Seed-bearing plants are disappearing at a rate 500 times quicker than would be expected of a natural rate, accounting for nearly 3 species a year since 1990, according to a new report published in the journal Nature.
The research project, which examined over 330,000 species, found that plants on islands and tropics were the most likely to be declared extinct, with trees, shrubs and woody perennials having the highest rate of extinction.
The study, conducted by the University of Stockholm in conjunction with the Royal Botanical Gardens, Kew, analysed a database dating from 2988 to track the status of every known plant species.
Rafaël Govaerts at the Royal Botanic Gardens, Kew, teamed up with plant evolutionary biologist Aelys Humphreys at Stockholm University in Sweden and others to analyse the data. They compared extinction rates across different regions and characteristics such as whether the plants were annuals that regrow from seed each year or perennials that endure year after year.
Together, the researchers found that an estimated 1,234 species had been reported extinct since the publication of Carl Linnaeus’ compendium of plant species, Species Plantarum, in 1753.
A map of plant extinctions produced by the team shows that flora in areas of high biodiversity and burgeoning human populations, such as Madagascar, the Brazilian rainforests, India and South Africa, are most at risk.
Humphreys says that the rates of extinction in the tropics is beyond what researchers expect, even when they account for the increased diversity of species in those habitats. And islands are particularly sensitive because they are likely to contain species found nowhere else in the world and are especially susceptible to environmental changes, says Humphreys.