of many forests that trees simply can't
regenerate.
Equally alarming is gamba grass, which is plaguing the savanna-woodlands of northern Australia. This tall African grass burns so fiercely that nearly every tree is killed. It's become so bad that Australian ecologist David Bowman recently suggested - only half in jest — that we should import African elephants to help control it.
Exotic diseases and pests are also a growing threat. Dutch elm disease is killing off millions of stately trees that once graced forests and cities. In North America, increasingly mild winters are favoring outbreaks of bark beetles, which can kill entire stands of trees. In rainforests, lianas - woody vines that parasitize trees and reduce their growth and survival - are increasing, possibly because their growth is being boosted by rising levels of carbon dioxide in the atmosphere.
How do paragraphs 6-8 contribute to the development of ideas in the passage?
• A. They describe various longtime threats to big trees.
• B. They describe various developing threats to big trees.
•C. They imply that logging is not a serious threat to big trees.
• D. They imply that understory plants are just as valuable as big trees.
1 answer
The correct answer is B. They describe various developing threats to big trees.
Paragraphs 6-8 outline different threats to big trees, focusing on exotic weeds, diseases, and pests that are increasingly affecting tree survival and regeneration. These threats highlight the evolving challenges faced by forests, which go beyond traditional factors such as logging.
