This island’s dazzling flora makes it the most plant-diverse on the planet

New Guinea’s biggest exports include coffee, cocoa and palm oil. And gold – there’s so much in the ground there that it’s home to the world’s largest gold mine.

But the island, the second biggest in the world and shared by the countries of Indonesia and Papua New Guinea, also boasts glittering biodiversity with untold ecological value.

With its mosaic of well-preserved mangroves, rainforest and alpine grasslands, it’s fascinated naturalists for years.

In fact, ever since the 17th century there have been efforts to catalogue its plants. Because researchers had mostly worked independently, though, they had struggled to put a figure on just how many species actually grow there.

So recently almost 100 botanists from across the world, in collaboration with institutions including London’s Natural History Museum; the Royal Botanic Gardens, Kew; and the Papua New Guinea University of technology, set about finding out.

‘Irreplaceable biodiversity’

Previous estimates of the number of known plants on the island ranged from 9,000 to 25,000.

To refine this figure, the researchers compiled a list of plant names from online sources and biologists' data sets. Then, 99 experts on New Guinea's plants verified more than 23,000 species names taken from over 700,000 original specimens.

As a result, the researchers found New Guinea has 13,634 species of plants from 1,742 genera and 264 families.

What do those numbers mean? In short, they’ve shot New Guinea to the island plant-diversity top spot, with 19% more plant diversity than the previous incumbent, Madagascar.

What’s more, the authors of the list, published in the journal Nature, found that 68% of the plants in New Guinea are endemic – they can’t be found anywhere else on Earth. This could be explained, they say, by its large surface area, its location between South-East Asia, Australia and the Pacific, and its complex tectonic history.

This richness of endemic species means that Indonesia and Papua New Guinea are uniquely responsible for the survival of this “irreplaceable biodiversity”, the Nature paper says.

Critical moment

Protecting this kind of biodiversity is vitally important to human health, economies and livelihoods.

It’s essential to foods, jobs and medicine, and more than half of the world’s GDP is highly or moderately dependent on nature, according to the World Economic Forum's Nature Risk Rising Report. Biodiversity loss is named among the top five risks facing the planet in the Forum’s Global Risks Report.

That we’re at a critical moment is undeniable. Human activity, such as the way we produce food and consume energy, has led to the decline of two-thirds of the world’s wildlife in just four decades, a new report from the WWF warns.

Extinction: The Facts, a recent documentary presented by the renowned UK naturalist Sir David Attenborough, included the fact that one in four of the plants assessed in the UN’s 2019 global study of biodiversity are at risk of extinction.

And the newly published fifth edition of the UN’s Global Biodiversity Outlook finds that none of the 20 Aichi Biodiversity Targets, set out in 2010, have been reached. Only six are deemed to have been “partially achieved”.

But experts say it’s not too late to safeguard our ecosystems if we make the right decisions now. And it’s proven that actions taken on the back of such decisions get results.

A recent study, for example, found that conservation projects have saved up to 48 bird and mammal species from extinction since 1993, when a global agreement to protect biodiversity was signed.

All of which means the meticulous work of researchers such as those documenting New Guinea’s plant life has never been more important.