Researchers have found that nearly 600 plant extinctions have taken place over the last two and a half centuries, according to a new paper published in Nature Ecology and Evolution.

The 571 proven plant extinctions lost since 1753 is twice the number of animal species lost in the same time frame and nearly four times as many plants lost as botanists recently estimated. The researchers with the Royal Botanic Gardens in the UK and Stockholm University also noted that many plant species disappeared without anyone ever knowing about them, pushing the true number of extinctions much higher.

The extinction rate — 500 times greater now than before the Industrial Revolution — is also quite alarming, according to The Guardian. This number, too, is likely an underestimate.

"This study is the first time we have an overview of what plants have already become extinct, where they have disappeared from and how quickly this is happening," said Aelys Humphreys, Ph.D., of Stockholm University, the BBC reported.

The paper documented all known plant extinctions in the world, finding that most lost plants were in the tropics and on islands. The researchers created a map that showed South Africa, Australia, Brazil, India, Madagascar and Hawaii as particular hotspots for plant extinction, according to The Guardian.

So what's causing the rapid rate of plant extinction? The main culprit is human activity like clear cutting forests for timber and converting land into fields for agriculture.

The researchers note that their paper also shows what lessons can be learned to stop future extinctions.

"Plants underpin all life on Earth," said Eimear Nic Lughadha, Ph.D., at the Royal Botanic Gardens, Kew, who was part of the research team, as The Guardian reported. "They provide the oxygen we breathe and the food we eat, as well as making up the backbone of the world's ecosystems – so plant extinction is bad news for all species."