer, Jack's first priority is then making these leaves.
00:01:52.640 --> 00:01:54.959
And make the leaves does he ever.
00:01:55.200 --> 00:02:02.480
As the leaves grow, they go from a bud to then having a blade, that's the leafy part, with a vein system and a stem.
00:02:02.719 --> 00:02:04.799
That's how the leaf connects to the tree.
00:02:04.959 --> 00:02:09.439
The blade is made up of hundreds, if not thousands, of tiny cells.
00:02:09.520 --> 00:02:13.520
And in these cells is a critical substance called chlorophyll.
00:02:13.680 --> 00:02:20.719
Chlorophyll is what gives the leaves their green color and is also required for a process called photosynthesis.
00:02:20.879 --> 00:02:21.840
So it's a lot of big words.
00:02:22.000 --> 00:02:23.599
Chlorophyll, that's the green stuff.
00:02:23.759 --> 00:02:26.400
Photosynthesis, that's what the green stuff does.
00:02:26.560 --> 00:02:35.840
Photosynthesis is where the tree takes carbon dioxide and water and combines them with sunlight and chlorophyll.
00:02:36.080 --> 00:02:37.759
Hang with me, it's a little sciencey.
00:02:38.080 --> 00:02:46.879
The chemical reaction of the carbon dioxide and water with the chlorophyll results in the production of sugars, which provide energy to the tree.
00:02:47.039 --> 00:02:56.080
Now the leaves do use a little bit of this energy, but the majority of it is transported in the form of a sugar solution to other parts of the tree that require it.
00:02:56.319 --> 00:02:58.080
Think the trunk and the roots.
00:02:58.319 --> 00:02:59.680
But that's not all.
00:02:59.919 --> 00:03:03.919
There are other substances also running around in those green leaves.
00:03:04.080 --> 00:03:07.120
They're called flavonoids and carotenoids.
00:03:07.280 --> 00:03:12.240
Flavonoids are yellow and carotenoids are orange, like carrots.
00:03:12.400 --> 00:03:14.159
Carotenoid, orange carrot.
00:03:14.319 --> 00:03:15.599
It's a correlation thing.
00:03:15.759 --> 00:03:20.560
These chemicals and their corresponding colors are present in the leaves all year long.
00:03:20.719 --> 00:03:26.319
We just can't see them because they're overpowered by the abundance of chlorophyll.
00:03:26.400 --> 00:03:32.879
But again, where do trees like our friend Jack get this chlorophyll, flavonoids, and carotenoids?
00:03:33.039 --> 00:03:36.159
It starts in the roots, but it ends in the leaves.
00:03:36.319 --> 00:03:39.360
You see, the roots and the trunk of the tree hold the sap.
00:03:39.680 --> 00:03:44.240
It is brought through the roots and trunk to the stem of the leaf and into the veins.
00:03:44.319 --> 00:03:47.919
But it can only do this with the help of sunshine.
00:03:48.080 --> 00:03:52.159
The sun acts as the fuel for this photosynthesis.
00:03:52.319 --> 00:03:58.080
Much like a traditional car can't go without gas, a tree can't grow without the sun.
00:03:58.240 --> 00:04:01.599
Without the sun, trees like Jack couldn't make chlorophyll.
00:04:01.759 --> 00:04:06.639
Remember, we need chlorophyll, sunshine, air, water for trees to grow?
00:04:06.800 --> 00:04:07.439
Let's go back.
00:04:07.599 --> 00:04:08.319
It's spring.
00:04:08.479 --> 00:04:12.719
The world is warming up, and the days of sun are getting longer.
00:04:13.039 --> 00:04:20.240
Jack is starting to grow leaves, and in those leaves, Jack begins to harvest carbon dioxide and sunshine.
00:04:20.319 --> 00:04:25.199
And through this chemical reaction of the leaf, he produces a sugary starch-like syrup.
00:04:25.439 --> 00:04:32.160
This starchy, sugary food is sent to every part of the tree where it is used in building bark and tissue.
00:04:32.480 --> 00:04:36.720
We humans also sometimes partake of this deliciousness.
00:04:36.879 --> 00:04:38.560
Have you ever had maple syrup?
00:04:38.800 --> 00:04:39.279
Yep.
00:04:39.439 --> 00:04:46.800
That comes from the process of photosynthesis in the leaves that then goes into the trunk as part of that sugary, starchy syrup.
00:04:46.959 --> 00:04:51.360
We then harvest it, boil it down, and it becomes Canadian deliciousness.
00:04:51.600 --> 00:04:55.120
But let's get back to Jack and off the maple syrup train here for a little bit.
00:04:55.279 --> 00:04:59.120
As the tree grows and summer is plentiful, life is good.
00:04:59.360 --> 00:05:04.000
Sunshine abounds, the days are long, and chlorophyll is all the rage.
00:05:04.160 --> 00:05:05.120
The leaves are green.
00:05:05.279 --> 00:05:07.279
But remember how chlorophyll is green?
00:05:07.519 --> 00:05:10.480
In the summer, there's a lot of chlorophyll, so everything is green.
00:05:10.560 --> 00:05:11.600
It's a sign of summer.
00:05:11.680 --> 00:05:12.720
We see it all the time.
00:05:12.879 --> 00:05:15.279
Food, sunshine, water are also available.
00:05:15.439 --> 00:05:18.800
This is how trees like Jack are able to grow and thrive in the summer.
00:05:19.040 --> 00:05:22.560
Everything that they require to grow, it's all plentiful.
00:05:22.720 --> 00:05:25.279
But before you know it, another season has changed.
00:05:25.439 --> 00:05:30.480
The days start to get shorter, it gets colder, and food is less plentiful.
00:05:30.639 --> 00:05:36.959
This change causes trees like our friend Jack to produce a stress hormone called abscissic acid.
00:05:37.120 --> 00:05:38.720
Try saying that three times fast.
00:05:38.879 --> 00:05:40.399
Oh my goodness, trying to do this today.
00:05:40.560 --> 00:05:42.160
Whew! Absissic acid.
00:05:42.319 --> 00:05:43.519
Absissific acid.
00:05:43.759 --> 00:05:45.439
Absisic acid.
00:05:45.680 --> 00:05:56.160
As the tree's stress goes up from a lack of food and an increase in colder weather, this abscic acid begins to close the connection between the leaves and the stems.
00:05:56.399 --> 00:06:06.399
This is why a fallen tree stem usually looks thinner and almost dried out compared to a healthy, strong stem in the spring or summer, because of the abscisic acid.
00:06:06.480 --> 00:06:13.439
As the stem dries out from this acid, it also stops receiving water and nutrients from the tree.
00:06:13.600 --> 00:06:17.360
This is critical because one of those things is chlorophyll.
00:06:17.680 --> 00:06:27.439
As this highway from root to leaf closes up, so does the access to chlorophyll and the green color lessens.
00:06:27.600 --> 00:06:32.319
We are then left with flavonoids and carotenoids that have always been there.
00:06:32.480 --> 00:06:38.480
We've just not been able to see them because they have been overpowered by the chlorophyll.
00:06:38.720 --> 00:06:47.199
And after a few weeks of cold and stress and absystic acid, Jack and his deciduous tree friends enter a state called dormancy.
00:06:47.360 --> 00:06:49.040
This is similar to hibernation.
00:06:49.199 --> 00:06:51.600
It helps the trees to conserve energy.
00:06:51.759 --> 00:06:56.639
As most of the world understands it, in the mid-bleak winter, trees are not actively growing.
00:06:56.800 --> 00:07:03.839
It's hard to grow when sunshine is your fuel for photosynthesis and there's not much of that sunshine to go around.
00:07:04.000 --> 00:07:10.560
So trees hibernate and they stay in that state until the world starts to warm and the days get longer again.
00:07:10.639 --> 00:07:13.759
And the cycle goes round and round and round.
00:07:13.920 --> 00:07:26.959
So what we see in the fall when the air gets crisp and cool and the leaves start to change color is actually those trees getting ready to go into hibernation, to go into a state of dormancy.
00:07:27.199 --> 00:07:32.879
You know, it is incredible to me that chlorophyll masks the incredibleness that is fall.
00:07:32.959 --> 00:07:36.720
The reds and the yellows and the oranges and the golds have been there all along.
00:07:36.959 --> 00:07:39.600
We just couldn't see them for the abundance.
00:07:39.839 --> 00:07:45.759
In the words of LM Montgomery, I'm so glad I live in a world where there are Octobers.
00:07:45.920 --> 00:07:49.199
I'm Mimi Fotz, and this has been Hello from the Van.
