TOEFL Listening

🎧 Listening Transcript

Listen to part of a lecture in an environmental science class. The professor is discussing the role of beavers in ecosystems. Professor: Now, many of you might think of beavers primarily as tree-cutters or dam builders, but their ecological impact goes far beyond that. Beavers are often called 'ecosystem engineers' because their dam-building activities create wetlands, which are among the most biodiverse habitats on Earth. These wetlands provide shelter and food for a wide range of species, from insects to amphibians to birds. Moreover, beaver ponds filter pollutants and sediment, improving water quality downstream. Interestingly, the benefits are not just local; they extend to the entire watershed. For example, by slowing water flow, beaver dams help prevent erosion and reduce the risk of floods. However, beaver populations have declined dramatically due to fur trapping and habitat loss, which has led to the degradation of many river systems. As a result, some conservationists are now reintroducing beavers to restore these ecosystems. This approach, known as 'rewilding,' has shown promising results in several countries, though it remains controversial among landowners who worry about flooding.