Using points and e from the lecture, explain two ways that vegetation can help prevent soil erosion on hillsides.

Task6 : Integrated speaking
Professor (W): Soil erosion is when soil is blown away by wind or washed away by the rain. Soil erosion caused by rain can be very damaging, especially on hillsides, but if

there’s vegetation, if there’re plants growing on a hillside, there’s usually less soil erosion. Vegetation helps prevent hillside soil erosion. Let’s consider two ways vegetation helps prevent erosion of soil from hillsides.
One way is by reducing the force of falling raindrops, so that the raindrops fall more gently to the ground. If rain falls to the ground gently, the soil isn’t disturbed, and it stays in place, doesn’t wash away. That’s why trees are often planted on hillsides. The leaves act like little umbrellas. When the rain comes down, even if it comes down hard, a lot of the raindrops first hit the leaves and then the raindrops fall to the ground— more gently than they would have otherwise. So the soil is less disturbed and less likely to wash away down the hill in a heavy rain.
Another way that vegetation helps prevent soil erosion on hillsides is by keeping the ground absorbent, by helping the ground soak up rainwater so that the water goes down into the ground instead of washing the soil away. How does vegetation help the ground soak up rainwater? Well, soil has several layers and the top layer is made partly of decomposing organic material—dead leaves and such—that comes from the plants growing in the soil. This top layer of soil is very spongy. It soaks up water—just like a sponge. In a pine forest, for example, the trees shed their needles year round, and these pine needles are constantly being added to the soil and can build up a very thick top layer of spongy soil. So on a hillside with a pine forest growing it, rainwater will soak into the ground, into the soil, rather than flowing down the hill and washing the soil away.