英國環境大臣斯皮爾曼(Caroline Spelman)表示，「對下個月要在名古屋舉辦的國際生物多樣性會議而言，這份報告出現的時機十分重要，全世界有1/5的植物因為人類活動而面臨滅絕的消息，令人十分不安。植物對人類的生存至關重要，提供了食物、飲水以及藥物，也能減輕並調適氣候變遷。」英國皇家植物園(邱園)主任霍珀教授(Stephen Hopper)則表示，「這是第一次我們對全球植物的滅絕風險有清楚的認識。」
2010年生物多樣性目標訂於2002年4月訂定，生物多樣性公約締約國承諾，要在2010年以前大幅降低全球生物多樣性的流失，不論是在全球、區域或是國家尺度上，以扶助貧窮的方式造福全地球上的生命。 這項目標已經在永續發展世界峰會以及聯合國大會中通過，並成為千禧發展目標(Millennium Development Goals)下的一個新目標。
根據皇家植物園的世界植物科名清單資料，科學家算出開花植物的數目，比先前估計的要多出10%至20%。這項研究成果發表在《皇家學會論文集B》(Proceedings of the Royal Society B)。
其中最高大的植物是由麥金德博士(Barbara Mackinder)命名的Berlinia korupensis，高達42公尺。這種與豌豆同類的植物會開美麗的白花並結出巨大的豆莢，在成熟時裂開將種子推離母株。
這次在喀麥隆魯普國家公園(Korup National Park)的調查顯示，這種植物極其稀有。「我們的調查中只發現了17株，」邱園的伯特(Xander van der Burgt)說。「儘管魯普國家公園受到保護，但是Berlinia korupensis仍然因為人類對公園產生的壓力而瀕臨滅絕。」
29日公佈的評估結果已經登錄到植物紅皮書採樣指數(Sampled Red List Index for Plants)內，這個指數分析了大量來自世界各地的植物樣本。
One in every five of the world's plant species is threatened with extinction, biodiversity experts said today in the first global analysis of extinction risk for the world's estimated 380,000 plant species.
Most of the threatened species are found in the tropics, the report shows. The greatest threat is habitat loss caused by human activities, mostly the conversion of natural habitats for agriculture or livestock use.
The analysis was released today as governments prepare to meet in Nagoya, Japan in mid-October to set new conservation targets at the United Nations Biodiversity Summit.
"This report comes at an important time in the lead up to the major international biodiversity meeting in Nagoya next month," said UK Environment Secretary Caroline Spelman. "It is deeply troubling that a fifth of the world's plants are facing extinction because of human activity. Plant life is vital to our very existence providing us with food, water, medicines, and the ability to mitigate and adapt to climate change."
For the first time we have a clear global picture of extinction risk to the world's known plants," said Professor Stephen Hopper, director of the Royal Botanic Gardens, Kew.
Scientists from the Kew, the Natural History Museum and the IUCN Specialist Groups assessed a representative sample of the world's plants, in response to the United Nations' International Year of Biodiversity and the 2010 Biodiversity Target.
The 2010 Biodiversity Target was set in April 2002, when the governments that are Parties to the Convention on Biological Diversity committed themselves to achieve by 2010 a significant reduction of the current rate of biodiversity loss at the global, regional and national levels as a contribution to poverty alleviation and to the benefit of all life on Earth.
This target was endorsed by the World Summit on Sustainable Development and the United Nations General Assembly and was incorporated as a new target under the Millennium Development Goals.
But in April, a report on over 30 indicators concluded that world leaders have failed to reduce the global rate of biodiversity loss by 2010 and have instead overseen biodiversity declines.
Next month the meeting in Nagoya will attempt to set a 2020 biodiversity target that will likely be to halt biodiversity loss and the degradation of ecosystems services by 2020, and to restore them wherever feasible.
"The 2020 biodiversity target that will be discussed in Nagoya is ambitious, but in a time of increasing loss of biodiversity it is entirely appropriate to scale up our efforts," said Hopper. "Plants are the foundation of biodiversity and their significance in uncertain climatic, economic and political times has been overlooked for far too long."
The assessment released today shows that plants are more threatened than birds and as threatened as mammals, but plant species are less threatened than amphibians or corals.
Both common and rare species were assessed in order to give an accurate picture of how plants are faring around the world.
The most threatened habitat is tropical rainforest. The study points out that the current rate of loss of tropical forest accounts for 20 percent of global carbon emissions.
Gymnosperms are the most endangered plant group. These seed-bearing plants whose seeds do not form inside fruits but outside, include conifers, cycads, ginkgo and the tropical evergreen trees, shrubs and lianas called gnetales. Many of these gnetum species are edible, as the seeds are roasted, and the foliage is used as a vegetable. Some are valued as herbal medicine.
"Scientists have estimated that, overall, there could be between 5 million and 50 million species, but fewer than two million of these species have been discovered to date," said lead author Lucas Joppa of Microsoft Research in Cambridge, UK. "Using novel methods, we were able to refine the estimate of total species for flowering plants, and calculate how many of those remain undiscovered."
Based on data from the online World Checklist of Selected Plant Families at the Royal Botanic Gardens, Kew, the scientists calculated that there are between 10 and 20 percent more undiscovered flowering plant species than previously estimated. The study was published in the journal "Proceedings of the Royal Society B."
Scientists are continually discovering plant species previously unknown to science. Among the more than 250 new species discovered or described by Kew scientists in the past year are massive flowering trees in the rainforests of Cameroon.
The tallest is the Berlinia korupensis, named by Dr. Barbara Mackinder, which stands 42 meters in height. A member of the pea family, the Berlinia bears beautiful white flowers with enormous pods that explode when ripe, propelling the seeds away from the mother tree.
Surveys of the Cameroon's Korup National Park show that this tree is extremely rare. "We found just 17 trees in our surveys," said Kew's Xander van der Burgt. "Even though Korup is protected, Berlinia korupensis is critically endangered due to human pressures on the park."
The assessment released today adds to the Sampled Red List Index for Plants, which analyzes a large sample of plant species that collectively represent of all the world's plants.
The Sampled Red List Index for Plants is part of the IUCN's authoritative Red List of Threatened Species, a worldwide effort to create a tool to monitor the changing status of the world's major groups of plants, fungi and animals.
"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 said. "All animal and bird life depends on them and so do we. Having the tools and knowledge to turn around loss of biodiversity is now more important than ever and the Sampled Red List Index for Plants gives conservationists and scientists one such tool."