Conserving China’s plant riches

There are around 320,000 different plant species on Earth, and China is home to 10% of them. But breakneck growth is putting unprecedented pressure on the country’s biodiversity. Alex Kirby reports on efforts to conserve China’s natural heritage.

Scientists think there are around 320,000 different plant species on Earth – and China is home to around 10% of them. It is a treasure-house of biodiversity, yet it is growing and industrialising at breakneck speed. The pressure on China’s plant life is intense, as agriculture and industry demand ever more land. More than 5,000 plant species are used in traditional Chinese medicine, and an estimated 11,000 species possess some economic significance. They need millions of hectares and huge quantities of water. But so do the farms and the factories. And the export trade increases the fragility of China’s riches still further.

Wuhan Botanical Garden has been chosen to host the third Global Botanic Gardens Congress, organised by the Chinese Academy of Sciences, the Hubei provincial government, Wuhan municipal government and Botanic Gardens Conservation International (BGCI). It runs from 16 to 20 April, with 600-plus participants expected. The congress theme is appropriate: “Building a Sustainable Future: The Role of Botanic Gardens.”

The work of botanic gardens has never been more important. There are over 2,500 botanic gardens worldwide, with almost every country having at least one. The UK has over 100, but China can boast more than 140. Together, the world’s gardens cultivate around 100,000 species (almost a third of known plants) and are major centres of research and expertise for plant conservation.

The Wuhan Congress will be a rare opportunity for the world’s plant experts to meet, and to share their experiences, knowledge and research. One of the key topics will be how to use plants sustainably, despite the many and growing demands on them.

Sustainable use is now high on China’s agenda. Apart from domestic pressures, the global demand for its flora can have devastating results. The biggest-selling cancer drug in the world, Taxol, is made from several yew species. In fact, yews have also been used in traditional Chinese medicine for centuries to treat diabetes, although the whole tree except for the flesh of the fruit surrounding the seed is dangerously poisonous.

A single course of treatment with Taxol requires the bark of 7.5 average-sized yews. To produce a kilogram of the drug takes 3,000 trees, and current world demand estimated to be around 700 kilograms a year. With India, China is the biggest manufacturer and exporter of the raw material, so it is little wonder that 80% of the yew resources in southwest China’s Yunnan province were destroyed in just three years.

Taxol is only one of the gifts that China’s pharmacopeia offers the world. Other examples include the colon cancer treatment irinotecan, a standard chemotherapy that interferes with the growth of cancer cells, and topotecan, a chemotherapy used for ovarian and lung cancer. Both are modifications of Camptotheca acuminata, a native of China, where it is known as Xi Shu, or “Happy Tree”.

But this international trade is not a new thing. The first known account of the trade in agarwood, prized for use in incense, perfumery and medicine, was compiled by a Chinese customs official in 1200 AD. In 1998, over 1,000 tonnes of agarwood were traded around the world.

The demand now exceeds supply so much that several species are classified by the International Union for the Conservation of Nature (IUCN) as threatened. Agarwood is also listed on Appendix II of the UN Convention on International Trade in Endangered Species (CITES), meaning that trade must be controlled to avoid threatening the species’ survival.

Around the world, in rich countries and poor ones, plants mean life. About 80% of people in the developing world depend on traditional plant-based medicines, and 75% of the top prescription drugs are derived in part from plants. They transform lives: Madagascar’s rosy periwinkle has improved the chances of surviving some forms of childhood leukaemia from 10% to 95% in the last 50 years.

Sustainable development is a priority for the United Nations Convention on Biological Diversity, the CBD, which works to conserve all the Earth’s species. It has developed a Global Strategy for Plant Conservation, agreed unanimously by all the 188 countries which have ratified the Convention. The congress will discuss how to reach this strategy’s list of 16 priorities for 2010. One way towards that is for individual countries to develop national strategies. The UK has done so, and after a meeting of British and Chinese experts in November 2006 – arranged by BGCI – China is close to being able to mark the congress by unveiling a strategy of its own at Wuhan.

The UK-China meeting was a pivotal point for plant conservation in China, bringing together a wide range of national and international partners. “Building on the excellent network we have established, we need to strengthen our collaboration in the future,” said Dr Jia Jiansheng, deputy director of the State Forestry Administration. “Continuing to work with CBD, BGCI and the UK Government, we join hands to conserve wild plants in China and overseas.”

But conserving a threatened species can be complicated. One Chinese plant, known to scientists as Cistanche deserticola and called suosuo dayun in China, provides a herb called roucongrong which is valued at home and abroad for treating impotence and infertility. It is in growing demand. But Cistanche will grow only as a parasite on another plant, Haloxylon, which is such good firewood that it is known as “coal in the desert”, and is also used for camel feed. So to save one plant, the conservationists have to work out how to rescue two.

Plants seldom attract as much attention from conservationists as some of the more obviously glamorous candidates for help. Campaigners routinely raise money in many countries to save the whale, the tiger and the panda, and many other of the “charismatic mega-fauna”: the big, iconic creatures now sliding towards oblivion.

Yet it is on plants that all life depends. Most terrestrial species either eat plants (if they are herbivores) or else eat prey which itself has fed on vegetation. Even zooplankton, the tiny animals which sustain almost all higher marine life, feed on plants – phytoplankton. Plants also produce the oxygen we breathe and absorb carbon dioxide, one of the main greenhouse gases.

But few people see a plant as any sort of icon. However, scientists believe that at least 60,000 plant species face some threat of extinction – and the total could be 100,000, between a quarter and one-third of the total number on Earth.

That is where BGCI, an independent, international organisation with its head office based at the UK’s Royal Botanic Garden at Kew, can help. It is the world’s largest plant conservation network, and its vision is a world in which plant diversity is valued and secure and supports all life.

And this year may see a historic breakthrough, both in China’s work to protect its own plants and in worldwide efforts to slow the inexorable slide of much of the plant kingdom towards extinction. It marks two anniversaries: the twentieth year since the establishment of BGCI, and the fiftieth birthday of Wuhan Botanical Garden, one of the crown jewels of China’s conservation work. Not only is the garden a stunning display case of many varieties of plants, but it is also a world-class scientific institute.

The problem is global, and much of the solution is likely to lie in China. The mountains of south-west China for example, are one of the world’s most diverse regions, with the greatest number of endemic plants (species found nowhere else) in the world. Of 12,000 plants found in the hotspot, 3,500 are endemic species. Among the most striking are the spring-flowering magnolias, half of which are known to be under threat of extinction in the wild.

China’s place in the fight to slow, arrest and hopefully reverse the loss of the world’s plants is pivotal. If it, facing the unparalleled challenges of very rapid modernisation and growth, can find the way towards the truly sustainable use of its unique flora, then every country can hope to do the same. It is a global test case: there are many governments waiting for China to give them a lead.

Alex Kirby is a British journalist. He worked for nearly twenty years for the British Broadcasting Corporation (BBC), being the environment correspondent for BBC News from 1987 to 1996. Now working as a freelance journalist, he continues to regularly contribute to the BBC and provides training in media skills to companies, universities and non-governmental organisations.

Homepage photo by German M