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© Frank

interviews

The Anthropocene with Peter Del Tredici

by Peter Del Tredici
May 21, 2018
This interview with Peter Del Tredici was conducted and condensed by frank news. Peter Del Tredici holds a BA degree in Zoology from the University of California, Berkeley, a MA degree in Biology from the University of Oregon, and a Ph.D. in Biology from Boston University. He's worked at the Arnold Arboretum of for 35 years as Plant Propagator, Curator of the Larz Anderson Bonsai Collection, Editor of Arnoldia, Director of Living Collections and Senior Research Scientist. Dr. Del Tredici taught in the Landscape Architecture Department at the Harvard Graduate School of Design from 1992 through 2016 and is currently teaching courses on Urban Ecology at MIT.
PeterPortraitFrank

What can planners learn from the natural environment?

Cities are built for people, first and foremost. We welcome nature to the extent that it fits with the human agenda. We want nature to be a certain way. If it's too weedy, or if it's a problem, we don't want that kind of nature. We only want certain things. There's this conflict built into cities with the human agenda versus the natural agenda. What's interesting about nature is, at least in my experience, nature does best when you leave it alone.

Whenever people try to improve nature, or do something for nature, that usually ends up making it worse, or screwing it up in some way.

Our ability to control natural processes is...we don't have a great track record. You can see this in California super easily when you look at the issue of fire. It’s not working. Leaving nature alone works really well, and it's messy. Nature is a messy thing. It doesn't fit with our aesthetic goals particularly. Harmonizing that with the human agenda is not an easy thing to do.

I know from the students who want to promote biodiversity, I say, you want to promote biodiversity? Leave it alone’. You cannot propose that at a design school, or a planning school. You can’t say, do nothing. That’s going to get you a failing grade. You have to propose some kind of intervention.

What I said to students at GSD is, figure out what it is you're trying to accomplish with your design and just design. If you do a good job of that, nature will take care of itself. Nature will come in and be fine.

Trying to consciously design a natural ecosystem is way beyond your capacity, and most people's capacity. It's too complex a system.

You can set the table for nature, and then manage it. Trying to control it doesn't work. Make sure your design is solid and is going to achieve the goals you want as it relates to the people. If you put in enough vegetation and open space, the nature will take care of itself.

Can you talk about Bussey Brook Meadow? How did you approach that?

It really is very complicated. If you have an infinite amount of money you can do whatever you want. Central Park looks the way it does, which is just sensational, because they use a special kind of mulch there. They take dollar bills and shred them and they spread them out two inches thick. That's how you achieve that. Now, if you don't have those resources, then what are your options? Sustainability from a landscape point of view means that you know the landscape design can be maintained with the resources that are available. What are your resources and what can you do? Cities like Boston and New York are prosperous cities. They've got the resources to actually maintain. And maintain is very different from management. Maintain means hold the status quo. Here's the design, and we want to keep this exactly the way it was originally intended. Management is something very different, that allows for future change over time. You are managing it, not to keep it the way it is, but to push it in certain directions. It involves some intervention, but you're not maintaining a fixed design. A lot of these natural areas need management. Nothing is self maintaining.

Maintenance is really a reflection of the socioeconomic condition of the city.

Go to places like Detroit where they have no money. What can you do when you have very little money, and you've got all this open space? How can we manage the landscape to promote biodiversity, but also make it a little more attractive? Maybe you put a little public art in there and you maintain a good path so you focus your subject, keeping the paths open. So we have good sightlines, so people don't have to worry about it. Or certain key elements that make people feel comfortable and wanting to go in there. But beyond that, you don't worry so much about what's happening in the woods around it.

With Bussey Brook Meadow, there was a group of people that really wanted to help with the Arboretum, and had a moral responsibility to turn that into what the rest of the Arboretum looked like. Which was a well maintained landscape with everything in its perfect place.

To me, that had been a derelict site for over 30 years and was just beginning to actually have some ecological value. If you’re going to rip out all of the non-native species, you'll be ripping out three quarters of vegetation.

Which would do more disturbance, would set everything back. Then you'd have to maintain it. I was in charge of the living collections and we didn't have the staff necessary to maintain a site like that, looking the way the rest of the Arboretum looks. So I said no. We will improve the site, but we're going to keep this as an urban wild.

If you ripped out the non native species it’d be three-quarters of the plant population under the guise of sustainability. People think planting native species is the right thing to do, but it isn’t always.

If you think of any urban site where the landscape totally transforms, think about Los Angeles, there's not a shred of any native soil anywhere in that entire city. It's all been either paved over, or compacted, or turned into some fancy landscape. There is no longer any native vegetation.

Nativity really describes a past condition. It doesn't describe the present condition, and it certainly doesn't describe a future condition. This desire to go back to an earlier point in time is a romantic notion that is unattainable.

I don't understand. The world has changed, those plants that used to grow there before Columbus landed, they were adapted to those conditions. Those conditions no longer exist. Not only from a land use point of view, but also from a climatological point of view. The plants that are best adapted to the current condition are not the ones that were growing here 500 years ago.

Endemic plants are not necessarily what’s best to focus on now?

They're not necessarily the best adapted. As soon as you bring in things from Europe, or Asia, that's nature, that's ecology. It’s letting the two of them fight it out. This is the thing about ecology and about evolution, the good guys don't always win. Whoever is the best adapted wins.

I think that's behind why a lot of Americans are uncomfortable with the idea of evolution, because it's not about the good guys winning. It’s just not. It’s about who’s the best adapted.

In terms of moving forward with climate change, that's actually what we need. We need the best adapted species in order to deal with this chaos and this mess that we created.

Can you define the Anthropocene?

It's a geological term and describes the geological time period in which humans have become a dominant driving force in terms of changing the actual surface of the earth. Geology is about describing the surface. In order to have a geological era you have to have a characteristic of rock that defines that era. For the Anthropocene, it's stuff called plastiglomerate.

They found these on beaches in Hawaii and I’m sure down the coast of California. Wherever people build bonfires and burn a lot of plastic trash. The plastic fuses with the sand in intense temperatures and you get this new kind of rock that is some combination of sand and plastic. That has never been found on the planet before. It is actually a geological structure. Plastic is not going anywhere. It’s forever. Plastic is the hallmark, from a geological point of view.

If you look at it broadly speaking, the impact of human population on the face of the earth, we're using over 50% of the total net primary productivity of the planet. The impact is gigantic.

The controversy is, should we start at the dawn of urbanization 2,000 years ago? Or should it be with the Industrial Revolution? Or, does it really come with the advent of the petrochemical? You could argue about when precisely the Anthropocene starts, but it really describes the human dominance of the whole face of the earth.

It implies that we've completely altered, and permanently changed the face of the earth.

Yes, permanently is the operative word.

Yet the controlling of our spaces is coupled with incredibly uncertain times in terms of ecology, and extreme weather events, and climate change. We’ve tried to build a world we can control, but we’re completely unprepared for allowing natural processes back into our practice.

We are now in control of all those natural processes. That's why they're chaotic. They're no longer being managed by people. Whether we know what we're doing or not. And we're dominating all of the processes that regulate life on Earth as we know it. They're all under human influence. That's where the chaos stems from.

What now?

I'm actually an optimist about this because I think first is getting realistic about it. That's why the concept of restoring past ecosystems bothers me. Because that is not a solution to how we move forward. Which isn't to say I don't believe in conservation and the preservation of natural areas. We should definitely do that. But when you come to the urban areas, and the suburban areas, really dominated by human actions, we have to get realistic about what is the best thing to do.

Going back in time is not the solution. Minimizing fossil fuels has got to be number one. Without doing that, nothing is going to have any impact. The question there is, can we do it quickly enough?

And you’re optimistic about that answer?

I'm optimistic about it if we get realistic about it. In other words, where my optimism comes from is this Anthropocene. It is not the end of the world. It's just a different world. The world is going to go on. It's just going to be a radically different world. That's as optimistic as you're going to get from me.

If you can accept the fact that it's different, is not going to be what it used to be, and that's okay, then that’s optimism.

What do you think it’s going to look like?

I spend a lot of time with my classes at Harvard asking, what's the world going to look like 20 years from now? Because this is when you're going to be at the peak of your practice. You need to think about not the way the world looks today, but the way it's going to look in the future. I can only speak about vegetation because that's all I know. The plants are stand ins for human activities. All of these plants represent things.

What's clear to me is that the weeds are winning, and that is not a bad thing. Nature is adapting. We may not like it, but nature is adapting to the conditions we created. And we need to learn to love it. We need to embrace it for what it is.

Just because you don't like it, doesn't mean it's not any good. The idea of calling them all invasive species, and calling for their eradication is wrong. You're actually making it worse, doing more disturbance.

I'm not an advocate of just letting them be. You do need to manage the vegetation, but you should manage it for a specific purpose. A lot of these plants are ugly, and people don't like them, and they're signs dereliction and neglect. I'm not advocating for doing nothing. But management and the criteria by which you evaluate a plant should not be, “was this here when Columbus landed or not?”. When that becomes the standard you use to decide which plant you're going to keep, or what you're going to get rid of, that's the wrong standard. From a design point of view, I think designers need to think hard about what plants to use, and know this idea of “we're only going to plant native vegetation”, is misguided.

What tools can planners use to figure out what will survive and thrive here in 5 years?

What it comes down to is that the focus should shift to ecological functionality. What this is actually accomplishing in terms of the big issues: stormwater management, heat, reducing temperatures, being aesthetically pleasing, improving soil conditions etc. Those should be the standards on which you evaluate performance. Function rather than form, and form being, oh what was here 500 years ago?. Emphasis on function rather than form. Thinking about vegetation. Is this doing the job that needs to be done?

What’s your favorite plant?

I am serially monogamous in my relationship with plants.

So at the moment then.

I spent over 30 years of my life studying the Ginkgo Tree. It's a Chinese tree. It's very iconic. It's the ultimate survivor. It's been on the planet for 50 million years. It’s the most adaptable tree. It can survive virtually anything. I spent a large part of my career studying why it is that this plant still exists. It's quite literally like a dinosaur. It should have gone extinct a long time ago but it didn't. What're the mechanisms it uses to survive?

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I study how trees survive catastrophic disturbance. That's really what I'm focused on, because disturbance is what’s going to mark the future. It's all about disturbance and what's the vegetation that's going to be most resilient in the face of these catastrophic disturbances. Both on the coast and inland as well.