Not to be outdone: New Guinea is the island with the greatest diversity of plants in the world. An international team has detected almost 14,000 different plant species there – that’s 20 percent more than, for example, in Madagascar. In addition, there are a particularly large number of endemic plants that only grow there, as the researchers report. But they suspect that their balance sheet is far from complete.
With an area of 786,000 square kilometers, New Guinea is around twenty times the size of Switzerland – making it the largest tropical island in the world. The diversity of its ecosystems ranges from the lowland jungle to the high-lying grasslands and sets further records: New Guinea has the largest tropical forest in Australasia, the richest coral reefs in the world and the richest biodiversity outside of the Amazon. Although the western part of the island is not yet fully explored, botanists have long known that the wilderness of New Guinea is home to many plant species. They have been collecting, naming and archiving thousands of plants there since the 17th century.
Record title for New Guinea
Today’s researchers have made use of this: A team of 99 scientists from 19 different countries has for the first time carried out an inventory of all vascular plants in New Guinea. To do this, the botanists working with Rodrigo Cámara-Leret from the University of Zurich evaluated the plant descriptions and names listed in online catalogs and other data collections. Experts for the flora of New Guinea then examined the 25,000 species names that resulted from 700,000 individual plant specimens. For this purpose, the original lists of names of the respective plant families were compared with the names on the online platforms.
The evaluations resulted in a list of 13,634 plant species that occur in New Guinea. This means that New Guinea’s island flora is around 20 percent richer than that of islands such as Madagascar or Borneo, as the researchers report. It has thus earned the title of the island with the world’s greatest diversity of plants. By far the most species-rich family are the orchids, they make up around 20 percent of the species. Almost a third of the list are trees. It is particularly noteworthy that 68 percent of the plants are endemic – they are exclusively native to the island. “Such a high endemic biodiversity is unsurpassed in tropical Asia,” says Cámara-Leret.
Help for future surveys
According to the scientists, the new checklist could greatly improve the accuracy of biogeographical and ecological studies. In addition, this would enable DNA sequencing to be focused on species-rich, highly endemic groups and also facilitate the discovery of other species. Thousands of unidentified specimens are in the collections and there are still unknown species to be discovered in the field. “We estimate that 3,000 to 4,000 species will be added in the next fifty years,” says co-author Michael Kessler of the Royal Botanic Gardens in Kew.
The challenge will be to preserve this rich island flora in the future. “The two states Indonesia and Papua New Guinea, to which the island of New Guinea belongs, bear great responsibility for the survival of this irreplaceable biodiversity,” says Cámara-Leret. But help from international initiatives is also necessary. Research in places like New Guinea aims to facilitate the protection of endemic species and the discovery of new plant species. The work is also important in order to better assess the effects of climate change and land use.
Source: University of Zurich, Royal Botanic Gardens; Technical article: Nature, doi: 10.1038 / s41586-020-2549-5