VOA慢速英语--研究人员发现入侵物种的“善良”一面

Researchers Find Bright Side to Some Invasive Species

Non-native species present threats to natural environments across the world by pushing out native organisms.

Their presence can seriously damage ecosystems² that provide clean water, food and other important resources to many living things.

Destructive, non-native species are called invasive species. Scientists have long struggled to find ways to slow or stop them.

But American researchers have discovered that some invasive species can also have a good effect on the environment.

One of them is Phragmites, a tall, fast-growing grass. This plant is thought to have first appeared in Europe in the early 19th century. Phragmites is not native to the United States. But it now is very common along the U.S. East Coast and can be found in wetlands across North America.

The U.S. Fish and Wildlife Service says the fast spread of Phragmites in the 20th century was likely caused by several things. They include the building of railroads and major expressways that affected³ natural habitat. There was also widespread development along the coast. A rich supply of minerals in coastal⁴ waters likely also drove plant growth.

Researchers found in a new study that one major benefit of invasive species is that they can eat up carbon dioxide. Scientists have blamed the gas for being a major cause of rising temperatures on Earth’s surface.

The study found that coastal ecosystems generally store more blue carbon when they are overtaken by invasive species. Blue carbon is a kind of carbon stored in oceans and coastal ecosystems.

The research showed that coastal ecosystems that had been overtaken by invasive species had about 40 percent more carbon than native habitats.

Christina Simkanin helped to prepare a report on the study. Simkanin is a biologist at the Smithsonian Environmental Research Center in Maryland. She says the findings were somewhat surprising.

“I think because non-native species are often thought of as being negative so often, and they do have detrimental⁵ impacts. But in this case, they seem to be storing carbon quicker.”

She added that Phragmites and some other non-native species keep increasing the carbon they take in because the plants grow and spread so quickly.

Simkanin says the issue can be complex when different kinds of invasive species are involved. While she does not believe it is a good idea to let invasive invaders⁶ take control, she thinks finding a solution is not always simple.

Such decisions are not likely to get any easier in the future. Smithsonian research shows that Phragmites will keep outcompeting native species as temperatures and carbon dioxide levels rise.

I’m Bryan Lynn.

Words in This Story

species – n. a group of plants or animals that share similar characteristics

ecosystem¹ – n. all the plants, animals and people living in an area considered their environment

habitat – n. the natural surroundings in which a plant or animal usually lives

benefit – n. a good or helpful result or effect?

negative – adj. not having enthusiasm or positive opinions about something

detrimental – adj. causing harm or damage

impact – n. a major influence or effect

1 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

2 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

3 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

4 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

5 detrimental   

adj.损害的，造成伤害的

参考例句：

• We know that heat treatment is detrimental to milk.我们知道加热对牛奶是不利的。
• He wouldn't accept that smoking was detrimental to health.他不相信吸烟有害健康。

6 invaders   

入侵者，侵略者，侵入物( invader的名词复数 )

参考例句：

• They prepared to repel the invaders. 他们准备赶走侵略军。
• The family has traced its ancestry to the Norman invaders. 这个家族将自己的世系追溯到诺曼征服者。