Plant Life: the state of the world’s plants

Plant Life: the state of the world’s plants
16 Sep
2016
The world’s first comprehensive report on plant species finds over one fifth at risk of extinction

Steven Bachman flips the pages of a report with intent, landing on a spread that reads 2,034 plant species were discovered last year. This seems like good news, but his sharp exhale says otherwise: ‘The scary thing for me is that 2,000 is also the number of plants we put on the Red List every year. So we’re not even gaining anything. We're just about breaking even.’

We are sitting at a table in the Royal Botanical Gardens at Kew. Nearby, elderly couples stoop over nodding flowers, toddlers trundle over grass and their parents, on sighting the visitor’s café, amble a little quicker. Bachman, however, is a researcher from the by-appointment-only side of Kew: the herbariums, labs and collections at its outer edges.Though he is surrounded by botanists, Bachman comes from the more technical background of Geographic Information Systems and conservation, he gets his kicks from plant distribution maps and big data.

‘Kew has had to expand its conservation elements,’ he says, ‘because extinction rates have become a real threat to biodiversity.’ In other words, extinction rates are pulling up the green rug from beneath them. ‘At the moment we are finding plants as fast as we are losing them. If we just focus on documenting them, by the time we are finished so much would already be gone.’

The report in his hands is Kew’s State of the World’s Plants, a document he helped coordinate. By pulling together the knowledge of more than 80 scientists, it declares there are now 391,000 species of plant known to science and aims to raise their profile. It needs to show how one in five of them is threatened with extinction.

SOTWP

GREEN SCREEN

What do plants mean for us? Two major blockbuster films explored this question in recent years. Christopher Nolan’s Interstellar showed the world on the brink of a plant apocalypse, a futuristic dustbowl in breadbasket America, where all but okra and corn has ceased to grow. Meanwhile, Ridley Scott’s The Martian devoted a full half-hour of its running time to Matt-Damon-as-botanist growing potatoes on Mars.

Our real-life relationship with plants is less of a plot device and more the green background that we have grown accustomed to. For most people, it starts with whatever hot drink they have in the morning: coffee, cocoa or a thousand kinds of tea. ‘It’s probably because plants are so ubiquitous that we have lost sight of them,’ says Bachman, sipping his own coffee. The report found that 5,538 species are used for food, 11,365 for materials and 17,810 for medicines. The numbers are big and irrefutable – we need them.

Nonetheless, plant extinctions rarely feature in news. ‘If there is an IUCN Red List update, you’ll rarely see plants on there,’ says Bachman. ‘You might see an individual rare species of orchid that has changed status, but never an overall idea of where plants stand with extinction.’

That’s because there are many plant species missing from the Red List, particularly the healthy ones. ‘While it is a comprehensive list of all species of mammals, birds and fish – including the ones with healthy populations – it has a tiny five per cent of all plants,’ explains Bachman. The simple reason for this is because there are so many plants. 391,000 is a daunting target compared to the 10,000 bird species and 5,500 mammals.

‘Those that are on the Red List are generally the endangered species, because we are worried about them,’ says Bachman. Thus, unfortunately, any averages from listed plants give a biased impression that most of them are doomed. Such a data gap gives conservation efforts something Bachman refers to as ‘green blindness’ – vital habitat and food plants can end up being overlooked as a sort of green matrix in which animals occur, instead of as a complex, crucial system unto themselves.

To avoid the bias pitfalls, Kew’s one in five figure was taken from a random sample of 7,000 Red List plants. It was first presented in Ngoya, Japan at the annual Convention on Global Biodiversity back in 2010. ‘It was a depressing situation,’ says Bachman describing the scene. ‘Country after country stood up to admit that they had failed to deliver on what had been ground-breaking targets to tackle biodiversity loss set in 1992.’ The upside was that his team at Kew, alongside the Natural History Museum and the IUCN managed to deliver this statistic. It was the most accurate figure put to plant extinction risk to date.

‘It drew a line in the sand,’ says Bachman, ‘and, eerily, it mirrored the extinction risks we were seeing in mammals and bird species, but that meant we were on the right track.’ From this data, we now know that plants are as threatened as mammals, more threatened than birds, but less threatened than amphibians. In conservation terms, it gave botanists something to work with. More recently, the State of the World’s Plants report has allowed the figure to re-emerge in the public eye and it has since become one of the strongest stories to come from the botanical gardens. ‘And we’re going to keep coming back to it,’ says Bachman, ‘we can show how that figure trends over time.’

PlantsMangrove forests suffered the greatest loss in vegetation productivity during the course of a single decade

UNUSUAL SUSPECTS

For once, climate change is not the main problem here. While warmer temperatures, altering rainfall patterns and increased CO2 are challenging plants, their current threats are much more immediate and physical – they come down to land-use. ‘For plants, a closer problem is clear cutting for agriculture, logging and residential development,’ says Bachman. ‘Basically, anything that involves going in and drastically altering an existing ecosystem.’

In fact, agriculture is the biggest threat, taking responsibility for 31 per cent of plant extinction risks, followed by biological resource use (logging and extraction) at 21.3 per cent, then residential and commercial development at 12.8 per cent. The remaining third is made up of natural systems modification (such as dams), invasive species, climate change, energy production and mining, pollution, transportation and finally geological events. ‘We expect these proportions to change,’ says Bachman, ‘particularly climate and invasive diseases. These two will probably exacerbate the harm continued to be caused by agriculture, resource use and development.’

SOTWP Figure19Threats to plants (Image: SOTWP report)

Because the data is based on a random sample of plants, it’s hard to pinpoint exactly where and what plants have hit dire straits. What can be observed is the significant changes to biomes over the last few years. By looking at satellite data, the team determined that mangroves and tropical forests experienced the largest land cover change between 2001 and 2012. In a decade, they also suffered the greatest loss in vegetation productivity. Agriculture, again, is thought to be the main culprit. ‘For tropical forests it’s conversion into monocultures such as oil palm and soya crops, for mangroves it’s conversion into shrimp farms,’ explains Bachman.

The pressure presents a moral grey area for crops that are touted for their efficiency and potential biofuel source. It also brings a degree of hypocrisy. ‘Green fields and hedgerows are perceived as natural and pastoral in more developed countries where most of the native woodland was converted long ago,’ says Bachman, ‘whereas those recent herringbone clear cuts provoke a very emotional response when they happen in the tropics.’

Jennifer Mark, a PhD candidate at the University of Bournemouth who contributed to the report, is particularly concerned with how these land conversions are impacting timber species. ‘While all plant extinctions are concerning, trees of a certain height support the growth around them,’ she says. Like the pillars of timber upholding the city of Venice, large tree species uphold whole forest ecosystems. As they grow, they create weather systems of their own, niches for other species to latch on to and cover for them to thrive. ‘Loss of habitat is the main concern for many smaller plant species and taking out the trees compromises the whole.’

The report found that deforestation rates are accelerating in Indonesia, Malaysia, Paraguay, Zambia and Angola over the past 12 years. However, at the same time deforestation rates have declined in Brazil as increasing amounts of primary tropical forests have been awarded conservation status. ‘How timber species are doing depends on where you look,’ says Mark, ‘because there’s overall clear cutting of trees en masse as well as selective harvesting. Such legal harvest can be sustainable or unsustainable, depending on the management.’ Illegal harvesting takes its own toll when high-profile trees such as rosewoods, mahoganies and ebonies are systematically felled and sold for a hefty price on the black market.

Kew Gardens

THE KNOWLEDGE GAP

For Mark, more data is needed to compile the first global tree assessment. For Bachman, more data means a more accurate IUCN Red List. ‘That’s why we are doing all this,’ he emphasises, ‘so that we are equipped to prioritise species that support other life, or ones that are particularly endangered.’ But for conservation scientists everywhere, addressing the knowledge gap around the 391,000 species is going to be the biggest challenge.

At our table in Kew, Bachman nods towards a crowd tilting backwards from a selfie stick. ‘The spread of technology has enormous potential,’ he says. While humans present problems for plants across the planet, armed with smartphones they could be the eyes and ears for new dawn of data collection. Already, new nature apps such as iSPOT and iNaturalist – a sort of Pokemon Go for real species – connects faraway explorers with experts. Phones could make a citizen scientist of everyone.

There will surely be teething issues with these. Varying geographic coverage could introduce biases and participators will need to know for certain what species they are documenting, but in the long run mobile tech could unlock a wealth of data about plants. ‘We have limited resources and can’t monitor everything at once,’ says Mark. ‘Citizen science could shorten the time it takes to compile assessments on a national, or international scale.’

But conservation is a two-way street. Just as the citizen is encouraged to engage in plant data, so is the botanist’s world opening up to the public. In a revolutionary move back in 2013, Matthew Hansen from the University of Maryland, used satellite data to publish beautiful, high resolution images of changes to global forest cover. ‘The accessibility of the so-called “Hansen data” and the maps they can create have really changed the game,’ says Mark. ‘Before, if you worked in forestry management or education and didn’t have access to these databases it would be hard to know the state of forests. Now, with online platforms like Global Forest Watch, you can practically watch them in real time.’

The louder back and forth will hopefully bring more voices and awareness into the mix. ‘Here you could walk around Kew and not know that one in five species are at risk,’ says Bachman. ‘We have to open up that conversation to a wider audience. It is in our best interest.’

This was published in the September 2016 edition of Geographical magazine.

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