Ecosystems and biomes | Ecology | Khan Academy

- [Voiceover] So, just as a bit of review.

If we take the members
of a certain species

that share the same area,

we call that a population.

Population.

All of the organisms in
this particular population

will be members of the same species.

There could be other
members of that species

that aren't in that same area,

and they wouldn't be a member
of this particular population.

And a certain area won't have just one,

or it doesn't tend to have
just one species in it.

So, we could call this population one.

You might have other populations there

of a different species.

So, this is another
species right over here.

All of them combined in the same area,

we could call this population,

population two.

And if you take...

And we could, obviously have
many more populations there.

And if you take all of the populations

in a given area,

there's flexibility on
how you define that area

or define that region,

you take those together,

so you're really taking
all of the living things

in a certain area, we
call that a community.

A community of populations.

Now, the community only
consists of living things,

the biotic factors.

So, let me write that down.

Biotic referring to the living
things in a certain area.

But if we want to think about
not just the living things,

but also the non-living
things in that region.

So, I'll write abiotic.

Let me do that in another color.

So, let's take the abiotic factors,

or the abiotic environment.

And, once again, we're
sharing the same region,

and that is flexible on
how you define that region.

You put all of these things together,

and then you get your ecosystem.

Your ecosystem, once again,

it could be a very small region,

it could be a very large region,

but it's made up of all living things,

the biotic factors, and
the non-living things,

the abiotic factors.

Now, what we're gonna
think about in this video

is just the types of
ecosystems that you might have.

Think a little bit about it,

and also begin to think about
how the different factors

interact with each other.

How there's conservation of matter

where, within an ecosystem,
matter tends to go

from one form to another.

You also have a flow of energy.

Energy tends to enter an ecosystem

in form of light, and that
energy gets transferred

from one organism to another,

and, sometimes, even involving
the non-living things,

eventually, getting turned

into actual heat.

Now, in terms of the types of ecosystems.

I already mentioned there's
a lot of variety there.

This, right here, is a
picture of a tide pool

at Half Moon Bay, not too
far from where I live.

I've actually been to the
tide pools at Half Moon Bay.

And you could consider
one particular tide pool,

both the abiotic factors, the water,

and the rock there,

as well as the biotic factors,

the starfish, the sea anemones,

and whatever else might be living there.

Those combined, that
could be an ecosystem.

You might say that the
entire beach is an ecosystem.

You might say that the entire
region is an ecosystem.

Once again, it depends
on how much you want

to zoom in or how much
you want to zoom out,

and you can zoom out a good bit.

This rain forest, right over here,

this is the Amazon rain forest.

You can consider the whole
rain forest an ecosystem,

or maybe you just want to study,

maybe you just want to study

what's happening in this exact
region, right over there.

You can also consider that an ecosystem.

You can consider what's
happening in the river, itself,

an ecosystem, or, maybe,
one part of that river.

And, as you notice, I'm
talking about some ecosystems

that are on land, and
some that are in water,

and that is a general way,
one way of classifying them.

So an ecosystem, you
could have it on land.

You could have it on, near, in the water.

So, you could say it's aquatic.

And then, if within aquatic,

you could have ones that...

You have salt water, or
partially salty water,

and these are called marine,

and the main marine ecosystem,

we're thinking about the
oceans and things like that.

And then, you have freshwater ecosystems.

Like if you are in the upper-Amazon,

that is freshwater that is flowing.

So we could say fresh, freshwater,

non-salty water.

And even though it looks
like rivers are big

and there's a lot of freshwater around us.

Obviously we need freshwater to live,

most of the aquatic ecosystems are marine,

are not involved freshwater.

Freshwater is a very small subset.

Now, this is just a few examples.

Even your body, you could view your body

as a whole ecosystem.

You could view parts of
your body as an ecosystem.

You could look at just...

You could look at just a fraction of...

If this is my hand right over here,

you could take just a
little square, there,

and you could consider that an ecosystem.

You can think about the different bacteria

that are there, other
types of microorganisms

that are there, and
how they're interacting

with the non-living things, the air.

How they're interacting
with the oil on your skin,

with the dead skin cells, and also,

how they're interacting
with the living skin cells,

and you, yourself.

Now, since we're in
the, since we're focused

on how we can classify ecosystems,

one thing that's often done

is classifying land ecosystems
into various categories.

And, right over here, we have depicted

the major types of land ecosystems

on our planet

and where you might find them.

And these different
types of land ecosystems,

these are called biomes.

Biomes.

And as you can see from this diagram,

tropical forests, you can
find it right over here.

This is the Amazon rain forest.

You can find it in Africa.

You can find it in Southeast Asia.

You can find it in
Central and even Southern

or North America.

You have boreal forests which you'll find

in more northern latitudes.

Savanna, desert, tundra,
chaparral, polar ice,

temperate forest, temperate grasslands,

and these are just helpful

for thinking about roughly
the types of ecosystem,

or ecosystems we would
find in those regions.

And it's typically most determined by

temperature, moisture, the climate.

Actually, the climate and the terrain

and the types of minerals
that you would find there,

that tends to be a pretty good indicator

for what it will be like,
what the life would be like.

But even with that said, there could

still be a lot of variety.

For example, the Sonoran
Desert, that is right over here

in the southwest United States,

in the northwest Mexico.

This is a desert, and there's deserts

all over the rest of the planet,

but they won't have...

They might be similar in a lot of ways,

but they won't have
the exact same climate,

or the exact same abiotic factors,

or the exact same biotic factors.

So, for example, right now
I'm gonna show you a picture,

pictures of the Sonoran
Desert and the Rock Desert

that's on the island of Boa Vista.

Boa Vista is right over there.

You really can't see it.

It's a very small island
off the coast of Africa.

And, as we see in these
diagrams, or in this picture,

you don't have to be an
expert to recognize that,

okay, these are both deserts.

They both look dry.

There's not a lot of water here,

but they are also very different.

The Sonoran Desert looks to have

at least a lot more life,

than the Rock Desert have here.

It's appropriately named the Rock Desert

because it seems, at
least to the naked eye,

it looks like all you can see is rock.

So biomes, once again, it's a very rough,

high-level way to
classifying land ecosystems.

But even the same biome
can be very, very...

Two things that are
categorizing in the same biome

could be very different.