One in five plants are threatened with extinction, according to a new study. And we're to blame.
Scientists from the International Union for the Conservation of Nature ( IUCN), London's Natural History Museum and the Royal Botanic Gardens, Kew evaluated 7,000 plant species (out of a known 380,000 species) and assessed their conservation status and the reasons why threatened species are in danger. Twenty-two percent of the species for which they could carry out an assessment were classified as threatened with extinction, and habitat loss was the main reason for species' declines, most often from conversion into farmland.
"This study confirms what we already suspected," says Stephen Hopper, Kew's director, "that plants are under threat and the main cause is human-induced habitat loss."
Gymnosperms, non-flowering plants that include conifers and ginkgo trees, were the most threatened group in the study. And tropical rain forests were the most threatened habitat; most threatened plant species grow in the tropics.
Reading evaluations of threatened species sometimes feels like deja vu. So many species are threatened (plants aren't quite the worst off—greater percentages of amphibians and corals are in danger), especially in the tropics, and habitat loss is often a major factor. But the decline of plants should be a wake-up call. Humans cannot survive if the plant species that feed, clothe and fuel us disappear.
"We cannot sit back and watch plant species disappear—plants are the basis of all life on earth, providing clean air, water, food and fuel," Hopper says. "All animal and bird life depends on them and so do we."