World Views
1:32 pm
Tue January 7, 2014

Exploring Large-Scale Human Influence On Landscape And Ecology

Erle Ellis investigated nitrogen cycling across an entire village in China under pre-industrial, nitrogen-limiting conditions relative to the nitrogen-saturated conditions of 1994 to assess the role of nitrogen cycling in sustainable agricultural management.
Erle Ellis investigated nitrogen cycling across an entire village in China under pre-industrial, nitrogen-limiting conditions relative to the nitrogen-saturated conditions of 1994 to assess the role of nitrogen cycling in sustainable agricultural management.
Credit Erle Ellis

Over the last three decades, certain environmental scientists have started characterizing a new geological epoch, the Anthropocene, to mark the moment when humans started profoundly affecting ecological landscapes.

University of Maryland, Baltimore County ecologist Erle Ellis studies how agriculture, hunting, settlements, and other human activity have changed landscapes. He estimates three-quarters of earth’s land could be characterized as anthropogenic. But even as humans influence their environment, the mass influx of residents into urban centers can reverse that process.

University of Maryland, Baltimore County ecologist Erle Ellis
University of Maryland, Baltimore County ecologist Erle Ellis
Credit Provided / Erle Ellis

“In the Northeast, for example, we have huge areas of regrowth forest in areas that were agriculture 100 years before,” Ellis says. “This is common also in places like China and Europe. You have more recovery of woodlands and other less-distributed types of vegetation as a result of urbanization.”

Ellis spent four years in the mid-90s studying the nitrogen cycle in China’s rural agricultural villages. Despite digging sediments out of river beds, using nitrogen-fixing green manures, and even purchasing human waste from cities, they were still nitrogen-limited until they started using synthetic nitrogen.

“Their yields went up about two-to-four times…so they were very satisfied with the new system, but it was completely changing their ecology,” Ellis says. “You see big changes in soils, crop yields, and populations – all these things change when you change the nitrogen cycle.”

INTERVIEW HIGHLIGHTS

On why his definition of “anthropogenic” doesn’t include climate change

The reality is that terrestrial ecosystems - ecosystems on land - have been interacting with changing climates for as long as there's been life on land. So that's not really a new thing. The rate of climate change now is novel and unprecedented, most likely. But it's not that unusual for ecosystems to be adapting to changing climates. But some of the other things that humans do to ecosystems on land are fairly novel, such as tillage and the formation of agricultural ecosystems. Human settlement - these are all relatively novel ecosystems.

On minimizing, rather than eliminating, negative human consequences

I see it as guiding human decisions and it's a lot of different decisions that get made. Many different scales. Many different people in the game, but focusing on what are the positive outcomes that we really want to see and how can we engage in making those things actually come true rather than just trying to stop bad humans from destroying the fragile nature. I think that model isn't realistic, and it doesn't really lead toward the outcomes that we want.

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FULL TRANSCRIPT

SUZETTE GRILLOT, HOST: Erle Ellis, welcome to World Views.

ERLE ELLIS: Thank you for having me.

GRILLOT: So Erle, you're doing some very interesting research that investigates the ecology of anthropogenic landscapes, and their changing at local to global scales. What does that mean? Can you tell us a little bit more about what anthropogenic landscape is?

ELLIS: So, in a nutshell, an anthropogenic landscape is a landscape that has been formed by human activity, usually over a significant period of time. So the ecologies of place like this, and I think they're all around us, so we're all familiar with them, are profoundly different than what you'd find before humans start interacting by using agriculture, building settlements, hunting - all sorts of human activities that change the ecologies of landscapes. And as these become more and more extensive across the world, the best estimate I have is about three-quarters of Earth's land is in this category. We are looking at a globally-significant ecological pattern. The anthropogenic landscape is inherently global at this time.

GRILLOT: So obviously the connection between humans and their environment, or the landscape that they're using. So everything from the way in which we alter the landscape to build buildings, to farm, to build homes, to make lawns, all of that is what you're talking about in terms of how we alter the world in which we're living from its natural state to something that is friendly to humans? Or preferable to humans?

ELLIS: Well, sometimes it's preferable to humans. I think that's the intention. Sometimes what we create we're not very fond of. You can imagine some kinds of ecosystems full of invasive species, or species invasions, I should say, that we're not so happy with, that are also caused by us. But the bottom line is you can't really imagine these ecologies occurring without us. They're inherently human ecologies.

GRILLOT: So you're not really talking about things like climate change, or the longer-term result of human interaction with the environment? Or are you? Is that a distant connection to what you're talking about here, in terms of anthropogenic landscapes?

ELLIS: My research focuses primarily on what I would call direct human interaction with landscapes and ecosystems. So that doesn't include climate change, which is an indirect effect. How human alter climate, and then how climate alters ecosystems. And the reality is that terrestrial ecosystems - ecosystems on land - have been interacting with changing climates for as long as there's been life on land. So that's not really a new thing. The rate of climate change now is novel and unprecedented, most likely. But it's not that unusual for ecosystems to be adapting to changing climates. But some of the other things that humans do to ecosystems on land are fairly novel, such as tillage and the formation of agricultural ecosystems. Human settlement - these are all relatively novel ecosystems.

GRILLOT: Particularly in mass quantities, in terms of urbanization, right? So how is that a growing urban world, where people are moving off of that natural landscape into cities, is that something that you're looking at at all? And what is the impact of that, or the implications of urbanization?

ELLIS: Ah, great question. And the most fascinating thing about what urbanization is doing to anthropogenic landscapes, and when we say anthropogenic landscapes, three-quarters of Earth's land could be characterized this way, as being transformed by human activity of one form or another. So it's a majority. Urban areas are actually not very extensive globally. 1-2 percent of Earth's land could be considered to be urban in the form urban settlements. But everyone moving into these very dense settlements away from areas that are less densely-populated - this concentration of people into cities is basically leading to a pretty massive recovery of woodlands in large areas of the world. And I don't know if you have that here in Oklahoma, I haven't studied it here specifically, but in the Northeast, for example, we have huge areas of regrowth forest in areas that were agriculture 100 years before. And this is common also in places like China and Europe. You have more recovery of woodlands and other less-disturbed types of vegetation as a result of urbanization. So some people think of urbanization as consuming everything across the surface of the earth, but in fact, it's actually in some ways the opposite.

GRILLOT: Because it's moved people off of that rural landscape and into cities so that rural landscapes can regenerate, I guess is what you're saying.

ELLIS: More or less. The one complicating factor that's really important is how the farming system responds to that when you have this low-labor-intensity farming, you're basically talking about large-scaled industrial agriculture. And generally in those kinds of farming systems nobody's interested in the marginal land. They only want to use the most productive land, because there's a lot of investment in every acre of land. So for that reason any kind of marginal lands - less ideal for agriculture - just get abandoned. And those are the areas that are recovering. And like I said, they don't always recover in ways that you don't necessarily get back a beautiful, pristine forest. You often get a very different kind of woodland, maybe all exotic species, or very dominated by exotics, that is not necessarily the ideal. But the reality is very different than just having agriculture going on everywhere.

GRILLOT: Maybe not ideal, but different, and recovered. So based on that then, I'm curious. Is the suggestion that we should be working more closely together as humans to understand how we're having an impact on our landscape? And alter our thinking so that we understand that these two things come together? They aren't separable. You can't separate humans from the environment? Or is the goal to try to do our best to have humans make as little impact as possible on their environment? Which is it?

ELLIS: That's a lot of questions there, and I don't know if I'd 100 percent characterize myself as an environmental advocate. I think I am very interested in communicating what I've learned scientifically about the way that ecosystems have been changing, and how humans are changing them, and what the consequences are for humans and for non-human species, and ecologies. I'm very interested in communicating that. I think one very simple message that maybe is nothing new is the idea that we do profoundly alter pretty much all of Earth's ecology now. And we do that whether we choose to do it intentionally, or whether we don't. It's simply a matter of being alive as a human being on Earth right now. We affect the ecology of the planet. And I like the idea that by engaging in that activity more intentionally, now that we know that we're engaging, let's be more cognizant of how we might make that engagement more positive for both humanity and non-human species. In many cases we just don't pay attention to the consequences and then it's not a surprise that the consequences aren't what we want in the end. And I think the good news is that when we really do focus more on the outcomes, we are able to essentially get the same needs met that we need to meet, but with consequences to other aspects of the landscape or ecosystems that are maybe much more positive. It's not inevitable that to use nature we must destroy it.

GRILLOT: So it's not necessarily a matter of humans should just stop messing with the environment, but that we should understand how we're messing with the environment, or how we have an impact on the environment so we can minimize the negative consequences. But it's not a matter of eliminating negative consequences, but minimizing.

ELLIS: Oh absolutely not. I think there's no possibility of eliminating human consequences, so I see it as guiding human decisions and it's a lot of different decisions that get made. Many different scales. Many different people in the game, but focusing on what are the positive outcomes that we really want to see and how can we engage in making those things actually come true rather than just trying to stop bad humans from destroying the fragile nature. I think that model isn't realistic, and it doesn't really lead toward the outcomes that we want.

GRILLOT: So other work that you're doing, also very interesting. You've looked at the long-term changes in nitrogen balance in village ecosystems in China, and changes in the biogeochemistry of carbon, nitrogen, phosphorous, and the landscapes in China. So what it is that you've learned in China? First of all, why China? Why look at these things there? And then what is it that you've learned there that's helpful to our understanding of the anthropogenic landscape more globally?

ELLIS: Well, I first ended up working in China because I was interested in understanding the ecology of agricultural systems that had been productive and sustained populations for thousands of years. In a sense, what does the ecology of sustainable agriculture look like by studying real ecologies? And the problem that I focused on in sustaining long-term productivity was the nitrogen limitations which are endemic to pretty much all terrestrial ecosystems. They’re nitrogen-limited. And agriculture probably the most, because they're getting the most plant materials removed from them. So nitrogen needs to be put in to these systems to keep them productive. So how did they manage to do this? I learned that part of it was extremely hard work recycling whatever they could, but even that isn't enough. They were actually, first of all, in a naturally-subsidized place being in a river floodplain. They were getting inputs of nitrogen from sediments they actually made the use of. They actually dug them out of the canals and put them on land. They even purchased inputs of nitrogen from soybean cake that was pressed from places from other areas. They purchased human manure from cities. It was remarkable. They did everything they possibly could to bring nitrogen. They used nitrogen-fixing green manures. Plants grown just for fertilizer that fixed nitrogen naturally. So they did all these things, but the bottom line is they still have a pretty profoundly nitrogen-limited agriculture. The other thing I found is that they had stopped doing all those traditional things because they now had synthetic nitrogen. So with the advent of synthetic nitrogen, their whole relationship with all those resources that they were using changed because it was so much easier to use synthetic nitrogen. Their yields went up by about two-to-four times.

GRILLOT: So you mean chemical-based fertilizers when you talk about synthetic nitrogen? That you would sprinkle across the ground?

ELLIS: That's right. And it was liberating for people who had to do some of the hardest physical labor you'll ever imagine. You're carrying sediments in buckets out of canals without any mechanical help. It's incredibly hard work. So they were very satisfied with the new system, but it was completely changing their ecology, and that's where I got interested in the long-term global changes caused by changes like the availability of chemical fertilizer. How does that affect the rest of the planet? And it does. You see big changes in soils, crop yields, and populations...all these things change when you change the nitrogen cycle.

GRILLOT: So ultimately then, looking at how we use our land, and whether we do it organically, or the ways in which we grow our crops, the day-to-day interaction that we have with our environment as humans, has led you and others to understand, for lack of a better term, the geological, chronological term that we're coming to some new era? Are we in a new era...call it an Anthropocene, something that is a whole different way of thinking about human and geological history, right? Can you tell us in the last minute that we have what would the next stage be? It seems like that would be the end, right? That human environmental interaction, that's it.

ELLIS: Well, in a nutshell, this concept that by transforming many of Earth's systems and the one that gets the most attention, and maybe it should, is the climate system being transformed by emissions of greenhouse gasses from burning fossil fuels. But it's also been transformed by use of synthetic fertilizer. Now, humans synthesize more nitrogen than all other natural systems on Earth. We have actually change the nitrogen cycle more than we've changed the carbon cycle. There's a host of other things we've transformed about the Earth's systems. The idea that as a result of this huge transformation of the Earth's systems we now have pushed the planet into a new geological time period - the Anthropocene - a new geological epoch characterized by human transformation of the Earth's system as a new paradigm for looking at the human role on the planet, and essentially what the prospects are. There are many ways of looking at that. Some view it as, like you said, the end of times. The Apocalypse, because now we've changed everything permanently. But I look at it from the geological point-of-view that epochs are very long periods of time, and we're likely to be here for thousands of years. This is maybe just the beginning of the Anthropocene, and that's the way I like to think about it. And it's not to say that everything we've done so far has been an improvement or to our own benefit or to the benefit of the planet, but the idea that it's a long-term process, and that we're going to be actively engaged in it for at least the foreseeable future.

GRILLOT: Well, sounds very interesting. Erle Ellis, thank you for sharing this with us and we'll have a lot more to talk about, it seems to me, in the future.

ELLIS: Thank you very much.

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