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LONDON, England (CNN) -- Up to half of the world's magnolia species are in danger of extinction, according to a new study by conservationists.
While popular ornamental species continue to bloom in gardens, the flowering plants face a more precarious future in the wild as their native forest habitats are increasingly threatened by human activities, the authors warn.
The Red List of the Magnoliaceae, produced jointly by Botanic Gardens Conservation International (BGCI) and Fauna & Flora International (FFI) following a global mapping project by researchers at the UK's Bournemouth University, identifies 131 endangered species from a worldwide total of 245.
Some two-thirds of magnolias are found in Asia but the subtropical plant also thrives in the parts of the U.S. and South America, BGCI Secretary General Sara Oldfield told CNN.
Oldfield said that widespread deforestation posed the biggest risk to magnolias in the wild: "General forest loss is the main threat, so it varies according to where the species is.
"For example, some of the species in Colombia are threatened by the development of coffee plantations or banana plantations. And on top of that there's exploitation of certain species. Some of them are used medically and that places an extra strain on the species. Others are used for timber and some of them are edible as well."
Many of the most critically affected species are found in China, including Magnolia phanerophlebia, of which only around 200 trees are estimated to exist in the wild and Magnolia sinica, believed to have a single population of fewer than 10 mature trees. Both species grow exclusively in Yunnan province -- now the focus of an extensive re-planting campaign organized by FFI.
"We hope to be able to extend this work to take action for other species, both in China and in other parts of the world." said Georgina Magin, Global Trees Campaign Coordinator at FFI.
China is also hosting the Global Botanic Gardens Congress in Wuhan this month, where the BGCI will launch a survey of garden collections of threatened species.
Oldfield said botanical gardens had a role to play in alleviating the risk to magnolias but warned it would be a "tragedy" to allow magnolia numbers in the wild to continue falling.
"I think botanical gardens can provide a good insurance policy, by bringing them into cultivation as a way of making sure they don't go completely extinct, but we want them to be secure in the wild as well," she said. "We've got to protect their habitats as well."
As well as helping to safeguard the future of a plant that has been cultivated by humans for centuries -- some specimens growing in Chinese temples are estimated to be up to 800 years old -- magnolias are a useful subject of study for conservationists because, as one of the oldest species of flowering plants, they provide a good indicator to the overall health of the wider forest.
"They are an ancient family," said Oldfield. "They've survived all sorts of geological and climactic upheavals in the past -- so now we know their status and we've mapped them we can use them to monitor what happens to the forests in the future."
Oldfield told CNN that magnolias' plight was merely one example of how environmental degradation was threatening plant life.
"We just happen to have up to date information on magnolias, but it's symptomatic of what's happening to plants in the wild in general," Oldfield said.
"Plants are taken for granted; it's a little green blindness. There's always the emphasis on saving animals, but actually if you don't save the plants then everything will go extinct."