原文已被隐藏，你可用 快捷键 - 或点击 显示原文 按钮来查看原文
第一段
1 .Now listen to part of a lecture on the topic you just read about.
该句暂无译文！
第二段
1 .Actually fires are a natural part of the ecological cycle and their role is not just destructive but also creative.
该句暂无译文！
2 .That is why the ¡°let it burn¡± policy is fundamentally a good one, even if it sometimes causes fires on the scale of the 1988 Yellowstone fire.
该句暂无译文！
3 .Let's look at what happened after the 88 fire.
该句暂无译文！
第三段
1 .First, vegetation. As you might imagine, scorched areas were in time colonized by new plants.
该句暂无译文！
2 .As a matter of fact, the plant life in Yellowstone became more diverse, because the fire created an opportunity for certain plants that could not grow otherwise.
该句暂无译文！
3 .For example, areas where the trees have been destroyed by the fire could now be taken over by smaller plants that needed open and shaded space to grow.
该句暂无译文！
4 .And another example, seeds of certain plants species won't germinate unless they're exposed to very high levels of heat.
该句暂无译文！
5 .So, those plants started appearing after the fire as well.
该句暂无译文！
第四段
1 .It's a similar story with the animals.
该句暂无译文！
2 .Not only did their populations recover, but the fire also created new opportunities.
该句暂无译文！
3 .For instance, the small plants that replace trees after the fire created an ideal habitat for certain small animals like rabbits or hares.
该句暂无译文！
4 .And when the rabbits and hares started thriving, so did some predators that depended on them for food.
该句暂无译文！
5 .So, certain food chains actually became stronger after the fire than they were before.
该句暂无译文！
第五段
1 .And last, fires like the 88 Yellowstone fire would be a problem for tourism if they happened every year.
该句暂无译文！
2 .But they don't.
该句暂无译文！
3 .It was a very unusual combination of factors that year, low rainfall, unusually strong winds, accumulation of dry undergrowth that caused the fire to be so massive.
该句暂无译文！
4 .This combination has not occurred since, and Yellowstone has not seen such fires since 1988.
该句暂无译文！
5 .Visitors came back to the park the next year and each year after that.
该句暂无译文！