Questions 29 through 34.
Listen to part of a talk in a forestry class. The instructor is discussing forest fire.
We all know that change is a fact of life. For North American forests, change often comes in the form of fire. After thousands of years of living with fire, many plant and animal species have come to depend on its periodic presence. Without fire, ecosystems can stagnate and lose their diversity of life.
In the past, before we understood the role that fire plays in the natural life cycle of our forests, our goal was to prevent or contain all forest fires. For almost ninety years, our land management agencies tried to eliminate fires. In many cases, we protected the trees, but at the expense of the forest community. Now we know that fire is a natural agent thal rejuvenates a forest. And we know that fire suppression can actually threaten the lives of healthy trees. So, today our policy is to allow natural fires to burn under close observation and to set “prescribed” fires under carefully controlled conditions
Research shows that forests go through natural fire cycles. Periodic fires are necessary for several reasons. Fire removes nutrients from standing dead trees and returns them to the earth, where they become available to the root systems of new trees. Fire also opens the forest to sunlight. Openings in the tree cover benefit a variety of wildlife by stimulating the growth of lush green plants, which are eaten by several species of animals.
Fire is nature’s way of controlling insect infestations. By contrast, fire suppression preserves dead wood that harbors insect pests, like the larvae of the mountain pine beetle. These beetle larvae feed on the inner bark of some trees, which blocks the flow of nutrients and eventually kills the trees. When dead trees burn dunng periodic outbreaks of fire, the heat kills off great numbers of beetles and larvae, providing a natural method of pest control.
The exclusion of fire from the ecosystem is creating unhealthy, overcrowded forests that contain more fuel for larger, more severe fires. For example, when a huge fire threatened a grove of giant sequoias in California, observers noted that the flames were fed by dead wood and combustible debris that had accumulated on the forest floor over years of fire suppression.
A large scale, intense forest fire causes more significant impacts to water, soil, and air resources than a managed prescribed fire. Prescribed fire, or controlled fire, has several purposes. Chiefly, it reduces the hazard of more serious wildfires by periodically burning accumulated weeds, brush, and other plants. If done carefully, prescribed burning also releases nutrients back into the soil and controls insect pests.
In Florida, prescribed burns are carried out every three to five years in one of the national forests. These controlled bums keep the forest open and reduce the growth of problem species We recognize that fire is a natural and revitalizing process that enhances the diversity of the forest. However, we also know that fire has consequences. There may be smoky, hazy skies and patches of blackened forest for a long time after a fire. There’s also the risk of a fire becoming too large and threatening inhabited areas. But we have to accept these realities if our forests are to retain their ecological balance.
Questions 35 through 39.
Listen to a conversation in the learning resource center of a university.
M: Um … I heard that the learning resource center has some kind of class on how to get help with studying for a test.
W: Uh huh We do have special workshops, but we don’t really have any classes that deal with just test preparation. But we do have tutors for particular subject areas. What test are you studying for?
M: Uh … not any test in particular But I, uh. I’m taking some difficult courses this semester and I have a lot of reading to do. I just feel like. I need to bone up on my study skills, vou know, learn how to study better.
W: Uh huh.
M: I spend a lot of time studying but still have trouble organizing my notes and stuff. I was hoping I could get some help with that.
W: OK. You could lake one of our special workshops. There are several of these each week. The workshops in study skills and time management are especially popular. Would you be interested in doing something like that?
M: Yeah, I would.
W: OK, We have several workshops. All of them are two hours long. Most are held in the evening, but there’s a couple that are on the weekend.
M: Yeah. I see thal. Evenings would be good for me because I work on weekends. Um … so the classes are just two–hour workshops that just meet once? Or does a class continue every week?
W: They’re just one-time workshops. I mean, except for the class called Super Student. That one runs for three Wednesday nights, starting next week.
M: Super Student? 1 get it… it makes you like Superman.
W: Well, I don’t know about that!
M: So, um, how does this work? Do you have to register for these workshops?
W: Yes, but it’s only a matter of signing up. Do you see that board over there? The white board next to it, just to the right of the computers?
W: Well, there’s a sheet there for every workshop offered this semester, and that’s how you sign up. Some of the workshops are given more than once. You just write your name in any available space, under a particular date and time. When there are no more spaces left, that means the class is closed. We have to have a limit ’cause there’s only so much space in our classroom.
M: How much does a workshop cost?
W: There isn’t any cost. All of the workshops are free to students.
M: Hey, that’s not a bad deal. OK, thanks for the info. I guess I’ll see if there’s any workshop thal looks good.
W: I’ll be right here if you have any more questions.
M: OK. Thanks.