获取验证码
收不到短信?点此接收语音验证码
电话拨打中...请留意来自125909888237的来电
60秒后可重新获取
《新东方在线注册条款》  、  《隐私权保护政策》  及  《儿童隐私保护政策》
账号密码登录 找回密码
国际手机登录
《新东方在线注册条款》  、  《隐私权保护政策》  及  《儿童隐私保护政策》
手机快速登录 找回密码
Official 32 Task 4
上一题
下一题
精听文本
Listening
00:00
00:00
查看文本
Narrator: Listen to part of a lecture in an Environmental Science class.
Professor: Roads, paved roads are everywhere and sometimes seem like part of the natural landscape.
But of course, roads are not part of nature, and in fact,
road construction can have harmful effects on the environment,
and seriously impact both animal life and plant life.
One harmful environmental effect of roads,
is that they contribute to the movement of plant species from one area to another.
This causes problems for existing plants, plants already growing in that area.
Because when a new plant species gets introduced into an area where it wasn't growing before,
the new plants compete for resources with the existing plant life.
For example, this happened in California with a weed called the yellow starthistle.
What happened was the starthistle seeds got stuck to the tires of cars driving down the road,
and the seeds were distributed to new areas.
This put the starthistle in competition for natural resources, like water, with the original plant life of the area.
That made it harder for the native plants to survive.
Also roads, especially major highways, can act as barriers,
and divide up an animal's habitat into smaller ones,
where there's not enough food to support the population.
These busy highways, with cars speeding past day and night, act like boundaries that animals are afraid to cross,
act like boundaries that animals are afraid to cross.
So they sometimes get shut in on a small piece of land where there isn't enough food to support them.
This is a serious problem for animals that need access to large expanses of land to look for food.
For example, there are these foxes, called kit foxes, that live in the southwestern United States.
They hunt small animals like mice and squirrels,
which are spread out over large areas of open grasslands.
And now because of these roads,
the kit fox population has declined significantly because now they don't get enough food.
Question

Using the examples of the star thistle and the Kit fox, describe two ways roads can affect the environment.