Science Friday - Herbicides Approved For Public Land | Hidden Physics In Van Gogh’s ‘The Starry Night’

Episode Date: October 3, 2024

This summer, the Bureau of Land Management approved seven herbicides to fight invasive plants in the West. Also, when scientists analyzed the swirls in the famous painting, they found Van Gogh depicted forces of nature with startling accuracy.What Newly Approved Herbicides Could Mean For Federal LandInvasive plants are a big problem across the western US.Cunning interlopers like cheatgrass, leafy spurge and red brome can outcompete native vegetation, crowd habitats and steal water and other vital soil nutrients.Of the 245 million acres controlled by the Bureau of Land Management, harmful non-native plants have already infested 79 million acres—an area larger than the states of Pennsylvania, Virginia and South Carolina combined. That’s why the federal agency felt the urgency to approve seven new herbicides to kill invasives on its land nationwide, said Seth Flanigan, a BLM senior invasive species specialist based in Idaho.“If we don’t remove this now, what is it going to look like 10 years from now?” he said.Read the rest of this article on sciencefriday.com.The Hidden Physics In Van Gogh’s ‘The Starry Night’One of Vincent Van Gogh’s most famous creations is “The Starry Night,” an oil painting of a quaint French village at night with a blue night sky that dramatically swirls around the yellow stars and moon.It’s easy to admire this painting as a casual viewer, but if you research fluid dynamics, one thing in particular stands out: those iconic swirls in the sky. To a physicist, they look an awful lot like the swirls that atmospheric turbulence produces. And some researchers have been wondering if Van Gogh’s swirls actually match the mathematical models of turbulence theory.Well, a team of researchers from China and France set out to analyze all the swirls in “The Starry Night,” and it turns out that Van Gogh had a knack for depicting the forces of nature. Their results were published in the journal Physics Of Fluid.Guest host Anna Rothschild sits down with Dr. Francois Schmitt, research professor in physics at the French National Centre for Scientific Research and co-author of the recent study, to talk about the hidden physics in this famous painting.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

What's the Bureau of Land Management going to do about invasive species on public lands? If we don't remove this now, what is it going to look like 10 years from now? It's Thursday, October 3rd, and you're listening to Science Friday. I'm Cyfry producer Dee Petershmet. The Bureau of Land Management has a big job, maintain 245 million acres of public land, and protect the wildlife that lives there. But invasive plants are holding back some of these efforts. And BLM recently approved the use of seven new herbicides to kill these invasive species on public land.

That's been controversial among some groups that say these herbicides could do the opposite of what they hope, damaging native wildlife. Guess how Santa Rothschild has that story. And then after that, we'll talk about the surprising physics hidden in one of Van Gogh's most famous paintings. Joining us to talk about this story is my guest, David Condos, Southern Utah reporter for public radio station K. U-E-R, based in St. George, Utah. David, welcome back to Science Friday. Oh, thank you, Anna. Glad to be here. Okay, David, so give us a bit of context here. How many acres of land might be sprayed with these herbicides and in which states? Yes. So when you're talking about the Western U.S., there is just a ton of federal land all over the place.

So the Bureau of Land Management, like you said, has those 245 million acres. And, you know, some of the states that have the most are, you know, like Alaska. Nevada, Utah, but there's also a lot of BLM land in places like California and Colorado, too. And when it comes to invasives, the BLM says it deals with these harmful non-native plants on about 79 million of those acres. And just to kind of give you some sense of scale for this, the 79 million acres would be bigger than the states of Pennsylvania, Virginia, and South Carolina combined. And so it's a lot. It's a lot. Yeah, the West is really big. And, you know, of course, that doesn't mean that all of those acres would be treated with herbicides necessarily. But, you know, just when you're talking about the amount of land that is dealing with this problem, yeah, it's huge. Okay. And so what are the specific invasive plants that BLM is so worried about? Yeah. So in my area, annual grasses like cheat grass and red brough are a big concern in other parts of the West.

it might be flowering plants like leafy spurge. But, you know, across all of them, you know, one thing these invasives have in common is that they are really prolific. And so they, you know, produce tons of seeds. They grow really quickly and can just take over a landscape. And, you know, that is what worries people like Seth Flanagan. He's an invasive species specialist with the BLM. If we don't remove this now, what is it going to look like 10 years from now? So there's this kind of sense of urgency that they need to do something now to prevent this from getting out of control.

So what are the herbicides that BLM has approved? Yeah, so there are seven of them. And you'll have to bear with me on these pronunciations because these are not words that I say every day. Okay, so here we go. So you have clephetidim, endaziflam, orzalin, aminocyclo pyroperichlor, fluazifop pebutyl, flumeoxicin, and amazimox. And bibbidi-bobbidi-boo. Yeah, yeah.

So they're a bit of a mouthful. But, you know, the BLM told me that there are so many on this list because they have different specialties. You know, some are for grasses, some are for shrubs. And they can also be applied in different ways. You know, one might be sprayed like from a truck or a backpack or, you know, others might be spread on the ground as powder. And they sort of target different types of plants, too.

That's the idea, yeah. Yeah. So if these herbicides are targeting different invasive plants, how do we know that they're not going to harm the native plant life in Utah? Yeah. So that's the real trick, right? Because, you know, these invasive plants are not on an island. They're, you know, right next to these native plants that you want to protect. And so, you know, the BLM believes that they can be effective in that way.

But other folks say it might not be foolproof. And so I talked with Dr. Kara Nelson, who directs the ecology restoration. lab at the University of Montana. And she's actually done a lot of research about this exact thing, about invasives and herbicides. And one was a greenhouse study that looked at, you know, what happened when you plant 10 species of native plants into soil treated with herbicides? And what we found, which was surprising, was that all of the species we tested had almost no germination when seeded into herbicide soil. And so with that, means is that in that study, the herbicides were hurting the native plant seeds just as much as the

invasives. And I should mention, you know, the two herbicides in that study were not the ones on this BLM list, but that's still, you know, maybe a sign for concern. Okay. So switching gears here for a moment, you spoke to some folks who work in tortoise conservation and they're particularly worried about these herbicides. What did they tell you? Yeah. So in southwest Utah, where I live, this is kind of the northern edge of the Mojave Desert. So, you know, threatened desert tortoises are just a big topic of conversation here all the time. You know, conservationists are already concerned that there's pressures that these tortoises face from development and habitat loss. And now on top of that, some are concerned about these inherent risks that come from bringing chemicals onto their landscape, you know,

essentially what's going to happen if a tortoise eats plants that have herbicide on them. And so I talked with Judy Homan, who's a board member with the Desert Tortoise Council. And she says, Because, you know, it's complicated because invasive plants aren't great. Like, they really hurt tortoise habitat too. But she says removing them still needs to be done in the right way. We're glad that they're moving forward with trying to come up with more tools in their toolbox to deal with invasive plants. But in the council's opinion, BLM could be doing more. We don't understand why they aren't doing more.

And by more, she means just other things the agency could also do. do to fight invasives. So she's concerned that some land managers may rely too heavily on just herbicides rather than using, you know, additional tactics. And specifically, she would like to see more prevention. So like requiring people to clean potential seeds off of their livestock or vehicles before they even go onto BLM land. Oh, gotcha. So, so like preventing the spread of, of these invasives into BLM land. Gotcha. That's right. What are some of the other tactics that you mentioned, that can maybe get rid of these plants without spraying the herbicides. Yeah. So one is just manually removing them. And so this is really easy to visualize. This is, you know, hand pulling

weeds. This is something a lot of listeners have probably done. This is something you can do in your yard or your town on a small scale. And, you know, this can actually be effective for for species like cheatgrass. But, you know, when you're talking about millions of acres, there are obvious limitations to that. But then, you know, another option that came up in my reporting, was, you know, why don't we just let sheep do the work for us? I mean, yeah, why have we thought of that? And so that University of Montana researcher, Karen Nelson, has studied that exact thing. And here's how it worked.

So these sheep were trained to eat specific invasive plants ahead of time. And then they were brought onto this land that had a bunch of those plants. And then they just did their thing. I mean, they're going to eat, right? Like, they don't realize that they're helping with weeds. They're just hungry. And so Nelson, the researcher, says that actually ended up being pretty effective. Like her study showed the sheep were overwhelmingly eating the invasives that they were trained to eat compared to the native plants next to them.

And the key to all of this, she says, was to keep moving the sheep around because, you know, once they'd eaten mostly invasives, then they would start eating more native plants. Perfect. It's like natural lawnmowers. Exactly. Yeah. It's called biological controls. And sometimes it can work. So have we seen herbicide application at this scale before?

Yeah. So this is not a new thing. I mean, even before these new herbicides got approved by the BLM, that agency already had 21 other herbicides on the list that it could use. And so that agency had been using herbicides for decades. Other federal agencies have as well. And Nelson, that researcher, actually did a study on this, trying to kind of quantify it. And the best they could do is they estimated around 1.2 million acres of U.S. public land were treated with herbicides in the year 2010. So, you know, quite a bit. Like, are those herbicides are already out there. But, you know, ultimately, Nelson said, you know, no matter what method people use to fight invasive plants, there really needs to be a change of the mindset behind that. Like it can't just be about getting rid of something bad. You also have to think about restoring something good.

Right. Yeah, preserving what's already there. And that's actually her second clip, if you want to play it. If you're just focusing on removing the weed, without consideration of what you need to do to rebuild that native plant community, you could be successful at removing that weed. But what you could end up with is secondary invasion by another weed. And that's because if you pull out cheekgrass, for example, it creates these empty niches in the land. that will be filled by something. And so she said seeding those areas with native plants might be just as vital as removing invasives.

Right, right. Because if you don't, then something else is just going to come in and fill that gap. Exactly. Yeah. These invasives are sneaky. Right. So what happens next? When might we actually see these herbicides in use?

Yeah. And that's an important note because, you know, just because this national BLM approval happened, that doesn't mean these herbicides are going to be used immediately. So the agency told me that each local land office would still need to do like environmental impact study, you know, public comment period, before these chemicals hit the ground. So, you know, residents will still get another chance to weigh in on this before it gets used in their area. Right. Well, that's all the time we have for now. And I'd like to thank my guest, David Condos, Southern Utah Reporter for Public Radio Station, KUER, based in St. George, Utah.

David, thank you so much for joining us. Thank you, Anna. And if you want to read more about this story, go to sciencefriady.com slash herbicide. We're going to turn to one of Vincent Van Gogh's most famous creations, starry night. You might already be seeing it in your head, an oil painting of a quaint French village with a blue night sky that dramatically swirls around the yellow stars and moon.

It's easy to admire this painting as a casual viewer, But if you research fluid dynamics, one thing in particular stands out. Those iconic swirls in the sky, to a physicist, they look an awful lot like the swirl's atmospheric turbulence produces. While a team of researchers from China and France set out to analyze all the swirls in Starry Night to see if they match the mathematical models of turbulence theory, it turns out that Van Gogh had a knack for depicting the forces of nature. Here to tell us about the hidden physics in this famous painting is my guest, Dr. Francois Schmit, research professor in physics at the French National Center for Scientific Research. He was part of that research team, and their results were published in the journal Physics of Fluids.

Dr. Schmidt, welcome to Science Friday. Hello. So there's been some debate about the swirling in the painting in physics circles for years now. And it revolves around something called Kolmogorov's law, which predicts how the atmosphere swirls and forms eddies. Did you find that Starry Night lines up with what the law predicts? Yes, exactly. The result of our study was to find that Kolmogorov law was quite nicely followed by the eddies and the swirls

that were in the painting of Van Gogh. There was a debate. in the community about this painting and to know if it follows Colmogorff Law and the Therl and the Edis are following this law. What we have done differently, simply to take into account all the eddies

in the painting. So there are 14 eddies in the painting and previous studies have considering only a part of this painting with only five eddies. So the main different for us was to consider all the eddies. Right. So we know that Van Gogh spent a lot of time in nature, painting nature. And I guess the big question here was, was he so good at observing nature that even some of the elements in his paintings actually mirrored like the atmospheric turbulence on a mathematical level?

Yes, exactly. Of course, he did not know any mathematics. And Colmogromo flow was found much later. But still he was able with his artistic eye to reproduce. in fact, some of the properties of turbulence. Let's talk a little bit about that. So, you know, for the lay audience, what exactly are we talking about when we say atmospheric turbulence? Yeah, turbulence in physics, in fluid mechanics, it's used to describe chaotic motion, and it applies to ocean, it applies to the atmosphere,

and in fact, also to the clouds. So how did you go about trying to figure out if the painting actually matches the fluid mechanics? The first step was to remove in the painting all that was not atmosphere. So there is a village, there is a landscape. So all this was removed, and then only the atmospheric part was kept. And then the color information was transformed into a luminance information. And then we used a very high resolution image, and we analyzed it as a numerical quantity.

Cool. So basically you sort of like equated the brightness of the colors and the paintings with energy and you measured the shapes and sizes of the brush strokes. And when you plugged that data into an algorithm, it's sort of aligned with the types of swirls and eddies we see naturally in the atmosphere. Yes, exactly. It's a statistical analysis. So in fact, globally, not each eddy follows the turbulence, but globally the statistics of the eddies correspond to this colmongoro flow. It's so incredible. Were you surprised that the swirls did sort of follow these atmospheric models? It was very surprising because in the same analysis, we see two laws of turbulence. One is this Kolmogorov flow for the eddies, for the swirls. And the other one is the effect of the oil mixing in the painting, which is called the bachelor law. So we see both laws in the same analysis, and we were really surprised by seeing this. Does this give you an even greater appreciation for Van Gogh as an artist after doing this research?

Yes, definitely, because turbulence is something which is very complex. In fact, it obeys some equation that still are not solved mathematically. It's a subjective impression, and hidden mass is something which is more objective. But what we have tried to do here is to have a mixture between the subjectivity and objectivity. So it's a meeting of art and science. Do you have any thoughts about why Van Gogh might have in particular been able to see the world in this way? Perhaps he had some other way to see the world because you know that he was a little, how to say, perturbed. So perhaps we can say he had another conscience level.

Perhaps he gave him some abilities to do what he has done. Yes, he lived a very turbulent life, so maybe it allowed him to see the turbulence in the atmosphere as well. Yeah, exactly. I think it's a good way to make the link between the two. Well, thank you so much for speaking with me. This research is fascinating. Thanks a lot. Dr. Francois Schmidt, research professor in physics at the French National Center for Scientific Research. That's all the time we have for today. Lots of folks help make the show possible, including... Sandy Roberts.

Robin Casmer. Jordan Smudjik Charles Bergquist George Harper On tomorrow's episode We'll round out the top news and science this week I'm SciFright producer D. Peter Schmidt See you then