However, since researchers have worked mostly independently from each other, a great uncertainty remains as to the exact number of plant species, with conflicting estimates ranging from 9,000 to 25,000. "Compared to other areas like Amazonia, for which plant checklists were recently published, New Guinea remained the 'Last Unknown'," says Rodrigo Cámara-Leret, a postdoctoral researcher in the lab of Prof. Jordi Bascompte in the UZH Department of Evolutionary Biology and Environmental Studies. Under his lead, 99 scientists from 56 institutions and 19 countries have now built the first expert-verified checklist for the 13,634 vascular plant species of New Guinea and its surrounding islands.

Merging databases and human knowledge

The researchers began their large-scale collaborative effort by compiling a list of plant names from online catalogues, institutional repositories and datasets curated by taxonomists. After standardizing the scientific names, 99 experts on New Guinea flora checked almost 25,000 species names derived from over 700,000 individual specimens. For this, they reviewed the list of original names in their plant family of expertise and assessed whether these names were correctly assigned in the online platforms. Finally, an independent comparison was performed between the list accepted by experts and a list contained in Plants of the World Online for New Guinea.

Tremendous, mostly endemic plant diversity

The resulting checklist contains 13,634 plants, demonstrating that New Guinea has the world's richest island flora ? with about 20% more species than Madagascar or Borneo. By far the most species-rich family are the orchids and almost a third of the species are trees. One particularly remarkable finding is that 68% of the plants are endemic ? they are only found in the region. "Such high endemic species richness is unmatched in tropical Asia," says Cámara-Leret, "It means that Indonesia and Papua New Guinea, the two states into which the island is divided, have a unique responsibility for the survival of this irreplaceable biodiversity."

Foundation for research and protection

The new authoritative checklist will improve the accuracy of biogeographic and ecological studies, help focus DNA sequencing on species-rich groups with high endemism, and facilitate the discovery of more species by taxonomists. Thousands of specimens remain unidentified in the collections and many unknown species have yet to be discovered in the wild. "We estimate that in the next 50 years, 3,000 to 4,000 species will be added," says Michael Kessler, co-author of the study and scientific curator of the Botanical Garden of the University of Zurich. These efforts will be important for conservation planning and modelling the impact of changes in climate and land use.

The collaboration also underscores that expert knowledge is still essential in the digital era ? reliance on online platforms alone would have erroneously inflated species counts by one fifth. However, many of the New Guinea plants experts are already or soon to be retired, and almost half of them are non-residents. The researchers therefore advocate building a critical mass of resident plant taxonomists.

Policy-wise, the study shows that long-term institutional and financial support is critical if significant advances are to be made over the next decades. "Our work demonstrates that international collaborative efforts using verified digital data can rapidly synthesize biodiversity information. This can serve as a model for accelerating research in other hyper-diverse areas such as Borneo," says Cámara-Leret. "Such initiatives pave the way for the grand challenge of conserving the richest island flora of the world."

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Journal Reference:

1. Rodrigo Cámara-Leret, David G. Frodin, Frits Adema, Christiane Anderson, Marc S. Appelhans, George Argent, Susana Arias Guerrero, Peter Ashton, William J. Baker, Anders S. Barfod, David Barrington, Renata Borosova, Gemma L. C. Bramley, Marie Briggs, Sven Buerki, Daniel Cahen, Martin W. Callmander, Martin Cheek, Cheng-Wei Chen, Barry J. Conn, Mark J. E. Coode, Iain Darbyshire, Sally Dawson, John Dransfield, Clare Drinkell, Brigitta Duyfjes, Atsushi Ebihara, Zacky Ezedin, Long-Fei Fu, Osia Gideon, Deden Girmansyah, Rafaël Govaerts, Helen Fortune-Hopkins, Gustavo Hassemer, Alistair Hay, Charlie D. Heatubun, D. J. Nicholas Hind, Peter Hoch, Peter Homot, Peter Hovenkamp, Mark Hughes, Matthew Jebb, Laura Jennings, Tiberius Jimbo, Michael Kessler, Ruth Kiew, Sandra Knapp, Penniel Lamei, Marcus Lehnert, Gwilym P. Lewis, Hans Peter Linder, Stuart Lindsay, Yee Wen Low, Eve Lucas, Jeffrey P. Mancera, Alexandre K. Monro, Alison Moore, David J. Middleton, Hidetoshi Nagamasu, Mark F. Newman, Eimear Nic Lughadha, Pablo H. A. Melo, Daniel J. Ohlsen, Caroline M. Pannell, Barbara Parris, Laura Pearce, Darin S. Penneys, Leon R. Perrie, Peter Petoe, Axel Dalberg Poulsen, Ghillean T. Prance, J. Peter Quakenbush, Niels Raes, Michele Rodda, Zachary S. Rogers, André Schuiteman, Pedro Schwartsburd, Robert W. Scotland, Mark P. Simmons, David A. Simpson, Peter Stevens, Michael Sundue, Weston Testo, Anna Trias-Blasi, Ian Turner, Timothy Utteridge, Lesley Walsingham, Bruce L. Webber, Ran Wei, George D. Weiblen, Maximilian Weigend, Peter Weston, Willem de Wilde, Peter Wilkie, Christine M. Wilmot-Dear, Hannah P. Wilson, John R. I. Wood, Li-Bing Zhang, Peter C. van Welzen. New Guinea has the world’s richest island flora. Nature, 2020; DOI: 10.1038/s41586-020-2549-5