Academic Reading — Test 2

Reading passage

The Millennium Seed Bank, operated by the Royal Botanic Gardens, Kew, is among the most ambitious conservation projects ever undertaken. Housed in a purpose-built facility at Wakehurst in West Sussex, it was opened in the year 2000 with a single, sweeping objective: to gather and preserve the seeds of wild plant species from across the globe before those species are lost. Unlike a traditional garden, which displays living plants for visitors to admire, the seed bank is essentially an insurance policy. Its collections are kept out of sight in underground vaults, ready to be called upon should a species vanish from the wild or should scientists need material for research and restoration. The underlying philosophy is straightforward: it is far cheaper, and far safer, to store seeds than to attempt to rescue a plant once its natural habitat has already disappeared. The strategy rests on a remarkable biological fact. The seeds of many plants are naturally able to survive long periods of dormancy, and this resilience can be greatly extended under the right artificial conditions. At Wakehurst, incoming seeds are first cleaned to remove fruit pulp, husks and other debris, then dried slowly in a room kept at low humidity. Once their moisture content has been reduced, the seeds are sealed in glass containers and frozen at minus twenty degrees Celsius. At this temperature the metabolic processes that would otherwise cause the seeds to deteriorate are slowed almost to a standstill. For many species, scientists estimate that seeds treated in this way could remain viable for hundreds, or even thousands, of years. This longevity is what makes a seed bank such an efficient form of conservation: a single freezer can hold the genetic heritage of countless populations in a space no larger than a modest cellar. Not every plant, however, can be banked using this method. A significant minority produce so-called recalcitrant seeds, which cannot tolerate drying and freezing without being killed. Many large tropical trees, including several species of oak and a number of rainforest giants, fall into this category. For such plants the conventional freezing approach is useless, and researchers must instead explore alternative techniques such as cryopreservation, in which delicate plant tissue is stored in liquid nitrogen at extremely low temperatures. Developing reliable methods for these difficult species remains one of the central scientific challenges facing the institution, and a substantial part of its laboratory work is devoted to the problem. Crucially, the Millennium Seed Bank does not operate alone. From the outset it was conceived as a global partnership, working with botanical institutions, universities and government agencies in more than ninety countries. Local partners are trained to collect seeds according to standardised protocols, and a portion of every collection is always retained in the country of origin rather than being shipped entirely to Britain. This arrangement reflects both a practical concern, since duplicate storage guards against the loss of a single collection, and an ethical one, since the nations that supply the seeds retain ownership of their own biological resources. The bank also places particular emphasis on plants that are useful to people, especially the wild relatives of crops, whose genes may one day help breeders develop varieties able to withstand drought, disease or a warming climate. The numbers involved are striking. By 2009 the project had achieved its initial goal of banking ten per cent of the world's wild plant species, and it has continued to expand ever since. Yet the people who run the bank are careful to stress that storing seeds is only ever half the task. A seed that cannot germinate is worthless, so each accession is periodically tested: a sample is removed from the freezer and encouraged to sprout under controlled conditions. If the germination rate falls below an acceptable level, fresh seed must be collected from the wild to replace the ageing stock. In this sense the bank is not a static museum but a living archive that demands continual monitoring. Its ultimate value will only become apparent in the decades and centuries to come, when the seeds it safeguards today may be used to restore landscapes, feed populations and repair some of the damage that human activity has inflicted on the natural world.