How Do Ecosystems Work?

Nothing in our environment exists in a vacuum -- everything is interconnected. Learn how the study of ecosystems attempts to learn about things through those connections in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
brain Stuff Lauren boglebam here. Let's say you meet a
person on a flight from Boston to Brisbane. The two
of you are seated next to each other for a
couple dozen hours, and you talk the entire time about books, politics,
current events, religion, the weather, et cetera. You hear some

(00:22):
of their personal stories, observe the way they eat and drink.
You watch them play a game on their phone, and
notice that they snore when they sleep. By the time
you get to Australia, you feel you've got a pretty
good sense of who this person is. You've become friends
and exchange contact info even But then their entire family
shows up to meet them at the airport, and immediately
you learn more and some of the assumptions you made

(00:43):
on the plane have to be reevaluated given this new input. Later,
they invite you to a family dinner at their home,
and their story broadens again. The smell of their house,
the taste of their drinking water, the view from their porch,
and the contents of their refrigerator and bookcases speak volumes
about These details reinforce what you thought you already knew,
and some change your mind. At some point your observations

(01:05):
become not about the person themselves, but about the whole
system in which they live. In order to understand anything,
it's helpful to understand everything, or as much as you
possibly can. In the study of ecology, the concept of
an ecosystem acknowledges the fact that, as the nineteenth century
naturalist John Muir said, when we try to pick out

(01:26):
anything by itself, we find it hitched to everything else
in the universe. But it's difficult to look at everything
at once, and natural systems, of all the things we
can investigate with science, are particularly hard to nail down,
but ecologists are always trying. In five and English botanist
named Arthur Tansley, strongly influenced by Danish botanist Eugenie's Varming,

(01:48):
introduced the term ecosystem in a paper titled The Use
and Abuse of Vegetal Concepts and Terms that was published
in the journal Ecology. He defined an ecosystem as the
whole system included not only the organism complex, but also
the whole complex of physical factors forming what we call
the environment. What Tansley was trying to get at was

(02:09):
the idea that you can look at a natural system
at a bunch of different levels, and that there was
one level that didn't have a name yet. For instance,
you could look at a wolverine that's a single organism,
just like the person you met on the plane, but
that wolverine doesn't live in a vacuum. It lives in
a population of other wolverines that interact and organize themselves
in specific ways. Thus, an ecologist can choose to investigate

(02:31):
wolverines at a population level, but that's not the only
way to study wolverines. Ecologists also talk about communities of
living things. A wolverine doesn't just interact with members of
its own species. It's an omnivore, so it eats other
animals like moose and rabbit, as well as berries, roots,
and eggs. It gets parasites, It digs burrows that affect
roots systems of plants. A wolverine influences lots of living

(02:55):
things in its home territory, and those living things affect
it tans. These definition of ecosystem acknowledged that there was
a level of scientific inquiry that could encompass all the
living organisms in the wolverines home. In addition, to the
stuff that's not alive. We spoke with Stephen Carpenter, a
scientist in the Center for Limnology at the University of

(03:15):
Wisconsin Madison. He said the ecosystem concept ecologists now use
has been refined since it was first introduced by Tansley
almost a century ago. Ecosystem science studies the interactions of
all the living and non living entities in a specified place.
This definition is consistent with modern concepts of energy, nutrient flow,
and biogeochemistry, which barely existed during Tansley's career. The allure

(03:41):
of the ecosystem to scientists has to do with the
system part of the word. If you look at an
ecosystem like you'd look at a computer, then an ecosystem
like a coral reef runs very similar software to that
of an arctic tundra where the wolverine lives, or to
that of a tropical forest, meaning that the same base
large scale processes can apply anywhere organic matter decomposes and

(04:05):
becomes nourishment for something else. In a grassland or a
mountain stream, nutrients like carbon, phosphorus, nitrogen, and sulfur get
passed around like monopoly money everywhere. It just happens a
lot faster, and there's a lot more of it in
say a tropical rainforest than in most deserts. Diseases are
carried along on water or air or by hapless organisms

(04:25):
in similar ways, and wherever you look, if a top
predator is removed from the ecosystem, the entire dynamic changes,
be it on a mountaintop in the Andes or in
Yellowstone National Park in Wyoming. This is to say ecosystems
are a good topic for theory, as a framework for
hanging ideas about how complex natural systems work. But while

(04:48):
being a theoretical idea, an ecosystem is also an actual thing.
It's just a thing without clear boundaries. According to Eugene
Odom's Fundamentals of Ecology, first wished in three you know
you've identified the edge of an ecosystem when more material
and energy is cycling within the boundary than crossing over it.

(05:09):
So a riffle and a stream cannot be an ecosystem
because all those certain types of fish and aquatic invertebrates
like to live in a fast, shallow section of a stream.
Abundant material is flowing into and out of the riffle
all the time. Some might stay in it for a while,
but most of it leaves pretty soon after it arrives.
Even the sediment and rocks don't stay forever. When they move,

(05:31):
it's mostly not inside the riffle, but into or out
of it. On the other hand, watersheds are classic ecosystem boundaries,
but they're extremely tricky as well. The river itself is
an ecosystem because although a lot of material and energy
passes in and out of it all the time, leaves
and soil and dead animals fall in. Terrestrial animals use

(05:52):
the river as a grocery store, et cetera. A lot
of cycling within it too, So although the river in
itself can be considered an eaty system, it's difficult to
view the river and the dry land around it is
truly separate, since material and energy are being exchanged across
the literally fluid boundary all the time in both directions.
Rivers flood after all, and deposit nutrient rich sediment on

(06:15):
the land. Ecosystems then are not static. We also spoke
with Kathleen Weathers, and ecologist at the Carey Institute of
Ecosystem Studies. She said the a biotic and biotic are
essential parts of the ecosystem, and they have boundaries, albeit
human defined boundaries. And not only do ecosystems have structure

(06:36):
and function, but these are controlled by many factors and
that ecosystems change throughout time. Today's episode was written by
Jescelin Shields and produced by Tyler Claying. Brain Stuff is
a production of I Heart Radio's How Stuff Works. For
more in this and lots of other topics, visit our
home planet, how stuff Works dot com and for more

(06:58):
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