For the first time ever, scientists at the Royal Botanic Gardens, Kew and Stockholm University, have compiled a global analysis of all plant extinction records documented from across the world. This unique data-set brings together data from fieldwork, literature and herbarium specimens, to show how many plant species have gone extinct in the last 250 years. It outlines what they are, where they have disappeared from, and what lessons we can learn to stop future extinction.
The study found that 571 plant species have disappeared in the last two and a half centuries. This figure was calculated after one of the authors of the study, Kew scientist Rafaël Govaerts, reviewed all publications on plant extinctions over more than three decades and found the number to be four times more than the current listing of extinct plants. This new number is also more than twice the number of birds, mammals and amphibians recorded as extinct (a combined total of 217 species).
Reviewing these data, the scientists found that plant extinction is occurring much faster than ‘natural’ background rates of extinction (the normal rate of loss in earth’s history before human intervention), as much as 500 times faster. Animals are also disappearing much faster than background rates, at least 1000 times faster. The authors of the study believe these numbers underestimate the true levels of ongoing plant extinction.
The scientists found the highest rates of plant extinction to be on islands, in the tropics and in areas with a Mediterranean climate. Also in typical biodiverse regions which are home to many unique species vulnerable to human activities. Authors Humphreys, Govaerts, Ficinski, Nic Lughadha and Vorontsova also found that plant species that are woody (such as trees and shrubs) and with a small geographical range (such as those confined to small islands) are more likely to be reported as extinct. These results suggest that the increase in plant extinction rate could be due to the same factors that are documented as threats to many surviving plants: fragmentation and destruction of native vegetation resulting in the reduction or loss of habitat of many range-restricted species.
The information gathered from this analysis will be fundamental to help predict and prevent future extinction. Researchers at Kew and Stockholm University hope these data will be used to focus conservation efforts on islands and in the tropics, where plant loss is common, and in areas where less is known about plant extinction such as Africa and South America.
A positive from the paper’s analysis, was the evidence that 430 species once considered extinct have gone on to be rediscovered. Rediscovery of a species thought to be extinct often means finding a few surviving individuals only, and 90% of rediscovered plants still have a high extinction risk.