听力材料：

　　Salvage logging may appear to be an effective way of helping forests recover after a destructive fire or storm, but it can actually result in serious loner-term environmental damage. Its economic benefits are also questionable.
　　回收性砍伐看起来似乎是个帮助森林从破坏性大火或者暴风雨中的损害中恢复的有效方法，但是事实上却会带来长期的环境损失。而它的经济利益也是存疑的。

　　First, cleaning up a forest after a fire or storm does not necessarily create the right conditions for tree growth. In fact, the natural process of wood decomposition enriches the soil and makes it more suitable for future generations of tree. The rapid removal of dead trees can result in soil that lacks the nutrients necessary for growth.
　　首先，在大火或者暴风雨之后的清理并不一定会给树的生长提供合适的生长环境。事实上，树木腐烂的自然过程可以使土壤变得肥沃，更适合以后树木的生长。迅速地移除死去的树木可能会导致土壤确实树木生长所必须的营养物质。

　　Second, it’s true that rotting wood can increase insect population, but is this really bad for the forest? In fact, spruce bark beetles have lived in Alaskan forest for nearly hundred years without causing major damage. And of course dead trees do not provide habitats only for harmful insects. They are also used by birds and other insects that are important contributors to the long-term health of forests. In the long run, therefore, salvage logging may end up doing more harm to forests than harmful insects do.
　　第二，的确那些腐烂的树木会让昆虫的数量增加，但是这就一定对森林不好吗?事实上，杉皮甲虫已经在阿拉斯加森林里生活了近百年，但是从来没有造成严重的灾害。而且，死树不是仅仅为害虫提供栖息地，鸟类和其他昆虫也会居于与此，这些鸟类和昆虫对于森林的长期健康是有利的。因而，从长远看，回收性砍伐最终给森林带来的危害要大于害虫。

　　And third, the economic benefits of salvage logging are small and don’t last very long. In severely damaged forests, much of the lumber can be recovered only by using helicopters and other vehicles that are expensive to use and maintain. Furthermore, jobs created by salvage logging are only temporary and are often filled by outsiders with more experience or training than local residents have.
　　第三，回收性砍伐的经济利益是很微小的而且不具有持久性。在严重受损的森林里，木材必须使用直升飞机或者其他交通工具才能回收，而这些的使用和保养费用都非常昂贵。而且，回收性砍伐提供的工作岗位都是临时的，同时这些工作岗位往往都被受过训练而且富有经验的外地人获得，本地人并不具有竞争力。

　　听力部分需要提取的观点是：
　　- Main point: 回收性砍伐弊大于利。
　　- Sub point 1: 回收性砍伐会使森林土壤失去营养。
　　- Sub point 2: 回收性砍伐会使鸟类和有益的昆虫失去栖息地，长久看来对森林无益。
　　- Sub point 3: 回收性砍伐经济利益很小。