2022年经济学人 外来入侵物种是否能对生态环境有利(1)（在线收听）

Alien plants and animals are not all bad.

外来入侵动植物不都是有害的。

Introduced species have a bad rap.

外来引进物种的名声很差。

From American grey squirrels displacing European red ones, to Japanese knotweed displacing just about everything everywhere, their purported negative effects on nature are there for all to see.

从美州灰松鼠取代欧洲红松鼠，到日本虎杖取代英国几乎所有本土植物，外来物种对自然造成的负面影响是有目共睹的。

But it is only the human eye which prefers the arboreal rodents in a particular place to be red rather than grey.

但希望在某个特定地点，树上住着红色啮齿动物，而不应该是灰色啮齿动物的，实际上只有人类。

Ecologically, both occupy the same niche.

从生态角度看，灰松鼠和红松鼠占据着相同的生态位。

Nor might people fret about knotweed growing at other plants’ expense if it did not also undermine human constructions such as buildings and roads.

人们也无需担心虎杖以其他植物消失为代价生长，只要它不会破坏建筑物和道路等人类建筑。

Until the middle of the 20th century, moving species around the world was reckoned a normal, often valuable, thing to do, while the consequences of their accidental movement were rarely considered.

到20世纪中叶以前，人们一直认为物种在世界各地的迁徙是一件正常的、并且通常极具价值的事情，而很少考虑它们偶然迁徙造成的后果。

It was not until the publication in 1958 of “The Ecology of Invasions by Animals and Plants”, by Charles Elton, one of the founders of scientific ecology, that values began to change.

直到1958年，科学生态学的创始人之一查尔斯·埃尔顿出版了《动植物入侵生态学》一书，人们的观念才开始发生变化。

Conservation is, as the name implies, a conservative business.

保护，顾名思义，在于保守。

Those involved often value “nativism” - the idea that the species mix in a particular place should remain as unchanged as possible.

参与动植物保护的人往往会坚持“本土主义”，即特定地点不同物种的组合应该尽可能保持稳定。

But this is just an opinion.

但这动植物保护的观点之一。

Other opinions are possible.

还有其他一些可能的观点。

A study published recently in Trends in Ecology & Evolution by Dov Sax of Brown University, in Rhode Island, thus asks how the benefits of introduced species might be better assessed, so that opinions can be more informed.

罗德岛州布朗大学的多夫·萨克斯近期在《生态学与进化趋势》上发表的一项研究提出了如何更好地评估引进外来物种的好处，为外来物种能够带来好处的观点提供依据。

Specifically, he and his compadres have recruited the vocabulary of moral philosophy.

具体地说，他和他的团队利用了道德哲学领域的词汇。

They thus identify three sets of reasons why an introduced species might be valuable: instrumental, intrinsic and relational.

他们据此确定了外来物种可能具有的三种价值：工具价值、内在价值和关系价值。

Instrumental values are easiest to grasp.

工具价值是最容易理解的。

They pertain to things that provide direct human advantage.

人类能够直接从具有工具价值的事物中获取利益。

Dr Sax and his colleagues ignored crops, since these are heavily managed by human beings and their benefits are obvious.

萨克斯博士和他的同事没有考虑农作物，因为农作物在很大程度上是由人类进行管理的，它们带来的好处是显而易见的。

But they included transplanted grass species that have gone wild, yet provide grazing for stock animals, and introduced forest trees that yield timber for construction.

但他们研究了移植后开始大量生长，可以作为牲畜饲料的草种，以及引入的可用于生产建筑用木材的林木。

One little-regarded but important example of instrumental value is the transport of Old World earthworms to North America, parts of which were left worm-free after the last ice age.

工具价值有一个鲜为人知但十分重要的例子，即旧世界蚯蚓入侵北美，自上一个冰河时代后到蚯蚓入侵之前，北美的一部分地区完全没有过蚯蚓的存在。

The presence of these is reckoned to have increased agricultural productivity by as much as 25% in previously worm-deprived areas, though recent work suggests other invertebrates have suffered.

据估计，蚯蚓的出现让以前没有蚯蚓的地区农业生产率提高了25%，但最近的研究也表明，其他无脊椎动物受到了蚯蚓入侵的影响。

Honeybees, too, are an Old World species introduced into the New.

蜜蜂也是从旧世界引入新世界的物种。

Their instrumental benefits in the form of honey and wax are obvious.

它们的蜂蜜和蜂蜡具有明显的工具价值。

But they also pollinate flowering plants, including many crops.

此外，它们也为开花植物，包括许多农作物授粉。

Honeybees’ role as pollinators also makes them pertinent to the second category, intrinsic values.

蜜蜂作为传粉者的角色也使它们与外来物种的第二种价值——内在价值——相关。

These pertain to the ecosystem into which the introduction has happened.

内在价值与物种引入的生态系统有关。

Since honeybees pollinate wild plants as well as domesticated ones, they have a positive intrinsic effect on their adopted habitats.

由于蜜蜂既为野生植物授粉，也为栽培植物授粉，它们对引入后的栖息地具有积极的内在影响。

Introduced species can bring other benefits.

引进的外来物种还具有其它好处。

Sometimes, in a manner reminiscent of the nursery rhyme in which an old lady swallows a fly, a spider to catch it, and a bird to catch the spider, an introduction may be made to undo a previous harm.

有时，外来物种的引进能让我们联想到一个童谣：老妇人吞下了一只苍蝇，又吞下一只蜘蛛去抓苍蝇，然后又吞下一只鸟去抓蜘蛛——引入外来物种或许能够消除该地此前受到的伤害。

Several introductions of damaging insects have been attacked successfully by further introductions of critters that eat them - though this has not worked so well for voracious introduced molluscs called giant African land snails.

一些地区已经通过引入其它生物成功地攻击了此前入侵此地的害虫——尽管对于贪吃的非洲大蜗牛这种软体动物来说，这种引入也造成了不小的危害。