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🎧 听力原文

Listen to part of a lecture in an environmental science class. The professor is discussing the impact of beaver dams on river ecosystems. 'Today, we're going to talk about a surprising ecological engineer: the beaver. When beavers build dams, they create ponds that slow down water flow. This might seem like a simple change, but it has profound effects. First, the slower water allows sediment to settle, which improves water clarity downstream. Second, the ponds create new habitats for fish, amphibians, and insects, increasing biodiversity. However, there are also challenges. Beavers can flood roads and farmland, causing conflicts with humans. In some regions, managers have used flow devices—pipes that control water levels—to reduce flooding while still allowing beavers to thrive. These devices have been successful in balancing ecological benefits with human needs. Interestingly, studies show that beaver-created wetlands can store more carbon than other types of wetlands, making them important in climate change mitigation. So, while beavers may be seen as pests in some areas, their role in ecosystem health is undeniable.'