IELTS Academic Reading Practice Test 22: Passage 1

On a remote island in the Norwegian Arctic, about 1,300 kilometres from the North Pole, a concrete entrance juts out of a snow-covered mountainside. Behind it, a tunnel leads deep into the rock to the storage halls of the Svalbard Global Seed Vault. Opened in 2008, the vault holds duplicate samples of seeds from gene banks all over the world, so that if a national collection is lost through war, natural disaster or mismanagement, a backup copy survives. The location was chosen with care. The vault lies about 130 metres above sea level, high enough to remain dry even if the polar ice were to melt, and the surrounding rock is permanently frozen. The halls are cooled to −18°C, but even if the electricity supply failed, the permafrost would keep the seeds frozen. There is space for 4.5 million samples, each of which typically contains around 500 seeds.

Why go to such lengths? The answer lies in the genetic diversity of the world's crops. Over thousands of years, farmers saved seeds from plants that did well in their local conditions, producing countless traditional varieties, each adapted to a particular combination of soil, climate and pests. During the twentieth century, much of this diversity disappeared, as farmers replaced their traditional varieties with a smaller number of modern, high-yielding ones. The lost varieties may have carried genes for tolerance of drought or heat, or other qualities that plant breeders will need as the climate changes. Once a variety has vanished, it cannot be recreated.

The idea of collecting seeds systematically owes much to the Russian botanist Nikolai Vavilov. In the 1920s and 1930s, Vavilov led expeditions to dozens of countries on five continents, gathering seeds of crops and their wild relatives. He noticed that the diversity of each crop was greatest in particular regions, which he believed were the places where it had first been domesticated, and he built up an enormous collection at his institute in Leningrad. During the siege of the city in the Second World War, members of his staff guarded the collection, and several of them starved to death rather than eat the seeds in their care. Vavilov himself did not live to see the end of the war: having fallen out of favour with the Soviet authorities, he died in prison in 1943.

The method used to store most seeds is surprisingly simple. Many plant species produce seeds that can survive being dried, and once their moisture content has been greatly reduced, they can be sealed in packets and frozen. In this state, the seeds' metabolism almost stops, and many can remain alive for decades. However, no seed lasts for ever, so gene banks must regularly check that their collections are still alive. They do this by taking a small number of seeds from a sample and seeing how many germinate. When this proportion falls too low, the seeds are planted and grown to maturity, and fresh seeds are harvested to replace the old ones, a process known as regeneration.

Not all plants can be saved in this way. The seeds of many tropical species, including cocoa, mango and rubber, as well as the acorns of oak trees, die if they are dried, so they cannot be frozen in the usual way. Other crops, such as bananas and potatoes, are normally grown not from seed but from parts of the parent plant, such as shoots or tubers, which means that the varieties farmers rely on are best preserved as living plants. Such collections are kept in fields or greenhouses, or as tiny plants growing in test tubes, and some material is frozen in liquid nitrogen at around −196°C. All of these methods cost far more than conventional seed storage.

The Svalbard vault does not own the seeds it stores: the institutions that deposit them remain their owners, and only they can withdraw them. For several years, no withdrawals were made. Then, in 2015, an international agricultural research centre that had been based in the Syrian city of Aleppo requested the return of some of its seeds. The civil war had forced the centre to abandon its headquarters, and the seeds it retrieved were used to rebuild its collections in Lebanon and Morocco. The vault has had problems of its own. In 2016, unusually warm weather caused meltwater to flow into the entrance tunnel. None of the seeds were affected, but the incident led to major improvements in the design of the entrance.

Seed banks have their critics. Some argue that storing seeds halts their evolution: varieties kept in a vault cannot continue to adapt to changing climates and new diseases, as they would if farmers kept growing them. Others point out that seed banks have so far focused mainly on crops, while thousands of wild plant species are also threatened. The Millennium Seed Bank in southern England, run by the Royal Botanic Gardens, Kew, was established partly to fill this gap, and works with partners in many countries to collect and store the seeds of wild plants, particularly those that are rare or endangered.