英语听力文摘483 啄木鸟医生
W: Woodpeckers puncture the bark of dead or dying trees, also known as snags, to find the wood-boring insects that make up their diet, and some species also excavate cavities in these trees for their nests.
M: So where does the fungus come in?
W: Well, scientists observed that the snags woodpeckers excavate generally contain decayed wood, which is caused by wood-decay fungi. Right. And this led them to wonder whether woodpeckers are attracted to certain types of decay, or if they’re the ones actually spreading the fungus that causes the decay.
M: So what did come first?
W: Well, it turns out that the relationship between the two is pretty complex. When woodpeckers puncture bark, they provide a way for airborne fungal spores to infect the wood. They also act as vectors, unintentionally picking up fungal spores and other microbes from one snag and carrying them in their beaks to another. And not surprisingly, species of woodpeckers that nest in cavities carry a significantly larger number of these, which is synergistic, because the decay makes it easier for them to excavate.
So even though we still don’t know which came first, this also isn’t merely an intellectual exercise. Woodpeckers are pretty important ecologically because the sites they excavate are used for foraging, roosting, and nesting by many other species as well. And now that there’s debate over whether snags contribute to forest fires and should be removed, it’s especially important to study potential ramifications.
啄木鸟啄破死树或垂死的树的树皮(也作断枝讲)，觅得吃木头的昆虫为食。有些物种也会在这些树上筑巢。
那么真菌是从哪来的呢?
恩，科学家们观察到啄木鸟啄洞的断枝通常包含由木腐菌造成的蛀木。是的。而且这引起观察家们思考：是某些类型的腐烂吸引了啄木鸟，还是说啄木鸟实际上传播了引起腐烂的真菌呢?
那么到底哪个在先?
恩，事实证明两者关系相当复杂。当啄木鸟啄树皮时，它们为空气传播的真菌孢子感染树木提供了方便，它们同时也是带菌者，无意中携带了真菌孢子和来自某根断枝的其他细菌，它们的喙载着这些细菌再传播给其他树木。毫不奇怪的是，那些在树洞里筑巢的啄木鸟携带着更大量的真菌，它们是协同作用着的，因为腐烂使得啄木鸟啄洞更容易了。
因此，即使我们不知道先有哪个，这也不仅仅是一种智力测验。从生态学的观点看，啄木鸟的角色相当重要，因为啄木鸟挖掘的树洞可以用于觅食，栖息，还可以被其他物种用来筑巢。既然人们关于断枝是否会导致森林火灾而应该被移除争论不休，那么研究一下可能出现的后果就特别重要了。
