【全國英語等級(jí)考試三級(jí)】Unit 3 環(huán)境—Monologue(2/2)

Another threat of forests is from invasive of species. These are non-native plants and animals that push out native kinds. They can cause a lot of economic damage. Some invaders are insects, some are diseases, and others are plants like the fast-growing kudzu vine. The agency says another threat to the health of wild lands is the loss of open space. It says over one hectare of forest or grass land is lost to development every minute. Development also leads to the division of large natural areas into smaller ones. The fourth threat to public lands is what the Forest Service calls unmanaged recreation. People can hunt, fish and camp in many national forest, but careless use of motor vehicles, and other actions can be destructive.