Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey
Speaker 1: brain Stuff Lauren boglebam here. Let's say you meet a
Speaker 1: person on a flight from Boston to Brisbane. The two
Speaker 1: of you are seated next to each other for a
Speaker 1: couple dozen hours, and you talk the entire time about books, politics,
Speaker 1: current events, religion, the weather, et cetera. You hear some
Speaker 1: of their personal stories, observe the way they eat and drink.
Speaker 1: You watch them play a game on their phone, and
Speaker 1: notice that they snore when they sleep. By the time
Speaker 1: you get to Australia, you feel you've got a pretty
Speaker 1: good sense of who this person is. You've become friends
Speaker 1: and exchange contact info even But then their entire family
Speaker 1: shows up to meet them at the airport, and immediately
Speaker 1: you learn more and some of the assumptions you made
Speaker 1: on the plane have to be reevaluated given this new input. Later,
Speaker 1: they invite you to a family dinner at their home,
Speaker 1: and their story broadens again. The smell of their house,
Speaker 1: the taste of their drinking water, the view from their porch,
Speaker 1: and the contents of their refrigerator and bookcases speak volumes
Speaker 1: about These details reinforce what you thought you already knew,
Speaker 1: and some change your mind. At some point your observations
Speaker 1: become not about the person themselves, but about the whole
Speaker 1: system in which they live. In order to understand anything,
Speaker 1: it's helpful to understand everything, or as much as you
Speaker 1: possibly can. In the study of ecology, the concept of
Speaker 1: an ecosystem acknowledges the fact that, as the nineteenth century
Speaker 1: naturalist John Muir said, when we try to pick out
Speaker 1: anything by itself, we find it hitched to everything else
Speaker 1: in the universe. But it's difficult to look at everything
Speaker 1: at once, and natural systems, of all the things we
Speaker 1: can investigate with science, are particularly hard to nail down,
Speaker 1: but ecologists are always trying. In five and English botanist
Speaker 1: named Arthur Tansley, strongly influenced by Danish botanist Eugenie's Varming,
Speaker 1: introduced the term ecosystem in a paper titled The Use
Speaker 1: and Abuse of Vegetal Concepts and Terms that was published
Speaker 1: in the journal Ecology. He defined an ecosystem as the
Speaker 1: whole system included not only the organism complex, but also
Speaker 1: the whole complex of physical factors forming what we call
Speaker 1: the environment. What Tansley was trying to get at was
Speaker 1: the idea that you can look at a natural system
Speaker 1: at a bunch of different levels, and that there was
Speaker 1: one level that didn't have a name yet. For instance,
Speaker 1: you could look at a wolverine that's a single organism,
Speaker 1: just like the person you met on the plane, but
Speaker 1: that wolverine doesn't live in a vacuum. It lives in
Speaker 1: a population of other wolverines that interact and organize themselves
Speaker 1: in specific ways. Thus, an ecologist can choose to investigate
Speaker 1: wolverines at a population level, but that's not the only
Speaker 1: way to study wolverines. Ecologists also talk about communities of
Speaker 1: living things. A wolverine doesn't just interact with members of
Speaker 1: its own species. It's an omnivore, so it eats other
Speaker 1: animals like moose and rabbit, as well as berries, roots,
Speaker 1: and eggs. It gets parasites, It digs burrows that affect
Speaker 1: roots systems of plants. A wolverine influences lots of living
Speaker 1: things in its home territory, and those living things affect
Speaker 1: it tans. These definition of ecosystem acknowledged that there was
Speaker 1: a level of scientific inquiry that could encompass all the
Speaker 1: living organisms in the wolverines home. In addition, to the
Speaker 1: stuff that's not alive. We spoke with Stephen Carpenter, a
Speaker 1: scientist in the Center for Limnology at the University of
Speaker 1: Wisconsin Madison. He said the ecosystem concept ecologists now use
Speaker 1: has been refined since it was first introduced by Tansley
Speaker 1: almost a century ago. Ecosystem science studies the interactions of
Speaker 1: all the living and non living entities in a specified place.
Speaker 1: This definition is consistent with modern concepts of energy, nutrient flow,
Speaker 1: and biogeochemistry, which barely existed during Tansley's career. The allure
Speaker 1: of the ecosystem to scientists has to do with the
Speaker 1: system part of the word. If you look at an
Speaker 1: ecosystem like you'd look at a computer, then an ecosystem
Speaker 1: like a coral reef runs very similar software to that
Speaker 1: of an arctic tundra where the wolverine lives, or to
Speaker 1: that of a tropical forest, meaning that the same base
Speaker 1: large scale processes can apply anywhere organic matter decomposes and
Speaker 1: becomes nourishment for something else. In a grassland or a
Speaker 1: mountain stream, nutrients like carbon, phosphorus, nitrogen, and sulfur get
Speaker 1: passed around like monopoly money everywhere. It just happens a
Speaker 1: lot faster, and there's a lot more of it in
Speaker 1: say a tropical rainforest than in most deserts. Diseases are
Speaker 1: carried along on water or air or by hapless organisms
Speaker 1: in similar ways, and wherever you look, if a top
Speaker 1: predator is removed from the ecosystem, the entire dynamic changes,
Speaker 1: be it on a mountaintop in the Andes or in
Speaker 1: Yellowstone National Park in Wyoming. This is to say ecosystems
Speaker 1: are a good topic for theory, as a framework for
Speaker 1: hanging ideas about how complex natural systems work. But while
Speaker 1: being a theoretical idea, an ecosystem is also an actual thing.
Speaker 1: It's just a thing without clear boundaries. According to Eugene
Speaker 1: Odom's Fundamentals of Ecology, first wished in three you know
Speaker 1: you've identified the edge of an ecosystem when more material
Speaker 1: and energy is cycling within the boundary than crossing over it.
Speaker 1: So a riffle and a stream cannot be an ecosystem
Speaker 1: because all those certain types of fish and aquatic invertebrates
Speaker 1: like to live in a fast, shallow section of a stream.
Speaker 1: Abundant material is flowing into and out of the riffle
Speaker 1: all the time. Some might stay in it for a while,
Speaker 1: but most of it leaves pretty soon after it arrives.
Speaker 1: Even the sediment and rocks don't stay forever. When they move,
Speaker 1: it's mostly not inside the riffle, but into or out
Speaker 1: of it. On the other hand, watersheds are classic ecosystem boundaries,
Speaker 1: but they're extremely tricky as well. The river itself is
Speaker 1: an ecosystem because although a lot of material and energy
Speaker 1: passes in and out of it all the time, leaves
Speaker 1: and soil and dead animals fall in. Terrestrial animals use
Speaker 1: the river as a grocery store, et cetera. A lot
Speaker 1: of cycling within it too, So although the river in
Speaker 1: itself can be considered an eaty system, it's difficult to
Speaker 1: view the river and the dry land around it is
Speaker 1: truly separate, since material and energy are being exchanged across
Speaker 1: the literally fluid boundary all the time in both directions.
Speaker 1: Rivers flood after all, and deposit nutrient rich sediment on
Speaker 1: the land. Ecosystems then are not static. We also spoke
Speaker 1: with Kathleen Weathers, and ecologist at the Carey Institute of
Speaker 1: Ecosystem Studies. She said the a biotic and biotic are
Speaker 1: essential parts of the ecosystem, and they have boundaries, albeit
Speaker 1: human defined boundaries. And not only do ecosystems have structure
Speaker 1: and function, but these are controlled by many factors and
Speaker 1: that ecosystems change throughout time. Today's episode was written by
Speaker 1: Jescelin Shields and produced by Tyler Claying. Brain Stuff is
Speaker 1: a production of I Heart Radio's How Stuff Works. For
Speaker 1: more in this and lots of other topics, visit our
Speaker 1: home planet, how stuff Works dot com and for more
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