Use of English

Fragile Ecosystems

Biodiversity refers to the variety of life within a particular habitat, region or even the entire planet, and it plays a vital role in keeping ecosystems stable. When one species disappears, the effects can spread (0) THROUGH the food chain and disturb the balance of the whole system. For example, if a key predator dies (1) .........., the population of its prey may rise sharply, which can then (2) .......... to overgrazing or the loss of plant cover. In turn, this may reduce the soil’s ability to hold water and increase the risk of erosion. Ecologists often study how species interact with one another and with their physical (3) ........... Factors such as temperature, rainfall and soil quality all influence whether a species can survive in a certain area. Human activity, however, has (4) .......... many natural habitats and has placed some species under serious threat. Conservationists argue that protected areas alone are not enough, and that damaged ecosystems must also be (5) .......... if biodiversity is to recover. In recent years, scientists have also become more aware of the role of pollinators, such as bees and butterflies, in supporting food production. If their numbers continue to fall, the effects on agriculture could be far more serious than people first (6) ........... For this reason, many governments now support farming methods that reduce the use of chemicals and (7) .......... wildlife. Although such measures may seem costly at first, experts insist that they will (8) .......... in the long term.