focusing on the loss of species

cherishie

Looking beyond the 10-year period, the botanists（植物学家） estimate（估计） that some 3,000 native plant species may become extinct in the foreseeable future—more than 10 percent of the approximately 25,000 species of plants in the United States.

The situation is the same or worse in most other parts of the world. It is estimated that about 20 percent of Earth’s approximately 300,000 plant species are in danger. Most of these plants are in the tropical rainforests that are being cut down, and many have not even been identified yet.

Why is extinction threatening so many U.S. species? The main reason is the destruction of habitats（生活环境）. This destruction is caused, especially in the Eastern United States, by land development, such as the construction of shopping centers and housing tracts（住宅区）. In the Western states, the poor management of public lands has been a critical factor. There, many habitats have been destroyed by the spread of exotic（外来的） plant species. 1) For example, June grass, which was introduced from Europe in the late 1800s, has invaded hundreds of square kilometers of Western lands, pushing out some native species of grass that are less able to compete for the usually scarce moisture.

Public indifference has also contributed to the problem. 2) Americans have rallied to（集结，这里可理解为“关注”） the cause of endangered animals such as whooping cranes and African elephants, but they seem unconcerned about endangered plants. Perhaps they consider wild animals to be public property, but plants are the property of the owner of the land on which they grow.

The consequences of habitat destruction are often most serious in the tropics（热带） and subtropics（亚热带）. Those regions have a much greater number of plant species than are found in cooler climates. And many species grow in only a small area, increasing the probability of their being wiped out. It is not surprising, therefore, that nearly 75 percent of the 680 species on the most-endangered list are located in just three states and Puerto Rico. Hawaii has 21 percent; Texas, 12.2 percent; Florida, 10.6 percent; and Puerto Rico, 10.1 percent. But nearly all of the 50 states have at least a few native plants that are among those facing extinction.

   Saving endangered plants is important for several reasons. Among those plants, there may be some that produce substances that could be of value in making medicines. Others might possess genetic traits（基因特质） that could be used to improve crop plants. We might also find that some plants are worth growing for their own sake—as food or perhaps for the oil in their seeds. But beyond such practical applications, there is a sense of loss when any species—a plant as much as an animal—disappears from the face of the Earth forever.