Listen to part of a lecture in an Environmental Science class.
(female 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, if 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 problem for existing plants, plants already growing in that area because when a new plant species gets into an area where it wasn’t growing before, the new plants compete for resources with existing plant life. For example, this happened in California with a weed called the yellow starthistle. What happened was the starthistle’s 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 is 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. 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 expanse 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."
Using the examples of the star thistle and the Kit fox, describe two ways roads can affect the environment.
There're mainly two harmful effects road construction has on our environment. The first one is that roads help some plants to move from one area to another. And the migrant plants then become a trouble for the existing plants in the area because the new-comers will compete with the local species for resources. A good example is the yellow star thistle in California. When there were cars driving down the road, the seeds of yellow star thistle got stuck in the tires and were then carried to new areas. They then competed with local species, which made it harder for local species to survive. Another is that the busy highways have become barriers for animals, and they divide up animals' habitat into smaller ones, where there usually isn't enough food to support the animal population. For example, the kit fox that feeds on mice and squirrels now get shut in smaller areas by highways and cannot get their food that is spread out over open grassland. As a result, its population has decreased. (173 words)
