经济学人下载:燃眉之急

Ecology is a complicated thing. Given the facts that elephant damage often kills trees and bush fires often kill trees
生态是一个复杂的东西。鉴于大象的破坏以及丛林大火经常会导致树木死亡的事实，

it would be reasonable to deduce that a combination of the two would make things worse.
我们有理由推论两者的结合会让事情变得更加糟糕。

Counter-intuitively, though, as research just published in Biotropica,
但万万没想到，南非曼德拉大学的本杰明·威格利

by Benjamin Wigley of Nelson Mandela University in South Africa shows,
发表于《Biotropica》的一项研究表明

if a tree has already been damaged, fire can actually help to make things better.
如果一棵树木已经遭到毁坏，火其实可以帮助事情变得更好。

One common way in which elephants harm trees is by stripping them of their bark.
大象伤害树木的常见方法之一是剥去它们的树皮。

Dr Wigley, who did indeed start from the obvious assumption,
威格利博士确实是从一个明显的假设开始的，

set off to find out how much worse bush fires would make the effects of this bark stripping.
他开始研究丛林大火会对剥树皮造成多大的影响。

To this end he set up a study in the Kruger National Park, a reserve on South Africa's border with Mozambique.
为此他在克鲁格国家公园开始了一项研究，克鲁格国家公园是一个位于南非与莫桑比克边境的保护区。

Since 1954, the Kruger has been the site of experiments in which plots of land have been burned at intervals,
自1954年起，克鲁格一直都是实验的试点，在这些实验中，研究人员每隔一段时间就焚烧一小块土地，

to discern the effects of fire on savannah ecology.
以观察大火对草原生态的影响。

Dr Wigley tapped into these experiments by looking at trees in three different zones.
威格利博士通过观察三个不同区域的树木进行了这些实验。

In one of these the vegetation was burned every year. In the second it was burned every other year.
其中一个区域中的植被每年被烧一次。第二个区域的植被每隔一年烧一次。

The third zone, by contrast, was actively shielded from fire.
而第三个区域的植被则被积极地保护起来不受大火灼烧。

To keep things consistent, he looked at the fate of a single tree species, the marula, in all three zones.
为了保持一致，他观察的是三个区域中同一种树木的命运—马鲁拉树。

He picked marulas because they are particular victims of elephant activity.
他选择马鲁拉树是因为它们是大象活动的特殊受害者。

Their fruit are delicious, and prized by elephants and people alike. But elephants also seem to enjoy eating their bark.
它们的果实很美味，深受大象和人类的珍视。但大象似乎喜欢吃它们的树皮。

In July 2016 he and his colleagues identified 20 marulas in every zone and used a hammer and a soil corer
2016年7月，他和他的同事在每个区域内确认了20棵马鲁拉树并用锤子和土壤去心器

to remove from each of them a circular section of bark 5cm in diameter.
从每棵树上取下直径5厘米的圆形树皮。

Having inflicted this damage, they monitored the wounds over the course of the following two years, to see what would happen.
在造成这种破坏之后，他们在接下来的两年里对伤口进行了监测，看看会发生什么。

To their surprise, they discovered that the wounds of trees in fire zones recovered far better than those of trees that had seen no fires at all.
让他们惊讶的是，他们发现火灾区树木的伤口恢复得比那些没经历过火灾的树木要快。

Wounded trees in the annual burn zone regrew 98% of their lost bark during the two years of the study.
在两年的研究中，年度火灾区中的受伤树木98%的树皮都重新长了出来。

Those living in the biennial burn zone regrew 92% of it. But those in the zone where fires were suppressed regrew only 72%.
那些两年一次火灾区中的树木的树皮重生了92%。但防火区的树木仅生长出了72%。

The researchers also found something else when they were measuring the trees' wounds: ants.
当测量树木伤口时，研究人员还发现了一些其他的东西：蚂蚁。

Ten of the 20 trees in the fire-suppression zone developed ant colonies in their wounds.
20棵防火区的树木中，有10棵的伤口上长出了蚁群。

The ants in question were a species that is known to damage trees and is presumed to impair tissue healing.
这些蚂蚁是一种已知的会损害树木的物种，据推测会损害组织愈合。

By contrast, only five trees in the biennial burn zone and three in the annual zone developed ants' nests in their wounds.
相比之下，两年一次的区域和年度区域中分别仅有5棵和3棵树的伤口中长出了蚁巢。

It looks, therefore, as if bush fires are cauterising trees' wounds by killing ants that might otherwise infest them.
因此，似乎丛林大火是在通过杀死可能感染树木的蚂蚁来烧灼树木的伤口。

Though such fires are surely harmful to healthy trees,
虽然这样的大火对健康树木无疑是有害的，

it seems, in an example of two negatives making a positive, as if they are actually helpful to sick ones.
但在这个负负得正的例子中，似乎它们实际上对生病的树木是有益的。