每日一翻：Plant Thorns Increase When Defense Needed

Plants thrive all over the planet, despite the fact that many animals love to snack on them. Various hypotheses account for all those plants. One is that predators kill enough plant-eating animals to give vegetation a chance. Another is that plants develop physical and chemical means to defend themselves.

尽管很多动物喜欢以植物为食，但是全世界的植物依然茁壮地生长着。对这个现象的解释有各种各样的假设：一种是食肉动物可以吃掉足够的食草动物从而让植物有机会生长；还有一种是说植物会通过物理和化学的方法去保护自己。

Now researchers have teased out some of these factors in an East African savannah.

现在，研究者们在东非大草原上的发现为此结论梳理出了一些证据。

The impala – an African antelope – eats grasses and trees and is itself eaten by wild dogs and leopards. Impala often munch on a tree called the acacia. Some acacia have thorns, and some don’t.The researchers found that the impala – perhaps not surprisingly – prefer thorn-free acacia. Also, the animals avoid woody areas where predators are more likely to hide.一种名叫黑斑羚的非洲羚羊以草和树为食，而它自己又是野狗和豹子的食物。黑斑羚经常吃金合欢属的植物。有些金合欢属植物有刺，而有些没有。研究者们发现黑斑羚喜欢没有刺的植物，这或许不会让人惊讶。同时，这些动物也不会呆在食肉动物藏匿的木本植物生长的地带。

And as a result, the thorn-free, vulnerable acacia are more plentiful in woody areas with plenty of predators. But the thorny acacia are more numerous on the open savannah, where they need to defend themselves. The study is in the journal Science. [Adam T. Ford et al,Large carnivores make savanna tree communities less thorny]

结论就是，没有刺的、易被吃掉的金合欢属植物在有很多食肉动物出没的木本植物生长的地带长得更茂盛，而带刺的植物则在开阔的大草原上更多，因为在那里它们需要自我保护。研究成果被发表在《科学》杂志上。

The researchers say their findings show that both plant defenses and carnivorous predators help plants thrive. They also say that when humans influence – in part by eliminating large predators – we disrupt longstanding, complex systems. And that we should really try to better understand such systems, and our effects on them.

研究人员说他们的发现表明植物的自我保护和食肉动物都能帮助植物更好的生长。他们还说人类带来的影响会破坏大自然长期形成的复杂的系统，比如人类屠杀大型食肉动物。我们应该真正的尽力去更好的理解这个生态系统和了解我们给它们带来的影响。

—Cynthia Graber