Instant Genius - Why are the world's plants disappearing – and can we save them?

Episode Date: October 30, 2023

In October, Kew Gardens released a report inspired by a dream of Charles Darwin’s. Described as the most comprehensive plant database ever produced, the State of the World’s Plants and Fungi 2023 report not only details the discoveries of over 18,000 new plant and fungi species since 2020 – but also the fact that many of these are already threatened with extinction. We spoke to one of the scientists behind the report – Dr Matilda Brown, conservation science analyst at RGB Kew – to learn more about why plants are disappearing all over the world and what we can do to save them. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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It's about quality. British audio experts name audio, alongside French acoustic specialist focal, combine handcrafted tradition with cutting edge innovation and high-end materials, delivering digital precision with analog warmth. So you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. Welcome to Instant Genius, a bite-sized masterclass in podcast form. I'm Noah Leach, news editor at BBC Science Focus magazine. In October, Q Gardens released a report inspired by a dream of Charles Darwin's. It's described as the most comprehensive plant database ever produced, and it not only details the discoveries of over 18,000 new plant and fungi species since 2020, but also the fact that many of these species are already

threatened with extinction. We spoke to one of the scientists behind the report, Dr. Matilda Brown, who's a conservation science analyst at Q. We talked about why plants are disappearing all over the world and what we can do to stop it before it's too late. So Matilda, Q recently released the State of the World's Plants and Fungy 2023 report. Please could you explain to us what the report found and what's happening with the world's plants? Yeah, thanks, Noah. So the report provides a global health check on the world's plants and fungi.

It gives us an idea. I mean, on one level, it does what it says on the tin, is it gives us this state of the world's plants and fungi. And where my work is focused is in plant extinction risk. And our contributions to this report are in two kind of big. scary numbers. The first is we found that 45% or nearly half of all flowering plants are threatened with extinction using new modelling. And the second is that we found that of the species we don't yet know about, of the species we're going to describe in the next years and decades, over three

quarters of those 77% are already threatened with extinction before we even know about them. For fungi, it's even trickier because it's harder to get that big picture of extinction risk because we've only described, I think this estimate puts us at around 10% of fungal diversity that we've got sort of species names for, and of those, less than 1% have conservation assessments. So it's not looking good for plants more broadly, but it's even harder to get the idea of what the picture is for fungi. Those are pretty damning figures. So let's dive straight in at the deep end.

What would the world even look like without plants and fungi? A world without plants and fungi is a world without humans. Plants and fungi, sort of by extension, underpin all aspects of humanity. They're what we eat, they're what we wear, they're what we get our medicines from. We know that nine out of ten of our medicines come from plants. And so they're responsible for the air that we breathe. So when we're talking about losing this amount of plant diversity, we're talking about losing an enormous amount of potential future opportunities.

So the medicines are an interesting one because the kind of plants that you see every day, the ones that are really widespread and common, are not as likely to be the ones that are threatened because, you know, by definition, they're the ones that we see. They're the ones that are widespread in common. It's those ones that are maybe more in places of the world that we don't know as well. They have more constricted geographic ranges, so they're confined to a smaller area. But they're also the ones that we tend to know the least about. So they're the ones that have this kind of greatest potential. And an example of this is a species that's described really recently, so in 2022. It's a species called Veparis Onani, and it's a medium-sized tree from the citrus family, so related to like your oranges and lemons, and it's found in the cloud forests of Cameroon. Its classified is endangered because of habitat loss. And even though we've only known about it for a year, we're already looking at its potential antimicrobial properties. So it's a great example of where these things that we are only just finding, out about have these potential untapped benefits to humanity.

So what medicines do we currently use that we perhaps are all familiar with that have already come from plants? So a really nice example is I'm not going to use the, I'm not a biochemist, I'm not going to attempt the drug names, but some of the drugs that we use to treat leukemia and Hodgkin's lymphoma, so cancer drugs come from Catharanthus Rosaeus or the Madagascar periwinkle, which is a gorgeous little pink flower, but I mean, you'd walk right past it. It's this sort of unassuming little plant that is endemic to Madagascar, but now that we know about its uses, has grown much more widely and is, I think the current estimates are putting it in the sort of tens of thousands of lives that the drugs derived from

this one plant have saved. So what about fungi? How do we currently use it? And what could we lose there? Yeah. So, I mean, we could talk about the medicinal uses of fungi. And one of the really exciting things is that they tend to be really, really potent, much more potent in terms of the sort of amount of active compounds than we get in plants. And so, I mean, we know about things like penicillin. It's kind of a classic example, but also things like our cholesterol medication, lovastatin comes from fungi. And we're just starting to explore now some of the other uses of fungi beyond, you know, the sort of culinary uses, but the uses of mycelium as like a building material are starting to be really exciting.

a bioremediator because we know that some fungi can actually digest plastics. I mean, the kind of uses of fungi is a really exciting frontier of science. Almost everything we eat also contains some kind of plant matter. So losing that would be an obvious direct threat to human existence. Yes. So there's a really fun, when you're talking about plants we eat in every meal, I think there's a fun, it's linked to the American tradition of Thanksgiving, but I've seen it on the internet of plants giving,

which is where people sit down at their dinner and they identify all the different species. And it's unreal. The vegetables, you're kind of surprised. You might have your broccoli. But it's when you get into all your herbs and your spices, that the number just goes way up and you realize that you can be sitting down to a meal

with that 20 plant species. And that's before we even get onto the beverages. And things like our tea and our coffee are obviously coming from plants. And some work that's come out of Q has found that actually Coffier-Arabica, which is the wild, well, it is the coffee species that we use, but it's also found in the wild, and it is endangered. So this species, it's a really interesting one from an extinction risk perspective in that

it's one of the few species we know that there's a risk from climate change because we know enough about coffee. It's so well documented that we can look at its whole range and look at the risk of climate change. And we found that, yeah, it's very seriously at risk in the wild from climate change. So why are these species actually threatened? This is a huge event that we're talking about, so there must be a big cause behind it, surely. The biggest threat to plants is habitat loss. I sort of pause before I say that because it is the biggest and most immediate documented threat.

It's for us working in extinction risk, it's something that we can look at on satellite imagery. we can see that the land has changed from intact rainforest through to agricultural land. And so when we're looking at a species range, it's much easier to document. And so that comes out overwhelmingly as the largest threat to plants. There are some other threats like over-collection for useful species and climate change is certainly on the horizon,

but it's a lot harder to document because to get an estimate of climate change, we really have to have enough information about a species to then look at it under different climate scenarios and look at what proportion of its range is going to be lost. And so for something like coffee, we can do that. But, I mean, we're looking at a third of a million odd species. It's just not going to be possible to look at each species individually.

We don't have enough information about the full ecological and geographic range of each species to then kind of model that individually. So habitat loss is the big one, that is immediate and documented. We're certainly worried about climate change in the future, but it's just a lot harder to put a number on it. And just to be clear, we're talking about habitat loss as a result of human expansion in one way or another. You mentioned agricultural there. Is that right? Yeah, yeah, absolutely. It's the land use conversion and predominantly from native vegetation through to other sources. And the biggest one for that is conversion of native vegetation to agricultural land.

And what about the threats to animal species? How tied to the risk of extinction in the plant and fungi kingdom are those animal threats as well? For example, are the kind of the threats to pollinator species like bees? Is that kind of compounding the loss of plant species? Yeah, so we know that animals, plants, fungi are all working in this kind of ecological web and it's hugely complex. We've got a lot of, I mean, a lot of researchers trying to work out. how all these different components interact, and we're only starting to get into which components interact with each other components of an ecosystem. And so it kind of makes intuitive sense flowing on from that, that habitat loss is the biggest threat to every kingdom. So it's the biggest threat to animals,

the biggest threat to plants, the biggest threat to fungi. And we know that if you want to minimize biodiversity loss, the best way to do that is to reduce that habitat loss, to keep that intact vegetation, to keep these ecosystems functioning. Could you tell us a bit more about the impact of species loss directly on animals and food chains more widely? Yeah, so I guess I'll start from almost the bottom up in this, and I'll start by talking at fungi, because more and more we're realizing how many fungi are interacting with plants,

and they're forming, allowing nutrients in the soil to be digested and sort of taken up by plants. and so we call those ectomycorrhizal fungi. And so the plants are depending on those fungi, but the fungi are depending on the plants because the plants are the host, but the plants are also depending on the fungi. And so we know that without one or other, then those systems are under a great deal of pressure, particularly in the world of orchids, we know that when we're trying to propagate threatened orchids, that we often can't get seeds to germinate and we can't get these orchids to survive, unless we get the fungal partners right as well.

So we need to, even when we're looking at single species and trying to conserve and grow single species, we need to bring the fungal partners with them or these plants can't survive. And then combined, there's obviously things like dispersal and pollination syndromes in forest. So we know that some species of plants have evolved specific fruits to be dispersed by certain animals. And so we know that we've got things like fruits in northeastern Australia that are perfectly suited to be dispersed by casseroys. And so if the casseroys went extinct, then the plant loses its way of dispersing its seeds. And if the plant goes extinct, then the casseroys have one less option in terms of food. And so these things kind of go all tie in together.

And I mean, I've picked on a few examples, but there's, as humans, we know a tiny fraction of these examples, which is why so often when we try and mess with the specific aspects of ecosystems, it goes horribly wrong. So over in the marine conservation world, often when we hear about the loss of fish populations, we're told that they're just going to be replaced by jellyfish. So is there an equivalent in the plant world? So if we remove the diversity of species, are loads of weeds just going to appear in their place? Or would we be looking at a world devoid of any green at all? It really depends on a whole heap of factors, and we're getting sort of really speculated now,

which is quite a fun place scientifically, but it would really depend on how we're losing these species. So if we're talking about a really climatic apocalypse where we've got huge drought events in particular is what comes to mind, that we might have large portions of the world that become uninhabitable for most plants. But if we're looking at habitat loss and then regeneration, we will just see, we'll probably see more of those weedy species. But it really depends on what's left in their place. You know, we're looking at a sort of feel or a pasture that's a monoculture crop. Or are we looking at something that is restored but lacking the species that were there beforehand? And that's where we might get the kind of the weedier ecosystem.

I mean, it's having species poor ecosystems is not necessarily a bad thing. if we look at like boreal forests in the high northern latitudes, the number of species in those ecosystems is way, way lower than we get in the tropics. And there's nothing kind of intrinsically wrong with that. But there's a cost to losing species that is, there's sort of twofold. And there's two kind of main ways that I rationalize it and kind of make sense of it. One is that opportunity cost, and that's the kind of human-centric approach, that we don't know what potential medicines or compounds or uses that we're losing if we lose these species in the wild.

And the second is that each species represents some amount of time of unique evolutionary history. And that could be millions of years or tens of millions of years, or even in some cases we're looking at like even up to 100 million years of evolutionary history, that these plants have been evolving, they've been adapting to their environment. It's irreplaceable, right? Like we can't just bring these plants back from the dead. We can't replicate tens of millions of years of evolution. And so there's that kind of intrinsic idea that we shouldn't be losing species just because they're not important to us, but also they might be.

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Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. Beyond the global, what's some of the local value in some of the species that are imminently threatened? So I'm thinking of the kind of locally scientific or cultural value in, say, indigenous communities or communities to whom some of these species are vital, but to the rest of the world may not be known. Yeah, so we increasingly in kind of Western science getting a handle on the the huge value of traditional knowledge in plants. And I think that's, it's a really complex area to get into because we, we want to go in and we want to, we want to get all this knowledge. We want to pull it all together.

That's what we are as scientists. So we're just knowledge freaks. We just want to pull out all that information. But to engage with communities in like a respectful. and a way that doesn't. So I think things like helicopter science are really challenging things to try and avoid where, and for anyone who's not familiar, that's where scientists kind of helicopter in, take the data, take the samples, and then helicopter back out and don't engage,

you'll give back to the community that in many cases will have known about these plants for a lot longer. So as an Australian, the kind of examples that spring to mind are a lot of the cultural knowledge held by Aboriginal Australians, which is, I mean, we're looking at 60,000 years of accumulated knowledge. And because of what Europeans have done in the country, there's, it's really, a lot of that knowledge has been lost, essentially. And there's, there's a lot, I think there's a lot that we have to do in that space in order to, to learn respectfully as well as, as well as kind of getting to share and open up some of the benefits if that's what the local communities are open to. So we're talking about threats to existence, but you are speaking as if this has

already started. So how far down the line of the kind of threats to extinction to actual extinction are we talking in terms of the global plant species populations? Again, this is another question that is really, it's something that we're working on to say, okay, well, something's threatened. what are the chances of it actually going extinct and what timeframe are we looking at there? And I know that there's some research in the works that's starting to put numbers on this, but the real obstacle to this is that it's really hard to document extinctions, particularly for plants because we often don't know where every individual is. It's not like an animal population where you might have seen critically endangered animal populations

and we've got collars on a good part of the populations, and we've kind of got a sense of where all the individuals are at any way. one point in time. For plants, it's a lot harder to go into a forest and say, okay, well, this species was here. I can't find it now. But is that just because I wasn't looking very hard? Is that because it wasn't in flower and I needed the flowers to identify it? Is that because it is, there's only juvenile plants and they look different to the adults? Is that because there's currently no mature adults, but it's in the seed bank. So give it a couple of years and it'll come back, especially after disturbance.

So documenting plant extinction risk is really, really hard. There's a couple places where we can do it, and that's things like islands. And there's an example recently that a member of our team was able to document the extinction of the Everglades orchid, Gavania, Floridiana, basically by doing repeated surveys and really showing that this entire range of this orchid

where it used to be, it's no longer there, and we've looked really hard. So without that kind of data on actual extinctions, and we do have some data. So we know that extinctions are happening more now than they were, is double the rate than they were before 1900. But to get it down into the finer range and to say, okay, well, if this species is endangered, if nothing happens, we think that it will be extinct in X years. That's a really hard question.

And it's much harder than you might sort of initially think of looking at these statistics have threatened. And so what we're looking at is really it's a threat level rather than necessarily a prediction. And it's a warning and a prioritisation tool that if we do nothing, which species are most likely to go extinct first in the future versus those that are likely to be able to hang on. So do we have time to fix this and how might we be able to go about doing that? We know that if we want to bend the curve of biodiversity loss, we need to act now. There are some things that we know we've already lost that we won't be able to get back, but that doesn't mean that we shouldn't be acting now to preserve as much biodiversity as we can.

We know that conserving ecosystems, because habitat loss is the biggest threat to all species, we know that preserving ecosystems is the best way to maximize that biodiversity into the future. By preserving an ecosystem, we're looking at all of the species within it that we're know about as well as the ones that we don't yet know about. And we know from this report the three quarters of the plants that we don't yet know about are already threatened with extinction. It's also much cheaper to do conservation on that landscape level. You know, we can look at species specific interventions and in the tropical nursery here at Q Gardens. We've got some amazing examples of where horticulture have brought back species from the brink of extinction.

There's the Café Maron, which was, we had to break the pollination, because it was down to one single individual. And so the horticulture that's were able to break that system to bring this plant back from the brink and we've now got some plants back in the ecosystem. But I mean, that's like life support, right? Like these plants that are only, that are not left in the wild on intensive care. And I mean, ask anyone in healthcare, you don't even need to be in healthcare, right, to know that that's not how we should be managing our systems, that it's not cost effective

and it's not ideal to be having everyone who's a little bit sick on intensive care. We want to be doing things like public health initiatives. We want to be keeping people, plants, fungi, animals, healthy and safe out in the world where they're supposed to be. Obviously, Q is responsible for the Millennium Seed Bank and there are other seed banks around the world. Could we use those as solutions to this problem or part of that, that wider solution? or even alternative specimens. Yes, seed banking is absolutely a part of the solution. But the problem is that it can't be the whole solution.

So we know that we can preserve the seeds of lots and lots of species. And I'm not going to try and remember the number in the Millennium Seed Bank off the top of my head because I'll get it wrong and my colleagues will destroy me for it. But there are some species that we can't bank the seeds for. So it's definitely part of the solution, but it's not everything. So we know that species in the ERACE family, there are aerodes. You just can't bank the seeds. They decay or they rot.

And so there needs to be other methods of ex situ conservation, as well as the in situ, ideally. And what about the evolution of new species? Is that kind of natural replacement rate out of kilter as a result of habitat loss? Yeah. So there's some, there's definitely, you know, evolution is ongoing, right? It's not a static, it's not a static thing that's done up until now. But in a human time frame, it kind of is. So when we're talking about the evolution of new species, there are some groups of plants that are really rapidly diversifying. And in general, the shorter your lifespan, the more likely you are to be able to speciate in a sort of more human rather than geological time frame. But for the most part, If we're talking about replenishing lost biodiversity, we're talking about tens or hundreds of millions of years. So, I mean, we look at something like orchids, and the results of this report show that orchids date back 83 million years.

So that's well and truly the first orchids were around when T-Rex was stomping around. So when we're looking at replenishing biodiversity through natural evolution and new species, eventually that would happen. but it's not going to help us as humans. So this report led to, I believe, a kind of international declaration of sorts. Could you explain to us what that means? So where the report's been left and what the next steps are? Yeah, so the report brings together over 200 scientists from 30 different countries. And we want it to be more than just a nice booklet with some beautiful pictures in it

and some amazing science, obviously. We had a symposium on the state of the world's plants and fungi, and one of the goals of that symposium was to begin drafting a declaration about the importance of describing new species and about tackling some of the gaps in our knowledge of plants and fungi. It's been described as the most comprehensive plant database ever produced. So what did it take to produce this report? You mentioned that there were the 200 scientists involved. So could you talk a bit more about the kind of mechanics behind that? The science in the report, and particularly the plant science, has been made possible because of a fulfillment of a dream that Charles Darwin had back in the 19th century. So he wanted, understandably, a list of all of the species of plants and where they lived.

And it sounds like a really simple request, right? But it was in the 1980s that Rafael Kavaretz, he was a student in Belgium at Belgium at the time, he realized that we still didn't have this list. And so he spent the next 35 years working on compiling these lists and with a huge team of collaborators, but certainly a project that he's led, which has now given us the world checklist of vascular plants. So vascular plants doesn't include mosses and algae, but includes everything else. So it's a list of all species from the tiniest fern that's squeezed in between two rocks all the way up to the towering eucalypts, the tallest of flowering plants, getting up to 100 metres tall, as well as where they live, so their geographic distribution. And that has led us, for the first time, look at some of these really comprehensive questions in plant science.

So we looked at threatened species, and we know that of all 350,000 vascular plant species, less than. than 20% have got a documented extinction risk assessment on things like the IUCN Red List. But there's enough because we're now, you know, even 20% is still 60,000 assessments. And they're all sort of miniature peer-reviewed publications. They've been meticulously assembled, reviewed and published. And so we can use that data set to look at what threatened species have in common, use that to build a model that predicts extinction risk, and then generate extinction risk predictions across all of the species that don't have documented extinction risk assessments.

And that's the first time that we've been able to do this, because we've looked at predicting other groups or smaller subsets before, but without the world checklist, there's a lot of species missing. And did you find new species in the process of building the report? Yeah, so since the last state of the world's plants and fungi report in 2020, we've described 8,500 new species of plants and over 10,000 new species of fungi. Do you have any particular favourites in the new species that have been described? I mean, it's really hard to go past the big water lily, Victoria Boliviana. It's just such a monster, right? This enormous big water lily.

But also, I think some of the fungal species are really exciting. I think living in London, it's really exciting to me that we could find a new fungal species just outside Heathrow. That's cordonarius, Heather. I think that's so, it just tells us where we're at in terms of our fungal description that we can be finding things in the outskirts, one of the biggest cities in the world. Finally, Matilda, I just wanted to ask whether there is anything that we can do to help slow species loss as individuals. There's things that we can do at all levels. So at the highest levels, we can make sure that we're preserving intact ecosystems as much as we can. At an individual level, we can try to reduce the amount of pressure we're putting on

those ecosystems. So we can look at bringing down our resource use, looking at consuming products that are responsibly sourced and not driving and contributing to that deforestation. But, I mean, if you're listening to this and you're finding the stats as intriguing as they are terrifying. Check out the report. We've barely kind of scratched the surface of all the science that's in there. Check out some of the work in plant and fungal science that we're doing here at Kew Gardens. And if you're looking for a new career, it might even spark a career in plant and fungal science where you can come and try to be part of the solution. You've been listening to Conservation Science analyst Dr. Matilda Brown, talking about Kew Gardens,

State of the World's Plant and Fungy 2023 report released in October. Thank you for listening to this episode of Instant Genius, brought to you by the team behind BBC Science Focus magazine. By the latest issue of science focus in store or visit us at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music

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