“Paradise island teeming with life”: New data reveals New Guinea has the highest plant diversity of any island in the world

Release date: 5 August 2020

  • Unique global collaboration sees Kew join forces with experts in 19 countries to compile first ever checklist of all New Guinea’s plants
  • They found the world’s largest tropical island has 16% more plants than biodiversity hotspot Madagascar, with over 13,000 species
  • Scientists hope new checklist will accelerate botanical research and inform conservation policy and planning
New Guinea is one of the few places left where the rainforest is unbroken as far as the eye can see (Tamrau Mountains, West Papua, Indonesia)
Tamrau Mountains, West Papua, Indonesia © RBG Kew

New research, published today in leading journal Nature, lists for the first time all of the plants in New Guinea, the world’s largest tropical island.

This unique list, compiled by 99 botanists from 56 institutions across 19 countries, is the first attempt to extensively document the island’s incredible plant diversity. The authors, from organisations including the Royal Botanic Gardens, Kew, the Natural History Museum, the Royal Botanic Garden, Edinburgh, and the Papua New Guinea University of Technology found there to be 13,634 species of plants from 1742 genera and 264 families, positioning New Guinea as the most floristically diverse island in the world.

This new number means that New Guinea has more plant diversity than well-known biodiversity hotspot Madagascar (16%), which has 11,488 species recorded. Of the checklist, the authors also found 68% (9,301) of the plants in New Guinea to be endemic to the island, meaning more than two thirds of its plants cannot be found anywhere else. This makes New Guinea the only island in the South East Asian archipelago with more endemic than non-endemic species and is unmatched in tropical Asia. This uniqueness, scientists believe, could be explained by its greater land surface area and habitat diversity, its location marking the junction between South East Asia, Australia and the Pacific, and by having one of the world’s most complex tectonic histories.

New Guinea has fascinated naturalists for centuries. It is home to some of the best-preserved ecosystems on the planet – from mangroves to huge expanses of lowland rainforest to alpine grasslands unmatched elsewhere in the Asia-Pacific region. Botanists have been identifying and naming plants collected in New Guinea since the 17th century, storing the samples in plant collections in herbaria in Papua New Guinea, Indonesia, the Netherlands, and the UK. However, despite notable advances in the past decades in resolving the taxonomy of many New Guinea plants, publications reman scattered, as botanists worked mostly independently from each other. Lacking a unifying effort to build a checklist to the region’s plants, great uncertainty remained as to how many plant species grew in New Guinea. Effectively, compared to other areas like the Amazon which has had plant checklists recently published, New Guinea remained the ‘one of the last unknowns for science’.

Dr Rodrigo Cámara-Leret, lead author and post-doc researcher at the University of Zurich and formerly at the Royal Botanic Gardens, Kew says: “New Guinea is extraordinary: it is a paradise island teeming with life. As the second largest island in the world after Greenland and the world’s largest tropical island, it supports a mosaic of ecosystems and is globally recognised as a centre of biological diversity. However, despite this, knowledge on New Guinea’s flora has remained scattered for years, limiting research in this megadiverse area. Our paper set out to address this.”

In order to solve this great uncertainty around the number of plants known to science on the island, which ranged from 9,000 – 25,000, the 99 botanists verified the identity of over 23,000 plant names from over 704,000 specimens in a large-scale collaborative effort.

They found that New Guinea contains almost three times the vascular plant species of Java (4,598) and 1.4 times the vascular plant species of the Philippines (9,432), the only two large South East Asian island regions with published Floras. Orchids accounted for 20% of the flora in Papua New Guinea and 17% of Indonesian New Guinea, comparable to that in megadiverse countries such as Ecuador (23%) and Colombia (15%) and tree species accounted for 29% of all the flora – by comparison, the Amazon had 2.6 times more trees, but in an area 6.4 times larger.

What next for New Guinea’s plants?

The scientists hope this expert-vetted checklist for New Guinea will be invaluable for conservation planning in the future. The world’s indicator of species’ status the IUCN Red List of Threatened Species requires accepted plant names and geographic distributions to make their conservation assessments, which includes modelling the impact of changes in climate and land use on plants. This data, which can be used by IUCN, will help to ensure the safety of the island’s flora.

The checklist will also hopefully facilitate the discovery and characterisation of even more new species on the island. The current collecting effort is still low, while land use change is an increasing threat to the biodiversity, so more botanical exploration is urgently needed so unknown species can be collected before they disappear. Since 1970, 2,812 new species have been published from New Guinea and the authors estimate that in 50 years, up to 4,000 species will be added to the list.

By making this checklist available globally, the authors hope that efforts will be scaled up to train the next generation of native plant taxonomists for the area, to digitise and unify historical collections around the world, and to find long-term financial support to accelerate research.

Dr Tim Utteridge, Head of Identification & Naming at the Royal Botanic Gardens, Kew said: “I have been working in Indonesia for over 20 years and have always been fascinated by the beautiful and bountiful biodiversity of New Guinea. Whilst this checklist is a step in the right direction, we all now have a unique responsibility for the survival of this irreplaceable biodiversity.”

Dr Sandra Knapp, Senior Research Botanist, Algae and Fungi at the Natural History Museum, said: “This incredible achievement just shows that while there is still much left to discover, if we come together as a global community with united goals and a willingness to share the unique resources we have, we can create a digitally innovative, first of its kind product. This should now serve as a baseline for much more work and discovery in the years to come.”

Dr Peter Wilkie, Head of Sapotaceae Research at the Royal Botanic Garden Edinburgh said: “It is clear, in the context of the biodiversity crisis, that this paper represents a milestone in our understanding of the New Guinea flora and provides a vital platform to accelerate scientific research and conservation. Research at its best is collaborative and this demonstrates what can be achieved when scientists from around the world work together and share expertise and data.”

“This checklist is a great starting point but there are still many species awaiting scientific description. Axel Dalberg Poulsen, a world renowned expert on the Ginger family, who undertakes many fieldtrips in New Guinea, with researchers from the island, sums-up the botanical wonder nicely when he advises us to ‘expect the unexpected.’ Begonia researcher Mark Hughes describes his work with botanists from Lae Botanic Garden as ‘a moving target,’ discovering many new begonia species and with only about 25% of them so far having scientific names. There is still much to be revealed.”


Contact us

For press enquiries or to request an interview, please contact Kew Press Office pr@kew.org or Heather McLeod h.mcleod@kew.org

Notes to Editors

About the research paper

About the Royal Botanic Gardens, Kew

The Royal Botanic Gardens, Kew is a world-famous scientific organisation, internationally respected for its outstanding collections as well as its scientific expertise in plant diversity, conservation and sustainable development in the UK and around the world. Kew Gardens is a major international and a top London visitor attraction. Kew Gardens’ 132 hectares of landscaped gardens, and Wakehurst, Kew’s Wild Botanic Garden, attract over 2.5 million visits every year. Kew Gardens was made a UNESCO World Heritage Site in July 2003 and celebrated its 260th anniversary in 2019. Wakehurst is home to Kew's Millennium Seed Bank, the largest wild plant seed bank in the world. RBG Kew receives approximately one third of its funding from Government through the Department for the Environment, Food and Rural Affairs (Defra) and research councils. Further funding needed to support RBG Kew’s vital work comes from donors, membership and commercial activity including ticket sales.

About the Natural History Museum 

The Natural History Museum is both a world-leading science research centre and the most-visited natural history museum in Europe. With a vision of a future in which both people and the planet thrive, it is uniquely positioned to be a powerful champion for balancing humanity’s needs with those of the natural world.  

It is custodian of one of the world’s most important scientific collections comprising over 80 million specimens. The scale of this collection enables researchers from all over the world to document how species have and continue to respond to environmental changes - which is vital in helping predict what might happen in the future and informing future policies and plans to help the planet.  

The Museum’s 300 scientists continue to represent one of the largest groups in the world studying and enabling research into every aspect of the natural world. Their science is contributing critical data to help the global fight to save the future of the planet from the major threats of climate change and biodiversity loss through to finding solutions such as the sustainable extraction of natural resources. 

The Museum uses its enormous global reach and influence to meet its mission to create advocates for the planet - to inform, inspire and empower everyone to make a difference for nature. We welcome over five million visitors each year; our digital output reaches hundreds of thousands of people in over 200 countries each month and our touring exhibitions have been seen by around 30 million people in the last 10 years.

About the Royal Botanic Garden Edinburgh

The Royal Botanic Garden Edinburgh (RBGE) is a leading international research organisation delivering knowledge, education, and plant conservation action around the world. In Scotland, its four Gardens at Edinburgh, Benmore, Dawyck and Logan attract more than a million visitors each year. It operates as a Non Departmental Public Body established under the National Heritage (Scotland) Act 1985, principally funded by the Scottish Government. It is also a registered charity, managed by a Board of Trustees appointed by Ministers. Its mission is “To explore, conserve and explain the world of plants for a better future.” Learn more: www.rbge.org.uk.